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[/] [open8_urisc/] [trunk/] [gnu/] [binutils/] [gold/] [ftruncate.c] - Blame information for rev 41

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Line No. Rev Author Line
1 27 khays
/* ftruncate emulations that work on some System V's.
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   This file is in the public domain.  */
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#include <config.h>
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/* Specification.  */
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#include <unistd.h>
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#include <sys/types.h>
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#include <fcntl.h>
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extern int ftruncate (int, off_t);
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#ifdef F_CHSIZE
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int
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ftruncate (int fd, off_t length)
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{
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  return fcntl (fd, F_CHSIZE, length);
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}
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#else /* not F_CHSIZE */
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# ifdef F_FREESP
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/* By William Kucharski <kucharsk@netcom.com>.  */
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#  include <sys/stat.h>
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#  include <errno.h>
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int
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ftruncate (int fd, off_t length)
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{
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  struct flock fl;
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  struct stat filebuf;
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  if (fstat (fd, &filebuf) < 0)
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    return -1;
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  if (filebuf.st_size < length)
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    {
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      /* Extend file length. */
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      if (lseek (fd, (length - 1), SEEK_SET) < 0)
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        return -1;
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      /* Write a "0" byte. */
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      if (write (fd, "", 1) != 1)
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        return -1;
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    }
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  else
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    {
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      /* Truncate length. */
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      fl.l_whence = 0;
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      fl.l_len = 0;
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      fl.l_start = length;
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      fl.l_type = F_WRLCK;      /* write lock on file space */
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      /* This relies on the *undocumented* F_FREESP argument to fcntl,
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         which truncates the file so that it ends at the position
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         indicated by fl.l_start.  Will minor miracles never cease?  */
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      if (fcntl (fd, F_FREESP, &fl) < 0)
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        return -1;
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    }
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  return 0;
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}
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# else /* not F_CHSIZE nor F_FREESP */
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#  if HAVE_CHSIZE                      /* native Windows, e.g. mingw */
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int
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ftruncate (int fd, off_t length)
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{
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  return chsize (fd, length);
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}
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#  else /* not F_CHSIZE nor F_FREESP nor HAVE_CHSIZE */
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#   include <errno.h>
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int
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ftruncate (int fd, off_t length)
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{
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  errno = EIO;
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  return -1;
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}
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#  endif /* not HAVE_CHSIZE */
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# endif /* not F_FREESP */
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#endif /* not F_CHSIZE */

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