.. .fl
#include <sfio.h> libsfio.a -lsfio libstdio.a -lstdio libsfio-mt.a -lsfio-mt libstdio-mt.a -lstdio-mt.Ss "DATA TYPES"
Void_t; Sfoff_t; Sflong_t; Sfulong_t; Sfdouble_t; Sfio_t; Sfdisc_t; ssize_t (*Sfread_f)(Sfio_t*, Void_t*, size_t, Sfdisc_t*); ssize_t (*Sfwrite_f)(Sfio_t*, const Void_t*, size_t, Sfdisc_t*); Sfoff_t (*Sfseek_f)(Sfio_t*, Sfoff_t, int, Sfdisc_t*); int (*Sfexcept_f)(Sfio_t*, int, Void_t*, Sfdisc_t*); Sffmt_t; int (*Sffmtext_f)(Sfio_t*, Void_t*, Sffmt_t*); int (*Sffmtevent_f)(Sfio_t*, int, Void_t*, Sffmt_t*); SFIO_VERSION.Ss "BIT FLAGS"
SF_STRING SF_READ SF_WRITE SF_APPENDWR (SF_APPEND) SF_LINE SF_SHARE SF_PUBLIC SF_MALLOC SF_STATIC SF_IOCHECK SF_WHOLE SF_MTSAFE SF_IOINTR.Ss "OPENING/CLOSING STREAMS"
Sfio_t* sfnew(Sfio_t* f, Void_t* buf, size_t size, int fd, int flags); Sfio_t* sfopen(Sfio_t* f, const char* string, const char* mode); Sfio_t* sfpopen(Sfio_t* f, const char* cmd, const char* mode); Sfio_t* sftmp(size_t size); int sfclose(Sfio_t* f);.Ss "THREAD SAFETY"
int sfmutex(Sfio_t* f, int type); SFMTX_LOCK SFMTX_TRYLOCK SFMTX_UNLOCK SFMTX_CLRLOCK.Ss "INPUT/OUTPUT OPERATIONS"
int sfgetc(Sfio_t* f); int sfputc(Sfio_t* f, int c); int sfnputc(Sfio_t* f, int c, int n); int sfungetc(Sfio_t* f, int c); Sfulong_t sfgetm(Sfio_t* f, Sfulong_t max); int sfputm(Sfio_t* f, Sfulong_t v, Sfulong_t max); Sfulong_t sfgetu(Sfio_t* f); int sfputu(Sfio_t* f, Sfulong_t v); Sflong_t sfgetl(Sfio_t* f); int sfputl(Sfio_t* f, Sflong_t v); Sfdouble_t sfgetd(Sfio_t* f); int sfputd(Sfio_t* f, Sfdouble_t v); char* sfgetr(Sfio_t* f, int rsc, int type); ssize_t sfputr(Sfio_t* f, const char* s, int rsc); Sfoff_t sfmove(Sfio_t* fr, Sfio_t* fw, Sfoff_t n, int rsc); ssize_t sfread(Sfio_t* f, Void_t* buf, size_t n); ssize_t sfwrite(Sfio_t* f, const Void_t* buf, size_t n); Sfoff_t sfseek(Sfio_t* f, Sfoff_t offset, int type); Void_t* sfreserve(Sfio_t* f, ssize_t n, int type);.Ss "DATA FORMATTING"
int sfscanf(Sfio_t* f, const char* format, ...); int sfsscanf(const char* s, const char* format, ...); int sfvsscanf(const char* s, const char* format, va_list args); int sfvscanf(Sfio_t* f, const char* format, va_list args); int sfprintf(Sfio_t* f, const char* format, ...); char* sfprints(const char* format, ...); char* sfvprints(const char* format, va_list args); ssize_t sfaprints(char** sp, const char* format, ...); ssize_t sfvaprints(char** sp, const char* format, va_list args); int sfsprintf(char* s, int n, const char* format, ...); int sfvsprintf(char* s, int n, const char* format, va_list args); int sfvprintf(Sfio_t* f, const char* format, va_list args); Sffmt_t; SFFMT_LEFT SFFMT_SIGN SFFMT_BLANK SFFMT_ZERO SFFMT_THOUSAND SFFMT_LONG SFFMT_LLONG SFFMT_SHORT SFFMT_LDOUBLE SFFMT_IFLAG SFFMT_ALTER SFFMT_SKIP SFFMT_ARGPOS SFFMT_VALUE int (*Sffmtext_f)(Sfio_t* f, Void_t* v, Sffmt_t* fe); int (*Sffmtevent_f)(Sfio_t* f, int type, Void_t* v, Sffmt_t* fe); void va_copy(va_list to, va_list fr); long sffmtversion(Sffmt_t* fe, type);.Ss "BUFFERING, SYNCHRONIZATION"
Void_t* sfsetbuf(Sfio_t* f, Void_t* buf, size_t size); int sfsync(Sfio_t* f); int sfpoll(Sfio_t** flist, int n, int timeout); Sfio_t* sfpool(Sfio_t* f, Sfio_t* poolf, int mode); int sfpurge(Sfio_t* f);.Ss "DISCIPLINE, EVENT HANDLING"
Sfdisc_t* sfdisc(Sfio_t* f, Sfdisc_t* disc); int sfraise(Sfio_t* f, int type, Void_t* data); ssize_t sfrd(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc); ssize_t sfwr(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc); Sfoff_t sfsk(Sfio_t* f, Sfoff_t offset, int type, Sfdisc_t* disc); SF_NEW SF_READ SF_WRITE SF_SEEK SF_CLOSING (SF_CLOSE) SF_DPUSH SF_DPOP SF_DPOLL SF_DBUFFER SF_SYNC SF_PURGE SF_FINAL SF_READY SF_LOCKED SF_ATEXIT SF_EVENT.Ss "STREAM CONTROL"
int sfresize(Sfio_t* f, Sfoff_t size); int sfset(Sfio_t* f, int flags, int i); int sfsetfd(Sfio_t* f, int fd); Sfio_t* sfstack(Sfio_t* base, Sfio_t* top); Sfio_t* sfswap(Sfio_t* f1, Sfio_t* f2);.Ss "STREAM INFORMATION"
Sfoff_t sfsize(Sfio_t* f); Sfoff_t sftell(Sfio_t* f); ssize_t sfvalue(Sfio_t* f); int sffileno(Sfio_t* f); int sfstacked(Sfio_t* f); int sfeof(Sfio_t* f); int sferror(Sfio_t* f); int sfclrerr(Sfio_t* f); int sfclrlock(Sfio_t* f); int sfnotify(void (*notify)(Sfio_t* f, int type, Void_t* data)); int sfwalk(Sfwalk_f walkf, Void_t* data, int type);.Ss "MISCELLANEOUS FUNCTIONS"
ssize_t sfmaxr(ssize_t maxr, int s); ssize_t sfslen(); int sfulen(Sfulong_t v); int sfllen(Sflong_t v); int sfdlen(Sfdouble_t v); ssize_t sfpkrd(int fd, Void_t* buf, size_t n, int rsc, long tm, int action);.Ss "FULL STRUCTURE SFIO_T"
#include <sfio_t.h> #define SFNEW(buf,size,file,flags,disc).Ss "EXAMPLE DISCIPLINES"
#include <sfdisc.h> int sfdcdio(Sfio_t* f, size_t bufsize); int sfdcdos(Sfio_t* f); int sfdcfilter(Sfio_t* f, const char* cmd); int sfdcseekable(Sfio_t* f); int sfdcslow(Sfio_t* f); int sfdcsubstream(Sfio_t* f, Sfio_t* parent, Sfoff_t offset, Sfoff_t extent); int sfdctee(Sfio_t* f, Sfio_t* tee); int sfdcunion(Sfio_t* f, Sfio_t** array, int n); int sfdclzw(Sfio_t* f); int sfdcgzip(Sfio_t* f, int flags);.Ss "STDIO-COMPATIBILITY"
#include <stdio.h> cc ... -lstdio -lsfio cc ... -lstdio-mt -lsfio-mt
Sfio provides I/O functions to manage buffered streams. Each Sfio stream is a file stream, representing a file (see \f5open(2)), or a string stream, representing a memory segment. Beyond the usual I/O operations on streams, Sfio provides I/O disciplines for extended data processing, stream stacks for recursive stream processing, and stream pools for automatic data synchronization. Applications can extend the \f5sfprintf()/sfscanf() functions to define their own conversion patterns as well as redefine existing ones.
A discipline defines analogues of the system calls \f5read(2), write(2) and \f5lseek(2). Such system calls or their discipline replacements are used to process stream data. Henceforth, ``system call'' will refer to either a system call or its discipline replacement.
A system call is said to cause an exception if its return value is non-positive. Unless overridden by exception handlers (see \f5sfdisc()), an interrupted system call (\f5errno == EINTR on UNIX systems) will be automatically reinvoked to continue the ongoing operation.
The buffer of a stream is typically a memory segment allocated via \f5malloc(3) or supplied by the application. File streams may also use memory mapping (\f5mmap(2)) if that is more efficient. When memory mapping is used, the underlying file should not be truncated while the stream is active. Memory mapping can be turned off using \f5sfsetbuf().
There are three standard streams: \f5sfstdin for input (file descriptor \f50 on UNIX systems), \f5sfstdout for normal output (file descriptor \f51), and \f5sfstderr for error output (file descriptor \f52).
.Ss "LIBRARIES"
This version of Sfio can be built and used for both uni-threaded and multi-threaded environments. In the former case, streams are not protected from simultaneous accesses by different threads. In the latter case, a stream is typically locked with a mutex during access so that another thread trying to access the same stream will block until the mutex is released. A program that does not use multiple threads can link with libsfio.a while a program that uses multiple threads should link with libsfio-mt.a. The libraries libstdio.a and libstdio-mt.a provide corresponding Stdio functions to link with code already compiled using the native header stdio.h instead of the one provided by Sfio.
.Ss "DATA TYPES"
.Ss " Void_t*" This defines a type suitable to exchange data of unknown types between application and Sfio. \f5Void_t is a macro defined as \f5void for ANSI-C and C++ and \f5char for other compilation environments.
.Ss " Sfoff_t" This defines an integral type suitable to address the largest possible file extent.
.Ss " Sfulong_t, Sflong_t, Sfdouble_t" These are respectively the largest unsigned integer, signed integer, and floating point value types on the local platform.
.Ss " Sfio_t" This defines the type of a stream handle.
.Ss " Sfdisc_t" .Ss " ssize_t (*Sfread_f)(Sfio_t*, Void_t*, size_t, Sfdisc_t*)" .Ss " ssize_t (*Sfwrite_f)(Sfio_t*, const Void_t*, size_t, Sfdisc_t*)" .Ss " Sfoff_t (*Sfseek_f)(Sfio_t*, Sfoff_t, int, Sfdisc_t*)" .Ss " int (*Sfexcept_f)(Sfio_t*, int, Void_t*, Sfdisc_t*)" \f5Sfdisc_t defines a stream discipline structure. \f5Sfread_f, \f5Sfwrite_f and \f5Sfseek_f are the types of discipline functions to replace the system calls: \f5read(2), \f5write(2) and \f5lseek(2). \f5Sfexcept_f is the type of an event-handling function. See \f5sfdisc() for more details.
