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/*
* lxc: linux Container library
*
* (C) Copyright IBM Corp. 2007, 2008
*
* Authors:
* Daniel Lezcano <dlezcano at fr.ibm.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#define _GNU_SOURCE
#include <stdio.h>
#undef _GNU_SOURCE
#include <stdlib.h>
#include <errno.h>
#include <mntent.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/inotify.h>
#include <netinet/in.h>
#include <net/if.h>
#include "error.h"
#include "config.h"
#include <lxc/log.h>
#include <lxc/cgroup.h>
#include <lxc/start.h>
lxc_log_define(lxc_cgroup, lxc);
#define MTAB "/proc/mounts"
enum {
CGROUP_NS_CGROUP = 1,
CGROUP_CLONE_CHILDREN,
};
static char *hasmntopt_multiple(struct mntent *mntent, const char *options)
{
const char *ptr = options;
const char *ptr2 = strchr(options, ',');
char *result;
while (ptr2 != NULL) {
char *option = strndup(ptr, ptr2 - ptr);
if (!option) {
SYSERROR("Temporary memory allocation error");
return NULL;
}
result = hasmntopt(mntent, option);
free(option);
if (!result) {
return NULL;
}
ptr = ptr2 + 1;
ptr2 = strchr(ptr, ',');
}
/* for multiple mount options, the return value is basically NULL
* or non-NULL, so this should suffice for our purposes */
return hasmntopt(mntent, ptr);
}
/*
* get_init_cgroup: get the cgroup init is in.
* dsg: preallocated buffer to put the output in
* subsystem: the exact cgroup subsystem to look up
* mntent: a mntent (from getmntent) whose mntopts contains the
* subsystem to look up.
*
* subsystem and mntent can both be NULL, in which case we return
* the first entry in /proc/1/cgroup.
*
* Returns a pointer to the answer, which may be "".
*/
static char *get_init_cgroup(const char *subsystem, struct mntent *mntent,
char *dsg)
{
FILE *f;
char *c, *c2;
char line[MAXPATHLEN];
*dsg = '\0';
f = fopen("/proc/1/cgroup", "r");
if (!f)
return dsg;
while (fgets(line, MAXPATHLEN, f)) {
c = index(line, ':');
if (!c)
continue;
c++;
c2 = index(c, ':');
if (!c2)
continue;
*c2 = '\0';
c2++;
if (!subsystem && !mntent)
goto good;
if (subsystem && strcmp(c, subsystem) != 0)
continue;
if (mntent && !hasmntopt(mntent, c))
continue;
good:
DEBUG("get_init_cgroup: found init cgroup for subsys %s at %s\n",
subsystem, c2);
strncpy(dsg, c2, MAXPATHLEN);
c = &dsg[strlen(dsg)-1];
if (*c == '\n')
*c = '\0';
goto found;
}
found:
fclose(f);
return dsg;
}
static int get_cgroup_flags(struct mntent *mntent)
{
int flags = 0;
if (hasmntopt(mntent, "ns"))
flags |= CGROUP_NS_CGROUP;
if (hasmntopt(mntent, "clone_children"))
flags |= CGROUP_CLONE_CHILDREN;
DEBUG("cgroup %s has flags 0x%x", mntent->mnt_dir, flags);
return flags;
}
static int get_cgroup_mount(const char *subsystem, char *mnt)
{
struct mntent *mntent;
char initcgroup[MAXPATHLEN];
FILE *file = NULL;
file = setmntent(MTAB, "r");
if (!file) {
SYSERROR("failed to open %s", MTAB);
return -1;
}
while ((mntent = getmntent(file))) {
if (strcmp(mntent->mnt_type, "cgroup"))
continue;
if (!subsystem || hasmntopt_multiple(mntent, subsystem)) {
int ret;
