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/* Copyright (C) 1991-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dirent.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h> /* For BUFSIZ. */
#include <sys/param.h> /* For MIN and MAX. */
#include <not-cancel.h>
/* The st_blksize value of the directory is used as a hint for the
size of the buffer which receives struct dirent values from the
kernel. st_blksize is limited to MAX_DIR_BUFFER_SIZE, in case the
file system provides a bogus value. */
#define MAX_DIR_BUFFER_SIZE 1048576U
enum {
opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
};
static bool
invalid_name (const char *name)
{
if (__glibc_unlikely (name[0] == '\0'))
{
/* POSIX.1-1990 says an empty name gets ENOENT;
but `open' might like it fine. */
__set_errno (ENOENT);
return true;
}
return false;
}
static DIR *
opendir_tail (int fd)
{
if (__glibc_unlikely (fd < 0))
return NULL;
/* Now make sure this really is a directory and nothing changed since the
`stat' call. The S_ISDIR check is superfluous if O_DIRECTORY works,
but it's cheap and we need the stat call for st_blksize anyway. */
struct stat64 statbuf;
if (__glibc_unlikely (__fstat64 (fd, &statbuf) < 0))
goto lose;
if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
{
__set_errno (ENOTDIR);
lose:
__close_nocancel_nostatus (fd);
return NULL;
}
return __alloc_dir (fd, true, 0, &statbuf);
}
#if IS_IN (libc)
DIR *
__opendirat (int dfd, const char *name)
{
if (__glibc_unlikely (invalid_name (name)))
return NULL;
return opendir_tail (__openat_nocancel (dfd, name, opendir_oflags));
}
#endif
/* Open a directory stream on NAME. */
DIR *
__opendir (const char *name)
{
if (__glibc_unlikely (invalid_name (name)))
return NULL;
return opendir_tail (__open_nocancel (name, opendir_oflags));
}
weak_alias (__opendir, opendir)
DIR *
__alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
{
/* We have to set the close-on-exit flag if the user provided the
file descriptor. */
if (!close_fd
&& __glibc_unlikely (__fcntl64_nocancel (fd, F_SETFD, FD_CLOEXEC) < 0))
goto lose;
const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64)
? sizeof (struct dirent64) : 4 * BUFSIZ);
const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64)
? sizeof (struct dirent64) : BUFSIZ);
size_t allocation = default_allocation;
#ifdef _STATBUF_ST_BLKSIZE
/* Increase allocation if requested, but not if the value appears to
be bogus. */
if (statp != NULL)
allocation = MIN (MAX ((size_t) statp->st_blksize, default_allocation),
MAX_DIR_BUFFER_SIZE);
#endif
DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation);
if (dirp == NULL)
{
allocation = small_allocation;
dirp = (DIR *) malloc (sizeof (DIR) + allocation);
if (dirp == NULL)
lose:
{
if (close_fd)
{
int save_errno = errno;
__close_nocancel_nostatus (fd);
__set_errno (save_errno);
}
return NULL;
}
}
dirp->fd = fd;
#if IS_IN (libc)
__libc_lock_init (dirp->lock);
#endif
dirp->allocation = allocation;
dirp->size = 0;
dirp->offset = 0;
dirp->filepos = 0;
dirp->errcode = 0;
return dirp;
}
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