.Ss " Sffmt_t" .Ss " int (*Sffmtext_f)(Sfio_t*, Void_t*, Sffmt_t*)" .Ss " int (*Sffmtevent_f)(Sfio_t*, int, Void_t*, Sffmt_t*)" \f5Sffmt_t defines a formatting environment that can be used to extend scanning and printing in the \f5sfprint()/sfscanf() functions. \f5Sffmtext_f and \f5Sffmtevent_f define the types of extension functions definable in \f5Sffmt_t. See \f5Sffmt_t below for more details.
.Ss " SFIO_VERSION" This is a macro value of type \f5long int that defines the current version number of Sfio. For example, the Sfio2000's version number is \f520000515L (which also indicates its latest version date: 05/15/2000). .Ss "BIT FLAGS" A number of bit flags control stream operations. They are set either at stream initialization or by calling \f5sfset(). Following are the flags: .Tp \f5SF_STRING: The stream is memory-based. .Tp \f5SF_READ, \f5SF_WRITE, \f5SF_APPENDWR (\f5SF_APPEND): Flags \f5SF_READ and \f5SF_WRITE indicate readability and writability. Flag \f5SF_APPENDWR asserts that the stream is a file opened in append mode (see \f5open(2) and \f5fcntl(2)) so that data is always output at the end of file. On systems without direct support for append mode, Sfio uses \f5lseek(2) or its discipline replacement to approximate this behavior. .Tp \f5SF_LINE: The stream is line-oriented. For a \f5SF_WRITE stream, this means that buffered data is flushed whenever a new-line character, \f5\en, is output. For a \f5SF_READ stream, \f5SF_LINE is only significant during calls to functions in the \f5sfscanf() family. \f5SF_LINE is set on initialization of any stream representing a terminal device. .Tp \f5SF_SHARE, \f5SF_PUBLIC: Flag \f5SF_SHARE means that the underlying file descriptor is shared by independent entities (for example, multiple processes). For a seekable file stream, \f5SF_SHARE means that the logical stream and the physical file positions will be made the same before a system call to perform physical I/O. There are different possibilities. If \f5SF_PUBLIC is not set, the physical file position is made equal to the logical stream position. If \f5SF_PUBLIC is set, there are two cases. If the physical file position has changed from its last known position, the logical stream position is made equal to the new physical file position. Finally, if the physical file location remains the same as its last known position, the physical file position is made the same as the logical stream position. For an unseekable stream (e.g., pipes or terminal devices), if possible, \f5SF_SHARE means that the block and record I/O operations (\f5sfread(), \f5sfwrite(), \f5sfmove(), \f5sfgetr(), \f5sfputr(), \f5sfreserve(), \f5sfscanf() and \f5sfvprintf()) will ensure: (1) after each writing operation, the stream is synchronized and (2) each reading operation only reads the requested amount. Note, however, that (2) is not always possible without proper OS facilities such as \f5recv(2) or \f5streamio(4). A standard stream that is seekable will be initialized with \f5SF_SHARE|SF_PUBLIC. .Tp \f5SF_MALLOC: The stream buffer was obtained via \f5malloc(3) and can be reallocated or freed. .Tp \f5SF_STATIC: The stream structure should not be freed when closed (\f5sfclose()). This flag is used by an applications that allocate their own stream structures. Such applications must use the header file \f5sfio_t.h instead of \f5sfio.h. .Tp \f5SF_IOCHECK: If the stream has a discipline exception handler, exceptions will be raised in \f5sfsync(), \f5sfpurge() or before a system call \f5read(2) or \f5write(2) (see \f5sfdisc()). .Tp \f5SF_WHOLE: This flag guarantees that data written in any single \f5sfwrite() or \f5sfputr() call will always be output as a whole to the output device. This is useful in certain applications (e.g., networking) where a complex object must be output without being split in different system calls. Note that the respective stream still buffers data as much as the buffer can accomodate. .Tp \f5SF_MTSAFE: This flag indicates that the respective stream may be accessed by more than one threads. A mutex lock will be used to ensure that only one thread at a time can access the stream. Note that this flag can only be set at stream opening time (see \f5sfopen(), \f5sfpopen() and \f5sfnew()). Certain fast macro functions such as \f5sfgetc() and \f5sfputc() will no longer behave as macros. Thus, an application that requires such fast macro functions should leave \f5SF_MTSAFE off and performs explicit locking with \f5sfmutex(). .Tp \f5SF_IOINTR: This flag indicates that I/O system calls should not be resumed after being interrupted by signals. It is useful for aborting I/O operations on such interruptions. Note, however, than certain operating systems (e.g., BSD Unix systems) may automatically resume interrupted system calls outside the scope of the library. On such systems, \f5SF_IOINTR will be ineffective.
.Ss " Sfio_t* sfnew(Sfio_t* f, Void_t* buf, size_t size, int fd, int flags)" This function creates or renews a stream. It returns the new stream on success and \f5NULL on error. .Tp \f5f: If \f5f is \f5NULL, a new stream is created. Otherwise, \f5f is reused. In this case, if \f5flags does not have \f5SF_EOF, \f5f shall be closed via \f5sfclose() before being reused. During a stream renewal, buffer, pool and discipline stack are preserved. Note that, except for \f5SF_STATIC streams, renewing a stream already closed will result in undefined behavior. .Tp \f5buf, \f5size: These determine a buffering scheme. See \f5sfsetbuf() for more details. .Tp \f5fd: If \f5SF_STRING is specified in \f5flags, this is ignored. Otherwise, \f5fd is a file descriptor (e.g., from \f5open(2)) to use for raw data I/O. Note that Sfio supports unseekable file descriptors opened for both read and write, e.g., sockets. .Tp \f5flags: This is composed from \f5SF_EOF and bit values defined in the BIT FLAGS section. Note, in particular, that a multi-threaded application should set the bit \f5SF_MTSAFE to protect the new stream from being simultaneously accessed by multiple threads. .Ss " Sfio_t* sfopen(Sfio_t* f, const char* string, const char* mode)" If \f5string is \f5NULL, \f5f is a file stream and \f5mode does not imply a string stream, \f5sfopen() changes the modes of \f5f according to \f5mode. In this case, \f5sfopen() returns \f5f on success and \f5NULL on error. This somewhat unusual usage of \f5sfopen() is good for resetting certain predefined modes in standard streams including text/binary and append that are inherited from some parent process. Note also that \f5SF_READ and \f5SF_WRITE can only be reset if the stream is not yet initialized. \f5sfopen() is normally used to create a new stream or renew a stream. In this case, it returns the new stream on success and \f5NULL on error. Below are the meanings of the arguments: .Tp \f5f: This is treated as in \f5sfnew(). .Tp \f5string: This is a file name or a string to perform I/O on. See above for when this is \f5NULL. .Tp \f5mode: This is composed from the set of letters \f5{s, r, w, +, a, b, t, x, m, u}. When conflicting options are present in the same \f5mode string, the last one will take effect. \f5s specifies opening a string stream. \f5string can be a null-terminated string or \f5NULL. Specifying \f5s alone is equivalent to specifying \f5sr. If \f5s is not specified, \f5string defines a file name. \f5r and \f5w specify read and write modes. Write mode creates and/or truncates the given file to make an empty file. The \f5+ modifier indicates that the stream is opened for both read and write. \f5a specifies append mode, i.e., data is always output at end of file. \f5b and \f5t specify binary and text modes. \f5x specifies exclusive mode, i.e., a file opened for writing should not already exist. \f5m specifies that the stream needs to be protected from simultaneous accesses by multiple threads. This turns on the bit flag \f5SF_MTSAFE. \f5u specifies that the stream is guaranteed to be accessed by only one thread at a time. The bit flag \f5SF_MTSAFE is left off. The absence of option \f5m is the same as the presence of option \f5u. .Ss " Sfio_t* sfpopen(Sfio_t* f, const char* cmd, const char* mode)" This function opens a stream that corresponds to the coprocess \f5cmd. The argument \f5mode should be composed from \f5r, \f5w, and \f5+. The argument \f5f, if not \f5NULL, is a stream to be renewed (see \f5sfnew()). \f5sfpopen() returns the new stream or \f5NULL on error. The standard input/output of \f5cmd is connected to the application via a pipe if the stream is opened for writing/reading. If the stream is opened for both reading and writing, there will be two different associated file descriptors, one for each type of I/O (note the effect on \f5sffileno()). On opening a coprocess for writing (i.e., \f5mode contains \f5w or \f5+), the signal handler for \f5SIGPIPE in the parent application will be set to \f5SIG_IGN if it is \f5SIG_DFL at that time. This protects the parent application from being accidentally killed on writing to a coprocess that closes its reading end. Applications that need to detect such write errors should use disciplines and exception handlers (see \f5sfdisc()). The command \f5cmd is executed by an interpreter which is either \f5/bin/sh or an executable command defined by the environment variable \f5SHELL. In either case, the interpreter is invoked with 2 arguments, respectively \f5-c and the given command \f5cmd. When the interpreter is \f5/bin/sh or \f5/bin/ksh, \f5sfpopen() may execute the command \f5cmd itself if there are no shell meta-characters in \f5cmd. .Ss " Sfio_t* sftmp(size_t size)" This function creates a stream for temporary data. It returns the new stream or \f5NULL on error. A stream created by \f5sftmp() can be completely or partially memory-resident. If \f5size is \f5SF_UNBOUND, the stream is a pure string stream. If \f5size is zero, the stream is a pure file stream. Otherwise, the stream is first created as a string stream but when its buffer grows larger than \f5size or on any attempt to change disciplines, a temporary file is created. Two environment variables, \f5TMPPATH and \f5TMPDIR, direct where temporary files are created. \f5TMPPATH, if defined, specifies a colon-separated set of directories to be used in a round-robin fashion to create files. If \f5TMPPATH is undefined, \f5TMPDIR can be used to specify a single directory to create files. If neither of \f5TMPPATH and \f5TMPDIR are defined, \f5/tmp is used. .Ss " int sfclose(Sfio_t* f)" This function closes the stream \f5f and frees its resources. \f5SF_STATIC should be used if the stream space is to be preserved. If \f5f is the base of a stream stack (see \f5sfstack()), all streams on the stack are closed. If \f5f is a \f5sfpopen-stream, \f5sfclose() waits until the associated command terminates and returns its exit status. \f5sfclose() returns \f5-1 for failure and \f50 for success. \f5SF_READ|SF_SHARE and \f5SF_WRITE streams are synchronized before closing (see \f5sfsync()). If \f5f has disciplines, their exception handlers will be called twice. The first exception handler call has the \f5type argument as one of \f5SF_CLOSING or \f5SF_NEW (see \f5sfdisc().) The latter, \f5SF_NEW is used when a stream is being closed via \f5sfnew() so that it can be renewed. The second call uses \f5type as \f5SF_FINAL and is done after all closing operations have succeeded but before the stream itself is deallocated. In either case, if the exception handler returns a negative value, \f5sfclose() will immediately return this value. If the exception handler returns a positive value, \f5sfclose() will immediately return a zero value.
