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72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/* Test for access to file, relative to open directory. Linux version.
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Copyright (C) 2006-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <fcntl.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <alloca.h>
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#include <sysdep.h>
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int
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faccessat (int fd, const char *file, int mode, int flag)
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{
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if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS))
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure)))
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return INLINE_SYSCALL (faccessat, 3, fd, file, mode);
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struct stat64 stats;
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if (__fxstatat64 (_STAT_VER, fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW))
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return -1;
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mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
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#if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH
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# error Oops, portability assumptions incorrect.
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#endif
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if (mode == F_OK)
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return 0; /* The file exists. */
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uid_t uid = (flag & AT_EACCESS) ? __geteuid () : __getuid ();
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/* The super-user can read and write any file, and execute any file
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that anyone can execute. */
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if (uid == 0 && ((mode & X_OK) == 0
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|| (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
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return 0;
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int granted = (uid == stats.st_uid
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? (unsigned int) (stats.st_mode & (mode << 6)) >> 6
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: (stats.st_gid == ((flag & AT_EACCESS)
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? __getegid () : __getgid ())
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|| __group_member (stats.st_gid))
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? (unsigned int) (stats.st_mode & (mode << 3)) >> 3
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: (stats.st_mode & mode));
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if (granted == mode)
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return 0;
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EACCES);
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}
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