| 1 | /* Internals for openat-like functions.
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| 2 |
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| 3 | Copyright (C) 2005-2006, 2009-2021 Free Software Foundation, Inc.
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| 4 |
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| 5 | This program is free software: you can redistribute it and/or modify
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| 6 | it under the terms of the GNU General Public License as published by
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| 7 | the Free Software Foundation; either version 3 of the License, or
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| 8 | (at your option) any later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 17 |
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| 18 | /* written by Jim Meyering */
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| 19 |
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| 20 | #ifndef _GL_HEADER_OPENAT_PRIV
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| 21 | #define _GL_HEADER_OPENAT_PRIV
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| 22 |
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| 23 | #include <errno.h>
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| 24 | #include <limits.h>
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| 25 | #include <stdlib.h>
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| 26 |
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| 27 | /* Maximum number of bytes that it is safe to allocate as a single
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| 28 | array on the stack, and that is known as a compile-time constant.
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| 29 | The assumption is that we'll touch the array very quickly, or a
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| 30 | temporary very near the array, provoking an out-of-memory trap. On
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| 31 | some operating systems, there is only one guard page for the stack,
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| 32 | and a page size can be as small as 4096 bytes. Subtract 64 in the
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| 33 | hope that this will let the compiler touch a nearby temporary and
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| 34 | provoke a trap. */
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| 35 | #define SAFER_ALLOCA_MAX (4096 - 64)
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| 36 |
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| 37 | #define SAFER_ALLOCA(m) ((m) < SAFER_ALLOCA_MAX ? (m) : SAFER_ALLOCA_MAX)
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| 38 |
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| 39 | #if defined PATH_MAX
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| 40 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (PATH_MAX)
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| 41 | #elif defined _XOPEN_PATH_MAX
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| 42 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (_XOPEN_PATH_MAX)
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| 43 | #else
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| 44 | # define OPENAT_BUFFER_SIZE SAFER_ALLOCA (1024)
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| 45 | #endif
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| 46 |
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| 47 | char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file);
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| 48 |
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| 49 | /* Trying to access a BUILD_PROC_NAME file will fail on systems without
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| 50 | /proc support, and even on systems *with* ProcFS support. Return
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| 51 | nonzero if the failure may be legitimate, e.g., because /proc is not
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| 52 | readable, or the particular .../fd/N directory is not present. */
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| 53 | #define EXPECTED_ERRNO(Errno) \
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| 54 | ((Errno) == ENOTDIR || (Errno) == ENOENT \
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| 55 | || (Errno) == EPERM || (Errno) == EACCES \
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| 56 | || (Errno) == ENOSYS /* Solaris 8 */ \
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| 57 | || (Errno) == EOPNOTSUPP /* FreeBSD */)
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| 58 |
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| 59 | /* Wrapper function shared among linkat and renameat. */
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| 60 | int at_func2 (int fd1, char const *file1,
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| 61 | int fd2, char const *file2,
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| 62 | int (*func) (char const *file1, char const *file2));
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| 63 |
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| 64 | #endif /* _GL_HEADER_OPENAT_PRIV */
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