kc3-lang/gnulib/lib/ftruncate.c

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• Hash : 0632e115
  Author :
  Date : 2006-09-13T22:38:14
  

  * _fpending.c: Include <config.h> unconditionally, since we no
  longer worry about uses that don't define HAVE_CONFIG_H.
  * acl.c, alloca.c, argmatch.c, atexit.c, backupfile.c:
  * basename.c, c-stack.c, c-strtod.c, calloc.c, canon-host.c:
  * canonicalize.c, chdir-long.c, chdir-safer.c, chown.c:
  * cloexec.c, close-stream.c, closeout.c, creat-safer.c:
  * cycle-check.c, diacrit.c, dirchownmod.c, dirfd.c, dirname.c:
  * dup-safer.c, dup2.c, error.c, euidaccess.c, exclude.c:
  * exitfail.c, fchmodat.c, fchown-stub.c, fd-safer.c:
  * file-type.c, fileblocks.c, filemode.c, filenamecat.c:
  * fnmatch.c, fopen-safer.c, fprintftime.c, free.c, fsusage.c:
  * ftruncate.c, fts-cycle.c, fts.c, full-write.c, gai_strerror.c:
  * getcwd.c, getdate.y, getdomainname.c, getgroups.c:
  * gethostname.c, gethrxtime.c, getloadavg.c, getlogin_r.c:
  * getndelim2.c, getnline.c, getopt.c, getopt1.c, getpass.c:
  * gettime.c, gettimeofday.c, getugroups.c, getusershell.c:
  * glob.c, group-member.c, hard-locale.c, hash-pjw.c, hash.c:
  * human.c, idcache.c, inet_ntop.c, inet_pton.c, inttostr.c:
  * isdir.c, lchown.c, linebuffer.c, long-options.c, lstat.c:
  * malloc.c, md5.c, memcasecmp.c, memchr.c, memcmp.c, memcoll.c:
  * memcpy.c, memmove.c, memrchr.c, mkancesdirs.c, mkdir-p.c:
  * mkdir.c, mkdirat.c, mkstemp-safer.c, mkstemp.c, modechange.c:
  * mountlist.c, nanosleep.c, obstack.c, open-safer.c:
  * openat-die.c, openat.c, pagealign_alloc.c, physmem.c:
  * pipe-safer.c, posixtm.c, posixver.c, putenv.c, quote.c:
  * quotearg.c, raise.c, readtokens.c, readtokens0.c, readutmp.c:
  * realloc.c, regex.c, rename.c, rmdir.c, rpmatch.c, safe-read.c:
  * same.c, save-cwd.c, savedir.c, setenv.c, settime.c, sha1.c:
  * sig2str.c, snprintf.c, strdup.c, strerror.c, strftime.c:
  * stripslash.c, strndup.c, strnlen.c, strpbrk.c, strtod.c:
  * strtoimax.c, strtol.c, strverscmp.c, tempname.c, time_r.c:
  * timegm.c, tmpfile-safer.c, unlinkdir.c, userspec.c, utime.c:
  * utimecmp.c, utimens.c, version-etc-fsf.c, version-etc.c:
  * xalloc-die.c, xgetcwd.c, xgethostname.c, xmalloc.c:
  * xmemcoll.c, xnanosleep.c, xreadlink.c, xstrtod.c:
  * xstrtoimax.c, xstrtol.c, xstrtoumax.c, yesno.c:
  Likewise.
  

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• lib/ftruncate.c

• /* ftruncate emulations that work on some System V's.
     This file is in the public domain.  */
  
  #include <config.h>
  
  #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 */
  

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