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295 lines
7.0 KiB
C
295 lines
7.0 KiB
C
/* Get file-specific information about a file. Linux version.
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Copyright (C) 1991-2022 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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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <mntent.h>
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#include <stdio_ext.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/sysmacros.h>
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#include "pathconf.h"
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#include "linux_fsinfo.h"
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#include <not-cancel.h>
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static long int posix_pathconf (const char *file, int name);
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/* Define this first, so it can be inlined. */
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#define __pathconf static posix_pathconf
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#include <sysdeps/posix/pathconf.c>
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/* Get file-specific information about FILE. */
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long int
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__pathconf (const char *file, int name)
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{
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struct statfs fsbuf;
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switch (name)
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{
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case _PC_LINK_MAX:
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return __statfs_link_max (__statfs (file, &fsbuf), &fsbuf, file, -1);
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case _PC_FILESIZEBITS:
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return __statfs_filesize_max (__statfs (file, &fsbuf), &fsbuf);
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case _PC_2_SYMLINKS:
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return __statfs_symlinks (__statfs (file, &fsbuf), &fsbuf);
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case _PC_CHOWN_RESTRICTED:
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return __statfs_chown_restricted (__statfs (file, &fsbuf), &fsbuf);
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default:
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return posix_pathconf (file, name);
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}
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}
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static long int
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distinguish_extX (const struct statfs *fsbuf, const char *file, int fd)
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{
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char buf[64];
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char path[PATH_MAX];
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struct __stat64_t64 st;
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if ((file == NULL ? __fstat64_time64 (fd, &st)
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: __stat64_time64 (file, &st)) != 0)
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/* Strange. The statfd call worked, but stat fails. Default to
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the more pessimistic value. */
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return EXT2_LINK_MAX;
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__snprintf (buf, sizeof (buf), "/sys/dev/block/%u:%u",
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__gnu_dev_major (st.st_dev), __gnu_dev_minor (st.st_dev));
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ssize_t n = __readlink (buf, path, sizeof (path));
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if (n != -1 && n < sizeof (path))
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{
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path[n] = '\0';
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char *base = strdupa (__basename (path));
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__snprintf (path, sizeof (path), "/sys/fs/ext4/%s", base);
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return __access (path, F_OK) == 0 ? EXT4_LINK_MAX : EXT2_LINK_MAX;
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}
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/* XXX Is there a better way to distinguish ext2/3 from ext4 than
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iterating over the mounted filesystems and compare the device
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numbers? */
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FILE *mtab = __setmntent ("/proc/mounts", "r");
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if (mtab == NULL)
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mtab = __setmntent (_PATH_MOUNTED, "r");
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/* By default be conservative. */
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long int result = EXT2_LINK_MAX;
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if (mtab != NULL)
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{
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struct mntent mntbuf;
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char tmpbuf[1024];
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/* No locking needed. */
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(void) __fsetlocking (mtab, FSETLOCKING_BYCALLER);
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while (__getmntent_r (mtab, &mntbuf, tmpbuf, sizeof (tmpbuf)))
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{
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if (strcmp (mntbuf.mnt_type, "ext2") != 0
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&& strcmp (mntbuf.mnt_type, "ext3") != 0
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&& strcmp (mntbuf.mnt_type, "ext4") != 0)
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continue;
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struct __stat64_t64 fsst;
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if (__stat64_time64 (mntbuf.mnt_dir, &fsst) >= 0
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&& st.st_dev == fsst.st_dev)
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{
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if (strcmp (mntbuf.mnt_type, "ext4") == 0)
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result = EXT4_LINK_MAX;
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break;
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}
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}
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/* Close the file. */
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__endmntent (mtab);
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}
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return result;
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}
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/* Used like: return statfs_link_max (__statfs (name, &buf), &buf); */
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long int
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__statfs_link_max (int result, const struct statfs *fsbuf, const char *file,
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int fd)
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{
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if (result < 0)
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{
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if (errno == ENOSYS)
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/* Not possible, return the default value. */
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return LINUX_LINK_MAX;
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/* Some error occured. */
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return -1;
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}
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switch (fsbuf->f_type)
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{
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case EXT2_SUPER_MAGIC:
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/* Unfortunately the kernel does not return a different magic number
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for ext4. This would be necessary to easily detect etx4 since it