.Ss "THREAD SAFETY"
The libraries \f5libsfio.a and \f5libstdio.a (providing binary compatibility to Stdio-based code) only support uni-threaded code. Multi-threaded applications should link with \f5libsfio-mt.a and \f5libstdio-mt.a. When this is done, certain platforms may require additional thread libraries for linkage. For example, Linux, Irix and Solaris require \f5-lpthread while HPUX requires \f5-lcma. Aside from linkage differences, the Sfio API remains identical in all cases. Note that unlike Stdio streams which are in thread-safe mode by default. Sfio streams can be opened in either uni-threaded or multi-threaded mode. A uni-threaded stream is more efficient than a multi-threaded one. For example, functions such as \f5sfgetc() and \f5sfputc() remain as macro or inline functions for a uni-threaded stream while they will act as full function calls in a multi-threaded case. The three standard streams \f5sfstdin/sfstdout/sfstderr are in multi-threaded mode by default (however, see \f5sfopen() for how this may be changed). Other Sfio streams are normally opened uni-threaded unless the flag \f5SF_MTSAFE or the option \f5m were specified. Stdio-based code can also make a Stdio stream uni-threaded by using the option \f5u when opening a file.
.Ss "int sfmutex(Sfio_t* f, int type)" This function acquires or releases a mutex (mutually exclusive) lock on the stream \f5f. It can be used by a thread to serialize a sequence of I/O operations executed together in some critical section. \f5sfmutex() is implicitly used by all Sfio operations on a stream with the flag \f5SF_MTSAFE to protect it from concurrent accesses via multiple threads. \f5sfmutex() returns \f50 on success and some non-zero value on failure. Each stream has a lock count which starts at \f50. When the count is positive, a single thread holds the stream. Only this thread can further lock or unlock the stream. A different thread attempting to acquire such a locked stream will suspend until the lock count returns to \f50. Each successful locking operation increases the lock count while each successful unlocking operation decreases it, thus, allowing nesting of matching lock/unlock operations. The \f5type argument of \f5sfmutex() takes on the below values: .Tp \f5SFMTX_LOCK: Locking a stream if it is unlocked or increasing the lock count of the stream if it is already locked by the same thread. This call will block until it is possible to lock the stream. .Tp \f5SFMTX_TRYLOCK: This is the non-blocking version of \f5SFMTX_LOCK. If the stream is already locked by a different thread, \f5sfmutex() will immediately return with an error status. .Tp \f5SFMTX_UNLOCK: Decreasing the lock count and releasing the stream when the lock count reaches 0. An attempt to unlock a stream without a previously successful lock may result in undefined behavior in certain implementations. The current Sfio implementation returns an error status. .Tp \f5SFMTX_CLRLOCK: Resetting the lock count to \f50 and releasing the stream. As with \f5SFMTX_LOCK, an attempt to clear the lock count without a previously successful lock may result in undefined behavior.
.Ss " int sfgetc(Sfio_t* f)" .Ss " int sfputc(Sfio_t* f, int c)" These functions read/write a byte from/to stream \f5f. \f5sfgetc() returns the byte read or \f5-1 on error. \f5sfputc() returns \f5c on success and \f5-1 on error. .Ss " ssize_t sfnputc(Sfio_t* f, int c, size_t n)" This function attempts to write the byte \f5c to \f5f \f5n times. It returns the number of bytes actually written or \f5-1 on failure. .Ss " int sfungetc(Sfio_t* f, int c)" This function pushes the byte \f5c back into \f5f. If \f5c matches the byte immediately before the current position in buffered data, the current position is simply backed up (note the effect on \f5sftell() and \f5sfseek()). There is no theoretical limit on the number of bytes that can be pushed back into a stream. Pushed back bytes not part of buffered data will be discarded on any operation that implies buffer synchronization. \f5sfungetc() returns \f5c on success and \f5-1 on failure. .Ss " Sfulong_t sfgetm(Sfio_t* f, Sfulong_t max)" .Ss " int sfputm(Sfio_t* f, Sfulong_t v, Sfulong_t max)" These functions read and write \f5Sfulong_t values encoded in a portable format given that the values are at most \f5max. Portability across a write architecture and a read architecture requires that the bit order in a byte is the same on both architectures and the written value is storable in an \f5Sfulong_t on the read architecture. \f5sfgetm() returns the value read or \f5-1 on error. \f5sfputm() returns the number of bytes written or \f5-1 on error. .Ss " Sfulong_t sfgetu(Sfio_t* f)" .Ss " int sfputu(Sfio_t* f, Sfulong_t v)" These functions read and write \f5Sfulong_t values in a compact variable-length portable format. Portability across a write architecture and a read architecture requires that the bit order in a byte is the same on both architectures and the written value is storable in an \f5Sfulong_t on the read architecture. \f5sfgetu() returns the value read or \f5-1 on error. \f5sfputu() returns the number of bytes written or \f5-1 on error. See also \f5sfulen(). .Ss " Sflong_t sfgetl(Sfio_t* f)" .Ss " int sfputl(Sfio_t* f, Sflong_t v)" These functions are similar to \f5sfgetu() and \f5sfputu() but for reading and writing (signed) \f5Sflong_t values. See also \f5sfllen(). .Ss " Sfdouble_t sfgetd(Sfio_t* f)" .Ss " int sfputd(Sfio_t* f, Sfdouble_t v)" These functions read and write \f5Sfdouble_t values. In this case, portability depends on the input and output architectures having the same floating point value representation. Values are coded and decoded using \f5ldexp(3) and \f5frexp(3) so they are constrained to the sizes supported by these functions. See also \f5sfdlen(). .Ss " char* sfgetr(Sfio_t* f, int rsc, int type)" This function reads a record of data ending in the record separator \f5rsc. After \f5sfgetr() returns, the length of the record even if it is incomplete can be retrieved with \f5sfvalue(). \f5sfgetr() returns the record on success and \f5NULL on error. See also \f5sfmaxr() for limiting the amount of data read to construct a record. The \f5type argument is composed of some subset of the below bit flags: .Tp \f5SF_STRING: A null byte will replace the record separator to make the record into a C string. Otherwise, the record separator is left alone. .Tp \f5SF_LOCKR: Upon successfully obtaining a record \f5r, the stream will be locked from further access until it is released with a call \f5sfread(f,r,0). .Tp \f5SF_LASTR: This should be used only after a failed \f5sfgetr() to retrieve the last incomplete record. In this case, \f5rsc is ignored. .Ss " ssize_t sfputr(Sfio_t* f, const char* s, int rsc)" This function writes the null-terminated string \f5s to \f5f. If \f5rsc is non-negative, \f5(unsigned char)rsc is output after the string. \f5sfputr() returns the number of bytes written or \f5-1 on failure. .Ss " Sfoff_t sfmove(Sfio_t* fr, Sfio_t* fw, Sfoff_t n, int rsc)" This function moves objects from input stream \f5fr to output stream \f5fw. \f5sfmove() returns the number of objects moved or \f5-1 on failure. An object can be either a byte if the record separator argument \f5rsc is negative or a record of \f5rsc is non-negative. In the latter case, a record is incomplete if it does not end in \f5rsc. Generally speaking, a stream can have at most one incomplete record. If \f5n is negative, all complete objects of \f5fr will be moved. Otherwise, \f5n indicates the number of objects to move. If either \f5fr or \f5fw is \f5NULL, it acts as if it is a stream corresponding to \f5/dev/null, the UNIX device that has no read data and throws away any write data. For example, the call \f5sfmove(f,(Sfio_t*)0,(Sfoff_t)(-1),'\en') counts the number of complete lines in stream \f5f. .Ss " ssize_t sfread(Sfio_t* f, Void_t* buf, size_t n)" This function reads up to \f5n bytes from \f5f into buffer \f5buf. It returns the number of bytes actually read or \f5-1 on error. .Ss " ssize_t sfwrite(Sfio_t* f, const Void_t* buf, size_t n)" This function writes \f5n bytes from \f5buf to \f5f. If \f5f is \f5SF_STRING, and the buffer is not large enough, an \f5SF_WRITE exception shall be raised. \f5sfwrite() returns the number of bytes written or \f5-1 on failure. .Ss " Sfoff_t sfseek(Sfio_t* f, Sfoff_t offset, int type)" This function sets a new I/O position for \f5f. It returns the new position or \f5-1 on failure. If the stream is a \f5SF_STRING stream and the new address is beyond the current buffer extent, an \f5SF_SEEK exception will be raised (see \f5sfdisc()). The new position is determined based on \f5offset and \f5type which is composed from the bit flags: .Tp \f50 or \f5SEEK_SET: \f5offset is the desired position. .Tp \f51 or \f5SEEK_CUR: \f5offset is relative to the current position (see \f5SF_PUBLIC below). .Tp \f52 or \f5SEEK_END: \f5offset is relative to the physical end of file. .Tp \f5SF_SHARE: The stream is treated as if it has the control bit \f5SF_SHARE on. This implies that a system call seek will be done to ensure that the location seeking to is valid. .Tp \f5SF_PUBLIC: The stream is treated as if it has the control bit \f5SF_PUBLIC on. If the physical file position has changed from its last known location, the current position is taken as the new physical position. Otherwise, the current position is the logical stream position. .Ss " Void_t* sfreserve(Sfio_t* f, ssize_t n, int type)" This function reserves a data block from the stream \f5f. It returns the reserved data block on success and \f5NULL on failure. If \f5f is a \f5SF_READ stream, the data block is a segment of input data. If \f5f is a \f5SF_WRITE stream, the data block is a buffer suitable for writing output data. For consistency, if \f5f is opened with \f5SF_READ|SF_WRITE, it will normally be treated as if it is a \f5SF_READ stream (see \f5sfset() for forcing a particular mode) but the returned buffer can also be written into (more below). However, it is possible to bias to \f5SF_WRITE when the \f5type argument is non-negative by adding the \f5SF_WRITE bit \f5type. In any case, a reserved data block is guaranteed to be valid only until a future access to the stream \f5f. When \f5f is \f5SF_READ, \f5SF_SHARE and unseekable, \f5sfreserve() will attempt to peek at input data without consuming it. This enables separate processes to share in reading input from unseekable file descriptors (e.g., pipes or devices). However, this use of \f5sfreserve() may fail on certain platforms that do not properly support peeking on unseekable file descriptors. After a \f5sfreserve() call, whether or not it succeeds, \f5sfvalue(f) gives the size of the available data block. Any partially reserved data block after a failed \f5sfreserve() call can be obtained in another \f5sfreserve() call with the argument \f5type being \f5SF_LASTR. The second argument \f5n to \f5sfreserve() will be ignored in this case. A \f5sfreserve() call is successful if it can obtain a data block of size at least the absolute value of \f5n. For a \f5SF_READ atream, the argument \f5n is treated as follows: .Tp \f5n < 0: \f5sfreserve() attempts to get at least \f5|n| bytes into the buffer. .Tp \f5n == 0: If the argument \f5type is \f50, \f5sfreserve() attempts to get at least \f51 byte into the buffer but does not consume it (as consistent with \f5n == 0). If \f5type != 0, no attempt will be made to read data into the buffer. For example, the call \f5sfreserve(f, 0, -1) only returns the buffer status, i.e., size of existing buffered data and pointer to such data, if any. The call \f5sfreserve(f, 0, SF_LOCKR) is similar but also locks the stream. .Tp \f5n > 0: \f5sfreserve() will use attempt to get at most \f5n bytes into the buffer. Further, if \f5type == \f5SF_LOCKR (see below), read attempts end on a positive amount. For a successful reservation, the argument \f5type dictates treatment as follows: .Tp \f5type == SF_LASTR: After a \f5sfreserve() call with \f5type != SF_LOCKR fails, there may be some left over data not accessible via conventional Sfio calls. Immediately after such a failed call, another call to \f5sfreserve with \f5type == SF_LASTR will return any left over data and also advance the stream I/O position by the amount of returned data. .Tp \f5type < 0: If \f5n > 0, the stream I/O position is advanced by \f5n. If \f5n < 0, the stream I/O position is advanced by the amount of available data. For example, a successful \f5sfreserve(f, -1, -1) call will return a buffer of data and simultanously advance the stream I/O position by the amount indicated by \f5sfvalue(f). .Tp \f5type == SF_LOCKR: The stream I/O position remains unchanged. In addition, \f5f will be locked from further access. As appropriate to the stream type (\f5SF_READ, \f5SF_WRITE or both), \f5f can be unlocked later with one of \f5sfread(f,rsrv,size) or \f5sfwrite(f,rsrv,size) where \f5rsrv is the reserved data block and \f5size is the amount of data to be consumed. For example, if \f5f is a locked \f5SF_READ stream, the call \f5sfread(f,rsrv,1) will reopen the stream and simultaneously advance the stream I/O position by \f51. Finally, a stream opened for both reading and writing can release the lock with either call (with associated operational semantics!) For example, the below code reads 10 bytes of data from a stream opened with both \f5SF_READ and \f5SF_WRITE, modifies the data in place, then rewrites the new data back to the stream:
