1
2 #pragma ident "%Z%%M% %I% %E% SMI"
3
4 /*
5 ** 2001 September 16
6 **
7 ** The author disclaims copyright to this source code. In place of
8 ** a legal notice, here is a blessing:
9 **
10 ** May you do good and not evil.
11 ** May you find forgiveness for yourself and forgive others.
12 ** May you share freely, never taking more than you give.
13 **
14 ******************************************************************************
15 **
16 ** This file contains code that is specific to particular operating
17 ** systems. The purpose of this file is to provide a uniform abstraction
18 ** on which the rest of SQLite can operate.
19 */
20 #include "os.h" /* Must be first to enable large file support */
21 #include "sqliteInt.h"
22
23 #if OS_UNIX
24 # include <time.h>
25 # include <errno.h>
26 # include <unistd.h>
27 # ifndef O_LARGEFILE
28 # define O_LARGEFILE 0
29 # endif
30 # ifdef SQLITE_DISABLE_LFS
31 # undef O_LARGEFILE
32 # define O_LARGEFILE 0
33 # endif
34 # ifndef O_NOFOLLOW
35 # define O_NOFOLLOW 0
36 # endif
37 # ifndef O_BINARY
38 # define O_BINARY 0
39 # endif
40 #endif
41
42
43 #if OS_WIN
44 # include <winbase.h>
45 #endif
46
47 #if OS_MAC
48 # include <extras.h>
49 # include <path2fss.h>
50 # include <TextUtils.h>
51 # include <FinderRegistry.h>
52 # include <Folders.h>
53 # include <Timer.h>
54 # include <OSUtils.h>
55 #endif
56
57 /*
58 ** The DJGPP compiler environment looks mostly like Unix, but it
59 ** lacks the fcntl() system call. So redefine fcntl() to be something
60 ** that always succeeds. This means that locking does not occur under
61 ** DJGPP. But its DOS - what did you expect?
62 */
63 #ifdef __DJGPP__
64 # define fcntl(A,B,C) 0
65 #endif
66
67 /*
68 ** Macros used to determine whether or not to use threads. The
69 ** SQLITE_UNIX_THREADS macro is defined if we are synchronizing for
70 ** Posix threads and SQLITE_W32_THREADS is defined if we are
71 ** synchronizing using Win32 threads.
72 */
73 #if OS_UNIX && defined(THREADSAFE) && THREADSAFE
74 # include <pthread.h>
75 # define SQLITE_UNIX_THREADS 1
76 #endif
77 #if OS_WIN && defined(THREADSAFE) && THREADSAFE
78 # define SQLITE_W32_THREADS 1
79 #endif
80 #if OS_MAC && defined(THREADSAFE) && THREADSAFE
81 # include <Multiprocessing.h>
82 # define SQLITE_MACOS_MULTITASKING 1
83 #endif
84
85 /*
86 ** Macros for performance tracing. Normally turned off
87 */
88 #if 0
89 static int last_page = 0;
90 __inline__ unsigned long long int hwtime(void){
91 unsigned long long int x;
92 __asm__("rdtsc\n\t"
93 "mov %%edx, %%ecx\n\t"
94 :"=A" (x));
95 return x;
96 }
97 static unsigned long long int g_start;
98 static unsigned int elapse;
99 #define TIMER_START g_start=hwtime()
100 #define TIMER_END elapse=hwtime()-g_start
101 #define SEEK(X) last_page=(X)
102 #define TRACE1(X) fprintf(stderr,X)
103 #define TRACE2(X,Y) fprintf(stderr,X,Y)
104 #define TRACE3(X,Y,Z) fprintf(stderr,X,Y,Z)
105 #define TRACE4(X,Y,Z,A) fprintf(stderr,X,Y,Z,A)
106 #define TRACE5(X,Y,Z,A,B) fprintf(stderr,X,Y,Z,A,B)
107 #else
108 #define TIMER_START
109 #define TIMER_END
110 #define SEEK(X)
111 #define TRACE1(X)
112 #define TRACE2(X,Y)
113 #define TRACE3(X,Y,Z)
114 #define TRACE4(X,Y,Z,A)
115 #define TRACE5(X,Y,Z,A,B)
116 #endif
117
118
119 #if OS_UNIX
120 /*
121 ** Here is the dirt on POSIX advisory locks: ANSI STD 1003.1 (1996)
122 ** section 6.5.2.2 lines 483 through 490 specify that when a process
123 ** sets or clears a lock, that operation overrides any prior locks set
124 ** by the same process. It does not explicitly say so, but this implies
125 ** that it overrides locks set by the same process using a different
126 ** file descriptor. Consider this test case:
127 **
128 ** int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
129 ** int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
130 **
131 ** Suppose ./file1 and ./file2 are really the same file (because
132 ** one is a hard or symbolic link to the other) then if you set
133 ** an exclusive lock on fd1, then try to get an exclusive lock
134 ** on fd2, it works. I would have expected the second lock to
135 ** fail since there was already a lock on the file due to fd1.
136 ** But not so. Since both locks came from the same process, the
137 ** second overrides the first, even though they were on different
138 ** file descriptors opened on different file names.
139 **
140 ** Bummer. If you ask me, this is broken. Badly broken. It means
141 ** that we cannot use POSIX locks to synchronize file access among
142 ** competing threads of the same process. POSIX locks will work fine
143 ** to synchronize access for threads in separate processes, but not
144 ** threads within the same process.
145 **
146 ** To work around the problem, SQLite has to manage file locks internally
147 ** on its own. Whenever a new database is opened, we have to find the
148 ** specific inode of the database file (the inode is determined by the
149 ** st_dev and st_ino fields of the stat structure that fstat() fills in)
150 ** and check for locks already existing on that inode. When locks are
151 ** created or removed, we have to look at our own internal record of the
152 ** locks to see if another thread has previously set a lock on that same
153 ** inode.
154 **
155 ** The OsFile structure for POSIX is no longer just an integer file
156 ** descriptor. It is now a structure that holds the integer file
157 ** descriptor and a pointer to a structure that describes the internal
158 ** locks on the corresponding inode. There is one locking structure
159 ** per inode, so if the same inode is opened twice, both OsFile structures
160 ** point to the same locking structure. The locking structure keeps
161 ** a reference count (so we will know when to delete it) and a "cnt"
162 ** field that tells us its internal lock status. cnt==0 means the
163 ** file is unlocked. cnt==-1 means the file has an exclusive lock.
164 ** cnt>0 means there are cnt shared locks on the file.
165 **
166 ** Any attempt to lock or unlock a file first checks the locking
167 ** structure. The fcntl() system call is only invoked to set a
168 ** POSIX lock if the internal lock structure transitions between
169 ** a locked and an unlocked state.
170 **
171 ** 2004-Jan-11:
172 ** More recent discoveries about POSIX advisory locks. (The more
173 ** I discover, the more I realize the a POSIX advisory locks are
174 ** an abomination.)
175 **
176 ** If you close a file descriptor that points to a file that has locks,
177 ** all locks on that file that are owned by the current process are
178 ** released. To work around this problem, each OsFile structure contains
179 ** a pointer to an openCnt structure. There is one openCnt structure
180 ** per open inode, which means that multiple OsFiles can point to a single
181 ** openCnt. When an attempt is made to close an OsFile, if there are
182 ** other OsFiles open on the same inode that are holding locks, the call
183 ** to close() the file descriptor is deferred until all of the locks clear.
184 ** The openCnt structure keeps a list of file descriptors that need to
185 ** be closed and that list is walked (and cleared) when the last lock
186 ** clears.
187 **
188 ** First, under Linux threads, because each thread has a separate
189 ** process ID, lock operations in one thread do not override locks
190 ** to the same file in other threads. Linux threads behave like
191 ** separate processes in this respect. But, if you close a file
192 ** descriptor in linux threads, all locks are cleared, even locks
193 ** on other threads and even though the other threads have different
194 ** process IDs. Linux threads is inconsistent in this respect.
195 ** (I'm beginning to think that linux threads is an abomination too.)
196 ** The consequence of this all is that the hash table for the lockInfo
197 ** structure has to include the process id as part of its key because
198 ** locks in different threads are treated as distinct. But the
199 ** openCnt structure should not include the process id in its
200 ** key because close() clears lock on all threads, not just the current
201 ** thread. Were it not for this goofiness in linux threads, we could
202 ** combine the lockInfo and openCnt structures into a single structure.
203 */
204
205 /*
206 ** An instance of the following structure serves as the key used
207 ** to locate a particular lockInfo structure given its inode. Note
208 ** that we have to include the process ID as part of the key. On some
209 ** threading implementations (ex: linux), each thread has a separate
210 ** process ID.
