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/* Copyright (C) 1991-2021 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>
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))
return NULL;
/* 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_buffer_size, in case the
file system provides a bogus value. */
enum { max_buffer_size = 1048576 };
const size_t allocation_size = 32768;
_Static_assert (allocation_size >= sizeof (struct dirent64),
"allocation_size < sizeof (struct dirent64)");
/* Increase allocation if requested, but not if the value appears to
be bogus. It will be between 32Kb and 1Mb. */
size_t allocation = MIN (MAX ((size_t) statp->st_blksize, allocation_size),
max_buffer_size);
DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation);
if (dirp == NULL)
{
if (close_fd)
__close_nocancel_nostatus (fd);
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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