rsrv = sfreserve(f, 10, 1); for(i = 0; i < 10; ++i) rsrv[i] = toupper(rsrv[i]); sfwrite(f, rsrv, 10);
.Ss "DATA FORMATTING"
Data printing and scanning are done via the \f5sfprintf() and \f5sfscanf() family of functions. These functions are similar to their ANSI-C \f5fprintf() and \f5fscanf() counterparts. However, the Sfio versions have been extended for both portability and generality. In particular, a notion of a formatting environment stack is introduced. Each formatting element on the stack defines a separate formatting pair of a format specification string, \f5char* format (the usual second argument in the formatting functions), and an argument list, \f5va_list args (the third argument in functions \f5sfvprintf() and \f5sfvscanf()). A formatting environment element may also specify extension functions to obtain or assign arguments and to provide new semantics for pattern processing. To simplify the description below, whenever we talk about an argument list, unless noted otherwise, it is understood that this means either the true argument list when there is no extension function or the action to be taken by such a function in processing arguments. The manipulation of the formatting environment stack is done via the pattern \f5! discussed below. .Ss "%! and Sffmt_t" The pattern \f5%! manipulates the formatting environment stack to (1) change the top environment to a new environment, (2) stack a new environment on top of the current top, or (3) pop the top environment. The bottom of the environment stack always contains a virtual environment with the original formatting pair and without any extension functions. The top environment of a stack, say \f5fe, is automatically popped whenever its format string is completely processed. In this case, its event-handling function (if any) is called as \f5(*eventf)(f,SF_FINAL,NIL(Void_t*),fe). The top environment can also be popped by giving an argument \f5NULL to \f5%! or by returning a negative value in an extension function. In these cases, the event-handling function is called as \f5(*eventf)(f,SF_DPOP,form,fe) where \f5form is the remainder of the format string. A negative return value from the event handling function will prevent the environment from being popped. A formatting environment is a structure of type \f5Sffmt_t which contains the following elements:
Sffmtext_f extf; /* extension processor */ Sffmtevent_f eventf; /* event handler */ char* form; /* format string to stack */ va_list args; /* corresponding arg list */ int fmt; /* pattern being processed */ ssize_t size; /* object size */ int flags; /* formatting control flags */ int width; /* width of field */ int precis; /* precision required */ int base; /* conversion base */ char* t_str; /* extfdata string */ int n_str; /* length of t_str */The first four elements of \f5Sffmt_t must be defined by the application before the structure is passed to a formatting function. The two function fields should not be changed during processing. Other elements of \f5Sffmt_t are set by the respective formatting function before it calls the extension function \f5Sffmt_t.extf and, subsequently, can be modified by this function to redirect formatting or scanning. For example, consider a call from a \f5sfprintf() function to process an unknown pattern \f5%t (which we may take to mean ``time'') based on a formatting environment \f5fe. \f5fe->extf may reset \f5fe->fmt to `\f5d' upon returing to cause \f5sfprintf() to process the value being formatted as an integer. Below are the fields of \f5Sffmt_t: .Tp \f5extf: \f5extf is a function to extend scanning and formatting patterns. Its usage is discussed below. .Tp \f5eventf: This is a function to process events as discussed earlier. .Tp \f5form and \f5args: This is the formatting pair of a specification string and corresponding argument list. When an environment \f5fe is being inserted into the stack, if \f5fe->form is \f5NULL, the top environment is changed to \f5fe and its associated extension functions but processing of the current formatting pair continues. On the other hand, if \f5fe->form is not \f5NULL, the new environment is pushed onto the stack so that pattern processing will start with the new formatting pair as well as any associated extension functions. During processing, whenever \f5extf is called, \f5form and \f5args will be set to the current values of the formatting pair in use. .Tp \f5fmt: This is set to the pattern being processed or one of '.', 'I', '('. .Tp \f5size: This is the size of the object being processed. .Tp \f5flags: This is a collection of bits defining the formatting flags specified for the pattern. The bits are: \f5SFFMT_LEFT: Flag \f5- in \f5sfprintf(). \f5SFFMT_SIGN: Flag \f5+ in \f5sfprintf(). \f5SFFMT_BLANK: Flag space in \f5sfprintf(). \f5SFFMT_ZERO: Flag \f50 in \f5sfprintf(). \f5SFFMT_THOUSAND: Flag \f5' in \f5sfprintf(). \f5SFFMT_LONG: Flag \f5l in \f5sfprintf() and \f5sfscanf(). \f5SFFMT_LLONG: Flag \f5ll in \f5sfprintf() and \f5sfscanf(). \f5SFFMT_SHORT: Flag \f5h in \f5sfprintf() and \f5sfscanf(). \f5SFFMT_LDOUBLE: Flag \f5L in \f5sfprintf() and \f5sfscanf(). \f5SFFMT_IFLAG: flag \f5I in \f5sfprintf() and \f5sfscanf(). \f5SFFMT_ALTER: Flag \f5# in \f5sfprintf() and \f5sfscanf(). \f5SFFMT_SKIP: Flag \f5* in \f5sfscanf(). \f5SFFMT_ARGPOS: This indicates argument processing for \f5pos$. \f5SFFMT_VALUE: This is set by \f5fe->extf to indicate that it is returning a value to be formatted or the address of an object to be assigned. .Tp \f5width: This is the field width. .Tp \f5precis: This is the precision. .Tp \f5base: This is the conversion base. .Tp \f5t_str and \f5n_str: This is the type string and its size. .Ss " int (*Sffmtext_f)(Sfio_t* f, Void_t* v, Sffmt_t* fe)" This is the type of the extension function \f5fe->extf to process patterns and arguments. Arguments are always processed in order and \f5fe->extf is called exactly once per argument. Note that, when \f5pos$ (below) is not used anywhere in a format string, each argument is used exactly once per a corresponding pattern. In that case, \f5fe->extf is called as soon as the pattern is recognized and before any scanning or formatting. On the other hand, when \f5pos$ is used in a format string, an argument may be used multiple times. In this case, all arguments shall be processed in order by calling \f5fe->extf exactly once per argument before any pattern processing. This case is signified by the flag \f5SFFMT_ARGPOS in \f5fe->flags. In addition to the predefined formatting patterns and other application-defined patterns, \f5fe->extf may be called with \f5fe->fmt being one of `\f5(' (left parenthesis), `\f5.' (dot), and `\f5I'. The left parenthesis requests a string to be used as the \f5extfdata string discussed below. In this case, upon returning, \f5fe->extf should set the \f5fe->size field to be the length of the string or a negative value to indicate a null-terminated string. The `\f5I' requests an integer to define the object size. The dot requests an integer for width, precision, base, or a separator. In this case, the \f5fe->size field will indicate how many dots have appeared in the pattern specification. Note that, if the actual conversion pattern is 'c' or 's', the value \f5*form will be one of these characters. .Tp \f5f: This is the input/output stream in the calling formatting function. During a call to \f5fe->extf, the stream shall be unlocked so that \f5fe->extf can read from or write to it as appropriate. .Tp \f5v: For both \f5sfscanf() and \f5sfprintf() functions, \f5v points to a location suitable for storing any scalars or pointers. On return, \f5fe->extf treats \f5v as discussed below. .Tp \f5fe: This is the current formatting environment.
The return value \f5rv of \f5fe->extf directs further processing. There are two cases. When \f5pos$ is present, a negative return value means to ignore \f5fe in further argument processing while a non-negative return value is treated as the case \f5rv == 0 below. When \f5pos$ is not present, \f5fe->extf is called per argument immediately before pattern processing and its return values are treated as below: .Tp \f5rv < 0: The environment stack is immediately popped. .Tp \f5rv == 0: The extension function has not consumed (in a scanning case) or output (in a printing case) data out of or into the given stream \f5f. The fields \f5fmt, \f5flags, \f5size, \f5width, \f5precis and \f5base of \f5fe shall direct further processing. For \f5sfprintf() functions, if \f5fe->flags has the bit \f5SFFMT_VALUE, \f5fe->extf should have set \f5*v to the value to be processed; otherwise, a value should be obtained from the argument list. Likewise, for \f5sfscanf() functions, \f5SFFMT_VALUE means that \f5*v should have a suitable address; otherwise, an address to assign value should be obtained from the argument list. When \f5pos$ is present, if \f5fe->extf changes \f5fe->fmt, this pattern shall be used regardless of the pattern defined in the format string. On the other hand, if \f5fe->fmt is unchanged by \f5fe->extf, the pattern in the format string is used. In any case, the effective pattern should be one of the standardly defined pattern. Otherwise, it shall be treated as unmatched. .Tp \f5rv > 0: The extension function has accessed the stream \f5f to the extent of \f5rv bytes. Processing of the current pattern ceases except that, for scanning functions, if \f5fe->flags does not contain the bit \f5SFFMT_SKIP, the assignment count shall increase by 1. .Ss "void va_copy(va_list to, va_list fr)" This macro function portably copies the argument list \f5fr to the argument list \f5to. It should be used to set the field \f5Sffmt_t.args. .Ss "long sffmtversion(Sffmt_t* fe, int type)" This macro function initializes the formatting environment \f5fe with a version number if \f5type is non-zero. Otherwise, it returns the current value of the version number of \f5fe. This is useful for applications to find out when the format of the structure \f5Sffmt_t changes. Note that the version number corresponds to the Sfio version number which is defined in the macro value \f5SFIO_VERSION. .Ss " int sfprintf(Sfio_t* f, const char* format, ...);" .Ss " char* sfprints(const char* format, ...);" .Ss " char* sfvprints(const char* format, va_list args);" .Ss " ssize_t sfaprints(char** sp, const char* format, ...);" .Ss " ssize_t sfvaprints(char** sp, const char* format, va_list args);" .Ss " int sfsprintf(char* s, int n, const char* format, ...)" .Ss " int sfvsprintf(char* s, int n, const char* format, va_list args);" .Ss " int sfvprintf(Sfio_t* f, const char* format, va_list args);" These functions format output data. \f5sfprintf() and \f5sfvprintf() write to output stream \f5f. \f5sfsprintf() and \f5sfvsprintf() write to buffer \f5s which is of size \f5n. \f5sfprints() and \f5sfvprints() construct data in some Sfio-defined buffer. \f5sfaprints() and \f5sfvaprints() are similar to \f5sfprints() and \f5sfvprints() but they return a string constructed via \f5malloc() in \f5*sp and expect this string to be freed by the caller when no longer needed. \f5sfvprintf() is the underlying primitive for the other functions. Except for \f5sfprints() and \f5sfvprints() which return a null-terminated string or \f5NULL, other functions return the number of output bytes or \f5-1 on failure. The length of string constructed by \f5sfprints(), \f5sfsprintf(), or \f5sfvsprintf() can be retrieved by \f5sfslen().
