view lib/ftruncate.c @ 6259:96c32553b4c6

Use a consistent style for including <config.h>. * __fpending.c, acl.c, argmatch.c, argp-help.c, argp-parse.c, argp-pvh.c, backupfile.c, basename.c, c-stack.c, calloc.c, check-version.c, cloexec.c, closeout.c, copy-file.c, creat-safer.c, cycle-check.c, dirfd.c, dirname.c, dup-safer.c, dup2.c, euidaccess.c, exclude.c, exitfail.c, fatal-signal.c, fd-safer.c, file-type.c, fileblocks.c, filemode.c, filenamecat.c, findprog.c, fnmatch.c, fopen-safer.c, free.c, fsusage.c, ftruncate.c, full-write.c, fwriteerror.c, getaddrinfo.c, getcwd.c, getdelim.c, getline.c, getlogin_r.c, getndelim2.c, getnline.c, getopt1.c, getpass.c, group-member.c, hard-locale.c, hash-pjw.c, hash.c, human.c, idcache.c, inet_ntop.c, isdir.c, long-options.c, malloc.c, memcasecmp.c, memcmp.c, memcoll.c, memcpy.c, memmove.c, mkdir-p.c, modechange.c, mountlist.c, open-safer.c, physmem.c, pipe-safer.c, pipe.c, poll.c, posixver.c, progname.c, progreloc.c, putenv.c, quote.c, quotearg.c, readline.c, readlink.c, realloc.c, regex.c, rename.c, rmdir.c, rpmatch.c, safe-read.c, same.c, save-cwd.c, savedir.c, sig2str.c, strcspn.c, strerror.c, stripslash.c, strncasecmp.c, strndup.c, strnlen.c, strnlen1.c, strsep.c, strstr.c, strtod.c, strtoimax.c, strtol.c, strverscmp.c, tempname.c, time_r.c, userspec.c, utimecmp.c, version-etc-fsf.c, version-etc.c, wait-process.c, xalloc-die.c, xgetcwd.c, xmalloc.c, xmemcoll.c, xnanosleep.c, xreadlink.c, xsetenv.c, xstrndup.c, xstrtoimax.c, xstrtol.c, xstrtoumax.c, yesno.c: Standardize inclusion of config.h. * __fpending.h, dirfd.h, getdate.h, human.h, inttostr.h: Removed inclusion of config.h from header files. * inttostr.c: Adjusted in-tree users. * timespec.h: Remove superfluous warning to include config.h. * atexit.c, chdir-long.c chown.c, fchown-stub.c, getgroups.c, gettimeofday.c, lchown.c, lstat.c, mkdir.c, mkstemp.c, nanosleep.c, openat.c, raise.c, readtokens0.c, readutmp.c, unlinkdir.c: Guard inclusion of config.h with HAVE_CONFIG_H.
author Paul Eggert <eggert@cs.ucla.edu>
date Mon, 19 Sep 2005 17:28:14 +0000
parents a535859efd14
children fd0ccce602e4
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>
#  if HAVE_UNISTD_H
#   include <unistd.h>
#  endif

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 */