int flags = get_cgroup_flags(mntent);
ret = snprintf(mnt, MAXPATHLEN, "%s%s%s",
mntent->mnt_dir,
get_init_cgroup(subsystem, NULL,
initcgroup),
(flags & CGROUP_NS_CGROUP) ? "" : "/lxc");
if (ret < 0 || ret >= MAXPATHLEN)
goto fail;
fclose(file);
DEBUG("using cgroup mounted at '%s'", mnt);
return 0;
}
};
fail:
DEBUG("Failed to find cgroup for %s\n",
subsystem ? subsystem : "(NULL)");
fclose(file);
return -1;
}
int lxc_ns_is_mounted(void)
{
static char buf[MAXPATHLEN];
return (get_cgroup_mount("ns", buf) == 0);
}
static int cgroup_rename_nsgroup(const char *mnt, const char *name, pid_t pid)
{
char oldname[MAXPATHLEN];
char newname[MAXPATHLEN];
int ret;
ret = snprintf(oldname, MAXPATHLEN, "%s/%d", mnt, pid);
if (ret >= MAXPATHLEN)
return -1;
ret = snprintf(newname, MAXPATHLEN, "%s/%s", mnt, name);
if (ret >= MAXPATHLEN)
return -1;
if (rename(oldname, newname)) {
SYSERROR("failed to rename cgroup %s->%s", oldname, newname);
return -1;
}
DEBUG("'%s' renamed to '%s'", oldname, newname);
return 0;
}
static int cgroup_enable_clone_children(const char *path)
{
FILE *f;
int ret = 0;
f = fopen(path, "w");
if (!f) {
SYSERROR("failed to open '%s'", path);
return -1;
}
if (fprintf(f, "1") < 1) {
ERROR("failed to write flag to '%s'", path);
ret = -1;
}
fclose(f);
return ret;
}
int lxc_cgroup_attach(const char *path, pid_t pid)
{
FILE *f;
char tasks[MAXPATHLEN];
int ret = 0;
snprintf(tasks, MAXPATHLEN, "%s/tasks", path);
f = fopen(tasks, "w");
if (!f) {
SYSERROR("failed to open '%s'", tasks);
return -1;
}
if (fprintf(f, "%d", pid) <= 0) {
SYSERROR("failed to write pid '%d' to '%s'", pid, tasks);
ret = -1;
}
fclose(f);
return ret;
}
/*
* rename cgname, which is under cgparent, to a new name starting
* with 'cgparent/dead'. That way cgname can be reused. Return
* 0 on success, -1 on failure.
*/
int try_to_move_cgname(char *cgparent, char *cgname)
{
char *newdir;
/* tempnam problems don't matter here - cgroupfs will prevent
* duplicates if we race, and we'll just fail at that (unlikely)
* point
*/
newdir = tempnam(cgparent, "dead");
if (!newdir)
return -1;
if (rename(cgname, newdir))
return -1;
WARN("non-empty cgroup %s renamed to %s, please manually inspect it\n",
cgname, newdir);
return 0;
}
/*
* create a cgroup for the container in a particular subsystem.
*/
static int lxc_one_cgroup_create(const char *name,
struct mntent *mntent, pid_t pid)
{
char cginit[MAXPATHLEN], cgname[MAXPATHLEN], cgparent[MAXPATHLEN];
char clonechild[MAXPATHLEN];
char initcgroup[MAXPATHLEN];
int flags, ret;
/* cgparent is the parent dir, /sys/fs/cgroup/<cgroup>/<init-cgroup>/lxc */
/* (remember get_init_cgroup() returns a path starting with '/') */
/* cgname is the full name, /sys/fs/cgroup/</cgroup>/<init-cgroup>/lxc/name */
ret = snprintf(cginit, MAXPATHLEN, "%s%s", mntent->mnt_dir,
get_init_cgroup(NULL, mntent, initcgroup));
if (ret < 0 || ret >= MAXPATHLEN) {
SYSERROR("Failed creating pathname for init's cgroup (%d)\n", ret);
return -1;
}
ret = snprintf(cgparent, MAXPATHLEN, "%s/lxc", cginit);