The standard patterns are: \f5n, s, c, %, h, i, d, p, u, o, x, X, g, G, e, E, f and \f5!. Except for \f5! which shall be described below, see the ANSI-C specification of \f5fprintf(3) for details on the other patterns. Let \f5z be some pattern type. A formatting pattern is defined as below:
%[pos$][flag][width][.precision[.base]][(extfdata)]z.Tp \f5pos$: A pattern can specify which argument in the argument list to use. This is done via \f5pos$ where \f5pos is the argument position. Arguments are numbered so that the first argument after \f5format is at position 1. If \f5pos is not specified, the argument following the most recently used one will be used. The pattern \f5%! (see below) cannot be used subsequent to a usage of \f5pos$. Doing so may cause unexpected behaviors. .Tp \f5flag: The flag characters are \f5h, \f5hh, \f5l, \f5ll, \f5L, \f5I, \f5j, \f5t, \f5z, \f5-, \f5+, space, \f50, \f5' and \f5#. Flag \f5I defines the size or type of the object being formatted. There are two cases: (1) \f5I by itself and (2) \f5I followed by either a decimal number or `*'. In the first case, for integer and floating point patterns, the object type is taken to be the largest appropriate type (i.e., one of \f5Sflong_t, \f5Sfulong_t or \f5Sfdouble_t). For conversion specifiers \f5s and \f5c, the flag is ignored. In the second case, a given decimal value would define a size while `*' would cause the size to be obtained from the argument list. Then, if the conversion specifier is \f5s, this size defines the length of the string or strings being formatted (see the discussion of \f5base below). For integer and floating point patterns, the size is used to select a type from one of the below lists as indicated by the conversion specifier:
Sflong_t, long, int, short Sfulong_t, unsigned long, unsigned int, unsigned short Sfdouble_t, double, floatThe selection algorithm always matches types from left to right in any given list. Although selection is generally based on sizes in bytes, for compatibility with Microsoft-C, the size 64 is matched with an appropriate type with the same number of bits, if any. If the given size does not match any of the listed types, it shall match one of \f5int, \f5unsigned int, and \f5double as defined by the formatting pattern. Below are a few examples of using the \f5I flag. The first example prints an \f5Sflong_t integer. This example is actually not portable and only works on platforms where \f5sizeof(Sflong_t) is 8. The second example shows how to that portably. The third example specifies printing a string of length 16. This length shall be used regardless of whether or not the given string is shorter or longer than 16. The last example shows the use of the pattern \f5%n to assign the amount of data already output into a \f5short integer \f5n_output.
sfprintf(sfstdout,"%I8d", Sflong_obj); sfprintf(sfstdout,"%I*d", sizeof(Sflong_obj), Sflong_obj); sfprintf(sfstdout,"%I*s", 16, s); sfprintf(sfstdout,"%d%I*n", 1001, sizeof(short), &n_output);Flags \f5h, \f5l, and \f5L are the ANSI-C conventions to select the types of input objects. For example, \f5%hd indicates a \f5short int while \f5%ld indicates a \f5long int. Flag \f5hh addresses the byte value types, i.e., \f5char and \f5unsigned char. Flags \f5z, \f5t and \f5j address respectively the types \f5size_t, \f5ptrdiff_t and \f5Sflong_t. Flags \f5ll and \f5L address respectively the largest integer and floating value types, i.e., \f5Sfulong_t, \f5Sflong_t, and \f5Sfdouble_t. Flag \f5- left-justifies data within the field (otherwise, right-justification). Flag \f5+ means that a signed conversion will always begin with a plus or minus sign. Flag space is ignored if \f5+ is specified; otherwise, it means that if the first character of a signed conversion is not a sign or if the result is empty, a space will be prepended. Flag \f50 means padding with zeros on the left. Flag \f5' outputs thousands-separator used by the current locale. \f5setlocale(3) should have been used to set the desired locale. Flag \f5# indicates an alternative format processing. For \f5%o, the first digit is always a zero. For \f5%x and \f5%X, a non-zero result will have a prefix \f50x or \f50X. For \f5%e, \f5%E, \f5%f, \f5%g, and \f5%G, the result always contains a decimal point. For \f5%g and \f5%G, trailing zeros will not be removed. For \f5%d, \f5%i and \f5%u, the form is base#number where base is the conversion base and number is represented by digits for this base. For example, a base \f52 conversion with \f5%#..2d for \f510 is \f52#1010 instead of \f51010 as printed with \f5%..2d. Finally, for \f5%c, bytes will be printed in the C format. For example, when the ASCII character set is used, the byte value 10 will be printed as \f5\\n while 255 is printed as \f5\\377. .Tp \f5width: This defines the width of the printing field. A value to be printed will be justified and padded if necessary to fill out the field width. .Tp \f5precis: After a first dot appears, an integral value defines a precision. For floating point value patterns, precision is the number of precision digits. For \f5%c, precision defines the number of times to repeat the character being formatted. For \f5%s, precision defines the maximum number of characters to output. .Tp \f5base: This is defined after exactly two dots have appeared. For \f5%i, \f5%d, and \f5%u, \f5base should be an integer value in the inclusive range \f5[2,64] and defines a conversion base. If \f5base is not in this range, it is defined to be \f510. The digits to represent numbers are:
01234567890 abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ @_For \f5%s and \f5%c, \f5base defines a separator. Then, for \f5%s, the input argument is taken to be a NULL-terminated array of strings while, for \f5%c, this is a null-terminated array of characters. The strings or characters will be formatted one of a time based on the usual width and precision rules. After each formatted string or character, except for the last one, the separator \f5base is output if it is a non-zero. There are further restrictions on the syntax of \f5%s and \f5%c when a separator is defined. Below are the legitimate sequences for \f5%s and \f5%c after the second dot:
\f5 s c \f5 *s *c \f5 z\f5s z\f5cIn the first case, no separator is defined so \f5base is set to zero. In the second case, \f5base is obtained from the argument list. In the third case, the character z must be non-alphanumeric and \f5base will be set to this character. The below example shows both the call and the result of printing a \f5NULL-terminated array of three strings \f5apple, \f5orange, and \f5grape:
sfprintf(sfstdout,"|%8..:s|",list); | apple: orange: grape|.Tp \f5(extfdata): This defines a string \f5extfdata to be passed to the extension function \f5Sffmt_t.extf. Parentheses shall be balanced. If \f5extfdata is \f5*, the string is obtained from the argument list.
.Ss " int sfscanf(Sfio_t* f, const char* format, ...)" .Ss " int sfsscanf(const char* s, const char* format, ...)" .Ss " int sfvsscanf(const char* s, const char* format, va_list args)" .Ss " int sfvscanf(Sfio_t* f, const char* format, va_list args)" These functions scan data items. \f5sfscanf() scans from the input stream \f5f while \f5sfsscanf() and \f5sfvsscanf() scan from the null-terminated string \f5s. \f5sfvscanf() is the underlying primitive that performs the actual scanning. Item types are determined from patterns in string \f5format. These functions return the number of items successfully scanned or \f5-1 on error.
A white space character (blank, tab, or new-line) in \f5format normally matches a maximal sequence of input white space characters. However, if the input stream is in \f5SF_LINE mode (see \f5sfset()), a new-line character only matches white spaces up to an input new-line character. This is useful to avoid blocking when scanning typed inputs.
The standard scan patterns are: \f5i, d, u, o, x, X, p, n, f, e, E, g, G, c, %, s, [] and \f5!. Except for \f5! which shall be described below, see the ANSI-C specification of \f5fscanf(3) for details on other patterns. Let \f5z be some pattern type. A formatting pattern is specified as below:
%[*][pos$][width][.width.base][(extfdata)][flag]z.Tp \f5pos$: A pattern can specify which argument in the argument list to use. This is done via \f5pos$ where \f5pos is the argument position. Arguments are numbered so that the first argument after \f5format is at position 1. If \f5pos is not specified, the argument following the most recently used one will be used. The pattern \f5%! (see below) cannot be used subsequent to a usage of \f5pos$. .Tp \f5*: This discards the corresponding scanned item. .Tp \f5width and \f5base: \f5width defines the maximum number of bytes to scan and \f5base defines the base of an integral value being scanned. The `.' (dot) notation also allows specifying a `*' (star) to obtain the value from the argument list. The below example specifies scanning 4 bytes to obtain the value of an integer in base 10. At the end of scanning, the variable \f5v should have the value \f51234.
sfsscanf("12345678","%.*.*d", 4, 10, &v);
.Tp
\f5(extfdata):
This defines a string \f5extfdata
to be passed to the extension function \f5Sffmt_t.extf.
Parentheses shall be balanced.
If \f5extfdata is \f5*, the string is obtained from the argument list.
.Tp
\f5flag:
This is \f5#, \f5I, or some sequence of \f5h, \f5l, and \f5L.
Flag \f5# is significant for pattern \f5%i and \f5%[.
For \f5%i, it means that the \f5# symbol does not have its usual
meaning in an input sequence \f5base#value.
For example, the scanning result of \f5%#i on input \f52#1001 is \f52
and the next \f5sfgetc() call will return \f5#.
For \f5%[, if the next character in the input stream does not match
the given scan set of characters, \f5# causes a match to a null string
instead of a failure.
Flag \f5I defines the size or type of the object being formatted.
There are two cases: (1) \f5I by itself and (2) \f5I
followed by either a decimal number or `*'.
In the first case, for integer and floating point patterns,
the object type is taken to be the largest appropriate type
(i.e., one of \f5Sflong_t, \f5Sfulong_t or \f5Sfdouble_t).
For string patterns such as \f5%s, the flag is ignored.
In the second case, a given decimal value would define a size while
`*' would cause the size to be obtained from the argument list.
For string patterns such as \f5%s or \f5%[, this size defines the
length of the buffer to store scanned data.
Specifying a buffer size only limits the amount of data copied into the buffer.
