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
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13
  14 #include "fd-util.h"
  15 #include "fileio.h"
  16 #include "log.h"
  17 #include "macro.h"
  18 #include "string-util.h"
  19 #include "sysctl-util.h"
  20
  21 char *sysctl_normalize(char *s) {
  22         char *n;
  23
  24         n = strpbrk(s, "/.");
  25         /* If the first separator is a slash, the path is
  26          * assumed to be normalized and slashes remain slashes
  27          * and dots remains dots. */
  28         if (!n || *n == '/')
  29                 return s;
  30
  31         /* Otherwise, dots become slashes and slashes become
  32          * dots. Fun. */
  33         while (n) {
  34                 if (*n == '.')
  35                         *n = '/';
  36                 else
  37                         *n = '.';
  38
  39                 n = strpbrk(n + 1, "/.");
  40         }
  41
  42         return s;
  43 }
  44
  45 int sysctl_write(const char *property, const char *value) {
  46         char *p;
  47         _cleanup_close_ int fd = -1;
  48
  49         assert(property);
  50         assert(value);
  51
  52         log_debug("Setting '%s' to '%s'", property, value);
  53
  54         p = strjoina("/proc/sys/", property);
  55         fd = open(p, O_WRONLY|O_CLOEXEC);
  56         if (fd < 0)
  57                 return -errno;
  58
  59         if (!endswith(value, "\n"))
  60                 value = strjoina(value, "\n");
  61
  62         if (write(fd, value, strlen(value)) < 0)
  63                 return -errno;
  64
  65         return 0;
  66 }
  67
  68 int sysctl_read(const char *property, char **content) {
  69         char *p;
  70
  71         assert(property);
  72         assert(content);
  73
  74         p = strjoina("/proc/sys/", property);
  75         return read_full_file(p, content, NULL);
  76 }