tools/perf/util/sysfs.c

   1
   2 #include "util.h"
   3 #include "sysfs.h"
   4
   5 static const char * const sysfs_known_mountpoints[] = {
   6         "/sys",
   7         0,
   8 };
   9
  10 static int sysfs_found;
  11 char sysfs_mountpoint[PATH_MAX];
  12
  13 static int sysfs_valid_mountpoint(const char *sysfs)
  14 {
  15         struct statfs st_fs;
  16
  17         if (statfs(sysfs, &st_fs) < 0)
  18                 return -ENOENT;
  19         else if (st_fs.f_type != (long) SYSFS_MAGIC)
  20                 return -ENOENT;
  21
  22         return 0;
  23 }
  24
  25 const char *sysfs_find_mountpoint(void)
  26 {
  27         const char * const *ptr;
  28         char type[100];
  29         FILE *fp;
  30
  31         if (sysfs_found)
  32                 return (const char *) sysfs_mountpoint;
  33
  34         ptr = sysfs_known_mountpoints;
  35         while (*ptr) {
  36                 if (sysfs_valid_mountpoint(*ptr) == 0) {
  37                         sysfs_found = 1;
  38                         strcpy(sysfs_mountpoint, *ptr);
  39                         return sysfs_mountpoint;
  40                 }
  41                 ptr++;
  42         }
  43
  44         /* give up and parse /proc/mounts */
  45         fp = fopen("/proc/mounts", "r");
  46         if (fp == NULL)
  47                 return NULL;
  48
  49         while (!sysfs_found &&
  50                fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
  51                       sysfs_mountpoint, type) == 2) {
  52
  53                 if (strcmp(type, "sysfs") == 0)
  54                         sysfs_found = 1;
  55         }
  56
  57         fclose(fp);
  58
  59         return sysfs_found ? sysfs_mountpoint : NULL;
  60 }