211 */
212 struct lockKey {
213 dev_t dev; /* Device number */
214 ino_t ino; /* Inode number */
215 pid_t pid; /* Process ID */
216 };
217
218 /*
219 ** An instance of the following structure is allocated for each open
220 ** inode on each thread with a different process ID. (Threads have
221 ** different process IDs on linux, but not on most other unixes.)
222 **
223 ** A single inode can have multiple file descriptors, so each OsFile
224 ** structure contains a pointer to an instance of this object and this
225 ** object keeps a count of the number of OsFiles pointing to it.
226 */
227 struct lockInfo {
228 struct lockKey key; /* The lookup key */
229 int cnt; /* 0: unlocked. -1: write lock. 1...: read lock. */
230 int nRef; /* Number of pointers to this structure */
231 };
232
233 /*
234 ** An instance of the following structure serves as the key used
235 ** to locate a particular openCnt structure given its inode. This
236 ** is the same as the lockKey except that the process ID is omitted.
237 */
238 struct openKey {
239 dev_t dev; /* Device number */
240 ino_t ino; /* Inode number */
241 };
242
243 /*
244 ** An instance of the following structure is allocated for each open
245 ** inode. This structure keeps track of the number of locks on that
246 ** inode. If a close is attempted against an inode that is holding
247 ** locks, the close is deferred until all locks clear by adding the
248 ** file descriptor to be closed to the pending list.
249 */
250 struct openCnt {
251 struct openKey key; /* The lookup key */
252 int nRef; /* Number of pointers to this structure */
253 int nLock; /* Number of outstanding locks */
254 int nPending; /* Number of pending close() operations */
255 int *aPending; /* Malloced space holding fd's awaiting a close() */
256 };
257
258 /*
259 ** These hash table maps inodes and process IDs into lockInfo and openCnt
260 ** structures. Access to these hash tables must be protected by a mutex.
261 */
262 static Hash lockHash = { SQLITE_HASH_BINARY, 0, 0, 0, 0, 0 };
263 static Hash openHash = { SQLITE_HASH_BINARY, 0, 0, 0, 0, 0 };
264
265 /*
266 ** Release a lockInfo structure previously allocated by findLockInfo().
267 */
releaseLockInfo(struct lockInfo * pLock)268 static void releaseLockInfo(struct lockInfo *pLock){
269 pLock->nRef--;
270 if( pLock->nRef==0 ){
271 sqliteHashInsert(&lockHash, &pLock->key, sizeof(pLock->key), 0);
272 sqliteFree(pLock);
273 }
274 }
275
276 /*
277 ** Release a openCnt structure previously allocated by findLockInfo().
278 */
releaseOpenCnt(struct openCnt * pOpen)279 static void releaseOpenCnt(struct openCnt *pOpen){
280 pOpen->nRef--;
281 if( pOpen->nRef==0 ){
282 sqliteHashInsert(&openHash, &pOpen->key, sizeof(pOpen->key), 0);
283 sqliteFree(pOpen->aPending);
284 sqliteFree(pOpen);
285 }
286 }
287
288 /*
289 ** Given a file descriptor, locate lockInfo and openCnt structures that
290 ** describes that file descriptor. Create a new ones if necessary. The
291 ** return values might be unset if an error occurs.
292 **
293 ** Return the number of errors.
294 */
findLockInfo(int fd,struct lockInfo ** ppLock,struct openCnt ** ppOpen)295 int findLockInfo(
296 int fd, /* The file descriptor used in the key */
297 struct lockInfo **ppLock, /* Return the lockInfo structure here */
298 struct openCnt **ppOpen /* Return the openCnt structure here */
299 ){
300 int rc;
301 struct lockKey key1;
302 struct openKey key2;
303 struct stat statbuf;
304 struct lockInfo *pLock;
305 struct openCnt *pOpen;
306 rc = fstat(fd, &statbuf);
307 if( rc!=0 ) return 1;
308 memset(&key1, 0, sizeof(key1));
309 key1.dev = statbuf.st_dev;
310 key1.ino = statbuf.st_ino;
311 key1.pid = getpid();
312 memset(&key2, 0, sizeof(key2));
313 key2.dev = statbuf.st_dev;
314 key2.ino = statbuf.st_ino;
315 pLock = (struct lockInfo*)sqliteHashFind(&lockHash, &key1, sizeof(key1));
316 if( pLock==0 ){
317 struct lockInfo *pOld;
318 pLock = sqliteMallocRaw( sizeof(*pLock) );
319 if( pLock==0 ) return 1;
320 pLock->key = key1;
321 pLock->nRef = 1;
322 pLock->cnt = 0;
323 pOld = sqliteHashInsert(&lockHash, &pLock->key, sizeof(key1), pLock);
324 if( pOld!=0 ){
325 assert( pOld==pLock );
326 sqliteFree(pLock);
327 return 1;
328 }
329 }else{
330 pLock->nRef++;
331 }
332 *ppLock = pLock;
333 pOpen = (struct openCnt*)sqliteHashFind(&openHash, &key2, sizeof(key2));
334 if( pOpen==0 ){
335 struct openCnt *pOld;
336 pOpen = sqliteMallocRaw( sizeof(*pOpen) );
337 if( pOpen==0 ){
338 releaseLockInfo(pLock);
339 return 1;
340 }
341 pOpen->key = key2;
342 pOpen->nRef = 1;
343 pOpen->nLock = 0;
344 pOpen->nPending = 0;
345 pOpen->aPending = 0;
346 pOld = sqliteHashInsert(&openHash, &pOpen->key, sizeof(key2), pOpen);
347 if( pOld!=0 ){
348 assert( pOld==pOpen );
349 sqliteFree(pOpen);
350 releaseLockInfo(pLock);
351 return 1;
352 }
353 }else{
354 pOpen->nRef++;
355 }
356 *ppOpen = pOpen;
357 return 0;
358 }
359
360 #endif /** POSIX advisory lock work-around **/
361
362 /*
363 ** If we compile with the SQLITE_TEST macro set, then the following block
364 ** of code will give us the ability to simulate a disk I/O error. This
365 ** is used for testing the I/O recovery logic.
366 */
367 #ifdef SQLITE_TEST
368 int sqlite_io_error_pending = 0;
369 #define SimulateIOError(A) \
370 if( sqlite_io_error_pending ) \
371 if( sqlite_io_error_pending-- == 1 ){ local_ioerr(); return A; }
local_ioerr()372 static void local_ioerr(){
373 sqlite_io_error_pending = 0; /* Really just a place to set a breakpoint */
374 }
375 #else
376 #define SimulateIOError(A)
377 #endif
378
379 /*
380 ** When testing, keep a count of the number of open files.
381 */
382 #ifdef SQLITE_TEST
383 int sqlite_open_file_count = 0;
384 #define OpenCounter(X) sqlite_open_file_count+=(X)
385 #else
386 #define OpenCounter(X)
387 #endif
388
389
390 /*
391 ** Delete the named file
392 */
sqliteOsDelete(const char * zFilename)393 int sqliteOsDelete(const char *zFilename){
394 #if OS_UNIX
395 unlink(zFilename);
396 #endif
397 #if OS_WIN
398 DeleteFile(zFilename);
399 #endif
400 #if OS_MAC
401 unlink(zFilename);
402 #endif
403 return SQLITE_OK;
404 }
405
406 /*
407 ** Return TRUE if the named file exists.
408 */
sqliteOsFileExists(const char * zFilename)409 int sqliteOsFileExists(const char *zFilename){
410 #if OS_UNIX
411 return access(zFilename, 0)==0;
412 #endif
413 #if OS_WIN
414 return GetFileAttributes(zFilename) != 0xffffffff;
415 #endif
416 #if OS_MAC
417 return access(zFilename, 0)==0;
418 #endif
419 }
420
421
422 #if 0 /* NOT USED */
423 /*
424 ** Change the name of an existing file.
425 */
426 int sqliteOsFileRename(const char *zOldName, const char *zNewName){
427 #if OS_UNIX
428 if( link(zOldName, zNewName) ){
429 return SQLITE_ERROR;
430 }
431 unlink(zOldName);
432 return SQLITE_OK;
433 #endif
434 #if OS_WIN
435 if( !MoveFile(zOldName, zNewName) ){
436 return SQLITE_ERROR;
437 }
438 return SQLITE_OK;
439 #endif
440 #if OS_MAC
441 /**** FIX ME ***/
442 return SQLITE_ERROR;
443 #endif
444 }
445 #endif /* NOT USED */
446
447 /*
448 ** Attempt to open a file for both reading and writing. If that
449 ** fails, try opening it read-only. If the file does not exist,
450 ** try to create it.