Scanned data beyond the buffer limit will be discarded.
For integer and floating point patterns,
the size is used to select a type from one of the below lists as
indicated by the conversion specifier:
Sflong_t, long, int, short Sfulong_t, unsigned long, unsigned int, unsigned short Sfdouble_t, double, floatThe selection algorithm always matches types from left to right in any given list. Although selection is generally based on sizes in bytes, for compatibility with Microsoft-C, the size 64 is matched with an appropriate type with the same number of bits, if any. If the given size does not match any of the listed types, it shall match one of \f5int, \f5unsigned int, and \f5double as indicated by the formatting pattern. Below are examples of using the \f5I flag. The first example scans a 64-bit integer. The second scans some floating point value whose size is explicitly computed and given. The last example scans a string into a buffer with the given size 128. Note that if the scanned string is longer than 127, only the first 127 bytes shall be copied into the buffer. The rest of the scanned data shall be discarded.
sfscanf(sfstdin,"%I64d", &int64_obj); sfscanf(sfstdin,"%I*f", sizeof(float_obj), &float_obj); sfscanf(sfstdin,"%I*s", 128, buffer);Flags \f5h, \f5l, and \f5L are the ANSI-C conventions for indicating the type of a scanned element. For example, \f5%hd means scanning a \f5short int. The flags \f5ll and \f5L mean respectively scanning an integer or a floating point value with largest size (i.e, \f5Sflong_t or \f5Sfdouble_t).
The \f5%i, \f5%d and \f5%u patterns scan numbers in bases from \f52 to \f564. \f5%i scans integral values in self-describing formats. Except for octal, decimal and hexadecimal numbers with the usual formats, numbers in general bases are assumed to be of the form: base#value where base is a number in base 10 and value is a number in the given base. For example, \f52#1001 is the binary representation of the decimal value \f59. If base is \f536 or less, the digits for value can be any combination of \f5[0-9], [a-z], [A-Z] where upper and lower case digits are not distinguishable. If base is larger than \f536, the set of digits is:
0123456789 abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ @_
.Ss "BUFFERING, SYNCHRONIZATION"
.Ss " Void_t* sfsetbuf(Sfio_t* f, Void_t* buf, size_t size)" This function changes the buffering scheme for the stream \f5f. The stream will be synchronized before any buffer modification. If a new buffer is successfully set and the old buffer has not been freed, \f5sfsetbuf() returns the old buffer. Otherwise, it returns \f5NULL. After a \f5sfsetbuf() call, \f5sfvalue() returns the size of the returned buffer. Sfio attempts to read data in blocks likely to be serviced fast by the file system. This means block sizes being multiples of a suitable alignment value (e.g., 512, 1024 or 8192). By default, the alignment value is computed via some internal mechanism depending on the local platform but it can also be explicitly set via the call \f5sfsetbuf(f, (Void_t*)f, size). In invocations of \f5sfsetbuf() other than the above case, the \f5size argument is treated as follows: .Tp \f5size == SF_UNBOUND: Sfio will pick a suitable buffer size. If \f5buf is \f5NULL, Sfio will also pick a suitable buffering scheme (such as memory mapping.) If \f5buf is not \f5NULL, its actual value is ignored but the buffer will be allocated via \f5malloc(3). This can be used to avoid memory mapping. .Tp \f5size > 0: This is the suggested size to use for buffering or memory mapping. If \f5buf is \f5NULL, Sfio will pick a suitable buffering scheme as discussed above. If \f5buf is not \f5NULL, then \f5buf and \f5size determine a buffer of the given size. .Tp \f5size == 0: If \f5buf is \f5NULL, the stream will be unbuffered. If \f5buf is not \f5NULL, \f5sfsetbuf() simply returns the stream buffer. In this case, no attempt will be made to synchronize the stream. .Ss " int sfsync(Sfio_t* f)" This function synchronizes the logical and physical views of stream \f5f. It returns a negative value for failure and \f50 for success. For a \f5SF_WRITE stream, synchronization means to write out any buffered data. For a seekable \f5SF_READ file stream, the physical file position is aligned with the logical stream position and, if \f5SF_SHARE is on, buffered data is discarded. If \f5f is \f5NULL, all streams are synchronized. If \f5f is the base of a stream stack (see \f5sfstack()), all stacked streams are synchronized. Note that a stacked stream can only be synchronized this way. If \f5f is in a pool (see \f5sfpool()) but not being the head, the pool head is synchronized. If \f5f has flag \f5SF_IOCHECK, the \f5SF_SYNC event is raised before and after synchronization. See \f5sfdisc() for details. .Ss " int sfpoll(Sfio_t** flist, int n, int timeout)" This function polls a set of streams to see if I/O operations can be performed on them without blocking. This is useful for multiplexing I/O over a set of streams. If a stream has a discipline, the exception function may be called before and after the stream is polled (see \f5sfdisc() for details). After a successful \f5sfpoll() call, for each ready stream \f5f, \f5sfvalue(f) returns a bit combination of \f5SF_READ and \f5SF_WRITE to tell which I/O mode is available. If \f5SF_READ is available, an attempt to read a byte will not block. If \f5SF_WRITE is available, an attempt to flush will not block. \f5sfpoll() returns the number of ready streams or \f5-1 on failure. .Tp \f5flist and \f5n: \f5flist is an array of \f5n streams to be polled. Upon return, ready streams are moved to the front of \f5flist in the same relative order. .Tp \f5timeout: This defines an elapse time in milliseconds to wait to see if any stream is ready for I/O. If \f5timeout is negative, \f5sfpoll() will block until some stream become ready. Note that \f5SF_STRING and normal file streams never block and are always ready for I/O. If a stream with discipline is being polled and its readiness is as yet undetermined (e.g., empty buffer,) the discipline exception function will be called with \f5SF_DPOLL before querying the operating system. .Ss " Sfio_t* sfpool(Sfio_t* f, Sfio_t* poolf, int mode)" This function manipulates pools of streams. In a pool, only one stream is at the head and can have buffered data. All other streams in the pool will be synchronized. A stream becomes head when it is used for some I/O operation. \f5sfpool() returns \f5NULL on failure. .Tp \f5f and \f5poolf: If \f5f is \f5NULL, \f5sfpool() simply returns the head of the pool containing \f5poolf. If \f5f is not \f5NULL and \f5poolf is \f5NULL, \f5f is deleted from its pool. In this case, if no other stream from the same pool can become head, \f5sfpool() will return \f5NULL; otherwise, it returns some stream from the remainder of the pool. If both \f5f and \f5poolf are not \f5NULL, \f5f is moved from its current pool (if any) into the same pool with \f5poolf. In this case, \f5poolf is returned. .Tp \f5mode: If \f5poolf is already in a pool, \f5mode is ignored. Otherwise, \f5mode should be \f50 or \f5SF_SHARE. A \f5SF_SHARE pool contains streams with \f5SF_WRITE mode. In addition, on change to a new head stream, buffered write data of the current head is transferred to the new head. .Ss " int sfpurge(Sfio_t* f)" This function discards all buffered data unless \f5f is a \f5SF_STRING stream. Note that if \f5f is a \f5SF_READ stream based on an unseekable device, purged data will not be recoverable. If \f5f is a \f5sfpopen-stream opened for both read and write, data of both the read and write pipe ends will be purged (see \f5sfset() to selectively turn off read or write mode if one set of data is to be preserved.) After purging, if \f5f has flag \f5SF_IOCHECK, the event \f5SF_PURGE is raised. \f5sfpurge() returns \f5-1 for failure and \f50 for success.
.Ss "DISCIPLINE, EVENT-HANDLING"
A file stream uses the system calls \f5read(2), \f5write(2) and \f5lseek(2) to read, write and position in the underlying file. Disciplines enable application-defined I/O methods including exception handling and data pre/post-processing. .Ss " Sfdisc_t* sfdisc(Sfio_t* f, Sfdisc_t* disc)" Each stream has a discipline stack whose bottom is a virtual discipline representing the actual system calls. \f5sfdisc() manipulates the discipline stack of stream \f5f. \f5f will be synchronized before any discipline stack manipulation. After a successful discipline stack manipulation, the stream I/O position (see \f5sfseek() and \f5sftell()) and extent (see \f5sfsize()) are updated to reflect that defined by the top discipline. \f5sfdisc() returns \f5NULL on failure. If the value of \f5disc is identical to the value of \f5f, then the top discipline on the discipline stack is returned without any further action. An application can then use this feature of \f5sfdisc() and the field \f5disc (below) of the discipline structure to traverse the entire discipline stack of a stream \f5f as follows:
for(disc = sfdisc(f, (Sfdisc_t*)f); disc; disc = disc->disc)If \f5disc is \f5SF_POPDISC or \f5(Sfdisc_t*)0, the top element of the stack, if any, is popped and its address is returned. Otherwise, \f5disc is pushed onto the discipline stack. In this case, if successful, \f5sfdisc() returns the discipline that was pushed down. Note that a discipline can be used on only one stream at a time. An application should take care to allocate different discipline structures for use with different streams. A discipline structure is of the type \f5Sfdisc_t which contains the following public fields:
Sfread_f readf; Sfwrite_f writef; Sfseek_f seekf; Sfexcept_f exceptf; Sfdisc_t* disc;
The first three fields of \f5Sfdisc_t specify alternative I/O functions. If any of them is \f5NULL, it is inherited from a discipline pushed earlier on the stack. Note that a file stream always has \f5read(2), \f5write(2), \f5lseek(2) and \f5NIL(Sfexcept_f) as the logical bottom discipline. Arguments to I/O discipline functions have the same meaning as that of the functions \f5sfrd(), \f5sfwr() and \f5sfsk() described below.
The exception function, \f5(*exceptf)() announces exceptional events during I/O operations. It is called as \f5(*exceptf)(Sfio_t* f, int type, Void_t* value, Sfdisc_t* disc). Unless noted otherwise, the return value of \f5(*exceptf)() is used as follows: .Tp \f5<0: The on-going operation shall terminate. .Tp \f5>0: If the event was raised due to an I/O error, the error has been repaired and the on-going operation shall continue normally. For some events, e.g., \f5SF_DPOLL, the return value may also have additional meanings. .Tp \f5=0: The on-going operation performs default actions with respect to the raised event. For example, on a reading error or reaching end of file, the top stream of a stack will be popped and closed and the on-going operation continue with the new top stream.
