sysctl.c

   1 /*
   2  * sysctl - sysctl set/get helpers
   3  * Subject to the GPL, version 2.
   4  */
   5
   6 #include <stdio.h>
   7 #include <fcntl.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <unistd.h>
  11 #include <linux/limits.h>
  12
  13 #include "built_in.h"
  14
  15 #define SYS_PATH "/proc/sys/"
  16
  17 int sysctl_set_int(const char *file, int value)
  18 {
  19         char path[PATH_MAX];
  20         char str[64];
  21         ssize_t ret;
  22         int fd;
  23
  24         strncpy(path, SYS_PATH, PATH_MAX);
  25         strncat(path, file, PATH_MAX - sizeof(SYS_PATH) - 1);
  26
  27         fd = open(path, O_WRONLY);
  28         if (unlikely(fd < 0))
  29                 return -1;
  30
  31         ret = snprintf(str, 63, "%d", value);
  32         if (ret < 0) {
  33                 close(fd);
  34                 return -1;
  35         }
  36
  37         ret = write(fd, str, strlen(str));
  38
  39         close(fd);
  40         return ret <= 0 ? -1 : 0;
  41 }
  42
  43 int sysctl_get_int(const char *file, int *value)
  44 {
  45         char path[PATH_MAX];
  46         char str[64];
  47         ssize_t ret;
  48         int fd;
  49
  50         strncpy(path, SYS_PATH, PATH_MAX);
  51         strncat(path, file, PATH_MAX - sizeof(SYS_PATH) - 1);
  52
  53         fd = open(path, O_RDONLY);
  54         if (fd < 0)
  55                 return -1;
  56
  57         ret = read(fd, str, sizeof(str));
  58         if (ret > 0) {
  59                 *value = atoi(str);
  60                 ret = 0;
  61         } else {
  62                 ret = -1;
  63         }
  64
  65         close(fd);
  66         return ret;
  67 }