451 **
452 ** On success, a handle for the open file is written to *id
453 ** and *pReadonly is set to 0 if the file was opened for reading and
454 ** writing or 1 if the file was opened read-only. The function returns
455 ** SQLITE_OK.
456 **
457 ** On failure, the function returns SQLITE_CANTOPEN and leaves
458 ** *id and *pReadonly unchanged.
459 */
sqliteOsOpenReadWrite(const char * zFilename,OsFile * id,int * pReadonly)460 int sqliteOsOpenReadWrite(
461 const char *zFilename,
462 OsFile *id,
463 int *pReadonly
464 ){
465 #if OS_UNIX
466 int rc;
467 id->dirfd = -1;
468 id->fd = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY, 0644);
469 if( id->fd<0 ){
470 #ifdef EISDIR
471 if( errno==EISDIR ){
472 return SQLITE_CANTOPEN;
473 }
474 #endif
475 id->fd = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
476 if( id->fd<0 ){
477 return SQLITE_CANTOPEN;
478 }
479 *pReadonly = 1;
480 }else{
481 *pReadonly = 0;
482 }
483 sqliteOsEnterMutex();
484 rc = findLockInfo(id->fd, &id->pLock, &id->pOpen);
485 sqliteOsLeaveMutex();
486 if( rc ){
487 close(id->fd);
488 return SQLITE_NOMEM;
489 }
490 id->locked = 0;
491 TRACE3("OPEN %-3d %s\n", id->fd, zFilename);
492 OpenCounter(+1);
493 return SQLITE_OK;
494 #endif
495 #if OS_WIN
496 HANDLE h = CreateFile(zFilename,
497 GENERIC_READ | GENERIC_WRITE,
498 FILE_SHARE_READ | FILE_SHARE_WRITE,
499 NULL,
500 OPEN_ALWAYS,
501 FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
502 NULL
503 );
504 if( h==INVALID_HANDLE_VALUE ){
505 h = CreateFile(zFilename,
506 GENERIC_READ,
507 FILE_SHARE_READ,
508 NULL,
509 OPEN_ALWAYS,
510 FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
511 NULL
512 );
513 if( h==INVALID_HANDLE_VALUE ){
514 return SQLITE_CANTOPEN;
515 }
516 *pReadonly = 1;
517 }else{
518 *pReadonly = 0;
519 }
520 id->h = h;
521 id->locked = 0;
522 OpenCounter(+1);
523 return SQLITE_OK;
524 #endif
525 #if OS_MAC
526 FSSpec fsSpec;
527 # ifdef _LARGE_FILE
528 HFSUniStr255 dfName;
529 FSRef fsRef;
530 if( __path2fss(zFilename, &fsSpec) != noErr ){
531 if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
532 return SQLITE_CANTOPEN;
533 }
534 if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
535 return SQLITE_CANTOPEN;
536 FSGetDataForkName(&dfName);
537 if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
538 fsRdWrShPerm, &(id->refNum)) != noErr ){
539 if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
540 fsRdWrPerm, &(id->refNum)) != noErr ){
541 if (FSOpenFork(&fsRef, dfName.length, dfName.unicode,
542 fsRdPerm, &(id->refNum)) != noErr )
543 return SQLITE_CANTOPEN;
544 else
545 *pReadonly = 1;
546 } else
547 *pReadonly = 0;
548 } else
549 *pReadonly = 0;
550 # else
551 __path2fss(zFilename, &fsSpec);
552 if( !sqliteOsFileExists(zFilename) ){
553 if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
554 return SQLITE_CANTOPEN;
555 }
556 if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNum)) != noErr ){
557 if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrPerm, &(id->refNum)) != noErr ){
558 if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdPerm, &(id->refNum)) != noErr )
559 return SQLITE_CANTOPEN;
560 else
561 *pReadonly = 1;
562 } else
563 *pReadonly = 0;
564 } else
565 *pReadonly = 0;
566 # endif
567 if( HOpenRF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNumRF)) != noErr){
568 id->refNumRF = -1;
569 }
570 id->locked = 0;
571 id->delOnClose = 0;
572 OpenCounter(+1);
573 return SQLITE_OK;
574 #endif
575 }
576
577
578 /*
579 ** Attempt to open a new file for exclusive access by this process.
580 ** The file will be opened for both reading and writing. To avoid
581 ** a potential security problem, we do not allow the file to have
582 ** previously existed. Nor do we allow the file to be a symbolic
583 ** link.
584 **
585 ** If delFlag is true, then make arrangements to automatically delete
586 ** the file when it is closed.
587 **
588 ** On success, write the file handle into *id and return SQLITE_OK.
589 **
590 ** On failure, return SQLITE_CANTOPEN.
591 */
sqliteOsOpenExclusive(const char * zFilename,OsFile * id,int delFlag)592 int sqliteOsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
593 #if OS_UNIX
594 int rc;
595 if( access(zFilename, 0)==0 ){
596 return SQLITE_CANTOPEN;
597 }
598 id->dirfd = -1;
599 id->fd = open(zFilename,
600 O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY, 0600);
601 if( id->fd<0 ){
602 return SQLITE_CANTOPEN;
603 }
604 sqliteOsEnterMutex();
605 rc = findLockInfo(id->fd, &id->pLock, &id->pOpen);
606 sqliteOsLeaveMutex();
607 if( rc ){
608 close(id->fd);
609 unlink(zFilename);
610 return SQLITE_NOMEM;
611 }
612 id->locked = 0;
613 if( delFlag ){
614 unlink(zFilename);
615 }
616 TRACE3("OPEN-EX %-3d %s\n", id->fd, zFilename);
617 OpenCounter(+1);
618 return SQLITE_OK;
619 #endif
620 #if OS_WIN
621 HANDLE h;
622 int fileflags;
623 if( delFlag ){
624 fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS
625 | FILE_FLAG_DELETE_ON_CLOSE;
626 }else{
627 fileflags = FILE_FLAG_RANDOM_ACCESS;
628 }
629 h = CreateFile(zFilename,
630 GENERIC_READ | GENERIC_WRITE,
631 0,
632 NULL,
633 CREATE_ALWAYS,
634 fileflags,
635 NULL
636 );
637 if( h==INVALID_HANDLE_VALUE ){
638 return SQLITE_CANTOPEN;
639 }
640 id->h = h;
641 id->locked = 0;
642 OpenCounter(+1);
643 return SQLITE_OK;
644 #endif
645 #if OS_MAC
646 FSSpec fsSpec;
647 # ifdef _LARGE_FILE
648 HFSUniStr255 dfName;
649 FSRef fsRef;
650 __path2fss(zFilename, &fsSpec);
651 if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
652 return SQLITE_CANTOPEN;
653 if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
654 return SQLITE_CANTOPEN;
655 FSGetDataForkName(&dfName);
656 if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
657 fsRdWrPerm, &(id->refNum)) != noErr )
658 return SQLITE_CANTOPEN;
659 # else
660 __path2fss(zFilename, &fsSpec);
661 if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
662 return SQLITE_CANTOPEN;
663 if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrPerm, &(id->refNum)) != noErr )
664 return SQLITE_CANTOPEN;
665 # endif
666 id->refNumRF = -1;
667 id->locked = 0;
668 id->delOnClose = delFlag;
669 if (delFlag)
670 id->pathToDel = sqliteOsFullPathname(zFilename);
671 OpenCounter(+1);
672 return SQLITE_OK;
673 #endif
674 }
675
676 /*
677 ** Attempt to open a new file for read-only access.
678 **
679 ** On success, write the file handle into *id and return SQLITE_OK.
680 **
681 ** On failure, return SQLITE_CANTOPEN.
