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/*
* fs.c filesystem APIs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: David Ahern <dsa@cumulusnetworks.com>
*
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/mount.h>
#include <ctype.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include "utils.h"
#define CGROUP2_FS_NAME "cgroup2"
/* if not already mounted cgroup2 is mounted here for iproute2's use */
#define MNT_CGRP2_PATH "/var/run/cgroup2"
/* return mount path of first occurrence of given fstype */
static char *find_fs_mount(const char *fs_to_find)
{
char path[4096];
char fstype[128]; /* max length of any filesystem name */
char *mnt = NULL;
FILE *fp;
fp = fopen("/proc/mounts", "r");
if (!fp) {
fprintf(stderr,
"Failed to open mounts file: %s\n", strerror(errno));
return NULL;
}
while (fscanf(fp, "%*s %4095s %127s %*s %*d %*d\n",
path, fstype) == 2) {
if (strcmp(fstype, fs_to_find) == 0) {
mnt = strdup(path);
break;
}
}
fclose(fp);
return mnt;
}
/* caller needs to free string returned */
char *find_cgroup2_mount(void)
{
char *mnt = find_fs_mount(CGROUP2_FS_NAME);
if (mnt)
return mnt;
mnt = strdup(MNT_CGRP2_PATH);
if (!mnt) {
fprintf(stderr, "Failed to allocate memory for cgroup2 path\n");
return NULL;
}
if (make_path(mnt, 0755)) {
fprintf(stderr, "Failed to setup vrf cgroup2 directory\n");
free(mnt);
return NULL;
}
if (mount("none", mnt, CGROUP2_FS_NAME, 0, NULL)) {
/* EBUSY means already mounted */
if (errno == EBUSY)
goto out;
if (errno == ENODEV) {
fprintf(stderr,
"Failed to mount cgroup2. Are CGROUPS enabled in your kernel?\n");
} else {
fprintf(stderr,
"Failed to mount cgroup2: %s\n",
strerror(errno));
}
free(mnt);
return NULL;
}
out:
return mnt;
}
int make_path(const char *path, mode_t mode)
{
char *dir, *delim;
int rc = -1;
delim = dir = strdup(path);
if (dir == NULL) {
fprintf(stderr, "strdup failed copying path");
return -1;
}
/* skip '/' -- it had better exist */
if (*delim == '/')
delim++;
while (1) {
delim = strchr(delim, '/');
if (delim)
*delim = '\0';
rc = mkdir(dir, mode);
if (mkdir(dir, mode) != 0 && errno != EEXIST) {
fprintf(stderr, "mkdir failed for %s: %s\n",
dir, strerror(errno));
goto out;
}
if (delim == NULL)
break;
*delim = '/';
delim++;
if (*delim == '\0')
break;
}
rc = 0;
out:
free(dir);
return rc;
}
int get_command_name(const char *pid, char *comm, size_t len)
{
char path[PATH_MAX];
char line[128];
FILE *fp;
if (snprintf(path, sizeof(path),
"/proc/%s/status", pid) >= sizeof(path)) {
return -1;
}
fp = fopen(path, "r");
if (!fp)
return -1;
comm[0] = '\0';
while (fgets(line, sizeof(line), fp)) {
char *nl, *name;
name = strstr(line, "Name:");
if (!name)
continue;
name += 5;
while (isspace(*name))
name++;
nl = strchr(name, '\n');
if (nl)
*nl = '\0';
strlcpy(comm, name, len);
break;
}
fclose(fp);
return 0;
}
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