src/shared/sysctl-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8
   9 #include "fd-util.h"
  10 #include "fileio.h"
  11 #include "log.h"
  12 #include "macro.h"
  13 #include "string-util.h"
  14 #include "sysctl-util.h"
  15
  16 char *sysctl_normalize(char *s) {
  17         char *n;
  18
  19         n = strpbrk(s, "/.");
  20         /* If the first separator is a slash, the path is
  21          * assumed to be normalized and slashes remain slashes
  22          * and dots remains dots. */
  23         if (!n || *n == '/')
  24                 return s;
  25
  26         /* Otherwise, dots become slashes and slashes become
  27          * dots. Fun. */
  28         while (n) {
  29                 if (*n == '.')
  30                         *n = '/';
  31                 else
  32                         *n = '.';
  33
  34                 n = strpbrk(n + 1, "/.");
  35         }
  36
  37         return s;
  38 }
  39
  40 int sysctl_write(const char *property, const char *value) {
  41         char *p;
  42         _cleanup_close_ int fd = -1;
  43
  44         assert(property);
  45         assert(value);
  46
  47         log_debug("Setting '%s' to '%.*s'.", property, (int) strcspn(value, NEWLINE), value);
  48
  49         p = strjoina("/proc/sys/", property);
  50         fd = open(p, O_WRONLY|O_CLOEXEC);
  51         if (fd < 0)
  52                 return -errno;
  53
  54         if (!endswith(value, "\n"))
  55                 value = strjoina(value, "\n");
  56
  57         if (write(fd, value, strlen(value)) < 0)
  58                 return -errno;
  59
  60         return 0;
  61 }
  62
  63 int sysctl_write_ip_property(int af, const char *ifname, const char *property, const char *value) {
  64         const char *p;
  65
  66         assert(IN_SET(af, AF_INET, AF_INET6));
  67         assert(property);
  68         assert(value);
  69
  70         p = strjoina("/proc/sys/net/ipv", af == AF_INET ? "4" : "6",
  71                      ifname ? "/conf/" : "", strempty(ifname),
  72                      property[0] == '/' ? "" : "/", property);
  73
  74         log_debug("Setting '%s' to '%s'", p, value);
  75
  76         return write_string_file(p, value, WRITE_STRING_FILE_VERIFY_ON_FAILURE | WRITE_STRING_FILE_DISABLE_BUFFER);
  77 }
  78
  79 int sysctl_read(const char *property, char **content) {
  80         char *p;
  81
  82         assert(property);
  83         assert(content);
  84
  85         p = strjoina("/proc/sys/", property);
  86         return read_full_file(p, content, NULL);
  87 }
  88
  89 int sysctl_read_ip_property(int af, const char *ifname, const char *property, char **ret) {
  90         _cleanup_free_ char *value = NULL;
  91         const char *p;
  92         int r;
  93
  94         assert(IN_SET(af, AF_INET, AF_INET6));
  95         assert(property);
  96
  97         p = strjoina("/proc/sys/net/ipv", af == AF_INET ? "4" : "6",
  98                      ifname ? "/conf/" : "", strempty(ifname),
  99                      property[0] == '/' ? "" : "/", property);
 100
 101         r = read_one_line_file(p, &value);
 102         if (r < 0)
 103                 return r;
 104
 105         if (ret)
 106                 *ret = TAKE_PTR(value);
 107
 108         return r;
 109 }