682 */
sqliteOsOpenReadOnly(const char * zFilename,OsFile * id)683 int sqliteOsOpenReadOnly(const char *zFilename, OsFile *id){
684 #if OS_UNIX
685 int rc;
686 id->dirfd = -1;
687 id->fd = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
688 if( id->fd<0 ){
689 return SQLITE_CANTOPEN;
690 }
691 sqliteOsEnterMutex();
692 rc = findLockInfo(id->fd, &id->pLock, &id->pOpen);
693 sqliteOsLeaveMutex();
694 if( rc ){
695 close(id->fd);
696 return SQLITE_NOMEM;
697 }
698 id->locked = 0;
699 TRACE3("OPEN-RO %-3d %s\n", id->fd, zFilename);
700 OpenCounter(+1);
701 return SQLITE_OK;
702 #endif
703 #if OS_WIN
704 HANDLE h = CreateFile(zFilename,
705 GENERIC_READ,
706 0,
707 NULL,
708 OPEN_EXISTING,
709 FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
710 NULL
711 );
712 if( h==INVALID_HANDLE_VALUE ){
713 return SQLITE_CANTOPEN;
714 }
715 id->h = h;
716 id->locked = 0;
717 OpenCounter(+1);
718 return SQLITE_OK;
719 #endif
720 #if OS_MAC
721 FSSpec fsSpec;
722 # ifdef _LARGE_FILE
723 HFSUniStr255 dfName;
724 FSRef fsRef;
725 if( __path2fss(zFilename, &fsSpec) != noErr )
726 return SQLITE_CANTOPEN;
727 if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
728 return SQLITE_CANTOPEN;
729 FSGetDataForkName(&dfName);
730 if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
731 fsRdPerm, &(id->refNum)) != noErr )
732 return SQLITE_CANTOPEN;
733 # else
734 __path2fss(zFilename, &fsSpec);
735 if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdPerm, &(id->refNum)) != noErr )
736 return SQLITE_CANTOPEN;
737 # endif
738 if( HOpenRF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNumRF)) != noErr){
739 id->refNumRF = -1;
740 }
741 id->locked = 0;
742 id->delOnClose = 0;
743 OpenCounter(+1);
744 return SQLITE_OK;
745 #endif
746 }
747
748 /*
749 ** Attempt to open a file descriptor for the directory that contains a
750 ** file. This file descriptor can be used to fsync() the directory
751 ** in order to make sure the creation of a new file is actually written
752 ** to disk.
753 **
754 ** This routine is only meaningful for Unix. It is a no-op under
755 ** windows since windows does not support hard links.
756 **
757 ** On success, a handle for a previously open file is at *id is
758 ** updated with the new directory file descriptor and SQLITE_OK is
759 ** returned.
760 **
761 ** On failure, the function returns SQLITE_CANTOPEN and leaves
762 ** *id unchanged.
763 */
sqliteOsOpenDirectory(const char * zDirname,OsFile * id)764 int sqliteOsOpenDirectory(
765 const char *zDirname,
766 OsFile *id
767 ){
768 #if OS_UNIX
769 if( id->fd<0 ){
770 /* Do not open the directory if the corresponding file is not already
771 ** open. */
772 return SQLITE_CANTOPEN;
773 }
774 assert( id->dirfd<0 );
775 id->dirfd = open(zDirname, O_RDONLY|O_BINARY, 0644);
776 if( id->dirfd<0 ){
777 return SQLITE_CANTOPEN;
778 }
779 TRACE3("OPENDIR %-3d %s\n", id->dirfd, zDirname);
780 #endif
781 return SQLITE_OK;
782 }
783
784 /*
785 ** If the following global variable points to a string which is the
786 ** name of a directory, then that directory will be used to store
787 ** temporary files.
788 */
789 const char *sqlite_temp_directory = 0;
790
791 /*
792 ** Create a temporary file name in zBuf. zBuf must be big enough to
793 ** hold at least SQLITE_TEMPNAME_SIZE characters.
794 */
sqliteOsTempFileName(char * zBuf)795 int sqliteOsTempFileName(char *zBuf){
796 #if OS_UNIX
797 static const char *azDirs[] = {
798 0,
799 "/var/tmp",
800 "/usr/tmp",
801 "/tmp",
802 ".",
803 };
804 static unsigned char zChars[] =
805 "abcdefghijklmnopqrstuvwxyz"
806 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
807 "0123456789";
808 int i, j;
809 struct stat buf;
810 const char *zDir = ".";
811 azDirs[0] = sqlite_temp_directory;
812 for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
813 if( azDirs[i]==0 ) continue;
814 if( stat(azDirs[i], &buf) ) continue;
815 if( !S_ISDIR(buf.st_mode) ) continue;
816 if( access(azDirs[i], 07) ) continue;
817 zDir = azDirs[i];
818 break;
819 }
820 do{
821 sprintf(zBuf, "%s/"TEMP_FILE_PREFIX, zDir);
822 j = strlen(zBuf);
823 sqliteRandomness(15, &zBuf[j]);
824 for(i=0; i<15; i++, j++){
825 zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
826 }
827 zBuf[j] = 0;
828 }while( access(zBuf,0)==0 );
829 #endif
830 #if OS_WIN
831 static char zChars[] =
832 "abcdefghijklmnopqrstuvwxyz"
833 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
834 "0123456789";
835 int i, j;
836 const char *zDir;
837 char zTempPath[SQLITE_TEMPNAME_SIZE];
838 if( sqlite_temp_directory==0 ){
839 GetTempPath(SQLITE_TEMPNAME_SIZE-30, zTempPath);
840 for(i=strlen(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
841 zTempPath[i] = 0;
842 zDir = zTempPath;
843 }else{
844 zDir = sqlite_temp_directory;
845 }
846 for(;;){
847 sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zDir);
848 j = strlen(zBuf);
849 sqliteRandomness(15, &zBuf[j]);
850 for(i=0; i<15; i++, j++){
851 zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
852 }
853 zBuf[j] = 0;
854 if( !sqliteOsFileExists(zBuf) ) break;
855 }
856 #endif
857 #if OS_MAC
858 static char zChars[] =
859 "abcdefghijklmnopqrstuvwxyz"
860 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
861 "0123456789";
862 int i, j;
863 char *zDir;
864 char zTempPath[SQLITE_TEMPNAME_SIZE];
865 char zdirName[32];
866 CInfoPBRec infoRec;
867 Str31 dirName;
868 memset(&infoRec, 0, sizeof(infoRec));
869 memset(zTempPath, 0, SQLITE_TEMPNAME_SIZE);
870 if( sqlite_temp_directory!=0 ){
871 zDir = sqlite_temp_directory;
872 }else if( FindFolder(kOnSystemDisk, kTemporaryFolderType, kCreateFolder,
873 &(infoRec.dirInfo.ioVRefNum), &(infoRec.dirInfo.ioDrParID)) == noErr ){
874 infoRec.dirInfo.ioNamePtr = dirName;
875 do{
876 infoRec.dirInfo.ioFDirIndex = -1;
877 infoRec.dirInfo.ioDrDirID = infoRec.dirInfo.ioDrParID;
878 if( PBGetCatInfoSync(&infoRec) == noErr ){
879 CopyPascalStringToC(dirName, zdirName);
880 i = strlen(zdirName);
881 memmove(&(zTempPath[i+1]), zTempPath, strlen(zTempPath));
882 strcpy(zTempPath, zdirName);
883 zTempPath[i] = ':';
884 }else{
885 *zTempPath = 0;
886 break;
887 }
888 } while( infoRec.dirInfo.ioDrDirID != fsRtDirID );
889 zDir = zTempPath;
890 }
891 if( zDir[0]==0 ){
892 getcwd(zTempPath, SQLITE_TEMPNAME_SIZE-24);
893 zDir = zTempPath;
894 }
895 for(;;){
896 sprintf(zBuf, "%s"TEMP_FILE_PREFIX, zDir);
897 j = strlen(zBuf);
898 sqliteRandomness(15, &zBuf[j]);
899 for(i=0; i<15; i++, j++){
900 zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
901 }
902 zBuf[j] = 0;
903 if( !sqliteOsFileExists(zBuf) ) break;
904 }
905 #endif
906 return SQLITE_OK;
907 }
908
909 /*
910 ** Close a file.
911 */
sqliteOsClose(OsFile * id)912 int sqliteOsClose(OsFile *id){
913 #if OS_UNIX
914 sqliteOsUnlock(id);
915 if( id->dirfd>=0 ) close(id->dirfd);
916 id->dirfd = -1;
917 sqliteOsEnterMutex();
918 if( id->pOpen->nLock ){
919 /* If there are outstanding locks, do not actually close the file just
920 ** yet because that would clear those locks. Instead, add the file
921 ** descriptor to pOpen->aPending. It will be automatically closed when
922 ** the last lock is cleared.
