1 /* $NetBSD: ftruncate.c,v 1.1.1.2 2012/09/09 16:07:42 christos Exp $ */
2
3 #ifndef LINT
4 static const char rcsid[] = "Id: ftruncate.c,v 1.3 2005/04/27 18:16:45 sra Exp ";
5 #endif
6
7 /*! \file
8 * \brief
9 * ftruncate - set file size, BSD Style
10 *
11 * shortens or enlarges the file as neeeded
12 * uses some undocumented locking call. It is known to work on SCO unix,
13 * other vendors should try.
14 * The #error directive prevents unsupported OSes
15 */
16
17 #include "port_before.h"
18
19 #if defined(M_UNIX)
20 #define OWN_FTRUNCATE
21 #include <stdio.h>
22 #ifdef _XOPEN_SOURCE
23 #undef _XOPEN_SOURCE
24 #endif
25 #ifdef _POSIX_SOURCE
26 #undef _POSIX_SOURCE
27 #endif
28
29 #include <fcntl.h>
30
31 #include "port_after.h"
32
33 int
__ftruncate(int fd,long wantsize)34 __ftruncate(int fd, long wantsize) {
35 long cursize;
36
37 /* determine current file size */
38 if ((cursize = lseek(fd, 0L, 2)) == -1)
39 return (-1);
40
41 /* maybe lengthen... */
42 if (cursize < wantsize) {
43 if (lseek(fd, wantsize - 1, 0) == -1 ||
44 write(fd, "", 1) == -1) {
45 return (-1);
46 }
47 return (0);
48 }
49
50 /* maybe shorten... */
51 if (wantsize < cursize) {
52 struct flock fl;
53
54 fl.l_whence = 0;
55 fl.l_len = 0;
56 fl.l_start = wantsize;
57 fl.l_type = F_WRLCK;
58 return (fcntl(fd, F_FREESP, &fl));
59 }
60 return (0);
61 }
62 #endif
63
64 #ifndef OWN_FTRUNCATE
65 int __bindcompat_ftruncate;
66 #endif
67