home *** CD-ROM | disk | FTP | other *** search
- /* ftruncate emulations that work on some System V's.
- This file is in the public domain. */
-
- #ifdef HAVE_CONFIG_H
- #include <config.h>
- #endif
-
- #include <sys/types.h>
- #include <fcntl.h>
-
- #ifdef F_CHSIZE
-
- int
- ftruncate (fd, length)
- int fd;
- off_t length;
- {
- return fcntl (fd, F_CHSIZE, length);
- }
-
- #else /* not F_CHSIZE */
- #ifdef F_FREESP
-
- /* By William Kucharski <kucharsk@netcom.com>. */
-
- #include <sys/stat.h>
- #include <errno.h>
- #ifdef HAVE_UNISTD_H
- #include <unistd.h>
- #endif
-
- int
- ftruncate (fd, length)
- int fd;
- off_t length;
- {
- struct flock fl;
- struct stat filebuf;
-
- if (fstat (fd, &filebuf) < 0)
- return -1;
-
- if (filebuf.st_size < length)
- {
- /* Extend file length. */
- if (lseek (fd, (length - 1), SEEK_SET) < 0)
- return -1;
-
- /* Write a "0" byte. */
- if (write (fd, "", 1) != 1)
- return -1;
- }
- else
- {
-
- /* Truncate length. */
-
- fl.l_whence = 0;
- fl.l_len = 0;
- fl.l_start = length;
- fl.l_type = F_WRLCK; /* write lock on file space */
-
- /* This relies on the *undocumented* F_FREESP argument to fcntl,
- which truncates the file so that it ends at the position
- indicated by fl.l_start. Will minor miracles never cease? */
-
- if (fcntl (fd, F_FREESP, &fl) < 0)
- return -1;
- }
-
- return 0;
- }
-
- #else /* not F_CHSIZE nor F_FREESP */
- #ifdef HAVE_CHSIZE
-
- int
- ftruncate (fd, length)
- int fd;
- off_t length;
- {
- return chsize (fd, length);
- }
-
- #else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */
-
- #include <errno.h>
- #ifndef errno
- extern int errno;
- #endif
-
- int
- ftruncate (fd, length)
- int fd;
- off_t length;
- {
- errno = EIO;
- return -1;
- }
-
- #endif /* not HAVE_CHSIZE */
- #endif /* not F_FREESP */
- #endif /* not F_CHSIZE */
-