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has a different LINK_MAX value. Therefore we have to find it out
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the hard way. */
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return distinguish_extX (fsbuf, file, fd);
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case F2FS_SUPER_MAGIC:
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return F2FS_LINK_MAX;
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case MINIX_SUPER_MAGIC:
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case MINIX_SUPER_MAGIC2:
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return MINIX_LINK_MAX;
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case MINIX2_SUPER_MAGIC:
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case MINIX2_SUPER_MAGIC2:
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return MINIX2_LINK_MAX;
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case XENIX_SUPER_MAGIC:
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return XENIX_LINK_MAX;
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case SYSV4_SUPER_MAGIC:
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case SYSV2_SUPER_MAGIC:
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return SYSV_LINK_MAX;
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case COH_SUPER_MAGIC:
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return COH_LINK_MAX;
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case UFS_MAGIC:
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case UFS_CIGAM:
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return UFS_LINK_MAX;
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case REISERFS_SUPER_MAGIC:
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return REISERFS_LINK_MAX;
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case XFS_SUPER_MAGIC:
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return XFS_LINK_MAX;
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case LUSTRE_SUPER_MAGIC:
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return LUSTRE_LINK_MAX;
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default:
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return LINUX_LINK_MAX;
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}
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}
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/* Used like: return statfs_filesize_max (__statfs (name, &buf), &buf); */
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long int
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__statfs_filesize_max (int result, const struct statfs *fsbuf)
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{
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if (result < 0)
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{
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if (errno == ENOSYS)
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/* Not possible, return the default value. */
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return 32;
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/* Some error occured. */
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return -1;
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}
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switch (fsbuf->f_type)
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{
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case F2FS_SUPER_MAGIC:
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return 256;
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case BTRFS_SUPER_MAGIC:
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return 255;
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case EXT2_SUPER_MAGIC:
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case UFS_MAGIC:
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case UFS_CIGAM:
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case REISERFS_SUPER_MAGIC:
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case XFS_SUPER_MAGIC:
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case SMB_SUPER_MAGIC:
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case NTFS_SUPER_MAGIC:
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case UDF_SUPER_MAGIC:
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case JFS_SUPER_MAGIC:
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case VXFS_SUPER_MAGIC:
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case CGROUP_SUPER_MAGIC:
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case LUSTRE_SUPER_MAGIC:
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return 64;
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case MSDOS_SUPER_MAGIC:
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case JFFS_SUPER_MAGIC:
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case JFFS2_SUPER_MAGIC:
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case NCP_SUPER_MAGIC:
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case ROMFS_SUPER_MAGIC:
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return 32;
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default:
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return 32;
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}
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}
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/* Used like: return statfs_link_max (__statfs (name, &buf), &buf); */
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long int
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__statfs_symlinks (int result, const struct statfs *fsbuf)
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{
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if (result < 0)
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{
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if (errno == ENOSYS)
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/* Not possible, return the default value. */
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return 1;
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/* Some error occured. */
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return -1;
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}
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switch (fsbuf->f_type)
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{
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case ADFS_SUPER_MAGIC:
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case BFS_MAGIC:
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case CRAMFS_MAGIC:
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case DEVPTS_SUPER_MAGIC:
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case EFS_SUPER_MAGIC:
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case EFS_MAGIC:
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case MSDOS_SUPER_MAGIC:
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case NTFS_SUPER_MAGIC:
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case QNX4_SUPER_MAGIC:
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case ROMFS_SUPER_MAGIC:
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/* No symlink support. */
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return 0;
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default:
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return 1;
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}
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}
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/* Used like: return __statfs_chown_restricted (__statfs (name, &buf), &buf);*/
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long int
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__statfs_chown_restricted (int result, const struct statfs *fsbuf)
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{
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if (result < 0)
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{
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if (errno == ENOSYS)
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/* Not possible, return the default value. */
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return 1;
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/* Some error occured. */
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return -1;
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}
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return 1;
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}
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