923 */
924 int *aNew;
925 struct openCnt *pOpen = id->pOpen;
926 pOpen->nPending++;
927 aNew = sqliteRealloc( pOpen->aPending, pOpen->nPending*sizeof(int) );
928 if( aNew==0 ){
929 /* If a malloc fails, just leak the file descriptor */
930 }else{
931 pOpen->aPending = aNew;
932 pOpen->aPending[pOpen->nPending-1] = id->fd;
933 }
934 }else{
935 /* There are no outstanding locks so we can close the file immediately */
936 close(id->fd);
937 }
938 releaseLockInfo(id->pLock);
939 releaseOpenCnt(id->pOpen);
940 sqliteOsLeaveMutex();
941 TRACE2("CLOSE %-3d\n", id->fd);
942 OpenCounter(-1);
943 return SQLITE_OK;
944 #endif
945 #if OS_WIN
946 CloseHandle(id->h);
947 OpenCounter(-1);
948 return SQLITE_OK;
949 #endif
950 #if OS_MAC
951 if( id->refNumRF!=-1 )
952 FSClose(id->refNumRF);
953 # ifdef _LARGE_FILE
954 FSCloseFork(id->refNum);
955 # else
956 FSClose(id->refNum);
957 # endif
958 if( id->delOnClose ){
959 unlink(id->pathToDel);
960 sqliteFree(id->pathToDel);
961 }
962 OpenCounter(-1);
963 return SQLITE_OK;
964 #endif
965 }
966
967 /*
968 ** Read data from a file into a buffer. Return SQLITE_OK if all
969 ** bytes were read successfully and SQLITE_IOERR if anything goes
970 ** wrong.
971 */
sqliteOsRead(OsFile * id,void * pBuf,int amt)972 int sqliteOsRead(OsFile *id, void *pBuf, int amt){
973 #if OS_UNIX
974 int got;
975 SimulateIOError(SQLITE_IOERR);
976 TIMER_START;
977 got = read(id->fd, pBuf, amt);
978 TIMER_END;
979 TRACE4("READ %-3d %7d %d\n", id->fd, last_page, elapse);
980 SEEK(0);
981 /* if( got<0 ) got = 0; */
982 if( got==amt ){
983 return SQLITE_OK;
984 }else{
985 return SQLITE_IOERR;
986 }
987 #endif
988 #if OS_WIN
989 DWORD got;
990 SimulateIOError(SQLITE_IOERR);
991 TRACE2("READ %d\n", last_page);
992 if( !ReadFile(id->h, pBuf, amt, &got, 0) ){
993 got = 0;
994 }
995 if( got==(DWORD)amt ){
996 return SQLITE_OK;
997 }else{
998 return SQLITE_IOERR;
999 }
1000 #endif
1001 #if OS_MAC
1002 int got;
1003 SimulateIOError(SQLITE_IOERR);
1004 TRACE2("READ %d\n", last_page);
1005 # ifdef _LARGE_FILE
1006 FSReadFork(id->refNum, fsAtMark, 0, (ByteCount)amt, pBuf, (ByteCount*)&got);
1007 # else
1008 got = amt;
1009 FSRead(id->refNum, &got, pBuf);
1010 # endif
1011 if( got==amt ){
1012 return SQLITE_OK;
1013 }else{
1014 return SQLITE_IOERR;
1015 }
1016 #endif
1017 }
1018
1019 /*
1020 ** Write data from a buffer into a file. Return SQLITE_OK on success
1021 ** or some other error code on failure.
1022 */
sqliteOsWrite(OsFile * id,const void * pBuf,int amt)1023 int sqliteOsWrite(OsFile *id, const void *pBuf, int amt){
1024 #if OS_UNIX
1025 int wrote = 0;
1026 SimulateIOError(SQLITE_IOERR);
1027 TIMER_START;
1028 while( amt>0 && (wrote = write(id->fd, pBuf, amt))>0 ){
1029 amt -= wrote;
1030 pBuf = &((char*)pBuf)[wrote];
1031 }
1032 TIMER_END;
1033 TRACE4("WRITE %-3d %7d %d\n", id->fd, last_page, elapse);
1034 SEEK(0);
1035 if( amt>0 ){
1036 return SQLITE_FULL;
1037 }
1038 return SQLITE_OK;
1039 #endif
1040 #if OS_WIN
1041 int rc;
1042 DWORD wrote;
1043 SimulateIOError(SQLITE_IOERR);
1044 TRACE2("WRITE %d\n", last_page);
1045 while( amt>0 && (rc = WriteFile(id->h, pBuf, amt, &wrote, 0))!=0 && wrote>0 ){
1046 amt -= wrote;
1047 pBuf = &((char*)pBuf)[wrote];
1048 }
1049 if( !rc || amt>(int)wrote ){
1050 return SQLITE_FULL;
1051 }
1052 return SQLITE_OK;
1053 #endif
1054 #if OS_MAC
1055 OSErr oserr;
1056 int wrote = 0;
1057 SimulateIOError(SQLITE_IOERR);
1058 TRACE2("WRITE %d\n", last_page);
1059 while( amt>0 ){
1060 # ifdef _LARGE_FILE
1061 oserr = FSWriteFork(id->refNum, fsAtMark, 0,
1062 (ByteCount)amt, pBuf, (ByteCount*)&wrote);
1063 # else
1064 wrote = amt;
1065 oserr = FSWrite(id->refNum, &wrote, pBuf);
1066 # endif
1067 if( wrote == 0 || oserr != noErr)
1068 break;
1069 amt -= wrote;
1070 pBuf = &((char*)pBuf)[wrote];
1071 }
1072 if( oserr != noErr || amt>wrote ){
1073 return SQLITE_FULL;
1074 }
1075 return SQLITE_OK;
1076 #endif
1077 }
1078
1079 /*
1080 ** Move the read/write pointer in a file.
1081 */
sqliteOsSeek(OsFile * id,off_t offset)1082 int sqliteOsSeek(OsFile *id, off_t offset){
1083 SEEK(offset/1024 + 1);
1084 #if OS_UNIX
1085 lseek(id->fd, offset, SEEK_SET);
1086 return SQLITE_OK;
1087 #endif
1088 #if OS_WIN
1089 {
1090 LONG upperBits = offset>>32;
1091 LONG lowerBits = offset & 0xffffffff;
1092 DWORD rc;
1093 rc = SetFilePointer(id->h, lowerBits, &upperBits, FILE_BEGIN);
1094 /* TRACE3("SEEK rc=0x%x upper=0x%x\n", rc, upperBits); */
1095 }
1096 return SQLITE_OK;
1097 #endif
1098 #if OS_MAC
1099 {
1100 off_t curSize;
1101 if( sqliteOsFileSize(id, &curSize) != SQLITE_OK ){
1102 return SQLITE_IOERR;
1103 }
1104 if( offset >= curSize ){
1105 if( sqliteOsTruncate(id, offset+1) != SQLITE_OK ){
1106 return SQLITE_IOERR;
1107 }
1108 }
1109 # ifdef _LARGE_FILE
1110 if( FSSetForkPosition(id->refNum, fsFromStart, offset) != noErr ){
1111 # else
1112 if( SetFPos(id->refNum, fsFromStart, offset) != noErr ){
1113 # endif
1114 return SQLITE_IOERR;
1115 }else{
1116 return SQLITE_OK;
1117 }
1118 }
1119 #endif
1120 }
1121
1122 /*
1123 ** Make sure all writes to a particular file are committed to disk.
1124 **
1125 ** Under Unix, also make sure that the directory entry for the file
1126 ** has been created by fsync-ing the directory that contains the file.
1127 ** If we do not do this and we encounter a power failure, the directory
1128 ** entry for the journal might not exist after we reboot. The next
1129 ** SQLite to access the file will not know that the journal exists (because
1130 ** the directory entry for the journal was never created) and the transaction
1131 ** will not roll back - possibly leading to database corruption.
