src/basic/chattr-util.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <sys/ioctl.h>
  25 #include <sys/stat.h>
  26 #include <linux/fs.h>
  27
  28 #include "chattr-util.h"
  29 #include "fd-util.h"
  30 #include "macro.h"
  31
  32 int chattr_fd(int fd, unsigned value, unsigned mask) {
  33         unsigned old_attr, new_attr;
  34         struct stat st;
  35
  36         assert(fd >= 0);
  37
  38         if (fstat(fd, &st) < 0)
  39                 return -errno;
  40
  41         /* Explicitly check whether this is a regular file or
  42          * directory. If it is anything else (such as a device node or
  43          * fifo), then the ioctl will not hit the file systems but
  44          * possibly drivers, where the ioctl might have different
  45          * effects. Notably, DRM is using the same ioctl() number. */
  46
  47         if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
  48                 return -ENOTTY;
  49
  50         if (mask == 0)
  51                 return 0;
  52
  53         if (ioctl(fd, FS_IOC_GETFLAGS, &old_attr) < 0)
  54                 return -errno;
  55
  56         new_attr = (old_attr & ~mask) | (value & mask);
  57         if (new_attr == old_attr)
  58                 return 0;
  59
  60         if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) < 0)
  61                 return -errno;
  62
  63         return 1;
  64 }
  65
  66 int chattr_path(const char *p, unsigned value, unsigned mask) {
  67         _cleanup_close_ int fd = -1;
  68
  69         assert(p);
  70
  71         if (mask == 0)
  72                 return 0;
  73
  74         fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
  75         if (fd < 0)
  76                 return -errno;
  77
  78         return chattr_fd(fd, value, mask);
  79 }
  80
  81 int read_attr_fd(int fd, unsigned *ret) {
  82         struct stat st;
  83
  84         assert(fd >= 0);
  85
  86         if (fstat(fd, &st) < 0)
  87                 return -errno;
  88
  89         if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
  90                 return -ENOTTY;
  91
  92         if (ioctl(fd, FS_IOC_GETFLAGS, ret) < 0)
  93                 return -errno;
  94
  95         return 0;
  96 }
  97
  98 int read_attr_path(const char *p, unsigned *ret) {
  99         _cleanup_close_ int fd = -1;
 100
 101         assert(p);
 102         assert(ret);
 103
 104         fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
 105         if (fd < 0)
 106                 return -errno;
 107
 108         return read_attr_fd(fd, ret);
 109 }