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
|
/* Copy a file descriptor, applying specific flags.
Copyright (C) 2009-2020 Free Software Foundation, Inc.
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 2, 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, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include "binary-io.h"
int
dup3 (int oldfd, int newfd, int flags)
{
#if HAVE_DUP3
# undef dup3
# if HAVE_SETDTABLESIZE
/* Avoid a cygwin crasher. */
setdtablesize (newfd + 1);
# endif
/* Try the system call first, if it exists. (We may be running with a glibc
that has the function but with an older kernel that lacks it.) */
{
/* Cache the information whether the system call really exists. */
static int have_dup3_really; /* 0 = unknown, 1 = yes, -1 = no */
if (have_dup3_really >= 0)
{
int result = dup3 (oldfd, newfd, flags);
if (!(result < 0 && errno == ENOSYS))
{
have_dup3_really = 1;
# if REPLACE_FCHDIR
if (0 <= result)
result = _gl_register_dup (oldfd, newfd);
# endif
return result;
}
have_dup3_really = -1;
}
}
#endif
if (newfd < 0 || newfd >= getdtablesize () || fcntl (oldfd, F_GETFD) == -1)
{
errno = EBADF;
return -1;
}
if (newfd == oldfd)
{
errno = EINVAL;
return -1;
}
/* Check the supported flags.
Note that O_NONBLOCK is not supported, because setting it on newfd
would implicitly also set it on oldfd. */
if ((flags & ~(O_CLOEXEC | O_BINARY | O_TEXT)) != 0)
{
errno = EINVAL;
return -1;
}
if (flags & O_CLOEXEC)
{
int result;
close (newfd);
result = fcntl (oldfd, F_DUPFD_CLOEXEC, newfd);
if (newfd < result)
{
close (result);
errno = EIO;
result = -1;
}
if (result < 0)
return -1;
}
else if (dup2 (oldfd, newfd) < 0)
return -1;
#if O_BINARY
if (flags & O_BINARY)
set_binary_mode (newfd, O_BINARY);
else if (flags & O_TEXT)
set_binary_mode (newfd, O_TEXT);
#endif
return newfd;
}
|
