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a620bd7935
The kernel interface uses type unsigned int, but there is an internal conversion to int, so INT_MAX is the correct limit. Part of the buffer will always be unused, but this is not a problem. Such huge buffers do not occur in practice anyway. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
124 lines
3.7 KiB
C
124 lines
3.7 KiB
C
/* Get directory entries. Linux/MIPSn64 LFS version.
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Copyright (C) 2018-2019 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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#include <assert.h>
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#include <sys/param.h>
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#include <unistd.h>
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#include <scratch_buffer.h>
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#include <limits.h>
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ssize_t
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__getdents64 (int fd, void *buf0, size_t nbytes)
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{
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char *buf = buf0;
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/* The system call takes an unsigned int argument, and some length
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checks in the kernel use an int type. */
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if (nbytes > INT_MAX)
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nbytes = INT_MAX;
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#ifdef __NR_getdents64
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ssize_t ret = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
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if (ret != -1)
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return ret;
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#endif
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/* Unfortunately getdents64 was only wire-up for MIPS n64 on Linux 3.10.
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If syscall is not available it need to fallback to non-LFS one. */
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struct kernel_dirent
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{
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unsigned long d_ino;
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unsigned long d_off;
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unsigned short int d_reclen;
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char d_name[256];
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};
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const size_t size_diff = (offsetof (struct dirent64, d_name)
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- offsetof (struct kernel_dirent, d_name));
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size_t red_nbytes = MIN (nbytes
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- ((nbytes / (offsetof (struct dirent64, d_name)
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+ 14)) * size_diff),
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nbytes - size_diff);
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struct scratch_buffer tmpbuf;
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scratch_buffer_init (&tmpbuf);
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if (!scratch_buffer_set_array_size (&tmpbuf, red_nbytes, sizeof (uint8_t)))
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INLINE_SYSCALL_ERROR_RETURN_VALUE (ENOMEM);
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struct kernel_dirent *skdp, *kdp;
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skdp = kdp = tmpbuf.data;
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ssize_t retval = INLINE_SYSCALL_CALL (getdents, fd, kdp, red_nbytes);
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if (retval == -1)
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{
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scratch_buffer_free (&tmpbuf);
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return -1;
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}
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off64_t last_offset = -1;
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struct dirent64 *dp = (struct dirent64 *) buf;
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while ((char *) kdp < (char *) skdp + retval)
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{
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const size_t alignment = _Alignof (struct dirent64);
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/* Since kdp->d_reclen is already aligned for the kernel structure
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this may compute a value that is bigger than necessary. */
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size_t new_reclen = ((kdp->d_reclen + size_diff + alignment - 1)
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& ~(alignment - 1));
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if ((char *) dp + new_reclen > buf + nbytes)
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{
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/* Our heuristic failed. We read too many entries. Reset
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the stream. */
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assert (last_offset != -1);
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__lseek64 (fd, last_offset, SEEK_SET);
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if ((char *) dp == buf)
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{
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scratch_buffer_free (&tmpbuf);
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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}
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break;
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}
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last_offset = kdp->d_off;
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dp->d_ino = kdp->d_ino;
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dp->d_off = kdp->d_off;
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dp->d_reclen = new_reclen;
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dp->d_type = *((char *) kdp + kdp->d_reclen - 1);
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memcpy (dp->d_name, kdp->d_name,
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kdp->d_reclen - offsetof (struct kernel_dirent, d_name));
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dp = (struct dirent64 *) ((char *) dp + new_reclen);
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kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
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}
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scratch_buffer_free (&tmpbuf);
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return (char *) dp - buf;
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}
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libc_hidden_def (__getdents64)
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weak_alias (__getdents64, getdents64)
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#if _DIRENT_MATCHES_DIRENT64
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strong_alias (__getdents64, __getdents)
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#endif
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