c/r: print criu's stdout when it fails

In particular, when CRIU fails before it has its log completely initialized
(e.g. if the log directory doesn't exist, or if the argument parser fails),
it prints this to stdout. Let's log that.

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>

diff --git a/src/lxc/criu.c b/src/lxc/criu.c
index a0c671894fe2ef1b394c40c15e1c9b5bfe642ff0..7b72c6ec8462c3129b76f4bec0c4582bf10459d8 100644 (file)
--- a/src/lxc/criu.c
+++ b/src/lxc/criu.c
@@ -530,12 +530,12 @@ out_unlock:
 
 // do_restore never returns, the calling process is used as the
 // monitor process. do_restore calls exit() if it fails.
-void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose)
+void do_restore(struct lxc_container *c, int status_pipe, char *directory, bool verbose)
 {
        pid_t pid;
        char pidfile[L_tmpnam];
        struct lxc_handler *handler;
-       int status;
+       int status, pipes[2] = {-1, -1};
 
        if (!tmpnam(pidfile))
                goto out;
@@ -561,6 +561,11 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
 
        resolve_clone_flags(handler);
 
+       if (pipe(pipes) < 0) {
+               SYSERROR("pipe() failed");
+               goto out_fini_handler;
+       }
+
        pid = fork();
        if (pid < 0)
                goto out_fini_handler;
@@ -570,8 +575,20 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
                struct lxc_rootfs *rootfs;
                int flags;
 
-               close(pipe);
-               pipe = -1;
+               close(status_pipe);
+               status_pipe = -1;
+
+               close(pipes[0]);
+               pipes[0] = -1;
+               if (dup2(pipes[1], STDERR_FILENO) < 0) {
+                       SYSERROR("dup2 failed");
+                       goto out_fini_handler;
+               }
+
+               if (dup2(pipes[1], STDOUT_FILENO) < 0) {
+                       SYSERROR("dup2 failed");
+                       goto out_fini_handler;
+               }
 
                if (unshare(CLONE_NEWNS))
                        goto out_fini_handler;
@@ -632,15 +649,18 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
                int ret;
                char title[2048];
 
+               close(pipes[1]);
+               pipes[1] = -1;
+
                pid_t w = waitpid(pid, &status, 0);
                if (w == -1) {
                        SYSERROR("waitpid");
                        goto out_fini_handler;
                }
 
-               ret = write(pipe, &status, sizeof(status));
-               close(pipe);
-               pipe = -1;
+               ret = write(status_pipe, &status, sizeof(status));
+               close(status_pipe);
+               status_pipe = -1;
 
                if (sizeof(status) != ret) {
                        SYSERROR("failed to write all of status");
@@ -649,7 +669,18 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
 
                if (WIFEXITED(status)) {
                        if (WEXITSTATUS(status)) {
-                               ERROR("criu process exited %d\n", WEXITSTATUS(status));
+                               char buf[4096];
+                               int n;
+
+                               n = read(pipes[0], buf, sizeof(buf));
+                               if (n < 0) {
+                                       SYSERROR("failed reading from criu stderr");
+                                       goto out_fini_handler;
+                               }
+
+                               buf[n] = 0;
+
+                               ERROR("criu process exited %d, output:\n%s\n", WEXITSTATUS(status), buf);
                                goto out_fini_handler;
                        } else {
                                int ret;
@@ -679,6 +710,8 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
                        goto out_fini_handler;
                }
 
+               close(pipes[0]);
+
                /*
                 * See comment in lxcapi_start; we don't care if these
                 * fail because it's just a beauty thing. We just
@@ -695,17 +728,22 @@ void do_restore(struct lxc_container *c, int pipe, char *directory, bool verbose
        }
 
 out_fini_handler:
+       if (pipes[0] >= 0)
+               close(pipes[0]);
+       if (pipes[1] >= 0)
+               close(pipes[1]);
+
        lxc_fini(c->name, handler);
        if (unlink(pidfile) < 0 && errno != ENOENT)
                SYSERROR("unlinking pidfile failed");
 
 out:
-       if (pipe >= 0) {
+       if (status_pipe >= 0) {
                status = 1;
-               if (write(pipe, &status, sizeof(status)) != sizeof(status)) {
+               if (write(status_pipe, &status, sizeof(status)) != sizeof(status)) {
                        SYSERROR("writing status failed");
                }
-               close(pipe);
+               close(status_pipe);
        }
 
        exit(1);