| Bill Richardson | 75fcf62 | 2010-03-16 13:05:12 -0700 | [diff] [blame] | 1 | /* Taken from util-linux source. GPLv2. |
| 2 | * Emits the current rootfs device. |
| 3 | * Works by searching /dev recursively for a BLK device with the same device |
| 4 | * number as '/'. |
| 5 | */ |
| 6 | |
| 7 | #include <stdio.h> |
| 8 | #include <err.h> |
| 9 | #include <sys/types.h> |
| 10 | #include <dirent.h> |
| 11 | #include <sys/stat.h> |
| 12 | #include <string.h> |
| 13 | |
| 14 | |
| 15 | static int |
| 16 | find_dev_recursive(char *dirnamebuf, int number) { |
| 17 | DIR *dp; |
| 18 | struct dirent *dir; |
| 19 | struct stat s; |
| 20 | int dirnamelen = 0; |
| 21 | |
| 22 | if ((dp = opendir(dirnamebuf)) == NULL) |
| 23 | err(1, "can't read directory %s", dirnamebuf); |
| 24 | dirnamelen = strlen(dirnamebuf); |
| 25 | while ((dir = readdir(dp)) != NULL) { |
| 26 | if (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, "..")) |
| 27 | continue; |
| 28 | if (dirnamelen + 1 + strlen(dir->d_name) > PATH_MAX) |
| 29 | continue; |
| 30 | dirnamebuf[dirnamelen] = '/'; |
| 31 | strcpy(dirnamebuf+dirnamelen+1, dir->d_name); |
| 32 | if (lstat(dirnamebuf, &s) < 0) |
| 33 | continue; |
| 34 | if ((s.st_mode & S_IFMT) == S_IFBLK && s.st_rdev == number) |
| 35 | return 1; |
| 36 | if ((s.st_mode & S_IFMT) == S_IFDIR && |
| 37 | find_dev_recursive(dirnamebuf, number)) |
| 38 | return 1; |
| 39 | } |
| 40 | dirnamebuf[dirnamelen] = 0; |
| 41 | closedir(dp); |
| 42 | return 0; |
| 43 | } |
| 44 | |
| 45 | int main(int argc, char *argv[]) { |
| 46 | struct stat s; |
| 47 | char *file = "/"; |
| 48 | static char name[PATH_MAX+1]; |
| 49 | |
| 50 | if (argc > 1) |
| 51 | file = argv[1]; |
| 52 | |
| 53 | if (stat(file, &s) < 0) |
| 54 | err(1, "unable to stat %s", file); |
| 55 | |
| 56 | if (!s.st_dev) |
| 57 | err(1, "unknown device number 0"); |
| 58 | |
| 59 | strcpy(name, "/dev"); |
| 60 | |
| 61 | if (!find_dev_recursive(name, s.st_dev)) { |
| 62 | fprintf(stderr, "unable to find match\n"); |
| 63 | return 1; |
| 64 | } |
| 65 | |
| 66 | printf("%s\n", name); |
| 67 | |
| 68 | return 0; |
| 69 | } |