149 lines
4.0 KiB
C
149 lines
4.0 KiB
C
/* Copyright (C) 1991-2018 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 <dirent.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <stdio.h> /* For BUFSIZ. */
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#include <sys/param.h> /* For MIN and MAX. */
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#include <not-cancel.h>
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/* The st_blksize value of the directory is used as a hint for the
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size of the buffer which receives struct dirent values from the
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kernel. st_blksize is limited to MAX_DIR_BUFFER_SIZE, in case the
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file system provides a bogus value. */
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#define MAX_DIR_BUFFER_SIZE 1048576U
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enum {
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opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
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};
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static bool
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invalid_name (const char *name)
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{
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if (__glibc_unlikely (name[0] == '\0'))
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{
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/* POSIX.1-1990 says an empty name gets ENOENT;
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but `open' might like it fine. */
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__set_errno (ENOENT);
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return true;
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}
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return false;
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}
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static DIR *
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opendir_tail (int fd)
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{
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if (__glibc_unlikely (fd < 0))
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return NULL;
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/* Now make sure this really is a directory and nothing changed since the
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`stat' call. The S_ISDIR check is superfluous if O_DIRECTORY works,
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but it's cheap and we need the stat call for st_blksize anyway. */
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struct stat64 statbuf;
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if (__glibc_unlikely (__fxstat64 (_STAT_VER, fd, &statbuf) < 0))
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goto lose;
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if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
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{
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__set_errno (ENOTDIR);
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lose:
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__close_nocancel_nostatus (fd);
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return NULL;
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}
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return __alloc_dir (fd, true, 0, &statbuf);
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}
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#if IS_IN (libc)
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DIR *
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__opendirat (int dfd, const char *name)
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{
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if (__glibc_unlikely (invalid_name (name)))
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return NULL;
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return opendir_tail (__openat_nocancel (dfd, name, opendir_oflags));
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}
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#endif
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/* Open a directory stream on NAME. */
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DIR *
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__opendir (const char *name)
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{
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if (__glibc_unlikely (invalid_name (name)))
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return NULL;
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return opendir_tail (__open_nocancel (name, opendir_oflags));
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}
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weak_alias (__opendir, opendir)
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DIR *
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__alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
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{
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/* We have to set the close-on-exit flag if the user provided the
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file descriptor. */
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if (!close_fd
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&& __glibc_unlikely (__fcntl64_nocancel (fd, F_SETFD, FD_CLOEXEC) < 0))
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goto lose;
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const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64)
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? sizeof (struct dirent64) : 4 * BUFSIZ);
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const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64)
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? sizeof (struct dirent64) : BUFSIZ);
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size_t allocation = default_allocation;
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#ifdef _STATBUF_ST_BLKSIZE
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/* Increase allocation if requested, but not if the value appears to
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be bogus. */
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if (statp != NULL)
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allocation = MIN (MAX ((size_t) statp->st_blksize, default_allocation),
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MAX_DIR_BUFFER_SIZE);
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#endif
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DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation);
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if (dirp == NULL)
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{
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allocation = small_allocation;
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dirp = (DIR *) malloc (sizeof (DIR) + allocation);
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if (dirp == NULL)
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lose:
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{
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if (close_fd)
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{
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int save_errno = errno;
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__close_nocancel_nostatus (fd);
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__set_errno (save_errno);
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}
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return NULL;
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}
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}
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dirp->fd = fd;
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#if IS_IN (libc)
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__libc_lock_init (dirp->lock);
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#endif
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dirp->allocation = allocation;
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dirp->size = 0;
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dirp->offset = 0;
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dirp->filepos = 0;
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dirp->errcode = 0;
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return dirp;
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}
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