1#ifndef LINT
2static const char rcsid[] = "$Id: ftruncate.c,v 1.3 2005/04/27 18:16:45 sra Exp $";
3#endif
4
5/*! \file
6 * \brief
7 * ftruncate - set file size, BSD Style
8 *
9 * shortens or enlarges the file as neeeded
10 * uses some undocumented locking call. It is known to work on SCO unix,
11 * other vendors should try.
12 * The #error directive prevents unsupported OSes
13 */
14
15#include "port_before.h"
16
17#if defined(M_UNIX)
18#define OWN_FTRUNCATE
19#include <stdio.h>
20#ifdef _XOPEN_SOURCE
21#undef _XOPEN_SOURCE
22#endif
23#ifdef _POSIX_SOURCE
24#undef _POSIX_SOURCE
25#endif
26
27#include <fcntl.h>
28
29#include "port_after.h"
30
31int
32__ftruncate(int fd, long wantsize) {
33	long cursize;
34
35	/* determine current file size */
36	if ((cursize = lseek(fd, 0L, 2)) == -1)
37		return (-1);
38
39	/* maybe lengthen... */
40	if (cursize < wantsize) {
41		if (lseek(fd, wantsize - 1, 0) == -1 ||
42		    write(fd, "", 1) == -1) {
43			return (-1);
44		}
45		return (0);
46	}
47
48	/* maybe shorten... */
49	if (wantsize < cursize) {
50		struct flock fl;
51
52		fl.l_whence = 0;
53		fl.l_len = 0;
54		fl.l_start = wantsize;
55		fl.l_type = F_WRLCK;
56		return (fcntl(fd, F_FREESP, &fl));
57	}
58	return (0);
59}
60#endif
61
62#ifndef OWN_FTRUNCATE
63int __bindcompat_ftruncate;
64#endif
65