fs.c revision 1dafceb1c9c6a57506fd4cbf57f721efe59afcda 
1/*
2 * fs.c         filesystem APIs
3 *
4 *		This program is free software; you can redistribute it and/or
5 *		modify it under the terms of the GNU General Public License
6 *		as published by the Free Software Foundation; either version
7 *		2 of the License, or (at your option) any later version.
8 *
9 * Authors:	David Ahern <dsa@cumulusnetworks.com>
10 *
11 */
12
13#include <sys/types.h>
14#include <sys/stat.h>
15#include <sys/socket.h>
16#include <sys/mount.h>
17#include <fcntl.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <unistd.h>
21#include <string.h>
22#include <errno.h>
23#include <limits.h>
24
25#include "utils.h"
26
27#define CGROUP2_FS_NAME "cgroup2"
28
29/* if not already mounted cgroup2 is mounted here for iproute2's use */
30#define MNT_CGRP2_PATH  "/var/run/cgroup2"
31
32/* return mount path of first occurrence of given fstype */
33static char *find_fs_mount(const char *fs_to_find)
34{
35	char path[4096];
36	char fstype[128];    /* max length of any filesystem name */
37	char *mnt = NULL;
38	FILE *fp;
39
40	fp = fopen("/proc/mounts", "r");
41	if (!fp) {
42		fprintf(stderr,
43			"Failed to open mounts file: %s\n", strerror(errno));
44		return NULL;
45	}
46
47	while (fscanf(fp, "%*s %4096s %127s %*s %*d %*d\n",
48		      path, fstype) == 2) {
49		if (strcmp(fstype, fs_to_find) == 0) {
50			mnt = strdup(path);
51			break;
52		}
53	}
54
55	fclose(fp);
56
57	return mnt;
58}
59
60/* caller needs to free string returned */
61char *find_cgroup2_mount(void)
62{
63	char *mnt = find_fs_mount(CGROUP2_FS_NAME);
64
65	if (mnt)
66		return mnt;
67
68	mnt = strdup(MNT_CGRP2_PATH);
69	if (!mnt) {
70		fprintf(stderr, "Failed to allocate memory for cgroup2 path\n");
71		return NULL;
72
73	}
74
75	if (make_path(mnt, 0755)) {
76		fprintf(stderr, "Failed to setup vrf cgroup2 directory\n");
77		free(mnt);
78		return NULL;
79	}
80
81	if (mount("none", mnt, CGROUP2_FS_NAME, 0, NULL)) {
82		/* EBUSY means already mounted */
83		if (errno != EBUSY) {
84			fprintf(stderr,
85				"Failed to mount cgroup2. Are CGROUPS enabled in your kernel?\n");
86			free(mnt);
87			return NULL;
88		}
89	}
90	return mnt;
91}
92
93int make_path(const char *path, mode_t mode)
94{
95	char *dir, *delim;
96	struct stat sbuf;
97	int rc = -1;
98
99	delim = dir = strdup(path);
100	if (dir == NULL) {
101		fprintf(stderr, "strdup failed copying path");
102		return -1;
103	}
104
105	/* skip '/' -- it had better exist */
106	if (*delim == '/')
107		delim++;
108
109	while (1) {
110		delim = strchr(delim, '/');
111		if (delim)
112			*delim = '\0';
113
114		if (stat(dir, &sbuf) != 0) {
115			if (errno != ENOENT) {
116				fprintf(stderr,
117					"stat failed for %s: %s\n",
118					dir, strerror(errno));
119				goto out;
120			}
121
122			if (mkdir(dir, mode) != 0) {
123				fprintf(stderr,
124					"mkdir failed for %s: %s",
125					dir, strerror(errno));
126				goto out;
127			}
128		}
129
130		if (delim == NULL)
131			break;
132
133		*delim = '/';
134		delim++;
135		if (*delim == '\0')
136			break;
137	}
138	rc = 0;
139out:
140	free(dir);
141
142	return rc;
143}
144