1132 */
1133 int sqliteOsSync(OsFile *id){
1134 #if OS_UNIX
1135 SimulateIOError(SQLITE_IOERR);
1136 TRACE2("SYNC %-3d\n", id->fd);
1137 if( fsync(id->fd) ){
1138 return SQLITE_IOERR;
1139 }else{
1140 if( id->dirfd>=0 ){
1141 TRACE2("DIRSYNC %-3d\n", id->dirfd);
1142 fsync(id->dirfd);
1143 close(id->dirfd); /* Only need to sync once, so close the directory */
1144 id->dirfd = -1; /* when we are done. */
1145 }
1146 return SQLITE_OK;
1147 }
1148 #endif
1149 #if OS_WIN
1150 if( FlushFileBuffers(id->h) ){
1151 return SQLITE_OK;
1152 }else{
1153 return SQLITE_IOERR;
1154 }
1155 #endif
1156 #if OS_MAC
1157 # ifdef _LARGE_FILE
1158 if( FSFlushFork(id->refNum) != noErr ){
1159 # else
1160 ParamBlockRec params;
1161 memset(¶ms, 0, sizeof(ParamBlockRec));
1162 params.ioParam.ioRefNum = id->refNum;
1163 if( PBFlushFileSync(¶ms) != noErr ){
1164 # endif
1165 return SQLITE_IOERR;
1166 }else{
1167 return SQLITE_OK;
1168 }
1169 #endif
1170 }
1171
1172 /*
1173 ** Truncate an open file to a specified size
1174 */
1175 int sqliteOsTruncate(OsFile *id, off_t nByte){
1176 SimulateIOError(SQLITE_IOERR);
1177 #if OS_UNIX
1178 return ftruncate(id->fd, nByte)==0 ? SQLITE_OK : SQLITE_IOERR;
1179 #endif
1180 #if OS_WIN
1181 {
1182 LONG upperBits = nByte>>32;
1183 SetFilePointer(id->h, nByte, &upperBits, FILE_BEGIN);
1184 SetEndOfFile(id->h);
1185 }
1186 return SQLITE_OK;
1187 #endif
1188 #if OS_MAC
1189 # ifdef _LARGE_FILE
1190 if( FSSetForkSize(id->refNum, fsFromStart, nByte) != noErr){
1191 # else
1192 if( SetEOF(id->refNum, nByte) != noErr ){
1193 # endif
1194 return SQLITE_IOERR;
1195 }else{
1196 return SQLITE_OK;
1197 }
1198 #endif
1199 }
1200
1201 /*
1202 ** Determine the current size of a file in bytes
1203 */
1204 int sqliteOsFileSize(OsFile *id, off_t *pSize){
1205 #if OS_UNIX
1206 struct stat buf;
1207 SimulateIOError(SQLITE_IOERR);
1208 if( fstat(id->fd, &buf)!=0 ){
1209 return SQLITE_IOERR;
1210 }
1211 *pSize = buf.st_size;
1212 return SQLITE_OK;
1213 #endif
1214 #if OS_WIN
1215 DWORD upperBits, lowerBits;
1216 SimulateIOError(SQLITE_IOERR);
1217 lowerBits = GetFileSize(id->h, &upperBits);
1218 *pSize = (((off_t)upperBits)<<32) + lowerBits;
1219 return SQLITE_OK;
1220 #endif
1221 #if OS_MAC
1222 # ifdef _LARGE_FILE
1223 if( FSGetForkSize(id->refNum, pSize) != noErr){
1224 # else
1225 if( GetEOF(id->refNum, pSize) != noErr ){
1226 # endif
1227 return SQLITE_IOERR;
1228 }else{
1229 return SQLITE_OK;
1230 }
1231 #endif
1232 }
1233
1234 #if OS_WIN
1235 /*
1236 ** Return true (non-zero) if we are running under WinNT, Win2K or WinXP.
1237 ** Return false (zero) for Win95, Win98, or WinME.
1238 **
1239 ** Here is an interesting observation: Win95, Win98, and WinME lack
1240 ** the LockFileEx() API. But we can still statically link against that
1241 ** API as long as we don't call it win running Win95/98/ME. A call to
1242 ** this routine is used to determine if the host is Win95/98/ME or
1243 ** WinNT/2K/XP so that we will know whether or not we can safely call
1244 ** the LockFileEx() API.
1245 */
1246 int isNT(void){
1247 static int osType = 0; /* 0=unknown 1=win95 2=winNT */
1248 if( osType==0 ){
1249 OSVERSIONINFO sInfo;
1250 sInfo.dwOSVersionInfoSize = sizeof(sInfo);
1251 GetVersionEx(&sInfo);
1252 osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
1253 }
1254 return osType==2;
1255 }
1256 #endif
1257
1258 /*
1259 ** Windows file locking notes: [similar issues apply to MacOS]
1260 **
1261 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
1262 ** those functions are not available. So we use only LockFile() and
1263 ** UnlockFile().
1264 **
1265 ** LockFile() prevents not just writing but also reading by other processes.
1266 ** (This is a design error on the part of Windows, but there is nothing
1267 ** we can do about that.) So the region used for locking is at the
1268 ** end of the file where it is unlikely to ever interfere with an
1269 ** actual read attempt.
1270 **
1271 ** A database read lock is obtained by locking a single randomly-chosen
1272 ** byte out of a specific range of bytes. The lock byte is obtained at
1273 ** random so two separate readers can probably access the file at the
1274 ** same time, unless they are unlucky and choose the same lock byte.
1275 ** A database write lock is obtained by locking all bytes in the range.
1276 ** There can only be one writer.
1277 **
1278 ** A lock is obtained on the first byte of the lock range before acquiring
1279 ** either a read lock or a write lock. This prevents two processes from
1280 ** attempting to get a lock at a same time. The semantics of
1281 ** sqliteOsReadLock() require that if there is already a write lock, that
1282 ** lock is converted into a read lock atomically. The lock on the first
1283 ** byte allows us to drop the old write lock and get the read lock without
1284 ** another process jumping into the middle and messing us up. The same
1285 ** argument applies to sqliteOsWriteLock().
1286 **
1287 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
1288 ** which means we can use reader/writer locks. When reader writer locks
1289 ** are used, the lock is placed on the same range of bytes that is used
1290 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme
1291 ** will support two or more Win95 readers or two or more WinNT readers.
1292 ** But a single Win95 reader will lock out all WinNT readers and a single
1293 ** WinNT reader will lock out all other Win95 readers.
1294 **
1295 ** Note: On MacOS we use the resource fork for locking.
1296 **
1297 ** The following #defines specify the range of bytes used for locking.
1298 ** N_LOCKBYTE is the number of bytes available for doing the locking.
1299 ** The first byte used to hold the lock while the lock is changing does
1300 ** not count toward this number. FIRST_LOCKBYTE is the address of
1301 ** the first byte in the range of bytes used for locking.
1302 */
1303 #define N_LOCKBYTE 10239
1304 #if OS_MAC
1305 # define FIRST_LOCKBYTE (0x000fffff - N_LOCKBYTE)
1306 #else
1307 # define FIRST_LOCKBYTE (0xffffffff - N_LOCKBYTE)
1308 #endif
1309
1310 /*
1311 ** Change the status of the lock on the file "id" to be a readlock.
1312 ** If the file was write locked, then this reduces the lock to a read.
1313 ** If the file was read locked, then this acquires a new read lock.
1314 **
1315 ** Return SQLITE_OK on success and SQLITE_BUSY on failure. If this
1316 ** library was compiled with large file support (LFS) but LFS is not
1317 ** available on the host, then an SQLITE_NOLFS is returned.
1318 */
1319 int sqliteOsReadLock(OsFile *id){
1320 #if OS_UNIX
1321 int rc;
1322 sqliteOsEnterMutex();
1323 if( id->pLock->cnt>0 ){
1324 if( !id->locked ){
1325 id->pLock->cnt++;
1326 id->locked = 1;
1327 id->pOpen->nLock++;
1328 }
1329 rc = SQLITE_OK;
1330 }else if( id->locked || id->pLock->cnt==0 ){
1331 struct flock lock;
1332 int s;
1333 lock.l_type = F_RDLCK;
1334 lock.l_whence = SEEK_SET;
1335 lock.l_start = lock.l_len = 0L;
1336 s = fcntl(id->fd, F_SETLK, &lock);
1337 if( s!=0 ){
1338 rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
1339 }else{
1340 rc = SQLITE_OK;
1341 if( !id->locked ){
1342 id->pOpen->nLock++;
1343 id->locked = 1;
1344 }
1345 id->pLock->cnt = 1;
1346 }
1347 }else{
1348 rc = SQLITE_BUSY;
1349 }
1350 sqliteOsLeaveMutex();
1351 return rc;
1352 #endif
1353 #if OS_WIN
1354 int rc;
1355 if( id->locked>0 ){
1356 rc = SQLITE_OK;
1357 }else{
1358 int lk;
1359 int res;
1360 int cnt = 100;
1361 sqliteRandomness(sizeof(lk), &lk);
1362 lk = (lk & 0x7fffffff)%N_LOCKBYTE + 1;
1363 while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0))==0 ){
1364 Sleep(1);
1365 }
1366 if( res ){
1367 UnlockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
1368 if( isNT() ){
1369 OVERLAPPED ovlp;
1370 ovlp.Offset = FIRST_LOCKBYTE+1;
1371 ovlp.OffsetHigh = 0;
1372 ovlp.hEvent = 0;
1373 res = LockFileEx(id->h, LOCKFILE_FAIL_IMMEDIATELY,
1374 0, N_LOCKBYTE, 0, &ovlp);
1375 }else{
1376 res = LockFile(id->h, FIRST_LOCKBYTE+lk, 0, 1, 0);
1377 }
1378 UnlockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0);
1379 }
1380 if( res ){
1381 id->locked = lk;
1382 rc = SQLITE_OK;
1383 }else{
1384 rc = SQLITE_BUSY;
1385 }
1386 }
1387 return rc;
1388 #endif
1389 #if OS_MAC
1390 int rc;
1391 if( id->locked>0 || id->refNumRF == -1 ){
1392 rc = SQLITE_OK;
1393 }else{
1394 int lk;
1395 OSErr res;
1396 int cnt = 5;
1397 ParamBlockRec params;
1398 sqliteRandomness(sizeof(lk), &lk);
1399 lk = (lk & 0x7fffffff)%N_LOCKBYTE + 1;
1400 memset(¶ms, 0, sizeof(params));
1401 params.ioParam.ioRefNum = id->refNumRF;
1402 params.ioParam.ioPosMode = fsFromStart;
1403 params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
1404 params.ioParam.ioReqCount = 1;
1405 while( cnt-->0 && (res = PBLockRangeSync(¶ms))!=noErr ){
1406 UInt32 finalTicks;
1407 Delay(1, &finalTicks); /* 1/60 sec */
1408 }
1409 if( res == noErr ){
1410 params.ioParam.ioPosOffset = FIRST_LOCKBYTE+1;
1411 params.ioParam.ioReqCount = N_LOCKBYTE;
1412 PBUnlockRangeSync(¶ms);
1413 params.ioParam.ioPosOffset = FIRST_LOCKBYTE+lk;
1414 params.ioParam.ioReqCount = 1;
1415 res = PBLockRangeSync(¶ms);
1416 params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
1417 params.ioParam.ioReqCount = 1;
1418 PBUnlockRangeSync(¶ms);
1419 }
1420 if( res == noErr ){
1421 id->locked = lk;
1422 rc = SQLITE_OK;
1423 }else{
1424 rc = SQLITE_BUSY;
1425 }
1426 }
1427 return rc;
1428 #endif
1429 }
1430
1431 /*
1432 ** Change the lock status to be an exclusive or write lock. Return
1433 ** SQLITE_OK on success and SQLITE_BUSY on a failure. If this
1434 ** library was compiled with large file support (LFS) but LFS is not
1435 ** available on the host, then an SQLITE_NOLFS is returned.
