| /* Get file-specific information about a file. Linux version. |
| Copyright (C) 1991-2018 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 |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <errno.h> |
| #include <mntent.h> |
| #include <stdio_ext.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <sys/sysmacros.h> |
| |
| #include "pathconf.h" |
| #include "linux_fsinfo.h" |
| #include <not-cancel.h> |
| |
| static long int posix_pathconf (const char *file, int name); |
| |
| /* Define this first, so it can be inlined. */ |
| #define __pathconf static posix_pathconf |
| #include <sysdeps/posix/pathconf.c> |
| |
| |
| /* Get file-specific information about FILE. */ |
| long int |
| __pathconf (const char *file, int name) |
| { |
| struct statfs fsbuf; |
| |
| switch (name) |
| { |
| case _PC_LINK_MAX: |
| return __statfs_link_max (__statfs (file, &fsbuf), &fsbuf, file, -1); |
| |
| case _PC_FILESIZEBITS: |
| return __statfs_filesize_max (__statfs (file, &fsbuf), &fsbuf); |
| |
| case _PC_2_SYMLINKS: |
| return __statfs_symlinks (__statfs (file, &fsbuf), &fsbuf); |
| |
| case _PC_CHOWN_RESTRICTED: |
| return __statfs_chown_restricted (__statfs (file, &fsbuf), &fsbuf); |
| |
| default: |
| return posix_pathconf (file, name); |
| } |
| } |
| |
| |
| static long int |
| distinguish_extX (const struct statfs *fsbuf, const char *file, int fd) |
| { |
| char buf[64]; |
| char path[PATH_MAX]; |
| struct stat64 st; |
| |
| if ((file == NULL ? fstat64 (fd, &st) : stat64 (file, &st)) != 0) |
| /* Strange. The statfd call worked, but stat fails. Default to |
| the more pessimistic value. */ |
| return EXT2_LINK_MAX; |
| |
| __snprintf (buf, sizeof (buf), "/sys/dev/block/%u:%u", |
| __gnu_dev_major (st.st_dev), __gnu_dev_minor (st.st_dev)); |
| |
| ssize_t n = __readlink (buf, path, sizeof (path)); |
| if (n != -1 && n < sizeof (path)) |
| { |
| path[n] = '\0'; |
| char *base = strdupa (__basename (path)); |
| __snprintf (path, sizeof (path), "/sys/fs/ext4/%s", base); |
| |
| return __access (path, F_OK) == 0 ? EXT4_LINK_MAX : EXT2_LINK_MAX; |
| } |
| |
| /* XXX Is there a better way to distinguish ext2/3 from ext4 than |
| iterating over the mounted filesystems and compare the device |
| numbers? */ |
| FILE *mtab = __setmntent ("/proc/mounts", "r"); |
| if (mtab == NULL) |
| mtab = __setmntent (_PATH_MOUNTED, "r"); |
| |
| /* By default be conservative. */ |
| long int result = EXT2_LINK_MAX; |
| if (mtab != NULL) |
| { |
| struct mntent mntbuf; |
| char tmpbuf[1024]; |
| |
| /* No locking needed. */ |
| (void) __fsetlocking (mtab, FSETLOCKING_BYCALLER); |
| |
| while (__getmntent_r (mtab, &mntbuf, tmpbuf, sizeof (tmpbuf))) |
| { |
| if (strcmp (mntbuf.mnt_type, "ext2") != 0 |
| && strcmp (mntbuf.mnt_type, "ext3") != 0 |
| && strcmp (mntbuf.mnt_type, "ext4") != 0) |
| continue; |
| |
| struct stat64 fsst; |
| if (stat64 (mntbuf.mnt_dir, &fsst) >= 0 |
| && st.st_dev == fsst.st_dev) |
| { |
| if (strcmp (mntbuf.mnt_type, "ext4") == 0) |
| result = EXT4_LINK_MAX; |
| break; |
| } |
| } |
| |
| /* Close the file. */ |
| __endmntent (mtab); |
| } |
| |
| return result; |
| } |
| |
| |
| /* Used like: return statfs_link_max (__statfs (name, &buf), &buf); */ |
| long int |
| __statfs_link_max (int result, const struct statfs *fsbuf, const char *file, |
| int fd) |
| { |
| if (result < 0) |