The argument \f5type of \f5(*exceptf)() identifies the particular exceptional event: .Tp \f5SF_LOCKED: The stream cannot be accessed. Note that this lock state is not related to the mutex lock that protects a stream from multiple accesses by different threads (see section THREAD SAFETY). Rather, the stream was frozen by certain operations such as \f5sfreserve() or \f5sfstack(). Thus, a stream can be in this state even if the application is uni-threaded. .Tp \f5SF_READ, \f5SF_WRITE: These events are raised around reading and writing operations. If \f5SF_IOCHECK is on, \f5SF_READ and \f5SF_WRITE are raised immediately before \f5read(2) and write(2) calls. In this case, \f5*((ssize_t*)value) is the amount of data to be processed. The return value of \f5(*exceptf)(), if negative, indicates that the stream is not ready for I/O and the calling operation will abort with failure. If it is positive, the stream is ready for I/O but the amount should be restricted to the amount specified by this value. If the return value is zero, the I/O operation is carried out normally. \f5SF_READ and \f5SF_WRITE are also raised on operation failures. In such a case, \f5*((ssize_t*)value) is the return value from the failed operation. .Tp \f5SF_SEEK: This event is raised when a seek operation fails. .Tp \f5SF_NEW, \f5SF_CLOSING (\f5SF_CLOSE), \f5SF_FINAL: These events are raised during a stream closing. \f5SF_NEW is raised for a stream about to be closed to be renewed (see \f5sfnew()). \f5SF_CLOSING is raised for a stream about to be closed. \f5SF_FINAL is raised after a stream has been closed and before its space is to be destroyed (see \f5sfclose()). For these events, a non-zero return value from \f5(*exceptf)() causes \f5sfclose() to return immediately with the same value. .Tp \f5SF_DPUSH, \f5SF_DPOP, \f5SF_DBUFFER: Events \f5SF_DPUSH and \f5SF_DPOP are raised when a discipline is about to be pushed or popped. \f5(Sfdisc_t*)value is the to-be top discipline, if any. A stream buffer is always synchronized before pushing or popping a discipline. If this synchronization fails, \f5SF_DBUFFER will be raised with \f5*((size_t*)value) being the amount of data still in the buffer. If the return value of \f5exceptf is non-negative, the push or pop operation will continue normally; otherwise, \f5sfdisc() returns failure. .Tp \f5SF_DPOLL: This event is raised by \f5sfpoll() to see if the stream is ready for I/O. \f5*((int*)value) indicates a time-out interval to wait. A negative return value from the exception function means blocking. A zero return value means that \f5sfpoll() should query the underlying file descriptor. A positive return value means non-blocking. In addition, this value will be a bit combination of \f5SF_READ and \f5SF_WRITE to indicate what I/O modes are ready. .Tp \f5SF_READY: This event is raised by \f5sfpoll() for each ready stream. The third argument to the event handler is an integer composed with the two bits \f5SF_READ and \f5SF_WRITE to indicate which I/O modes are ready. .Tp \f5SF_SYNC, \f5SF_PURGE: If \f5SF_IOCHECK is set, these events are raised respectively for a \f5sfsync() or \f5sfpurge() call. In each case, the respective event is raised once before the appropriate operation (synchronization or purging) with \f5((int)value) being \f51 and once after with \f5((int)value) being \f50. Note that \f5sfsync() is called for each \f5SF_WRITE or \f5SF_SHARE|SF_READ stream on closing. .Tp \f5SF_ATEXIT: This event is raised for each open stream before the process exits. .Ss " int sfraise(Sfio_t* f, int type, Void_t* data)" If \f5f is non-\f5NULL, \f5sfraise() calls all exception handlers of \f5f with the event \f5type and associated \f5data. If an exception handler returns a non-zero value, \f5sfraise() immediate returns the same value. Application-defined events should start from the value \f5SF_EVENT so as to avoid confusion with system-defined events, \f5sfraise() returns \f50 on success and \f5-1 on failure. If \f5f is \f5NULL, \f5sfraise() iterates over all streams and raise events as described above. In this case, \f5sfraise() returns \f50 on success and a negative value on failure. The absolute value of the return value tells how many streams failed on raising the given event. .Ss " ssize_t sfrd(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc)" .Ss " ssize_t sfwr(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc)" .Ss " Sfoff_t sfsk(Sfio_t* f, Sfoff_t offset, int type, Sfdisc_t* disc)" These functions provides safe methods for a discipline I/O function to invoke earlier discipline I/O functions and to properly handle exceptions. They should not be used in any other context. \f5sfrd() and \f5sfwr() return the number of bytes read or written. \f5sfsk() returns the new seek position. On error, all three functions return a negative value which should be \f5-1 or the value returned by the exception handler.
.Ss "STREAM CONTROL"
.Ss " int sfresize(Sfio_t* f, Sfoff_t size)" This function resizes the stream \f5f\P so that its extent is \f5size. If the stream corresponds to a file, the file size is set to \f5size via the system call \f5ftruncate(). When a stream is made larger, the new data space is filled with zero's. \f5sfresize() returns \f50 on success and a negative value on failure. .Ss " int sfset(Sfio_t* f, int flags, int set)" This function sets control flags for the stream \f5f. It returns the previous set of flags or \f50 on error. Settable flags are: \f5SF_READ, \f5SF_WRITE, \f5SF_IOCHECK, \f5SF_LINE, \f5SF_SHARE, \f5SF_PUBLIC, \f5SF_MALLOC and \f5SF_STATIC. Note that \f5SF_READ and \f5SF_WRITE can be turned on or off only if the stream was opened as \f5SF_READ|SF_WRITE. Turning off one of them means that the stream is to be treated exclusively in the other mode. It is not possible to turn off both. If legal, an attempt to turn on either \f5SF_READ or \f5SF_WRITE will cause the stream to be in the given I/O mode. .Tp \f5set == 0: If \f5flags is zero, the current set of flags is simply returned. Note that when a stream is first opened, not all of its flags are initialized yet (more below). If \f5flags is non-zero, an attempt is made to turn off the specified flags. .Tp \f5set != 0: If \f5flags is zero, the stream is initialized if not yet done so. Then the current set of flags is returned. If \f5flags is non-zero, an attempt is made to turn on the specified flags. .Ss " int sfsetfd(Sfio_t* f, int fd)" This function changes the file descriptor of \f5f. Before a change is realized, \f5(*notify)(f,SF_SETFD,newfd) (see \f5sfnotify()) is called. \f5sfsetfd() returns \f5-1 on failure and the new file descriptor on success. .Tp \f5fd >= 0: If the current file descriptor is non-negative, it will be changed using \f5dup(3) to a value larger or equal to \f5fd. Upon a successful change, the previous file descriptor will be closed. If the current file descriptor is negative, it will be set to \f5fd and the stream will be reinitialized. .Tp \f5fd < 0: The stream is synchronized (see \f5sfsync()) and its file descriptor will be set to this value. Then, except for \f5sfclose(), the stream will be inaccessible until a future \f5sfsetfd() call resets the file descriptor to a non-negative value. Thus, \f5sfsetfd(f,-1) can be used to avoid closing the file descriptor of \f5f when \f5f is closed. .Ss " Sfio_t* sfstack(Sfio_t* base, Sfio_t* top)" This function stacks or unstacks stream. Every stream stack is identified by a base stream via which all I/O operations are performed. However, an I/O operation always takes effect on the top stream. If the top stream reaches the end of file or has an unrecoverable error condition, it is automatically popped and closed (see also \f5sfdisc() for alternative handling of these conditions). .Tp \f5base: This is the base stream of the stack. If it is \f5NULL, \f5sfstack() does nothing and returns \f5top. .Tp \f5top: If this is \f5SF_POPSTACK or \f5(Sfio_t*)0, the stack is popped and \f5sfstack() returns the popped stream. Otherwise, \f5top is pushed on top of the stack identified by \f5base and \f5sfstack() returns the \f5base stream. .Ss " Sfio_t* sfswap(Sfio_t* f1, Sfio_t* f2)" This function swaps contents of \f5f1 and \f5f2. This fails if either stream is in a stream stack but not being a base stream. If \f5f2 is \f5NULL, a new stream is constructed as a duplicate of \f5f1. \f5sfswap() returns \f5f2 or \f5f1 duplicate on success and \f5NULL on failure.
.Ss "STREAM INFORMATION"
.Ss " Sfoff_t sfsize(Sfio_t* f)" This function returns the size of stream \f5f (see \f5sfnew()). If \f5f is not seekable or if its size is not determinable, \f5sfsize() returns \f5-1. .Ss " Sfoff_t sftell(Sfio_t* f)" This function returns the current I/O position in stream \f5f. Note that if \f5f is \f5SF_APPEND and a writing operation was just performed, the current I/O position is at the physical end of file. If \f5f is unseekable, \f5sftell returns the number of bytes read from or written to \f5f. See also \f5sfungetc(). .Ss " ssize_t sfvalue(Sfio_t* f)" This function returns the string or buffer length for \f5sfreserve(), \f5sfsetbuf(), and \f5sfgetr(). .Ss " int sffileno(Sfio_t* f)" This function returns the file descriptor of stream \f5f. .Ss " int sfstacked(Sfio_t* f)" This function returns a non-zero value if stream \f5f has been stacked. .Ss " int sfeof(Sfio_t* f)" .Ss " int sferror(Sfio_t* f)" .Ss " int sfclrerr(Sfio_t* f)" \f5sfeof() tells whether or not the stream has an end-of-file condition. \f5sferror() tells whether or not the stream has an error condition. \f5sfclrerr() clears both end-of-file and error conditions. The end-of-file and error conditions are also cleared on an I/O operation. .Ss " int sfclrlock(Sfio_t* f)" This function restores the stream back to a normal state. This means clearing locks and possibly throwing away unprocessed data. As such, this operation is unsafe and should be used with care. For example, it may be used before a long jump (\f5longjmp(3)) out of some discipline I/O function to restore the internal stream states. \f5sfclrlock() returns the current set of flags. .Ss " int sfnotify((void(*)notify)(Sfio_t*, int, void*) )" This sets a function \f5(*notify)() to be called as \f5(*notify)(f, type, data) on various stream events. Arguments \f5type and \f5data indicate the reason for the call and accompanying data: .Tp \f5SF_NEW: \f5f is being opened and \f5data is the underlying file descriptor. .Tp \f5SF_CLOSING (\f5SF_CLOSE): \f5f is the stream being closed and \f5data is the underlying file descriptor. .Tp \f5SF_SETFD: The file descriptor of \f5f is being changed to the one defined by \f5data (see \f5sfsetfd().) .Tp \f5SF_READ: An attempt to change \f5f to read mode failed. \f5data is the file descriptor of the stream. .Tp \f5SF_WRITE: An attempt to change \f5f to write mode failed. \f5data is the file descriptor of the stream. .Tp \f5SF_MTACCESS: When a notifying function was registered (see \f5sfnotify()), every Sfio call on a stream with flag \f5SF_MTSAFE will invoke the notifying function once on entry after the stream is locked as \f5(*notify)(f, SF_MTACCESS, Sfio_t** fp), and once on return before unlocking as as \f5(*notify)(f, SF_MTACCESS, (Sfio_t**)0). In the call entry case, the notification function could use the argument \f5fp to set a stream that would be used for performing the actual I/O operation. In this way, certain global streams such as the standard streams \f5sfstdin, \f5sfstdout and \f5sfstderr could be made to act differently when used in different streams. .Ss " int sfwalk(Sfwalk_f walkf, Void_t* data, int type)" This function invokes \f5(*walkf)(f, data) on every open stream \f5f whose flags as defined by \f5sfset() contains all bit flags given in \f5type. On such a call, if the return value is negative, \f5sfwalk() will terminate. \f5sfwalk() returns 0 if no stream was processed. Otherwise, it returns the return value from the last invocation of \f5walkf(). As an example, the call \f5sfwalk(walkf, data, SF_READ) will iterate over all streams opened for reading. Similarly, \f5sfwalk(walkf, data, SF_READ|SF_WRITE) iterates over all streams opened for both reading and writing. Lastly, \f5sfwalk(walkf, data, 0) iterates over all streams.