1436 */
1437 int sqliteOsWriteLock(OsFile *id){
1438 #if OS_UNIX
1439 int rc;
1440 sqliteOsEnterMutex();
1441 if( id->pLock->cnt==0 || (id->pLock->cnt==1 && id->locked==1) ){
1442 struct flock lock;
1443 int s;
1444 lock.l_type = F_WRLCK;
1445 lock.l_whence = SEEK_SET;
1446 lock.l_start = lock.l_len = 0L;
1447 s = fcntl(id->fd, F_SETLK, &lock);
1448 if( s!=0 ){
1449 rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
1450 }else{
1451 rc = SQLITE_OK;
1452 if( !id->locked ){
1453 id->pOpen->nLock++;
1454 id->locked = 1;
1455 }
1456 id->pLock->cnt = -1;
1457 }
1458 }else{
1459 rc = SQLITE_BUSY;
1460 }
1461 sqliteOsLeaveMutex();
1462 return rc;
1463 #endif
1464 #if OS_WIN
1465 int rc;
1466 if( id->locked<0 ){
1467 rc = SQLITE_OK;
1468 }else{
1469 int res;
1470 int cnt = 100;
1471 while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0))==0 ){
1472 Sleep(1);
1473 }
1474 if( res ){
1475 if( id->locked>0 ){
1476 if( isNT() ){
1477 UnlockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
1478 }else{
1479 res = UnlockFile(id->h, FIRST_LOCKBYTE + id->locked, 0, 1, 0);
1480 }
1481 }
1482 if( res ){
1483 res = LockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
1484 }else{
1485 res = 0;
1486 }
1487 UnlockFile(id->h, FIRST_LOCKBYTE, 0, 1, 0);
1488 }
1489 if( res ){
1490 id->locked = -1;
1491 rc = SQLITE_OK;
1492 }else{
1493 rc = SQLITE_BUSY;
1494 }
1495 }
1496 return rc;
1497 #endif
1498 #if OS_MAC
1499 int rc;
1500 if( id->locked<0 || id->refNumRF == -1 ){
1501 rc = SQLITE_OK;
1502 }else{
1503 OSErr res;
1504 int cnt = 5;
1505 ParamBlockRec params;
1506 memset(¶ms, 0, sizeof(params));
1507 params.ioParam.ioRefNum = id->refNumRF;
1508 params.ioParam.ioPosMode = fsFromStart;
1509 params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
1510 params.ioParam.ioReqCount = 1;
1511 while( cnt-->0 && (res = PBLockRangeSync(¶ms))!=noErr ){
1512 UInt32 finalTicks;
1513 Delay(1, &finalTicks); /* 1/60 sec */
1514 }
1515 if( res == noErr ){
1516 params.ioParam.ioPosOffset = FIRST_LOCKBYTE + id->locked;
1517 params.ioParam.ioReqCount = 1;
1518 if( id->locked==0
1519 || PBUnlockRangeSync(¶ms)==noErr ){
1520 params.ioParam.ioPosOffset = FIRST_LOCKBYTE+1;
1521 params.ioParam.ioReqCount = N_LOCKBYTE;
1522 res = PBLockRangeSync(¶ms);
1523 }else{
1524 res = afpRangeNotLocked;
1525 }
1526 params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
1527 params.ioParam.ioReqCount = 1;
1528 PBUnlockRangeSync(¶ms);
1529 }
1530 if( res == noErr ){
1531 id->locked = -1;
1532 rc = SQLITE_OK;
1533 }else{
1534 rc = SQLITE_BUSY;
1535 }
1536 }
1537 return rc;
1538 #endif
1539 }
1540
1541 /*
1542 ** Unlock the given file descriptor. If the file descriptor was
1543 ** not previously locked, then this routine is a no-op. If this
1544 ** library was compiled with large file support (LFS) but LFS is not
1545 ** available on the host, then an SQLITE_NOLFS is returned.
1546 */
1547 int sqliteOsUnlock(OsFile *id){
1548 #if OS_UNIX
1549 int rc;
1550 if( !id->locked ) return SQLITE_OK;
1551 sqliteOsEnterMutex();
1552 assert( id->pLock->cnt!=0 );
1553 if( id->pLock->cnt>1 ){
1554 id->pLock->cnt--;
1555 rc = SQLITE_OK;
1556 }else{
1557 struct flock lock;
1558 int s;
1559 lock.l_type = F_UNLCK;
1560 lock.l_whence = SEEK_SET;
1561 lock.l_start = lock.l_len = 0L;
1562 s = fcntl(id->fd, F_SETLK, &lock);
1563 if( s!=0 ){
1564 rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
1565 }else{
1566 rc = SQLITE_OK;
1567 id->pLock->cnt = 0;
1568 }
1569 }
1570 if( rc==SQLITE_OK ){
1571 /* Decrement the count of locks against this same file. When the
1572 ** count reaches zero, close any other file descriptors whose close
1573 ** was deferred because of outstanding locks.
1574 */
1575 struct openCnt *pOpen = id->pOpen;
1576 pOpen->nLock--;
1577 assert( pOpen->nLock>=0 );
1578 if( pOpen->nLock==0 && pOpen->nPending>0 ){
1579 int i;
1580 for(i=0; i<pOpen->nPending; i++){
1581 close(pOpen->aPending[i]);
1582 }
1583 sqliteFree(pOpen->aPending);
1584 pOpen->nPending = 0;
1585 pOpen->aPending = 0;
1586 }
1587 }
1588 sqliteOsLeaveMutex();
1589 id->locked = 0;
1590 return rc;
1591 #endif
1592 #if OS_WIN
1593 int rc;
1594 if( id->locked==0 ){
1595 rc = SQLITE_OK;
1596 }else if( isNT() || id->locked<0 ){
1597 UnlockFile(id->h, FIRST_LOCKBYTE+1, 0, N_LOCKBYTE, 0);
1598 rc = SQLITE_OK;
1599 id->locked = 0;
1600 }else{
1601 UnlockFile(id->h, FIRST_LOCKBYTE+id->locked, 0, 1, 0);
1602 rc = SQLITE_OK;
1603 id->locked = 0;
1604 }
1605 return rc;
1606 #endif
1607 #if OS_MAC
1608 int rc;
1609 ParamBlockRec params;
1610 memset(¶ms, 0, sizeof(params));
1611 params.ioParam.ioRefNum = id->refNumRF;
1612 params.ioParam.ioPosMode = fsFromStart;
1613 if( id->locked==0 || id->refNumRF == -1 ){
1614 rc = SQLITE_OK;
1615 }else if( id->locked<0 ){
1616 params.ioParam.ioPosOffset = FIRST_LOCKBYTE+1;
1617 params.ioParam.ioReqCount = N_LOCKBYTE;
1618 PBUnlockRangeSync(¶ms);
1619 rc = SQLITE_OK;
1620 id->locked = 0;
1621 }else{
1622 params.ioParam.ioPosOffset = FIRST_LOCKBYTE+id->locked;
1623 params.ioParam.ioReqCount = 1;
1624 PBUnlockRangeSync(¶ms);
1625 rc = SQLITE_OK;
1626 id->locked = 0;
1627 }
1628 return rc;
1629 #endif
1630 }
1631
1632 /*
1633 ** Get information to seed the random number generator. The seed
1634 ** is written into the buffer zBuf[256]. The calling function must
1635 ** supply a sufficiently large buffer.
