1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
/* ftruncate emulations that work on some System V's.
This file is in the public domain. */
/* Copyright (C) 2012-2019 Free Software Foundation, Inc.
This file is part of gold.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#include <config.h>
/* Specification. */
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
extern int ftruncate (int, off_t);
#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>
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 /* native Windows, e.g. mingw */
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 */
|
