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65 lines
2.6 KiB
C
65 lines
2.6 KiB
C
/* Internals for openat-like functions.
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Copyright (C) 2005-2006, 2009-2021 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* written by Jim Meyering */
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#ifndef _GL_HEADER_OPENAT_PRIV
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#define _GL_HEADER_OPENAT_PRIV
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#include <errno.h>
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#include <limits.h>
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#include <stdlib.h>
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/* Maximum number of bytes that it is safe to allocate as a single
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array on the stack, and that is known as a compile-time constant.
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The assumption is that we'll touch the array very quickly, or a
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temporary very near the array, provoking an out-of-memory trap. On
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some operating systems, there is only one guard page for the stack,
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and a page size can be as small as 4096 bytes. Subtract 64 in the
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hope that this will let the compiler touch a nearby temporary and
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provoke a trap. */
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#define SAFER_ALLOCA_MAX (4096 - 64)
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#define SAFER_ALLOCA(m) ((m) < SAFER_ALLOCA_MAX ? (m) : SAFER_ALLOCA_MAX)
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#if defined PATH_MAX
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# define OPENAT_BUFFER_SIZE SAFER_ALLOCA (PATH_MAX)
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#elif defined _XOPEN_PATH_MAX
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# define OPENAT_BUFFER_SIZE SAFER_ALLOCA (_XOPEN_PATH_MAX)
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#else
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# define OPENAT_BUFFER_SIZE SAFER_ALLOCA (1024)
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#endif
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char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file);
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/* Trying to access a BUILD_PROC_NAME file will fail on systems without
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/proc support, and even on systems *with* ProcFS support. Return
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nonzero if the failure may be legitimate, e.g., because /proc is not
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readable, or the particular .../fd/N directory is not present. */
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#define EXPECTED_ERRNO(Errno) \
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((Errno) == ENOTDIR || (Errno) == ENOENT \
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|| (Errno) == EPERM || (Errno) == EACCES \
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|| (Errno) == ENOSYS /* Solaris 8 */ \
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|| (Errno) == EOPNOTSUPP /* FreeBSD */)
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/* Wrapper function shared among linkat and renameat. */
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int at_func2 (int fd1, char const *file1,
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int fd2, char const *file2,
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int (*func) (char const *file1, char const *file2));
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#endif /* _GL_HEADER_OPENAT_PRIV */
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