| Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | #include <linux/stringify.h> |
| 3 | #include <sys/types.h> |
| 4 | #include <sys/stat.h> |
| 5 | #include <fcntl.h> |
| 6 | #include <stdio.h> |
| 7 | #include <stdlib.h> |
| 8 | #include <string.h> |
| 9 | #include "fs.h" |
| 10 | |
| 11 | int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys) |
| 12 | { |
| 13 | FILE *fp; |
| 14 | char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1]; |
| 15 | char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path; |
| 16 | char *token, *saved_ptr = NULL; |
| 17 | |
| 18 | fp = fopen("/proc/mounts", "r"); |
| 19 | if (!fp) |
| 20 | return -1; |
| 21 | |
| 22 | /* |
| 23 | * in order to handle split hierarchy, we need to scan /proc/mounts |
| 24 | * and inspect every cgroupfs mount point to find one that has |
| 25 | * perf_event subsystem |
| 26 | */ |
| 27 | path_v1[0] = '\0'; |
| 28 | path_v2[0] = '\0'; |
| 29 | |
| 30 | while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %" |
| 31 | __stringify(PATH_MAX)"s %*d %*d\n", |
| 32 | mountpoint, type, tokens) == 3) { |
| 33 | |
| 34 | if (!path_v1[0] && !strcmp(type, "cgroup")) { |
| 35 | |
| 36 | token = strtok_r(tokens, ",", &saved_ptr); |
| 37 | |
| 38 | while (token != NULL) { |
| 39 | if (subsys && !strcmp(token, subsys)) { |
| 40 | strcpy(path_v1, mountpoint); |
| 41 | break; |
| 42 | } |
| 43 | token = strtok_r(NULL, ",", &saved_ptr); |
| 44 | } |
| 45 | } |
| 46 | |
| 47 | if (!path_v2[0] && !strcmp(type, "cgroup2")) |
| 48 | strcpy(path_v2, mountpoint); |
| 49 | |
| 50 | if (path_v1[0] && path_v2[0]) |
| 51 | break; |
| 52 | } |
| 53 | fclose(fp); |
| 54 | |
| 55 | if (path_v1[0]) |
| 56 | path = path_v1; |
| 57 | else if (path_v2[0]) |
| 58 | path = path_v2; |
| 59 | else |
| 60 | return -1; |
| 61 | |
| 62 | if (strlen(path) < maxlen) { |
| 63 | strcpy(buf, path); |
| 64 | return 0; |
| 65 | } |
| 66 | return -1; |
| 67 | } |