c/r: save criu's stdout during dump too

This also allows us to commonize some bits of the dup2 code.

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

diff --git a/src/lxc/criu.c b/src/lxc/criu.c
index 867139b67a5db9310d7d093fbfa1d54e3da1d423..f49968bad533b8a65aa8f209aa03697429074b6f 100644 (file)
--- a/src/lxc/criu.c
+++ b/src/lxc/criu.c
@@ -62,6 +62,9 @@
 lxc_log_define(lxc_criu, lxc);
 
 struct criu_opts {
+       /* the thing to hook to stdout and stderr for logging */
+       int pipefd;
+
        /* The type of criu invocation, one of "dump" or "restore" */
        char *action;
 
@@ -134,6 +137,7 @@ static void exec_criu(struct criu_opts *opts)
 
        char buf[4096], tty_info[32];
        size_t pos;
+
        /* If we are currently in a cgroup /foo/bar, and the container is in a
         * cgroup /lxc/foo, lxcfs will give us an ENOENT if some task in the
         * container has an open fd that points to one of the cgroup files
@@ -541,6 +545,21 @@ static void exec_criu(struct criu_opts *opts)
 
        INFO("execing: %s", buf);
 
+       /* before criu inits its log, it sometimes prints things to stdout/err;
+        * let's be sure we capture that.
+        */
+       if (dup2(opts->pipefd, STDOUT_FILENO) < 0) {
+               SYSERROR("dup2 stdout failed");
+               goto err;
+       }
+
+       if (dup2(opts->pipefd, STDERR_FILENO) < 0) {
+               SYSERROR("dup2 stderr failed");
+               goto err;
+       }
+
+       close(opts->pipefd);
+
 #undef DECLARE_ARG
        execv(argv[0], argv);
 err:
@@ -781,15 +800,6 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_
 
                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;
@@ -816,6 +826,7 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_
                        }
                }
 
+               os.pipefd = pipes[1];
                os.action = "restore";
                os.user = opts;
                os.c = c;
@@ -1013,29 +1024,38 @@ static bool do_dump(struct lxc_container *c, char *mode, struct migrate_opts *op
 {
        pid_t pid;
        char *criu_version = NULL;
+       int criuout[2];
 
        if (!criu_ok(c, &criu_version))
                return false;
 
-       if (mkdir_p(opts->directory, 0700) < 0)
+       if (pipe(criuout) < 0) {
+               SYSERROR("pipe() failed");
                return false;
+       }
+
+       if (mkdir_p(opts->directory, 0700) < 0)
+               goto fail;
 
        pid = fork();
        if (pid < 0) {
                SYSERROR("fork failed");
-               return false;
+               goto fail;
        }
 
        if (pid == 0) {
                struct criu_opts os;
                struct lxc_handler h;
 
+               close(criuout[0]);
+
                h.name = c->name;
                if (!cgroup_init(&h)) {
                        ERROR("failed to cgroup_init()");
                        exit(1);
                }
 
+               os.pipefd = criuout[1];
                os.action = mode;
                os.user = opts;
                os.c = c;
@@ -1050,27 +1070,51 @@ static bool do_dump(struct lxc_container *c, char *mode, struct migrate_opts *op
                exit(1);
        } else {
                int status;
+               ssize_t n;
+               char buf[4096];
+               bool ret;
+
+               close(criuout[1]);
+
                pid_t w = waitpid(pid, &status, 0);
                if (w == -1) {
                        SYSERROR("waitpid");
+                       close(criuout[0]);
                        return false;
                }
 
+               n = read(criuout[0], buf, sizeof(buf));
+               close(criuout[0]);
+               if (n < 0) {
+                       SYSERROR("read");
+                       n = 0;
+               }
+               buf[n] = 0;
+
                if (WIFEXITED(status)) {
                        if (WEXITSTATUS(status)) {
                                ERROR("dump failed with %d\n", WEXITSTATUS(status));
-                               return false;
+                               ret = false;
+                       } else {
+                               ret = true;
                        }
-
-                       return true;
                } else if (WIFSIGNALED(status)) {
                        ERROR("dump signaled with %d\n", WTERMSIG(status));
-                       return false;
+                       ret = false;
                } else {
                        ERROR("unknown dump exit %d\n", status);
-                       return false;
+                       ret = false;
                }
+
+               if (!ret)
+                       ERROR("criu output: %s", buf);
+               return ret;
        }
+fail:
+       close(criuout[0]);
+       close(criuout[1]);
+       rmdir(opts->directory);
+       return false;
 }
 
 bool __criu_pre_dump(struct lxc_container *c, struct migrate_opts *opts)