[PATCH 2/2] tests: commandtest: Make 'test4' checking daemonization more reliable

[Peter Krempa <pkrempa@xxxxxxxxxx>]

The 'commandhelper' checks effectively whether the parent process is
still around to report whether it was daemonized or not.

This creates a unlikely race condition in cases when we do actually
daemonize the process as the intermediate process used for the
daemonization might not have terminated yet which would report wrong
result leading to test failure.

For now there's just 'test4' which actually daemonizes the process.

Add an argument '--check-daemonize' which asks for retires of the
daemonization check in cases where we expect that the commandhelper is
going to be daemonized and use it in 'test4' to make the test more
reliable.

I've observed the test failure sporradically when my box is more loaded
e.g. while building two trees at once.

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 tests/commanddata/test4.log |  1 +
 tests/commandhelper.c       | 17 ++++++++++++++++-
 tests/commandtest.c         |  3 ++-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/tests/commanddata/test4.log b/tests/commanddata/test4.log
index 24a37a7e96..4fd40cc474 100644
--- a/tests/commanddata/test4.log
+++ b/tests/commanddata/test4.log
@@ -1,3 +1,4 @@
+ARG:--check-daemonize
 ENV:DISPLAY=:0.0
 ENV:HOME=/home/test
 ENV:HOSTNAME=test
diff --git a/tests/commandhelper.c b/tests/commandhelper.c
index 4266e11902..b366483771 100644
--- a/tests/commandhelper.c
+++ b/tests/commandhelper.c
@@ -72,6 +72,8 @@ int main(int argc, char **argv) {
     char *buffers[3] = {NULL, NULL, NULL};
     size_t buflen[3] = {0, 0, 0};
     char c;
+    bool daemonize_check = false;
+    size_t daemonize_retries = 3;

     if (!log)
         return ret;
@@ -83,6 +85,8 @@ int main(int argc, char **argv) {
             sscanf(argv[i], "%u%c", &readfds[numreadfds++], &c) != 1) {
             printf("Could not parse fd %s\n", argv[i]);
             goto cleanup;
+        } else if (STREQ(argv[i], "--check-daemonize")) {
+            daemonize_check = true;
         }
     }

@@ -126,7 +130,18 @@ int main(int argc, char **argv) {
             fprintf(log, "FD:%zu\n", i);
     }

-    fprintf(log, "DAEMON:%s\n", getpgrp() != getppid() ? "yes" : "no");
+    while (true) {
+        bool daemonized = getpgrp() != getppid();
+
+        if (daemonize_check && !daemonized && daemonize_retries-- > 0) {
+            usleep(100*1000);
+            continue;
+        }
+
+        fprintf(log, "DAEMON:%s\n", daemonized ? "yes" : "no");
+        break;
+    }
+
     if (!(cwd = getcwd(NULL, 0)))
         goto cleanup;
     if (strlen(cwd) > strlen(".../commanddata") &&
diff --git a/tests/commandtest.c b/tests/commandtest.c
index f0e60ee5fe..9bef825239 100644
--- a/tests/commandtest.c
+++ b/tests/commandtest.c
@@ -255,7 +255,8 @@ static int test3(const void *unused G_GNUC_UNUSED)
  */
 static int test4(const void *unused G_GNUC_UNUSED)
 {
-    virCommandPtr cmd = virCommandNew(abs_builddir "/commandhelper");
+    virCommandPtr cmd = virCommandNewArgList(abs_builddir "/commandhelper",
+                                             "--check-daemonize", NULL);
     char *pidfile = virPidFileBuildPath(abs_builddir, "commandhelper");
     pid_t pid;
     int ret = -1;
-- 
2.26.2