tools/lib/api/fs/fs.c

   1 /* TODO merge/factor in debugfs.c here */
   2
   3 #include <errno.h>
   4 #include <stdbool.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <sys/vfs.h>
   8
   9 #include "debugfs.h"
  10 #include "fs.h"
  11
  12 static const char * const sysfs__fs_known_mountpoints[] = {
  13         "/sys",
  14         0,
  15 };
  16
  17 static const char * const procfs__known_mountpoints[] = {
  18         "/proc",
  19         0,
  20 };
  21
  22 struct fs {
  23         const char              *name;
  24         const char * const      *mounts;
  25         char                     path[PATH_MAX + 1];
  26         bool                     found;
  27         long                     magic;
  28 };
  29
  30 enum {
  31         FS__SYSFS  = 0,
  32         FS__PROCFS = 1,
  33 };
  34
  35 static struct fs fs__entries[] = {
  36         [FS__SYSFS] = {
  37                 .name   = "sysfs",
  38                 .mounts = sysfs__fs_known_mountpoints,
  39                 .magic  = SYSFS_MAGIC,
  40         },
  41         [FS__PROCFS] = {
  42                 .name   = "proc",
  43                 .mounts = procfs__known_mountpoints,
  44                 .magic  = PROC_SUPER_MAGIC,
  45         },
  46 };
  47
  48 static bool fs__read_mounts(struct fs *fs)
  49 {
  50         bool found = false;
  51         char type[100];
  52         FILE *fp;
  53
  54         fp = fopen("/proc/mounts", "r");
  55         if (fp == NULL)
  56                 return NULL;
  57
  58         while (!found &&
  59                fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
  60                       fs->path, type) == 2) {
  61
  62                 if (strcmp(type, fs->name) == 0)
  63                         found = true;
  64         }
  65
  66         fclose(fp);
  67         return fs->found = found;
  68 }
  69
  70 static int fs__valid_mount(const char *fs, long magic)
  71 {
  72         struct statfs st_fs;
  73
  74         if (statfs(fs, &st_fs) < 0)
  75                 return -ENOENT;
  76         else if (st_fs.f_type != magic)
  77                 return -ENOENT;
  78
  79         return 0;
  80 }
  81
  82 static bool fs__check_mounts(struct fs *fs)
  83 {
  84         const char * const *ptr;
  85
  86         ptr = fs->mounts;
  87         while (*ptr) {
  88                 if (fs__valid_mount(*ptr, fs->magic) == 0) {
  89                         fs->found = true;
  90                         strcpy(fs->path, *ptr);
  91                         return true;
  92                 }
  93                 ptr++;
  94         }
  95
  96         return false;
  97 }
  98
  99 static const char *fs__get_mountpoint(struct fs *fs)
 100 {
 101         if (fs__check_mounts(fs))
 102                 return fs->path;
 103
 104         return fs__read_mounts(fs) ? fs->path : NULL;
 105 }
 106
 107 static const char *fs__mountpoint(int idx)
 108 {
 109         struct fs *fs = &fs__entries[idx];
 110
 111         if (fs->found)
 112                 return (const char *)fs->path;
 113
 114         return fs__get_mountpoint(fs);
 115 }
 116
 117 #define FS__MOUNTPOINT(name, idx)       \
 118 const char *name##__mountpoint(void)    \
 119 {                                       \
 120         return fs__mountpoint(idx);     \
 121 }
 122
 123 FS__MOUNTPOINT(sysfs,  FS__SYSFS);
 124 FS__MOUNTPOINT(procfs, FS__PROCFS);