| { |
| if (errno == ENOSYS) |
| /* Not possible, return the default value. */ |
| return LINUX_LINK_MAX; |
| |
| /* Some error occured. */ |
| return -1; |
| } |
| |
| switch (fsbuf->f_type) |
| { |
| case EXT2_SUPER_MAGIC: |
| /* Unfortunately the kernel does not return a different magic number |
| for ext4. This would be necessary to easily detect etx4 since it |
| has a different LINK_MAX value. Therefore we have to find it out |
| the hard way. */ |
| return distinguish_extX (fsbuf, file, fd); |
| |
| case F2FS_SUPER_MAGIC: |
| return F2FS_LINK_MAX; |
| |
| case MINIX_SUPER_MAGIC: |
| case MINIX_SUPER_MAGIC2: |
| return MINIX_LINK_MAX; |
| |
| case MINIX2_SUPER_MAGIC: |
| case MINIX2_SUPER_MAGIC2: |
| return MINIX2_LINK_MAX; |
| |
| case XENIX_SUPER_MAGIC: |
| return XENIX_LINK_MAX; |
| |
| case SYSV4_SUPER_MAGIC: |
| case SYSV2_SUPER_MAGIC: |
| return SYSV_LINK_MAX; |
| |
| case COH_SUPER_MAGIC: |
| return COH_LINK_MAX; |
| |
| case UFS_MAGIC: |
| case UFS_CIGAM: |
| return UFS_LINK_MAX; |
| |
| case REISERFS_SUPER_MAGIC: |
| return REISERFS_LINK_MAX; |
| |
| case XFS_SUPER_MAGIC: |
| return XFS_LINK_MAX; |
| |
| case LUSTRE_SUPER_MAGIC: |
| return LUSTRE_LINK_MAX; |
| |
| default: |
| return LINUX_LINK_MAX; |
| } |
| } |
| |
| |
| /* Used like: return statfs_filesize_max (__statfs (name, &buf), &buf); */ |
| long int |
| __statfs_filesize_max (int result, const struct statfs *fsbuf) |
| { |
| if (result < 0) |
| { |
| if (errno == ENOSYS) |
| /* Not possible, return the default value. */ |
| return 32; |
| |
| /* Some error occured. */ |
| return -1; |
| } |
| |
| switch (fsbuf->f_type) |
| { |
| case F2FS_SUPER_MAGIC: |
| return 256; |
| |
| case BTRFS_SUPER_MAGIC: |
| return 255; |
| |
| case EXT2_SUPER_MAGIC: |
| case UFS_MAGIC: |
| case UFS_CIGAM: |
| case REISERFS_SUPER_MAGIC: |
| case XFS_SUPER_MAGIC: |
| case SMB_SUPER_MAGIC: |
| case NTFS_SUPER_MAGIC: |
| case UDF_SUPER_MAGIC: |
| case JFS_SUPER_MAGIC: |
| case VXFS_SUPER_MAGIC: |
| case CGROUP_SUPER_MAGIC: |
| case LUSTRE_SUPER_MAGIC: |
| return 64; |
| |
| case MSDOS_SUPER_MAGIC: |
| case JFFS_SUPER_MAGIC: |
| case JFFS2_SUPER_MAGIC: |
| case NCP_SUPER_MAGIC: |
| case ROMFS_SUPER_MAGIC: |
| return 32; |
| |
| default: |
| return 32; |
| } |
| } |
| |
| |
| /* Used like: return statfs_link_max (__statfs (name, &buf), &buf); */ |
| long int |
| __statfs_symlinks (int result, const struct statfs *fsbuf) |
| { |
| if (result < 0) |
| { |
| if (errno == ENOSYS) |
| /* Not possible, return the default value. */ |
| return 1; |
| |
| /* Some error occured. */ |
| return -1; |
| } |
| |
| switch (fsbuf->f_type) |
| { |
| case ADFS_SUPER_MAGIC: |
| case BFS_MAGIC: |
| case CRAMFS_MAGIC: |
| case DEVPTS_SUPER_MAGIC: |
| case EFS_SUPER_MAGIC: |
| case EFS_MAGIC: |
| case MSDOS_SUPER_MAGIC: |
| case NTFS_SUPER_MAGIC: |
| case QNX4_SUPER_MAGIC: |
| case ROMFS_SUPER_MAGIC: |
| /* No symlink support. */ |
| return 0; |
| |
| default: |
| return 1; |
| } |
| } |
| |
| |
| /* Used like: return __statfs_chown_restricted (__statfs (name, &buf), &buf);*/ |
| long int |
| __statfs_chown_restricted (int result, const struct statfs *fsbuf) |
| { |
| if (result < 0) |
| { |
| if (errno == ENOSYS) |
| /* Not possible, return the default value. */ |
| return 1; |
| |
| /* Some error occured. */ |
| return -1; |
| } |
| |
| return 1; |
| } |