64 lines
1.1 KiB
C
64 lines
1.1 KiB
C
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#ifndef LINT
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static const char rcsid[] = "$Id: ftruncate.c,v 1.1.1.1 2001/05/17 22:48:45 itojun Exp $";
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#endif
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/*
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* ftruncate - set file size, BSD Style
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*
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* shortens or enlarges the file as neeeded
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* uses some undocumented locking call. It is known to work on SCO unix,
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* other vendors should try.
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* The #error directive prevents unsupported OSes
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*/
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#include "port_before.h"
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#if defined(M_UNIX)
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#define OWN_FTRUNCATE
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#include <stdio.h>
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#ifdef _XOPEN_SOURCE
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#undef _XOPEN_SOURCE
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#endif
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#ifdef _POSIX_SOURCE
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#undef _POSIX_SOURCE
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#endif
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#include <fcntl.h>
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#include "port_after.h"
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int
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__ftruncate(int fd, long wantsize) {
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long cursize;
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/* determine current file size */
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if ((cursize = lseek(fd, 0L, 2)) == -1)
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return (-1);
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/* maybe lengthen... */
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if (cursize < wantsize) {
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if (lseek(fd, wantsize - 1, 0) == -1 ||
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write(fd, "", 1) == -1) {
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return (-1);
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}
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return (0);
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}
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/* maybe shorten... */
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if (wantsize < cursize) {
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struct flock fl;
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fl.l_whence = 0;
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fl.l_len = 0;
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fl.l_start = wantsize;
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fl.l_type = F_WRLCK;
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return (fcntl(fd, F_FREESP, &fl));
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}
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return (0);
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}
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#endif
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#ifndef OWN_FTRUNCATE
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int __bindcompat_ftruncate;
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#endif
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