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690652882b
Commit 298d0e3129 ("Consolidate Linux
getdents{64} implementation") broke the implementation because it does
not take into account struct offset differences.
The new implementation is close to the old one, before the
consolidation, but has been cleaned up slightly.
116 lines
3.6 KiB
C
116 lines
3.6 KiB
C
/* Get directory entries. Linux LFS version.
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Copyright (C) 1997-2018 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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<http://www.gnu.org/licenses/>. */
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#include <string.h>
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#include <dirent.h>
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#include <errno.h>
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/* The kernel struct linux_dirent64 matches the 'struct getdents64' type. */
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ssize_t
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__getdents64 (int fd, char *buf, size_t nbytes)
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{
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return INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
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}
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#if _DIRENT_MATCHES_DIRENT64
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strong_alias (__getdents64, __getdents)
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#else
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# include <shlib-compat.h>
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# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
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# include <olddirent.h>
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# include <unistd.h>
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static ssize_t
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handle_overflow (int fd, __off64_t offset, ssize_t count)
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{
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/* If this is the first entry in the buffer, we can report the
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error. */
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if (count == 0)
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{
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__set_errno (EOVERFLOW);
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return -1;
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}
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/* Otherwise, seek to the overflowing entry, so that the next call
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will report the error, and return the data read so far.. */
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if (__lseek64 (fd, offset, SEEK_SET) != 0)
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return -1;
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return count;
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}
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ssize_t
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__old_getdents64 (int fd, char *buf, size_t nbytes)
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{
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/* We do not move the individual directory entries. This is only
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possible if the target type (struct __old_dirent64) is smaller
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than the source type. */
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_Static_assert (offsetof (struct __old_dirent64, d_name)
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<= offsetof (struct dirent64, d_name),
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"__old_dirent64 is larger than dirent64");
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_Static_assert (__alignof__ (struct __old_dirent64)
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<= __alignof__ (struct dirent64),
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"alignment of __old_dirent64 is larger than dirent64");
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ssize_t retval = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
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if (retval > 0)
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{
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char *p = buf;
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char *end = buf + retval;
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while (p < end)
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{
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struct dirent64 *source = (struct dirent64 *) p;
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/* Copy out the fixed-size data. */
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__ino_t ino = source->d_ino;
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__off64_t offset = source->d_off;
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unsigned int reclen = source->d_reclen;
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unsigned char type = source->d_type;
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/* Check for ino_t overflow. */
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if (__glibc_unlikely (ino != source->d_ino))
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return handle_overflow (fd, offset, p - buf);
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/* Convert to the target layout. Use a separate struct and
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memcpy to side-step aliasing issues. */
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struct __old_dirent64 result;
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result.d_ino = ino;
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result.d_off = offset;
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result.d_reclen = reclen;
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result.d_type = type;
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/* Write the fixed-sized part of the result to the
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buffer. */
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size_t result_name_offset = offsetof (struct __old_dirent64, d_name);
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memcpy (p, &result, result_name_offset);
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/* Adjust the position of the name if necessary. Copy
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everything until the end of the record, including the
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terminating NUL byte. */
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if (result_name_offset != offsetof (struct dirent64, d_name))
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memmove (p + result_name_offset, source->d_name,
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reclen - offsetof (struct dirent64, d_name));
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p += reclen;
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}
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}
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return retval;
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}
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# endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2) */
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#endif /* _DIRENT_MATCHES_DIRENT64 */
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