[lxc-devel] [lxc/master] improve detect_ramfs_rootfs() and add test
brauner on Github
lxc-bot at linuxcontainers.org
Tue Sep 6 12:54:09 UTC 2016
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From 65ae2cf8388ed12e0b93357db02eb113c556da5c Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at canonical.com>
Date: Tue, 6 Sep 2016 13:49:13 +0200
Subject: [PATCH 1/2] utils: make detect_ramfs_rootfs() return bool
Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
---
src/lxc/utils.c | 28 ++++++++++++++++------------
src/lxc/utils.h | 2 +-
2 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index 27362da..e56a7e0 100644
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -1108,36 +1108,40 @@ bool switch_to_ns(pid_t pid, const char *ns) {
* IIUC, so long as we've chrooted so that rootfs is not our root,
* the rootfs entry should always be skipped in mountinfo contents.
*/
-int detect_ramfs_rootfs(void)
+bool detect_ramfs_rootfs(void)
{
- char buf[LINELEN], *p;
FILE *f;
+ char *p, *p2;
+ char *line = NULL;
+ size_t len = 0;
int i;
- char *p2;
f = fopen("/proc/self/mountinfo", "r");
if (!f)
- return 0;
- while (fgets(buf, LINELEN, f)) {
- for (p = buf, i=0; p && i < 4; i++)
- p = strchr(p+1, ' ');
+ return false;
+
+ while (getline(&line, &len, f) != -1) {
+ for (p = line, i = 0; p && i < 4; i++)
+ p = strchr(p + 1, ' ');
if (!p)
continue;
- p2 = strchr(p+1, ' ');
+ p2 = strchr(p + 1, ' ');
if (!p2)
continue;
*p2 = '\0';
- if (strcmp(p+1, "/") == 0) {
+ if (strcmp(p + 1, "/") == 0) {
// this is '/'. is it the ramfs?
- p = strchr(p2+1, '-');
+ p = strchr(p2 + 1, '-');
if (p && strncmp(p, "- rootfs rootfs ", 16) == 0) {
+ free(line);
fclose(f);
- return 1;
+ return true;
}
}
}
+ free(line);
fclose(f);
- return 0;
+ return false;
}
char *on_path(char *cmd, const char *rootfs) {
diff --git a/src/lxc/utils.h b/src/lxc/utils.h
index 98b4e13..84b9d55 100644
--- a/src/lxc/utils.h
+++ b/src/lxc/utils.h
@@ -291,7 +291,7 @@ extern bool dir_exists(const char *path);
uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval);
int detect_shared_rootfs(void);
-int detect_ramfs_rootfs(void);
+bool detect_ramfs_rootfs(void);
char *on_path(char *cmd, const char *rootfs);
bool file_exists(const char *f);
bool cgns_supported(void);
From f7e61003cdf1376dd0a3d1cc2fb3e8599920b9ee Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at canonical.com>
Date: Tue, 6 Sep 2016 14:51:01 +0200
Subject: [PATCH 2/2] tests: add test for detect_ramfs_rootfs()
Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
---
src/tests/lxc-test-utils.c | 118 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 118 insertions(+)
diff --git a/src/tests/lxc-test-utils.c b/src/tests/lxc-test-utils.c
index 4c1c373..46d72ff 100644
--- a/src/tests/lxc-test-utils.c
+++ b/src/tests/lxc-test-utils.c
@@ -21,13 +21,131 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <unistd.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
#include "lxctest.h"
#include "utils.h"
+void test_detect_ramfs_rootfs(void)
+{
+ size_t i;
+ int ret;
+ int fret = EXIT_FAILURE;
+ size_t len = 5 /* /proc */ + 21 /* /int_as_str */ + 7 /* /ns/mnt */ + 1 /* \0 */;
+ char path[len];
+ int init_ns = -1;
+ char tmpf[] = "/tmp/tmpf_XXXXXX";
+ int fd = -1;
+ FILE *fp = NULL;
+ char *mountinfo[] = {
+ "18 24 0:17 / /sys rw,nosuid,nodev,noexec,relatime shared:7 - sysfs sysfs rw",
+ "19 24 0:4 / /proc rw,nosuid,nodev,noexec,relatime shared:13 - proc proc rw",
+ "20 24 0:6 / /dev rw,nosuid,relatime shared:2 - devtmpfs udev rw,size=4019884k,nr_inodes=1004971,mode=755",
+ "21 20 0:14 / /dev/pts rw,nosuid,noexec,relatime shared:3 - devpts devpts rw,gid=5,mode=620,ptmxmode=000",
+ "22 24 0:18 / /run rw,nosuid,noexec,relatime shared:5 - tmpfs tmpfs rw,size=807912k,mode=755",
+
+ /* This is what we care about. */
+ "24 0 8:2 / / rw - rootfs rootfs rw,size=1004396k,nr_inodes=251099",
+
+ "25 18 0:12 / /sys/kernel/security rw,nosuid,nodev,noexec,relatime shared:8 - securityfs securityfs rw",