if (ret < 0 || ret >= MAXPATHLEN) {
SYSERROR("Failed creating pathname for cgroup parent (%d)\n", ret);
return -1;
}
ret = snprintf(cgname, MAXPATHLEN, "%s/%s", cgparent, name);
if (ret < 0 || ret >= MAXPATHLEN) {
SYSERROR("Failed creating pathname for cgroup (%d)\n", ret);
return -1;
}
flags = get_cgroup_flags(mntent);
/* Do we have the deprecated ns_cgroup subsystem? */
if (flags & CGROUP_NS_CGROUP) {
WARN("using deprecated ns_cgroup");
return cgroup_rename_nsgroup(cginit, name, pid);
}
ret = snprintf(clonechild, MAXPATHLEN, "%s/cgroup.clone_children",
cginit);
if (ret < 0 || ret >= MAXPATHLEN) {
SYSERROR("Failed creating pathname for clone_children (%d)\n", ret);
return -1;
}
/* we check if the kernel has clone_children, at this point if there
* no clone_children neither ns_cgroup, that means the cgroup is mounted
* without the ns_cgroup and it has not the compatibility flag
*/
if (access(clonechild, F_OK)) {
ERROR("no ns_cgroup option specified");
return -1;
}
/* enable the clone_children flag of the cgroup */
if (cgroup_enable_clone_children(clonechild)) {
SYSERROR("failed to enable 'clone_children flag");
return -1;
}
/* if /sys/fs/cgroup/<cgroup>/<init-cgroup>/lxc does not exist, create it */
if (access(cgparent, F_OK) && mkdir(cgparent, 0755)) {
SYSERROR("failed to create '%s' directory", cgparent);
return -1;
}
/*
* There is a previous cgroup. Try to delete it. If that fails
* (i.e. it is not empty) try to move it out of the way.
*/
if (!access(cgname, F_OK) && rmdir(cgname)) {
if (try_to_move_cgname(cgparent, cgname)) {
SYSERROR("failed to remove previous cgroup '%s'", cgname);
return -1;
}
}
/* Let's create the cgroup */
if (mkdir(cgname, 0755)) {
SYSERROR("failed to create '%s' directory", cgname);
return -1;
}
/* Let's add the pid to the 'tasks' file */
if (lxc_cgroup_attach(cgname, pid)) {
SYSERROR("failed to attach pid '%d' to '%s'", pid, cgname);
rmdir(cgname);
return -1;
}
INFO("created cgroup '%s'", cgname);
return 0;
}
/*
* for each mounted cgroup, create a cgroup for the container
*/
int lxc_cgroup_create(const char *name, pid_t pid)
{
struct mntent *mntent;
FILE *file = NULL;
int err = -1;
int found = 0;
file = setmntent(MTAB, "r");
if (!file) {
SYSERROR("failed to open %s", MTAB);
return -1;
}
while ((mntent = getmntent(file))) {
DEBUG("checking '%s' (%s)", mntent->mnt_dir, mntent->mnt_type);
if (!strcmp(mntent->mnt_type, "cgroup")) {
INFO("[%d] found cgroup mounted at '%s',opts='%s'",
++found, mntent->mnt_dir, mntent->mnt_opts);
err = lxc_one_cgroup_create(name, mntent, pid);
if (err)
goto out;
}
};
if (!found)
ERROR("No cgroup mounted on the system");
out:
endmntent(file);
return err;
}
int recursive_rmdir(char *dirname)
{
struct dirent dirent, *direntp;
DIR *dir;
int ret;
char pathname[MAXPATHLEN];
dir = opendir(dirname);
if (!dir) {
WARN("failed to open directory: %m");
return -1;
}
while (!readdir_r(dir, &dirent, &direntp)) {
struct stat mystat;
if (!direntp)
break;
if (!strcmp(direntp->d_name, ".") ||
!strcmp(direntp->d_name, ".."))
