user-cr: UTS support and test

user-cr: UTS support and test

[Dan Smith]

This is the updated set to match the change in the checkpoint format.

[PATCH 1/2] Add UTS support to mktree (v4)

[Dan Smith]

Read the namespace records from the restore stream and do the unshare()
necessary to create a new namespace.  For UTS, set hostname and domainname
to match what was stored in the checkpoint.

Changes:
 - Check return of sethostname() and setdomainname()
 - Update to match new struct name and header type to kernel patch
 - Update the method used to read the node and domain names to match
   what the updated kernel patch is doing

Signed-off-by: Dan Smith <danms-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 mktree.c |  120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 120 insertions(+), 0 deletions(-)

diff --git a/mktree.c b/mktree.c
index 55149dd..fcfa779 100644
--- a/mktree.c
+++ b/mktree.c
@@ -14,6 +14,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <signal.h>
+#include <sched.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <asm/unistd.h>
@@ -98,9 +99,11 @@ static int cr_write_tree(struct cr_ctx *ctx);
 static int cr_read(int fd, void *buf, int count);
 static int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
 static int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
+static int cr_read_string(struct cr_ctx *ctx, char **buf, int len);
 
 static int cr_read_head(struct cr_ctx *ctx);
 static int cr_read_head_arch(struct cr_ctx *ctx);
+static int cr_read_namespaces(struct cr_ctx *ctx);
 static int cr_read_tree(struct cr_ctx *ctx);
 
 struct pid_swap {
@@ -191,6 +194,12 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+	ret = cr_read_namespaces(&ctx);
+	if (ret < 0) {
+		perror("read c/r namespaces");
+		exit(1);
+	}
+
 	ret = cr_fork_feeder(&ctx);
 	if (ret < 0)
 		exit(1);
@@ -511,6 +520,30 @@ static int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type)
 	return ret;
 }
 
+static int cr_read_string(struct cr_ctx *ctx, char **buf, int len)
+{
+	struct cr_hdr *h = (struct cr_hdr *) ctx->buf;
+	int ret;
+
+	ret = cr_read(STDIN_FILENO, h, sizeof(*h));
+	if (ret < 0)
+		return ret;
+	if (h->type != CR_HDR_STRING)
+		return -1;
+
+	*buf = (char *) malloc(len);
+	if (!*buf)
+		return -ENOMEM;
+
+	ret = cr_read(STDIN_FILENO, *buf, len);
+	if (ret < 0) {
+		free(*buf);
+		*buf = NULL;
+	}
+
+	return ret;
+}
+
 /*
  * read/write the checkpoint image: similar to in-kernel code
  */
@@ -557,6 +590,93 @@ static int cr_read_head_arch(struct cr_ctx *ctx)
 	return 0;
 }
 
+static int cr_read_task_utsns(struct cr_ctx *ctx)
+{
+	int parent;
+	struct cr_hdr_utsns hh;
+	char *namebuf = NULL;
+	int ret = 0;
+
+	parent = cr_read_obj_type(ctx, &hh, sizeof(hh),
+				  CR_HDR_UTSNS);
+	if (parent < 0)
+		return parent;
+	else if (parent != 0) {
+		errno = -EINVAL;
+		return -1;
+	}
+
+	ret = cr_read_string(ctx, &namebuf, hh.nodename_len);
+	if (ret < 0)
+		goto out;
+
+	if (sethostname(namebuf, strlen(namebuf)) < 0) {
+		perror("sethostname");
+		goto out;
+	}
+
+	free(namebuf);
+	namebuf = NULL;
+
+	ret = cr_read_string(ctx, &namebuf, hh.domainname_len);
+	if (ret < 0)
+		goto out;
+
+	if (setdomainname(namebuf, strlen(namebuf)) < 0)
+		perror("setdomainname");
+ out:
+	free(namebuf);
+
+	return 0;
+}
+
+static int cr_read_task_namespaces(struct cr_ctx *ctx)
+{
+	struct cr_hdr_namespaces hh;
+	int parent;
+	int ret;
+
+	parent = cr_read_obj_type(ctx, &hh, sizeof(hh), CR_HDR_NS);
+	if (parent < 0)
+		return parent;
+	else if (parent != 0) {
+		errno = -EINVAL;
+		return -1;
+	}
+
+	if (hh.types == 0)
+		return 0;
+
+	if (unshare(CLONE_NEWUTS) != 0) {
+		perror("unshare(CLONE_NEWUTS)");
+		return -1;
+	}
+
+	if (hh.types & CR_NS_UTS) {
+		ret = cr_read_task_utsns(ctx);
+		if (ret < 0)
+			return ret;
+
+		/* Read other namespaces here */
+	}
+
+	return 0;
+}
+
+static int cr_read_namespaces(struct cr_ctx *ctx)
+{
+	int n;
+	int ret = 0;
+
+	for (n = 0; n < ctx->pids_nr; n++) {
+		ret = cr_read_task_namespaces(ctx);
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+
 static int cr_read_tree(struct cr_ctx *ctx)
 {
 	struct cr_hdr *h = (struct cr_hdr *) ctx->buf;
-- 
1.5.6.3

