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If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] .TH truncate 3C "5 Apr 2002" "SunOS 5.11" "Standard C Library Functions" .SH NAME truncate, ftruncate \- set a file to a specified length .SH SYNOPSIS .LP .nf #include \fBint\fR \fBtruncate\fR(\fBconst char *\fR\fIpath\fR, \fBoff_t\fR \fIlength\fR); .fi .LP .nf \fBint\fR \fBftruncate\fR(\fBint\fR \fIfildes\fR, \fBoff_t\fR \fIlength\fR); .fi .SH DESCRIPTION .sp .LP The \fBtruncate()\fR function causes the regular file named by \fIpath\fR to have a size equal to \fIlength\fR bytes. .sp .LP If the file previously was larger than \fIlength\fR, the extra data is discarded. If the file was previously shorter than length, its size is increased, and the extended area appears as if it were zero-filled. .sp .LP The application must ensure that the process has write permission for the file. .sp .LP This function does not modify the file offset for any open file descriptions associated with the file. .sp .LP The \fBftruncate()\fR function causes the regular file referenced by \fIfildes\fR to be truncated to \fIlength\fR. If the size of the file previously exceeded \fIlength\fR, the extra data is no longer available to reads on the file. If the file previously was smaller than this size, \fBftruncate()\fR increases the size of the file with the extended area appearing as if it were zero-filled. The value of the seek pointer is not modified by a call to \fBftruncate()\fR. .sp .LP The \fBftruncate()\fR function works only with regular files and shared memory. If \fIfildes\fR refers to a shared memory object, \fBftruncate()\fR sets the size of the shared memory object to \fIlength\fR. If \fIfildes\fR refers to a directory or is not a valid file descriptor open for writing, \fBftruncate()\fR fails. .sp .LP If the effect of \fBftruncate()\fR is to decrease the size of a shared memory object or memory mapped file and whole pages beyond the new end were previously mapped, then the whole pages beyond the new end shall be discarded. .sp .LP If the effect of \fBftruncate()\fR is to increase the size of a shared memory object, it is unspecified if the contents of any mapped pages between the old end-of-file and the new are flushed to the underlying object. .sp .LP These functions do not modify the file offset for any open file descriptions associated with the file. On successful completion, if the file size is changed, these functions will mark for update the \fBst_ctime\fR and \fBst_mtime\fR fields of the file, and if the file is a regular file, the \fBS_ISUID\fR and \fBS_ISGID\fR bits of the file mode are left unchanged. .sp .LP If the request would cause the file size to exceed the soft file size limit for the process, the request will fail and a \fBSIGXFSZ\fR signal will be generated for the process. .SH RETURN VALUES .sp .LP Upon successful completion, \fBftruncate()\fR and \fBtruncate()\fR return \fB0\fR. Otherwise, \fB\(mi1\fR is returned and \fBerrno\fR is set to indicate the error. .SH ERRORS .sp .LP The \fBftruncate()\fR and \fBtruncate()\fR functions will fail if: .sp .ne 2 .mk .na \fB\fBEINTR\fR\fR .ad .RS 19n .rt A signal was caught during execution. .RE .sp .ne 2 .mk .na \fB\fBEINVAL\fR\fR .ad .RS 19n .rt The \fIlength\fR argument was less than 0. .RE .sp .ne 2 .mk .na \fB\fBEFBIG\fR or \fBEINVAL\fR\fR .ad .RS 19n .rt The \fIlength\fR argument was greater than the maximum file size. .RE .sp .ne 2 .mk .na \fB\fBEIO\fR\fR .ad .RS 19n .rt An I/O error occurred while reading from or writing to a file system. .RE .sp .ne 2 .mk .na \fB\fBEROFS\fR\fR .ad .RS 19n .rt The named file resides on a read-only file system. .RE .sp .LP The \fBtruncate()\fR function will fail if: .sp .ne 2 .mk .na \fB\fBEACCES\fR\fR .ad .RS 16n .rt A component of the path prefix denies search permission, or write permission is denied on the file. .RE .sp .ne 2 .mk .na \fB\fBEFAULT\fR\fR .ad .RS 16n .rt The \fIpath\fR argument points outside the process' allocated address space. .RE .sp .ne 2 .mk .na \fB\fBEINVAL\fR\fR .ad .RS 16n .rt The \fIpath\fR argument is not an ordinary file. .RE .sp .ne 2 .mk .na \fB\fBEISDIR\fR\fR .ad .RS 16n .rt The named file is a directory. .RE .sp .ne 2 .mk .na \fB\fBELOOP\fR\fR .ad .RS 16n .rt Too many symbolic links were encountered in resolving \fIpath\fR. .RE .sp .ne 2 .mk .na \fB\fBEMFILE\fR\fR .ad .RS 16n .rt The maximum number of file descriptors available to the process has been reached. .RE .sp .ne 2 .mk .na \fB\fBENAMETOOLONG\fR\fR .ad .RS 16n .rt The length of the specified pathname exceeds {\fBPATH_MAX\fR} bytes, or the length of a component of the pathname exceeds {\fBNAME_MAX\fR} bytes. .RE .sp .ne 2 .mk .na \fB\fBENOENT\fR\fR .ad .RS 16n .rt A component of \fIpath\fR does not name an existing file or \fIpath\fR is an empty string. .RE .sp .ne 2 .mk .na \fB\fBENFILE\fR\fR .ad .RS 16n .rt Additional space could not be allocated for the system file table. .RE .sp .ne 2 .mk .na \fB\fBENOTDIR\fR\fR .ad .RS 16n .rt A component of the path prefix of \fIpath\fR is not a directory. .RE .sp .ne 2 .mk .na \fB\fBENOLINK\fR\fR .ad .RS 16n .rt The \fIpath\fR argument points to a remote machine and the link to that machine is no longer active. .RE .sp .LP The \fBftruncate()\fR function will fail if: .sp .ne 2 .mk .na \fB\fBEAGAIN\fR\fR .ad .RS 19n .rt The file exists, mandatory file/record locking is set, and there are outstanding record locks on the file (see \fBchmod\fR(2)). .RE .sp .ne 2 .mk .na \fB\fBEBADF\fR or \fBEINVAL\fR\fR .ad .RS 19n .rt The \fIfildes\fR argument is not a file descriptor open for writing. .RE .sp .ne 2 .mk .na \fB\fBEFBIG\fR\fR .ad .RS 19n .rt The file is a regular file and \fIlength\fR is greater than the offset maximum established in the open file description associated with \fIfildes\fR. .RE .sp .ne 2 .mk .na \fB\fBEINVAL\fR\fR .ad .RS 19n .rt The \fIfildes\fR argument references a file that was opened without write permission. .RE .sp .ne 2 .mk .na \fB\fBEINVAL\fR\fR .ad .RS 19n .rt The \fIfildes\fR argument does not correspond to an ordinary file. .RE .sp .ne 2 .mk .na \fB\fBENOLINK\fR\fR .ad .RS 19n .rt The \fIfildes\fR argument points to a remote machine and the link to that machine is no longer active. .RE .sp .LP The \fBtruncate()\fR function may fail if: .sp .ne 2 .mk .na \fB\fBENAMETOOLONG\fR\fR .ad .RS 16n .rt Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {\fBPATH_MAX\fR}. .RE .SH USAGE .sp .LP The \fBtruncate()\fR and \fBftruncate()\fR functions have transitional interfaces for 64-bit file offsets. See \fBlf64\fR(5). .SH ATTRIBUTES .sp .LP See \fBattributes\fR(5) for descriptions of the following attributes: .sp .sp .TS tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) . ATTRIBUTE TYPEATTRIBUTE VALUE _ Interface StabilityStandard _ MT-LevelMT-Safe .TE .SH SEE ALSO .sp .LP \fBchmod\fR(2), \fBfcntl\fR(2), \fBopen\fR(2), \fBattributes\fR(5), \fBlf64\fR(5), \fBstandards\fR(5)