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6ec2e0f5 SDJ |
1 | /* Internals for openat-like functions. |
2 | ||
5df4cba6 | 3 | Copyright (C) 2005-2006, 2009-2020 Free Software Foundation, Inc. |
6ec2e0f5 SDJ |
4 | |
5 | This program is free software: you can redistribute it and/or modify | |
6 | it under the terms of the GNU General Public License as published by | |
7 | the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program 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 | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
c0c3707f | 16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
6ec2e0f5 SDJ |
17 | |
18 | /* written by Jim Meyering */ | |
19 | ||
20 | #ifndef _GL_HEADER_OPENAT_PRIV | |
21 | #define _GL_HEADER_OPENAT_PRIV | |
22 | ||
23 | #include <errno.h> | |
24 | #include <limits.h> | |
25 | #include <stdlib.h> | |
26 | ||
27 | /* Maximum number of bytes that it is safe to allocate as a single | |
28 | array on the stack, and that is known as a compile-time constant. | |
29 | The assumption is that we'll touch the array very quickly, or a | |
30 | temporary very near the array, provoking an out-of-memory trap. On | |
31 | some operating systems, there is only one guard page for the stack, | |
32 | and a page size can be as small as 4096 bytes. Subtract 64 in the | |
33 | hope that this will let the compiler touch a nearby temporary and | |
34 | provoke a trap. */ | |
35 | #define SAFER_ALLOCA_MAX (4096 - 64) | |
36 | ||
37 | #define SAFER_ALLOCA(m) ((m) < SAFER_ALLOCA_MAX ? (m) : SAFER_ALLOCA_MAX) | |
38 | ||
39 | #if defined PATH_MAX | |
40 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (PATH_MAX) | |
41 | #elif defined _XOPEN_PATH_MAX | |
42 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (_XOPEN_PATH_MAX) | |
43 | #else | |
44 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (1024) | |
45 | #endif | |
46 | ||
47 | char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file); | |
48 | ||
49 | /* Trying to access a BUILD_PROC_NAME file will fail on systems without | |
50 | /proc support, and even on systems *with* ProcFS support. Return | |
51 | nonzero if the failure may be legitimate, e.g., because /proc is not | |
52 | readable, or the particular .../fd/N directory is not present. */ | |
53 | #define EXPECTED_ERRNO(Errno) \ | |
54 | ((Errno) == ENOTDIR || (Errno) == ENOENT \ | |
55 | || (Errno) == EPERM || (Errno) == EACCES \ | |
56 | || (Errno) == ENOSYS /* Solaris 8 */ \ | |
57 | || (Errno) == EOPNOTSUPP /* FreeBSD */) | |
58 | ||
59 | /* Wrapper function shared among linkat and renameat. */ | |
60 | int at_func2 (int fd1, char const *file1, | |
61 | int fd2, char const *file2, | |
62 | int (*func) (char const *file1, char const *file2)); | |
63 | ||
64 | #endif /* _GL_HEADER_OPENAT_PRIV */ |