+ "26 20 0:20 / /dev/shm rw,nosuid,nodev shared:4 - tmpfs tmpfs rw",
+ "27 22 0:21 / /run/lock rw,nosuid,nodev,noexec,relatime shared:6 - tmpfs tmpfs rw,size=5120k",
+ "28 18 0:22 / /sys/fs/cgroup ro,nosuid,nodev,noexec shared:9 - tmpfs tmpfs ro,mode=755",
+ "29 28 0:23 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime shared:10 - cgroup cgroup rw,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd",
+ "30 18 0:24 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime shared:11 - pstore pstore rw",
+ "31 18 0:25 / /sys/firmware/efi/efivars rw,nosuid,nodev,noexec,relatime shared:12 - efivarfs efivarfs rw",
+ "32 28 0:26 / /sys/fs/cgroup/cpu,cpuacct rw,nosuid,nodev,noexec,relatime shared:14 - cgroup cgroup rw,cpu,cpuacct",
+ "33 28 0:27 / /sys/fs/cgroup/net_cls,net_prio rw,nosuid,nodev,noexec,relatime shared:15 - cgroup cgroup rw,net_cls,net_prio",
+ "34 28 0:28 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime shared:16 - cgroup cgroup rw,blkio",
+ "35 28 0:29 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime shared:17 - cgroup cgroup rw,freezer",
+ "36 28 0:30 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime shared:18 - cgroup cgroup rw,memory",
+ "37 28 0:31 / /sys/fs/cgroup/hugetlb rw,nosuid,nodev,noexec,relatime shared:19 - cgroup cgroup rw,hugetlb",
+ "38 28 0:32 / /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime shared:20 - cgroup cgroup rw,cpuset",
+ "39 28 0:33 / /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,devices",
+ "40 28 0:34 / /sys/fs/cgroup/pids rw,nosuid,nodev,noexec,relatime shared:22 - cgroup cgroup rw,pids",
+ "41 28 0:35 / /sys/fs/cgroup/perf_event rw,nosuid,nodev,noexec,relatime shared:23 - cgroup cgroup rw,perf_event",
+ "42 19 0:36 / /proc/sys/fs/binfmt_misc rw,relatime shared:24 - autofs systemd-1 rw,fd=32,pgrp=1,timeout=0,minproto=5,maxproto=5,direct",
+ "43 18 0:7 / /sys/kernel/debug rw,relatime shared:25 - debugfs debugfs rw",
+ "44 20 0:37 / /dev/hugepages rw,relatime shared:26 - hugetlbfs hugetlbfs rw",
+ "45 20 0:16 / /dev/mqueue rw,relatime shared:27 - mqueue mqueue rw",
+ "46 43 0:9 / /sys/kernel/debug/tracing rw,relatime shared:28 - tracefs tracefs rw",
+ "76 18 0:38 / /sys/fs/fuse/connections rw,relatime shared:29 - fusectl fusectl rw",
+ "78 24 8:1 / /boot/efi rw,relatime shared:30 - vfat /dev/sda1 rw,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro",
+ };
+
+ ret = snprintf(path, len, "/proc/self/ns/mnt");
+ if (ret < 0 || (size_t)ret >= len) {
+ lxc_error("%s\n", "Failed to create path with snprintf().");
+ goto non_test_error;
+ }
+
+ init_ns = open(path, O_RDONLY | O_CLOEXEC);
+ if (init_ns < 0) {
+ lxc_error("%s\n", "Failed to open initial mount namespace.");
+ goto non_test_error;
+ }
+
+ if (unshare(CLONE_NEWNS) < 0) {
+ lxc_error("%s\n", "Could not unshare mount namespace.");
+ goto non_test_error;
+ }
+
+ fd = mkstemp(tmpf);
+ if (fd < 0) {
+ lxc_error("%s\n", "Could not create temporary file.");
+ goto non_test_error;
+ }
+
+ fp = fdopen(fd, "r+");
+ if (!fp) {
+ lxc_error("%s\n", "Could not fdopen() temporary file.");
+ goto non_test_error;
+ }
+
+ for (i = 0; i < sizeof(mountinfo) / sizeof(mountinfo[0]); i++) {
+ if (fprintf(fp, "%s\n", mountinfo[i]) < 0) {
+ lxc_error("Could not write \"%s\" to temporary file.", mountinfo[i]);
+ goto non_test_error;
+ }
+ }
+ fclose(fp);
+ fp = NULL;
+
+ if (mount(tmpf, "/proc/self/mountinfo", NULL, MS_BIND, 0) < 0) {
+ lxc_error("%s\n", "Could not overmount \"/proc/self/mountinfo\".");
+ goto non_test_error;
+ }
+
+ lxc_test_assert_abort(detect_ramfs_rootfs());
+ fret = EXIT_SUCCESS;
+
+non_test_error:
+ if (fp)
+ fclose(fp);
+ else if (fd > 0)
+ close(fd);
+ if (init_ns > 0) {
+ if (setns(init_ns, 0) < 0) {
+ lxc_error("Failed to switch back to initial mount namespace: %s.\n", strerror(errno));
+ fret = EXIT_FAILURE;
+ }
+ close(init_ns);
+ }
+ if (fret == EXIT_SUCCESS)
+ return;
+ exit(fret);
+}
+
void test_lxc_string_replace(void)
{
char *s;
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