1636 */
1637 int sqliteOsRandomSeed(char *zBuf){
1638 /* We have to initialize zBuf to prevent valgrind from reporting
1639 ** errors. The reports issued by valgrind are incorrect - we would
1640 ** prefer that the randomness be increased by making use of the
1641 ** uninitialized space in zBuf - but valgrind errors tend to worry
1642 ** some users. Rather than argue, it seems easier just to initialize
1643 ** the whole array and silence valgrind, even if that means less randomness
1644 ** in the random seed.
1645 **
1646 ** When testing, initializing zBuf[] to zero is all we do. That means
1647 ** that we always use the same random number sequence.* This makes the
1648 ** tests repeatable.
1649 */
1650 memset(zBuf, 0, 256);
1651 #if OS_UNIX && !defined(SQLITE_TEST)
1652 {
1653 int pid;
1654 time((time_t*)zBuf);
1655 pid = getpid();
1656 memcpy(&zBuf[sizeof(time_t)], &pid, sizeof(pid));
1657 }
1658 #endif
1659 #if OS_WIN && !defined(SQLITE_TEST)
1660 GetSystemTime((LPSYSTEMTIME)zBuf);
1661 #endif
1662 #if OS_MAC
1663 {
1664 int pid;
1665 Microseconds((UnsignedWide*)zBuf);
1666 pid = getpid();
1667 memcpy(&zBuf[sizeof(UnsignedWide)], &pid, sizeof(pid));
1668 }
1669 #endif
1670 return SQLITE_OK;
1671 }
1672
1673 /*
1674 ** Sleep for a little while. Return the amount of time slept.
1675 */
1676 int sqliteOsSleep(int ms){
1677 #if OS_UNIX
1678 #if defined(HAVE_USLEEP) && HAVE_USLEEP
1679 usleep(ms*1000);
1680 return ms;
1681 #else
1682 sleep((ms+999)/1000);
1683 return 1000*((ms+999)/1000);
1684 #endif
1685 #endif
1686 #if OS_WIN
1687 Sleep(ms);
1688 return ms;
1689 #endif
1690 #if OS_MAC
1691 UInt32 finalTicks;
1692 UInt32 ticks = (((UInt32)ms+16)*3)/50; /* 1/60 sec per tick */
1693 Delay(ticks, &finalTicks);
1694 return (int)((ticks*50)/3);
1695 #endif
1696 }
1697
1698 /*
1699 ** Static variables used for thread synchronization
1700 */
1701 static int inMutex = 0;
1702 #ifdef SQLITE_UNIX_THREADS
1703 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
1704 #endif
1705 #ifdef SQLITE_W32_THREADS
1706 static CRITICAL_SECTION cs;
1707 #endif
1708 #ifdef SQLITE_MACOS_MULTITASKING
1709 static MPCriticalRegionID criticalRegion;
1710 #endif
1711
1712 /*
1713 ** The following pair of routine implement mutual exclusion for
1714 ** multi-threaded processes. Only a single thread is allowed to
1715 ** executed code that is surrounded by EnterMutex() and LeaveMutex().
1716 **
1717 ** SQLite uses only a single Mutex. There is not much critical
1718 ** code and what little there is executes quickly and without blocking.
1719 */
1720 void sqliteOsEnterMutex(){
1721 #ifdef SQLITE_UNIX_THREADS
1722 pthread_mutex_lock(&mutex);
1723 #endif
1724 #ifdef SQLITE_W32_THREADS
1725 static int isInit = 0;
1726 while( !isInit ){
1727 static long lock = 0;
1728 if( InterlockedIncrement(&lock)==1 ){
1729 InitializeCriticalSection(&cs);
1730 isInit = 1;
1731 }else{
1732 Sleep(1);
1733 }
1734 }
1735 EnterCriticalSection(&cs);
1736 #endif
1737 #ifdef SQLITE_MACOS_MULTITASKING
1738 static volatile int notInit = 1;
1739 if( notInit ){
1740 if( notInit == 2 ) /* as close as you can get to thread safe init */
1741 MPYield();
1742 else{
1743 notInit = 2;
1744 MPCreateCriticalRegion(&criticalRegion);
1745 notInit = 0;
1746 }
1747 }
1748 MPEnterCriticalRegion(criticalRegion, kDurationForever);
1749 #endif
1750 assert( !inMutex );
1751 inMutex = 1;
1752 }
1753 void sqliteOsLeaveMutex(){
1754 assert( inMutex );
1755 inMutex = 0;
1756 #ifdef SQLITE_UNIX_THREADS
1757 pthread_mutex_unlock(&mutex);
1758 #endif
1759 #ifdef SQLITE_W32_THREADS
1760 LeaveCriticalSection(&cs);
1761 #endif
1762 #ifdef SQLITE_MACOS_MULTITASKING
1763 MPExitCriticalRegion(criticalRegion);
1764 #endif
1765 }
1766
1767 /*
1768 ** Turn a relative pathname into a full pathname. Return a pointer
1769 ** to the full pathname stored in space obtained from sqliteMalloc().
1770 ** The calling function is responsible for freeing this space once it
1771 ** is no longer needed.
1772 */
1773 char *sqliteOsFullPathname(const char *zRelative){
1774 #if OS_UNIX
1775 char *zFull = 0;
1776 if( zRelative[0]=='/' ){
1777 sqliteSetString(&zFull, zRelative, (char*)0);
1778 }else{
1779 char zBuf[5000];
1780 sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), "/", zRelative,
1781 (char*)0);
1782 }
1783 return zFull;
1784 #endif
1785 #if OS_WIN
1786 char *zNotUsed;
1787 char *zFull;
1788 int nByte;
1789 nByte = GetFullPathName(zRelative, 0, 0, &zNotUsed) + 1;
1790 zFull = sqliteMalloc( nByte );
1791 if( zFull==0 ) return 0;
1792 GetFullPathName(zRelative, nByte, zFull, &zNotUsed);
1793 return zFull;
1794 #endif
1795 #if OS_MAC
1796 char *zFull = 0;
1797 if( zRelative[0]==':' ){
1798 char zBuf[_MAX_PATH+1];
1799 sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), &(zRelative[1]),
1800 (char*)0);
1801 }else{
1802 if( strchr(zRelative, ':') ){
1803 sqliteSetString(&zFull, zRelative, (char*)0);
1804 }else{
1805 char zBuf[_MAX_PATH+1];
1806 sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), zRelative, (char*)0);
1807 }
1808 }
1809 return zFull;
1810 #endif
1811 }
1812
1813 /*
1814 ** The following variable, if set to a non-zero value, becomes the result
1815 ** returned from sqliteOsCurrentTime(). This is used for testing.
1816 */
1817 #ifdef SQLITE_TEST
1818 int sqlite_current_time = 0;
1819 #endif
1820
1821 /*
1822 ** Find the current time (in Universal Coordinated Time). Write the
1823 ** current time and date as a Julian Day number into *prNow and
1824 ** return 0. Return 1 if the time and date cannot be found.
1825 */
1826 int sqliteOsCurrentTime(double *prNow){
1827 #if OS_UNIX
1828 time_t t;
1829 time(&t);
1830 *prNow = t/86400.0 + 2440587.5;
1831 #endif
1832 #if OS_WIN
1833 FILETIME ft;
1834 /* FILETIME structure is a 64-bit value representing the number of
1835 100-nanosecond intervals since January 1, 1601 (= JD 2305813.5).
1836 */
1837 double now;
1838 GetSystemTimeAsFileTime( &ft );
1839 now = ((double)ft.dwHighDateTime) * 4294967296.0;
1840 *prNow = (now + ft.dwLowDateTime)/864000000000.0 + 2305813.5;
1841 #endif
1842 #ifdef SQLITE_TEST
1843 if( sqlite_current_time ){
1844 *prNow = sqlite_current_time/86400.0 + 2440587.5;
1845 }
1846 #endif
1847 return 0;
1848 }
1849