[PATCH 2/2] Add a simple UTS test program

[Dan Smith]

This program creates a top-level UTS namespace and then forks a child.  The
parent sets the hostname to a different value every second and the child
prints the value.  If the child's value changes with the parent, even after
restart, then the pair are running in the same UTS namespace.  The test
self-checkpoints every iteration.

Signed-off-by: Dan Smith <danms-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 utstest.c |  114 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 114 insertions(+), 0 deletions(-)
 create mode 100644 utstest.c

diff --git a/utstest.c b/utstest.c
new file mode 100644
index 0000000..1afca49
--- /dev/null
+++ b/utstest.c
@@ -0,0 +1,114 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sched.h>
+#include <string.h>
+#include <stdlib.h>
+#include <asm/unistd.h>
+
+#define OUTFILE "/tmp/cr-test.out"
+#define CKPTDIR "/tmp"
+
+int ckpt = 0;
+
+int do_checkpoint(void)
+{
+	char fn[256];
+	int fd;
+	int ret;
+
+	snprintf(fn, sizeof(fn)-1, CKPTDIR "/ckpt-%i", ckpt++);
+
+	fd = open(fn, O_WRONLY | O_CREAT | O_TRUNC, 0666);
+	if (fd < 0) {
+		perror(fn);
+		return -1;
+	}
+
+	ret = syscall(__NR_checkpoint, getpid(), fd, 0);
+	if (ret < 0)
+		printf("Checkpoint to %s returned %i (%m)\n", fn, ret);
+
+	close(fd);
+
+	return ret;
+}
+
+void child(int fd, int subunshare)
+{
+	char hostname[256] = "foo";
+	int ret;
+
+	if (subunshare) {
+		ret = unshare(CLONE_NEWUTS);
+		if (ret) {
+			printf("unshare: %m");
+			exit(1);
+		}
+	}
+
+	while (1) {
+		ret = gethostname(hostname, sizeof(hostname));
+		if (ret) {
+			perror("gethostname");
+			_exit(1);
+		}
+
+		printf("Hostname in child is:  %s\n", hostname);
+		sleep(1);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int ret;
+	int fd;
+	int i = 0;
+	int subunshare = 0;
+
+#ifndef NOUTS
+	ret = unshare(CLONE_NEWUTS);
+	if (ret) {
+		perror("unshare");
+		return 1;
+	}
+#endif
+
+	/* Pass '-u' to test nested namespace */
+	if ((argc == 2) && (strcmp(argv[1], "-u") == 0))
+		subunshare = 1;
+
+	fd = open(OUTFILE, O_RDWR | O_CREAT | O_TRUNC, 0666);
+	if (fd < 0) {
+		perror(OUTFILE);
+		return 1;
+	}
+
+	dup2(fd, 1);
+	dup2(fd, 2);
+	close(0);
+
+	setlinebuf(stdout);
+	setlinebuf(stderr);
+
+	if (fork() == 0)
+		child(fd, subunshare);
+
+	while (1) {
+#ifndef NOUTS
+		char hostname[256];
+
+		snprintf(hostname, sizeof(hostname)-1, "test%i", i++);
+		ret = sethostname(hostname, strlen(hostname));
+		if (ret) {
+			perror("sethostname");
+			return 1;
+		}
+
+		printf("Hostname in parent is: %s\n", hostname);
+#endif
+		do_checkpoint();
+		sleep(1);
+	}
+}
-- 
1.5.6.3