run: Avoid execve() when measuring test coverage

Normally, we want to save a process and get better signal handling
by replacing the `flatpak run` process with bubblewrap.

However, when we're doing profiling or measuring coverage, we want to
exit cleanly so that profiling data can be recorded, which is done in
an atexit() hook. In this situation, bypass the execve() optimization;
instead, start bubblewrap in the background, immediately wait for it,
and propagate its exit status.

Signed-off-by: Simon McVittie <[email protected]>

Makefile.am

@@ -210,7 +210,7 @@ AM_DISTCHECK_CONFIGURE_FLAGS = \
 
 coverage:
  $(AM_V_GEN) $(MAKE) $(AM_MAKEFLAGS) lcov-clean
- $(AM_V_GEN) $(MAKE) check
+ $(AM_V_GEN) FLATPAK_TEST_COVERAGE=1 $(MAKE) check
  $(AM_V_GEN) $(MAKE) $(AM_MAKEFLAGS) genlcov
 
 lcov-clean:

common/flatpak-run.c

@@ -30,6 +30,7 @@
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 #include <sys/vfs.h>
+#include <sys/wait.h>
 #include <sys/personality.h>
 #include <grp.h>
 #include <unistd.h>
@@ -4489,15 +4490,17 @@ flatpak_run_app (FlatpakDecomposed *app_ref,
  commandline = flatpak_quote_argv ((const char **) bwrap->argv->pdata, -1);
  g_debug ("Running '%s'", commandline);
 
- if ((flags & FLATPAK_RUN_FLAG_BACKGROUND) != 0)
+ if ((flags & (FLATPAK_RUN_FLAG_BACKGROUND)) != 0 ||
+ g_getenv ("FLATPAK_TEST_COVERAGE") != NULL)
  {
  GPid child_pid;
  char pid_str[64];
  g_autofree char *pid_path = NULL;
  GSpawnFlags spawn_flags;
 
  spawn_flags = G_SPAWN_SEARCH_PATH;
- if (flags & FLATPAK_RUN_FLAG_DO_NOT_REAP)
+ if (flags & FLATPAK_RUN_FLAG_DO_NOT_REAP ||
+ (flags & FLATPAK_RUN_FLAG_BACKGROUND) == 0)
  spawn_flags |= G_SPAWN_DO_NOT_REAP_CHILD;
 
  /* We use LEAVE_DESCRIPTORS_OPEN to work around dead-lock, see flatpak_close_fds_workaround */
@@ -4521,6 +4524,22 @@ flatpak_run_app (FlatpakDecomposed *app_ref,
  g_snprintf (pid_str, sizeof (pid_str), "%d", child_pid);
  pid_path = g_build_filename (instance_id_host_dir, "pid", NULL);
  g_file_set_contents (pid_path, pid_str, -1, NULL);
+
+ if ((flags & (FLATPAK_RUN_FLAG_BACKGROUND)) == 0)
+ {
+ int wait_status;
+
+ if (waitpid (child_pid, &wait_status, 0) != child_pid)
+ return glnx_throw_errno_prefix (error, "Failed to wait for child process");
+
+ if (WIFEXITED (wait_status))
+ exit (WEXITSTATUS (wait_status));
+
+ if (WIFSIGNALED (wait_status))
+ exit (128 + WTERMSIG (wait_status));
+
+ return glnx_throw (error, "Unknown wait status from waitpid(): %d", wait_status);
+ }
  }
  else
  {