util/anon_file: const string param
[mesa.git] / src / util / anon_file.c
1 /*
2 * Copyright © 2012 Collabora, Ltd.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the
13 * next paragraph) shall be included in all copies or substantial
14 * portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
20 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
21 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 */
25
26 /*
27 * Based on weston shared/os-compatibility.c
28 */
29
30 #ifndef WIN32
31 #include "anon_file.h"
32
33 #include <unistd.h>
34 #include <fcntl.h>
35 #include <errno.h>
36
37 #ifdef __FreeBSD__
38 #include <sys/mman.h>
39 #elif defined(HAVE_MEMFD_CREATE)
40 #include <sys/syscall.h>
41 #include <linux/memfd.h>
42 #else
43 #include <stdio.h>
44 #include <stdlib.h>
45 #endif
46
47 #if !(defined(__FreeBSD__) || defined(HAVE_MEMFD_CREATE) || defined(HAVE_MKOSTEMP))
48 static int
49 set_cloexec_or_close(int fd)
50 {
51 long flags;
52
53 if (fd == -1)
54 return -1;
55
56 flags = fcntl(fd, F_GETFD);
57 if (flags == -1)
58 goto err;
59
60 if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1)
61 goto err;
62
63 return fd;
64
65 err:
66 close(fd);
67 return -1;
68 }
69 #endif
70
71 #if !(defined(__FreeBSD__) || defined(HAVE_MEMFD_CREATE))
72 static int
73 create_tmpfile_cloexec(char *tmpname)
74 {
75 int fd;
76
77 #ifdef HAVE_MKOSTEMP
78 fd = mkostemp(tmpname, O_CLOEXEC);
79 #else
80 fd = mkstemp(tmpname);
81 #endif
82
83 if (fd < 0) {
84 return fd;
85 }
86
87 #ifndef HAVE_MKOSTEMP
88 fd = set_cloexec_or_close(fd);
89 #endif
90
91 unlink(tmpname);
92 return fd;
93 }
94 #endif
95
96 /*
97 * Create a new, unique, anonymous file of the given size, and
98 * return the file descriptor for it. The file descriptor is set
99 * CLOEXEC. The file is immediately suitable for mmap()'ing
100 * the given size at offset zero.
101 *
102 * An optional name for debugging can be provided as the second argument.
103 *
104 * The file should not have a permanent backing store like a disk,
105 * but may have if XDG_RUNTIME_DIR is not properly implemented in OS.
106 *
107 * If memfd or SHM_ANON is supported, the filesystem is not touched at all.
108 * Otherwise, the file name is deleted from the file system.
109 *
110 * The file is suitable for buffer sharing between processes by
111 * transmitting the file descriptor over Unix sockets using the
112 * SCM_RIGHTS methods.
113 */
114 int
115 os_create_anonymous_file(off_t size, const char *debug_name)
116 {
117 int fd, ret;
118 #ifdef __FreeBSD__
119 (void*)debug_name;
120 fd = shm_open(SHM_ANON, O_CREAT | O_RDWR | O_CLOEXEC, 0600);
121 #elif defined(HAVE_MEMFD_CREATE)
122 if (!debug_name)
123 debug_name = "mesa-shared";
124 fd = syscall(SYS_memfd_create, debug_name, MFD_CLOEXEC);
125 #else
126 const char *path;
127 char *name;
128
129 path = getenv("XDG_RUNTIME_DIR");
130 if (!path) {
131 errno = ENOENT;
132 return -1;
133 }
134
135 if (debug_name)
136 asprintf(&name, "%s/mesa-shared-%s-XXXXXX", path, debug_name);
137 else
138 asprintf(&name, "%s/mesa-shared-XXXXXX", path);
139 if (!name)
140 return -1;
141
142 fd = create_tmpfile_cloexec(name);
143
144 free(name);
145 #endif
146
147 if (fd < 0)
148 return -1;
149
150 ret = ftruncate(fd, size);
151 if (ret < 0) {
152 close(fd);
153 return -1;
154 }
155
156 return fd;
157 }
158 #endif