1/* shm_open -- open a POSIX shared memory object. Generic POSIX file version.
2 Copyright (C) 2001-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <unistd.h>
20
21#if ! _POSIX_MAPPED_FILES
22
23# include <rt/shm_open.c>
24
25#else
26
27# include <fcntl.h>
28# include <shm-directory.h>
29
30
31/* Open shared memory object. */
32int
33shm_open (const char *name, int oflag, mode_t mode)
34{
35 SHM_GET_NAME (EINVAL, -1, "");
36
37# ifdef O_NOFOLLOW
38 oflag |= O_NOFOLLOW;
39# endif
40# ifdef O_CLOEXEC
41 oflag |= O_CLOEXEC;
42# endif
43
44 /* Disable asynchronous cancellation. */
45 int state;
46 pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &state);
47
48 int fd = open (shm_name, oflag, mode);
49 if (fd == -1 && __glibc_unlikely (errno == EISDIR))
50 /* It might be better to fold this error with EINVAL since
51 directory names are just another example for unsuitable shared
52 object names and the standard does not mention EISDIR. */
53 __set_errno (EINVAL);
54
55# ifndef O_CLOEXEC
56 if (fd != -1)
57 {
58 /* We got a descriptor. Now set the FD_CLOEXEC bit. */
59 int flags = fcntl (fd, F_GETFD, 0);
60
61 if (__glibc_likely (flags != -1))
62 {
63 flags |= FD_CLOEXEC;
64 flags = fcntl (fd, F_SETFD, flags);
65 }
66
67 if (flags == -1)
68 {
69 /* Something went wrong. We cannot return the descriptor. */
70 int save_errno = errno;
71 close (fd);
72 fd = -1;
73 __set_errno (save_errno);
74 }
75 }
76# endif
77
78 pthread_setcancelstate (state, NULL);
79
80 return fd;
81}
82
83#endif /* _POSIX_MAPPED_FILES */
84