view lib/ftruncate.c @ 6275:fd0ccce602e4

Sync from coreutils. * .cppi-disable: Add regcomp.c, regex_internal.c, regex_internal.h, stat-time.h. * argmatch.h: Include verify.h (ARGMATCH_VERIFY): Use verify rather than rolling our own. (ARGMATCH_ASSERT): Remove; unused. * canonicalize.c: Assume STDC_HEADERS. * exclude.c: Include "strcase.h". * regex_internal.h [!defined _LIBC]: Likewise. * getusershell.c: Include stdio--.h rather than stdio.h and stdio-safer.h. (getusershell): Call fopen, not fopen_safer. * save-cwd.c: Include fcntl--.h rather than fcntl.h. Do not include unistd-safer.h. (save_cwd): Don't call fd_safer; no longer needed now that we include fcntl--.h. * modules/argmatch (Depends-on): Add verify. * modules/getloadavg (Depends-on): Depend on fcntl-safer, not unistd-safer. * modules/save-cwd (Depends-on): Likewise. * backupfile.m4, calloc.m4, chown.m4, cloexec.m4, dup2.m4: * fileblocks.m4, free.m4, ftruncate.m4, getcwd.m4, getpagesize.m4: * getugroups.m4, group-member.m4, idcache.m4, link-follow.m4: * mkstemp.m4, mktime.m4, mountlist.m4, nanosleep.m4, pathmax.m4: * physmem.m4, posixver.m4, putenv.m4, safe-read.m4, same.m4: * save-cwd.m4, stdio-safer.m4, unistd-safer.m4, unlinkdir.m4: * userspec.m4, xgetcwd.m4, xreadlink.m4: Don't bother checking for string.h, stdlib.h, unistd.h. * fts.m4 (gl_FUNC_FTS_CORE): Don't require AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK; that's now the lstat module's job. * jm-macros.m4 (gl_MACROS): Likewise. * prereq.m4 (gl_PREREQ): Add gl_FUNC_LSTAT. * backupfile.c: Use ARGMATCH_VERIFY, just in case. * posixtm.c (posixtime) [lint]: Initialize *all* of tm0, not just the .tm_year member, since otherwise gcc-4.0 would now warn about tm_zone, tm_gmtoff, tm_isdst, tm_yday, tm_wday. * quotearg.c (quotearg_n_options): Change code to be suboptimal, in order to avoid an unsuppressible warning from gcc on 64-bit systems. * lstat.m4 (gl_FUNC_LSTAT): Use AC_LIBSOURCES to require lstat.c and lstat.h. Remove obsolete comment. * xreadlink.m4: Use AC_LIBSOURCES and AC_LIBOBJ. * xstrtod.m4: Likewise.
author Paul Eggert <eggert@cs.ucla.edu>
date Fri, 23 Sep 2005 04:15:13 +0000
parents 96c32553b4c6
children 8a1a9361108c
line wrap: on
line source

/* 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 (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>
#  include <unistd.h>

int
ftruncate (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 */
#  if HAVE_CHSIZE

int
ftruncate (int fd, off_t length)
{
  return chsize (fd, length);
}

#  else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */

#   include <errno.h>

int
ftruncate (int fd, off_t length)
{
  errno = EIO;
  return -1;
}

#  endif /* not HAVE_CHSIZE */
# endif /* not F_FREESP */
#endif /* not F_CHSIZE */