continue;
snprintf(pathname, MAXPATHLEN, "%s/%s", dirname, direntp->d_name);
ret = stat(pathname, &mystat);
if (ret)
continue;
if (S_ISDIR(mystat.st_mode))
recursive_rmdir(pathname);
}
ret = rmdir(dirname);
if (closedir(dir))
ERROR("failed to close directory");
return ret;
}
int lxc_one_cgroup_destroy(struct mntent *mntent, const char *name)
{
char cgname[MAXPATHLEN], initcgroup[MAXPATHLEN];
char *cgmnt = mntent->mnt_dir;
int flags = get_cgroup_flags(mntent);
snprintf(cgname, MAXPATHLEN, "%s%s%s/%s", cgmnt,
get_init_cgroup(NULL, mntent, initcgroup),
(flags & CGROUP_NS_CGROUP) ? "" : "/lxc", name);
DEBUG("destroying %s\n", cgname);
if (recursive_rmdir(cgname)) {
SYSERROR("failed to remove cgroup '%s'", cgname);
return -1;
}
DEBUG("'%s' unlinked", cgname);
return 0;
}
/*
* for each mounted cgroup, destroy the cgroup for the container
*/
int lxc_cgroup_destroy(const char *name)
{
struct mntent *mntent;
FILE *file = NULL;
int ret, err = -1;
file = setmntent(MTAB, "r");
if (!file) {
SYSERROR("failed to open %s", MTAB);
return -1;
}
while ((mntent = getmntent(file))) {
if (!strcmp(mntent->mnt_type, "cgroup")) {
ret = lxc_one_cgroup_destroy(mntent, name);
if (ret) {
fclose(file);
return ret;
}
err = 0;
}
}
fclose(file);
return err;
}
/*
* lxc_cgroup_path_get: put into *path the pathname for
* %subsystem and cgroup %name. If %subsystem is NULL, then
* the first mounted cgroup will be used (for nr_tasks)
*/
int lxc_cgroup_path_get(char **path, const char *subsystem, const char *name)
{
static char buf[MAXPATHLEN];
static char retbuf[MAXPATHLEN];
/* what lxc_cgroup_set calls subsystem is actually the filename, i.e.
'devices.allow'. So for our purposee we trim it */
if (subsystem) {
snprintf(retbuf, MAXPATHLEN, "%s", subsystem);
char *s = index(retbuf, '.');
if (s)
*s = '\0';
DEBUG("%s: called for subsys %s name %s\n", __func__, retbuf, name);
}
if (get_cgroup_mount(subsystem ? retbuf : NULL, buf)) {
ERROR("cgroup is not mounted");
return -1;
}
snprintf(retbuf, MAXPATHLEN, "%s/%s", buf, name);
DEBUG("%s: returning %s for subsystem %s", __func__, retbuf, subsystem);
*path = retbuf;
return 0;
}
int lxc_cgroup_set(const char *name, const char *filename, const char *value)
{
int fd, ret;
char *dirpath;
char path[MAXPATHLEN];
ret = lxc_cgroup_path_get(&dirpath, filename, name);
if (ret)
return -1;
snprintf(path, MAXPATHLEN, "%s/%s", dirpath, filename);
fd = open(path, O_WRONLY);
if (fd < 0) {
ERROR("open %s : %s", path, strerror(errno));
return -1;
}
ret = write(fd, value, strlen(value));
if (ret < 0) {
ERROR("write %s : %s", path, strerror(errno));
goto out;
}
ret = 0;
out:
close(fd);
return ret;
}
int lxc_cgroup_get(const char *name, const char *filename,
char *value, size_t len)
{
int fd, ret = -1;
char *dirpath;
char path[MAXPATHLEN];
ret = lxc_cgroup_path_get(&dirpath, filename, name);
if (ret)
return -1;
snprintf(path, MAXPATHLEN, "%s/%s", dirpath, filename);
fd = open(path, O_RDONLY);
if (fd < 0) {
ERROR("open %s : %s", path, strerror(errno));
return -1;
}
ret = read(fd, value, len);
if (ret < 0)
ERROR("read %s : %s", path, strerror(errno));
close(fd);
return ret;
}
int lxc_cgroup_nrtasks(const char *name)
{
char *dpath;
char path[MAXPATHLEN];
int pid, ret, count = 0;
FILE *file;
ret = lxc_cgroup_path_get(&dpath, NULL, name);
if (ret)
return -1;
snprintf(path, MAXPATHLEN, "%s/tasks", dpath);
file = fopen(path, "r");
if (!file) {
SYSERROR("fopen '%s' failed", path);
return -1;
}
while (fscanf(file, "%d", &pid) != EOF)
count++;
fclose(file);
return count;
}
|