support: Add support_capture_subprogram

Its API is similar to support_capture_subprocess, but rather creates a
new process based on the input path and arguments.  Under the hoods it
uses posix_spawn to create the new process.

It also allows the use of other support_capture_* functions to check
for expected results and free the resources.

Checked on x86_64-linux-gnu.

	* support/Makefile (libsupport-routines): Add support_subprocess,
	xposix_spawn, xposix_spawn_file_actions_addclose, and
	xposix_spawn_file_actions_adddup2.
	(tst-support_capture_subprocess-ARGS): New rule.
	* support/capture_subprocess.h (support_capture_subprogram): New
	prototype.
	* support/support_capture_subprocess.c (support_capture_subprocess):
	Refactor to use support_subprocess and support_capture_poll.
	(support_capture_subprogram): New function.
	* support/tst-support_capture_subprocess.c (write_mode_to_str,
	str_to_write_mode, test_common, parse_int, handle_restart,
	do_subprocess, do_subprogram, do_multiple_tests): New functions.
	(do_test): Add support_capture_subprogram tests.
	* support/subprocess.h: New file.
	* support/support_subprocess.c: Likewise.
	* support/xposix_spawn.c: Likewise.
	* support/xposix_spawn_file_actions_addclose.c: Likewise.
	* support/xposix_spawn_file_actions_adddup2.c: Likewise.
	* support/xspawn.h: Likewise.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 152 insertions, 0 deletions

diff --git a/support/support_subprocess.c b/support/support_subprocess.c
new file mode 100644
index 0000000000..0c8cc6af30
--- /dev/null
+++ b/support/support_subprocess.c
@@ -0,0 +1,152 @@
+/* Create subprocess.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <support/xspawn.h>
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <support/subprocess.h>
+
+static struct support_subprocess
+support_suprocess_init (void)
+{
+  struct support_subprocess result;
+
+  xpipe (result.stdout_pipe);
+  TEST_VERIFY (result.stdout_pipe[0] > STDERR_FILENO);
+  TEST_VERIFY (result.stdout_pipe[1] > STDERR_FILENO);
+
+  xpipe (result.stderr_pipe);
+  TEST_VERIFY (result.stderr_pipe[0] > STDERR_FILENO);
+  TEST_VERIFY (result.stderr_pipe[1] > STDERR_FILENO);
+
+  TEST_VERIFY (fflush (stdout) == 0);
+  TEST_VERIFY (fflush (stderr) == 0);
+
+  return result;
+}
+
+struct support_subprocess
+support_subprocess (void (*callback) (void *), void *closure)
+{
+  struct support_subprocess result = support_suprocess_init ();
+
+  result.pid = xfork ();
+  if (result.pid == 0)
+    {
+      xclose (result.stdout_pipe[0]);
+      xclose (result.stderr_pipe[0]);
+      xdup2 (result.stdout_pipe[1], STDOUT_FILENO);
+      xdup2 (result.stderr_pipe[1], STDERR_FILENO);
+      xclose (result.stdout_pipe[1]);
+      xclose (result.stderr_pipe[1]);
+      callback (closure);
+      _exit (0);
+    }
+  xclose (result.stdout_pipe[1]);
+  xclose (result.stderr_pipe[1]);
+
+  return result;
+}
+
+struct support_subprocess
+support_subprogram (const char *file, char *const argv[])
+{
+  struct support_subprocess result = support_suprocess_init ();
+
+  posix_spawn_file_actions_t fa;
+  /* posix_spawn_file_actions_init does not fail.  */
+  posix_spawn_file_actions_init (&fa);
+
+  xposix_spawn_file_actions_addclose (&fa, result.stdout_pipe[0]);
+  xposix_spawn_file_actions_addclose (&fa, result.stderr_pipe[0]);
+  xposix_spawn_file_actions_adddup2 (&fa, result.stdout_pipe[1], STDOUT_FILENO);
+  xposix_spawn_file_actions_adddup2 (&fa, result.stderr_pipe[1], STDERR_FILENO);
+  xposix_spawn_file_actions_addclose (&fa, result.stdout_pipe[1]);
+  xposix_spawn_file_actions_addclose (&fa, result.stderr_pipe[1]);
+
+  result.pid = xposix_spawn (file, &fa, NULL, argv, NULL);
+
+  xclose (result.stdout_pipe[1]);
+  xclose (result.stderr_pipe[1]);
+
+  return result;
+}
+
+int
+support_process_wait (struct support_subprocess *proc)
+{
+  xclose (proc->stdout_pipe[0]);
+  xclose (proc->stderr_pipe[0]);
+
+  int status;
+  xwaitpid (proc->pid, &status, 0);
+  return status;
+}
+
+
+static bool
+support_process_kill (int pid, int signo, int *status)
+{
+  /* Kill the whole process group.  */
+  kill (-pid, signo);
+  /* In case setpgid failed in the child, kill it individually too.  */
+  kill (pid, signo);
+
+  /* Wait for it to terminate.  */
+  pid_t killed;
+  for (int i = 0; i < 5; ++i)
+    {
+      int status;
+      killed = xwaitpid (pid, &status, WNOHANG|WUNTRACED);
+      if (killed != 0)
+        break;
+
+      /* Delay, give the system time to process the kill.  If the
+         nanosleep() call return prematurely, all the better.  We
+         won't restart it since this probably means the child process
+         finally died.  */
+      nanosleep (&((struct timespec) { 0, 100000000 }), NULL);
+    }
+  if (killed != 0 && killed != pid)
+    return false;
+
+  return true;
+}
+
+int
+support_process_terminate (struct support_subprocess *proc)
+{
+  xclose (proc->stdout_pipe[0]);
+  xclose (proc->stderr_pipe[0]);
+
+  int status;
+  pid_t killed = xwaitpid (proc->pid, &status, WNOHANG|WUNTRACED);
+  if (killed != 0 && killed == proc->pid)
+    return status;
+
+  /* Subprocess is still running, terminate it.  */
+  if (!support_process_kill (proc->pid, SIGTERM, &status) )
+    support_process_kill (proc->pid, SIGKILL, &status);
+
+  return status;
+}