[libvirt] [PATCH 5/6] virtlockd: make re-exec more robust

[Michael Chapman]

virtlockd's argv[0] may not contain a full path to the binary, however
it should contain something that can be looked up in the PATH. Use
execvp() to do path lookup when re-executing ourselves.

After re-execution, we must not attempt to daemonize again. It's not
only unnecessary, but it also means we end up with the wrong PID and so
we can't validate the state file.

Instead, build a new argv for the new program that does not include
--daemon.

Signed-off-by: Michael Chapman <mike at very.puzzling.org>
---
 src/locking/lock_daemon.c | 49 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 6 deletions(-)

diff --git a/src/locking/lock_daemon.c b/src/locking/lock_daemon.c
index ae09ef8..32ca4d6 100644
--- a/src/locking/lock_daemon.c
+++ b/src/locking/lock_daemon.c
@@ -1000,6 +1000,7 @@ cleanup:
 
 static int
 virLockDaemonPreExecRestart(virNetServerPtr srv,
+                            const char *argv0,
                             char **argv)
 {
     virJSONValuePtr child;
@@ -1075,7 +1076,7 @@ virLockDaemonPreExecRestart(virNetServerPtr srv,
         goto cleanup;
     }
 
-    if (execv(argv[0], argv) < 0) {
+    if (execvp(argv0, argv) < 0) {
         virReportSystemError(errno, "%s",
                              _("Unable to restart self"));
         goto cleanup;
@@ -1389,11 +1390,47 @@ int main(int argc, char **argv) {
     virNetServerUpdateServices(lockDaemon->srv, true);
     virNetServerRun(lockDaemon->srv);
 
-    if (execRestart &&
-        virLockDaemonPreExecRestart(lockDaemon->srv, argv) < 0)
-        ret = VIR_LOCK_DAEMON_ERR_REEXEC;
-    else
-        ret = 0;
+    ret = VIR_LOCK_DAEMON_ERR_NONE;
+    if (execRestart) {
+        char **restart_argv = NULL;
+        size_t count = 0;
+
+        if (VIR_EXPAND_N(restart_argv, count, 1) < 0)
+            goto no_memory;
+        if (VIR_STRDUP(restart_argv[count - 1], argv[0]) < 0)
+            goto no_memory;
+        if (verbose) {
+            if (VIR_EXPAND_N(restart_argv, count, 1) < 0)
+                goto no_memory;
+            if (VIR_STRDUP(restart_argv[count - 1], "--verbose") < 0)
+                goto no_memory;
+        }
+        if (remote_config_file && !implicit_conf) {
+            if (VIR_EXPAND_N(restart_argv, count, 2) < 0)
+                goto no_memory;
+            if (VIR_STRDUP(restart_argv[count - 2], "--config") < 0)
+                goto no_memory;
+            if (VIR_STRDUP(restart_argv[count - 1], remote_config_file) < 0)
+                goto no_memory;
+        }
+        if (pid_file) {
+            if (VIR_EXPAND_N(restart_argv, count, 2) < 0)
+                goto no_memory;
+            if (VIR_STRDUP(restart_argv[count - 2], "--pid-file") < 0)
+                goto no_memory;
+            if (VIR_STRDUP(restart_argv[count - 1], pid_file) < 0)
+                goto no_memory;
+        }
+        if (VIR_EXPAND_N(restart_argv, count, 1) < 0)
+            goto no_memory;
+
+        if (virLockDaemonPreExecRestart(lockDaemon->srv, argv[0], restart_argv) < 0)
+            ret = VIR_LOCK_DAEMON_ERR_REEXEC;
+
+        while (count)
+            VIR_FREE(restart_argv[--count]);
+        VIR_FREE(restart_argv);
+    }
 
 cleanup:
     virObjectUnref(lockProgram);
-- 
1.8.4.2