src/basic/chattr-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <sys/ioctl.h>
  23 #include <sys/stat.h>
  24 #include <linux/fs.h>
  25
  26 #include "chattr-util.h"
  27 #include "fd-util.h"
  28 #include "macro.h"
  29
  30 int chattr_fd(int fd, unsigned value, unsigned mask) {
  31         unsigned old_attr, new_attr;
  32         struct stat st;
  33
  34         assert(fd >= 0);
  35
  36         if (fstat(fd, &st) < 0)
  37                 return -errno;
  38
  39         /* Explicitly check whether this is a regular file or
  40          * directory. If it is anything else (such as a device node or
  41          * fifo), then the ioctl will not hit the file systems but
  42          * possibly drivers, where the ioctl might have different
  43          * effects. Notably, DRM is using the same ioctl() number. */
  44
  45         if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
  46                 return -ENOTTY;
  47
  48         if (mask == 0)
  49                 return 0;
  50
  51         if (ioctl(fd, FS_IOC_GETFLAGS, &old_attr) < 0)
  52                 return -errno;
  53
  54         new_attr = (old_attr & ~mask) | (value & mask);
  55         if (new_attr == old_attr)
  56                 return 0;
  57
  58         if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) < 0)
  59                 return -errno;
  60
  61         return 1;
  62 }
  63
  64 int chattr_path(const char *p, unsigned value, unsigned mask) {
  65         _cleanup_close_ int fd = -1;
  66
  67         assert(p);
  68
  69         if (mask == 0)
  70                 return 0;
  71
  72         fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
  73         if (fd < 0)
  74                 return -errno;
  75
  76         return chattr_fd(fd, value, mask);
  77 }
  78
  79 int read_attr_fd(int fd, unsigned *ret) {
  80         struct stat st;
  81
  82         assert(fd >= 0);
  83
  84         if (fstat(fd, &st) < 0)
  85                 return -errno;
  86
  87         if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
  88                 return -ENOTTY;
  89
  90         if (ioctl(fd, FS_IOC_GETFLAGS, ret) < 0)
  91                 return -errno;
  92
  93         return 0;
  94 }
  95
  96 int read_attr_path(const char *p, unsigned *ret) {
  97         _cleanup_close_ int fd = -1;
  98
  99         assert(p);
 100         assert(ret);
 101
 102         fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 103         if (fd < 0)
 104                 return -errno;
 105
 106         return read_attr_fd(fd, ret);
 107 }