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 <limits.h>
  12
  13 #include "built_in.h"
  14 #include "sysctl.h"
  15
  16 int sysctl_set_int(const char *file, int value)
  17 {
  18         char path[PATH_MAX];
  19         char str[64];
  20         ssize_t ret;
  21         int fd;
  22
  23         strncpy(path, SYSCTL_PROC_PATH, PATH_MAX);
  24         strncat(path, file, PATH_MAX - sizeof(SYSCTL_PROC_PATH) - 1);
  25
  26         fd = open(path, O_WRONLY);
  27         if (unlikely(fd < 0))
  28                 return -1;
  29
  30         ret = snprintf(str, 63, "%d", value);
  31         if (ret < 0) {
  32                 close(fd);
  33                 return -1;
  34         }
  35
  36         ret = write(fd, str, strlen(str));
  37
  38         close(fd);
  39         return ret <= 0 ? -1 : 0;
  40 }
  41
  42 int sysctl_get_int(const char *file, int *value)
  43 {
  44         char path[PATH_MAX];
  45         char str[64];
  46         ssize_t ret;
  47         int fd;
  48
  49         strncpy(path, SYSCTL_PROC_PATH, PATH_MAX);
  50         strncat(path, file, PATH_MAX - sizeof(SYSCTL_PROC_PATH) - 1);
  51
  52         fd = open(path, O_RDONLY);
  53         if (fd < 0)
  54                 return -1;
  55
  56         ret = read(fd, str, sizeof(str));
  57         if (ret > 0) {
  58                 *value = atoi(str);
  59                 ret = 0;
  60         } else {
  61                 ret = -1;
  62         }
  63
  64         close(fd);
  65         return ret;
  66 }