.Ss "MISCELLANEOUS FUNCTIONS"
.Ss " ssize_t sfmaxr(ssize_t maxr, int set)" Certain records may require too much memory for storage, thus, causing undesirable side effects. Therefore, the library normally bounds the amount of memory used by \f5sfgetr(). A different memory bound can be set via \f5sfmaxr(). While a positive \f5maxr hints to \f5sfgetr() to use only about that much memory to construct a record, a non-positive bound allows \f5sfgetr() to use as much memory as necessary. \f5sfmaxr() sets the value only if \f5set is non-zero. It returns the value before setting or the current value if not setting. .Ss " ssize_t sfslen()" This function returns the length of a string just constructed by \f5sfsprintf() or \f5sfprints(). See also \f5sfvalue(). .Ss " int sfulen(Sfulong_t v)" .Ss " int sfllen(Sflong_t v)" .Ss " int sfdlen(Sfdouble_t v)" These functions return respectively the number of bytes required to code the \f5Sfulong_t, \f5Sflong_t or \f5Sfdouble_t value \f5v by \f5sfputu(), \f5sfputl() or \f5sfputd(). .Ss " ssize_t sfpkrd(int fd, char* buf, size_t n, int rsc, long tm, int action)" This function acts directly on the file descriptor \f5fd. It does a combination of peeking on incoming data and a time-out read. Upon success, it returns the number of bytes received. A return value of \f50 means that the end-of-file condition has been detected. A negative value represents an error. .Tp \f5buf, \f5n: These define a buffer and its size to read data into. .Tp \f5rsc: If \f5>=0, this defines a record separator. If the last returned byte is not the record separator, then the read data did not contain a complete record. Otherwise, it contains one or more records. See also \f5action below. .Tp \f5tm: If \f5>=0, this defines a time interval in milliseconds to wait for incoming data. .Tp \f5action: If \f5action > 0, \f5sfpkrd() will peek on incoming data but will not read past it. Therefore, a future \f5sfpkrd() or \f5read(2) will see the same data again. If \f5action <= 0, \f5sfpkrd() will not peek and there are two cases. If \f5rsc < 0, an attempt is made to read \f5n bytes. If \f5rsc >= 0, an attempt is made to read one record.
.Ss "FULL STRUCTURE SFIO_T"
.Ss " #include <sfio_t.h>" Most applications based on Sfio only need to include the header file \f5sfio.h which defines an abbreviated \f5Sfio_t structure without certain fields private to Sfio. However, there are times (e.g., debugging) when an application may require more details about the full \f5Sfio_t structure. In such cases, the header file \f5sfio_t.h can be used in place of \f5sfio.h. Note that an application doing this will become sensitive to changes in the internal architecture of Sfio. .Ss " #define SFNEW(buf,size,file,flags,disc)" This macro function is defined in \f5sfio_t.h for use in static initialization of an \f5Sfio_t structure. It requires five arguments: .Tp \f5buf, size: These define a buffer and its size. .Tp \f5file: This defines the underlying file descriptor if any. .Tp \f5flags: This is composed from bit flags described above. .Tp \f5disc: This defines a discipline if any.
.Ss "EXAMPLE DISCIPLINES"
The below functions create disciplines and insert them into the given streams \f5f. These functions return \f50 on success and \f5-1 on failure. .Ss "int sfdcdio(Sfio_t* f, size_t bufsize)" This creates a discipline that uses the direct IO feature available on file systems such as SGI's XFS to speed up IO. The argument \f5bufsize suggests a buffer size to use for data transfer. .Ss "int sfdcdos(Sfio_t* f)" This creates a discipline to read DOS text files. It basically transforms pairs of \er\en to \en. .Ss "int sfdcfilter(Sfio_t* f, const char* cmd)" This creates a discipline that sends data from \f5f to the given command \f5cmd to process, then reads back the processed data. .Ss "int sfdcseekable(Sfio_t* f)" This creates a discipline that makes an unseekable reading stream seekable. .Ss "int sfdcslow(Sfio_t* f)" This creates a discipline that makes all Sfio operations return immediately on interrupts. This is useful for dealing with slow devices. .Ss "int sfdcsubstream(Sfio_t* f, Sfio_t* parent, Sfoff_t offset, Sfoff_t extent)" This creates a discipline that makes \f5f acts as if it corresponds exactly to the subsection of \f5parent starting at \f5offset with size \f5extent. .Ss "int sfdctee(Sfio_t* f, Sfio_t* tee)" This creates a discipline that copies to the stream \f5tee any data written to \f5f. .Ss "int sfdcunion(Sfio_t* f, Sfio_t** array, int n)" This creates a discipline that makes \f5f act as if it is the concatenation of the \f5n streams given in \f5array. .Ss "int sfdclzw(Sfio_t* f)" This creates a discipline that would decompress data in \f5f. The stream \f5f should have data from a source compressed by the Unix compress program. .Ss "int sfdcgzip(Sfio_t* f, int opt)" This creates a discipline for reading/writing data compressed by zlib. The argument \f5opt defines the optimization level.
.Ss "STDIO-COMPATIBILITY"
Sfio provides compatibility functions for all various popular Stdio implementations at source and binary level. The source Stdio-compatibility interface provides the header file \f5stdio.h that defines a set of macros or inlined functions to map Stdio calls to Sfio ones. This mapping may benignly extend or change the meaning of certain original Stdio operations. For example, the Sfio's version of \f5popen() allows a coprocess to be opened for both reading and writing unlike the original call which only allows a coprocess to be opened for a single mode. Similarly, the Sfio's \f5fopen() call can be used to create string streams in addition to file streams.
The standard streams \f5stdin, \f5stdout and \f5stderr are mapped via \f5#define to \f5sfstdin, \f5sfstdout and \f5sfstderr. The latter are typically declared of the type \f5Sfio_t*. Certain older Stdio applications require these to be declared as addresses of structures so that static initializations of the sort ``\f5FILE* f = stdin;'' would work. Such applications should use the compile time flag \f5SF_FILE_STRUCT to achieve the desired effect.
The binary Stdio-compatibility libraries, \f5libstdio.a and \f5libstdio-mt.a, provide complete implementations of Stdio functions suitable for linking applications already compiled with native header \f5stdio.h. These functions are also slightly altered or extended as discussed above.
Below are the supported Stdio functions:
FILE* fopen(const char* file, const char* mode); FILE* freopen(const char* file, const char* mode, FILE* stream); FILE* fdopen(int filedesc, const char* mode); FILE* popen(const char* command, const char* mode); FILE* tmpfile(); int fclose(FILE* stream); int pclose(FILE* stream); void flockfile(FILE* stream) int ftrylockfile(FILE* stream) void funlockfile(FILE* stream) void setbuf(FILE* stream, char* buf); int setvbuf(FILE* stream, char* buf, int mode, size_t size); void setbuffer(FILE* stream, char* buf, size_t size); int setlinebuf(FILE* stream); int fflush(FILE* stream); int fpurge(FILE* stream); int fseek(FILE* stream, long offset, int whence); void rewind(FILE* stream); int fgetpos(FILE* stream, fpos_t* pos); int fsetpos(FILE* stream, fpos_t* pos); long ftell(FILE* stream); int getc(FILE* stream); int fgetc(FILE* stream); int getchar(void); int ungetc(int c, FILE* stream); int getw(FILE* stream); char* gets(char* s); char* fgets(char* s, int n, FILE* stream); size_t fread(Void_t* ptr, size_t size, size_t nelt, FILE* stream); int putc(int c, FILE* stream); int fputc(int c, FILE* stream); int putchar(int c); int putw(int w, FILE* stream); int puts(const char* s, FILE* stream); int fputs(const char* s, FILE* stream); size_t fwrite(const Void_t* ptr, size_t size, size_t nelt, FILE* stream); int fscanf(FILE* stream, const char* format, ...); int vfscanf(FILE* stream, const char* format, va_list args); int _doscan(FILE* stream, const char* format, va_list args); int scanf(const char* format, ...); int vscanf(const char* format, va_list args); int sscanf(const char* s, const char* format, ...); int vsscanf(const char* s, const char* format, va_list args); int fprintf(FILE* stream, const char* format, ...); int vfprintf(FILE* stream, const char* format, va_list args); int _doprnt(FILE* stream, const char* format, va_list args); int printf(const char* format, ...); int vprintf(const char* format, va_list args); int sprintf(const char* s, const char* format, ...); int snprintf(const char* s, int n, const char* format, ...); int vsprintf(const char* s, const char* format, va_list args); int vsnprintf(const char* s, int n, const char* format, va_list args); int feof(FILE* stream); int ferror(FILE* stream); int clearerr(FILE* stream);
.Ss "RECENT CHANGES"
A few exception types have been added. In particular, exception handlers shall be raised with \f5SF_LOCKED on accessing a stream frozen either by an ongoing operation or a previous operation (e.g., \f5sfgetr()). Before a process exits, the event \f5SF_ATEXIT is raised for each open stream.
A number of disciplines were added for various processing functions. Of interests are disciplines to use the direct I/O feature on IRIX6.2, read DOS text files, and decompress files compressed by Unix compress.
Various new stream and function flags have been added. For example, the third argument of \f5sfgetr() is now a set of bit flags and not just a three-value object. However, the old semantics of this argument of \f5sfgetr() is still supported.
The \f5sfopen() call has been extended so that sfopen(f,NULL,mode) can be used to changed the mode of a file stream before any I/O operations. This is most useful for changing the modes of the standard streams.
The buffering strategy has been significantly enhanced for streams that perform many seek operations. Also, the handling of stream and file positions have been better clarified so that applications that share file descriptors across streams and/or processes can be sure that the file states will be consistent.
The strategy for mapping between Sfio and Stdio streams in the binary compatibility package has been significantly enhanced for efficiency. For most platforms, the mapping is now constant time per look-up.
The \f5SF_BUFCONST flag was deleted. This is largely unused anyway.
The library can be built for thread-safety. This is based largely on Posix pthread mutexes except for on UWIN where native Windows APIs are used.
The functions \f5sfgetm() and \f5sfputm() were added to encode unsigned integer values with known ranges.
The flag \f5SF_APPEND is identical to \f5SF_APPENDWR. However it conflicts with a different token of the same name defined in the system header \f5stat.h of BSDI Unix systems. On such systems, we shall not define \f5SF_APPEND and this symbol may be removed in a future release.
Similarly, the exception \f5SF_CLOSE is identical to \f5SF_CLOSING. However it conflicts with a different token of the same name defined in the system header \f5socket.h of AIX Unix systems. On such systems, we shall not define \f5SF_CLOSE and this symbol may be removed in a future release.
The printing and scanning functions were extended to handle multibyte characters and to conform to the C99 standard.
The function \f5sfpoll() was rehauled to make it useful for writing servers that must commnunicate with multiple streams without blocking.
The formatting pattern \f5%c for \f5sf*printf was extended to allow the flag \f5# to print unprintable character values using the C convention. For example, \f5%#c prints the octal value 012 as \f5\\n.
David G. Korn, dgk@research.att.com, and
Glenn S. Fowler, gsf@research.att.com.