src/shared/sysctl-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6
   7   systemd is free software; you can redistribute it and/or modify it
   8   under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   systemd is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include "fd-util.h"
  28 #include "fileio.h"
  29 #include "log.h"
  30 #include "macro.h"
  31 #include "string-util.h"
  32 #include "sysctl-util.h"
  33
  34 char *sysctl_normalize(char *s) {
  35         char *n;
  36
  37         n = strpbrk(s, "/.");
  38         /* If the first separator is a slash, the path is
  39          * assumed to be normalized and slashes remain slashes
  40          * and dots remains dots. */
  41         if (!n || *n == '/')
  42                 return s;
  43
  44         /* Otherwise, dots become slashes and slashes become
  45          * dots. Fun. */
  46         while (n) {
  47                 if (*n == '.')
  48                         *n = '/';
  49                 else
  50                         *n = '.';
  51
  52                 n = strpbrk(n + 1, "/.");
  53         }
  54
  55         return s;
  56 }
  57
  58 int sysctl_write(const char *property, const char *value) {
  59         char *p;
  60         _cleanup_close_ int fd = -1;
  61
  62         assert(property);
  63         assert(value);
  64
  65         log_debug("Setting '%s' to '%s'", property, value);
  66
  67         p = strjoina("/proc/sys/", property);
  68         fd = open(p, O_WRONLY|O_CLOEXEC);
  69         if (fd < 0)
  70                 return -errno;
  71
  72         if (!endswith(value, "\n"))
  73                 value = strjoina(value, "\n");
  74
  75         if (write(fd, value, strlen(value)) < 0)
  76                 return -errno;
  77
  78         return 0;
  79 }
  80
  81 int sysctl_read(const char *property, char **content) {
  82         char *p;
  83
  84         assert(property);
  85         assert(content);
  86
  87         p = strjoina("/proc/sys/", property);
  88         return read_full_file(p, content, NULL);
  89 }