From 7ade8fa8fb048c03fe9d1cf8f02e2d435cba620f Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sun, 6 Mar 2022 01:21:41 +0200
Subject: [PATCH] pwtest: fix daemon log scrambling

Nonblocking pipes can scramble logs if we read too slow, so use max size
buffers.

Also use CLOEXEC for the pipes to be safer, and minor other fixes.
---
 test/pwtest.c | 47 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 38 insertions(+), 9 deletions(-)

diff --git a/test/pwtest.c b/test/pwtest.c
index 9c09072f8..d50b3953e 100644
--- a/test/pwtest.c
+++ b/test/pwtest.c
@@ -475,8 +475,6 @@ pwtest_spawn(const char *file, char *const argv[])
 	pid = fork();
 	if (pid == 0) {
 		/* child process */
-		setlinebuf(stderr);
-		setlinebuf(stdout);
 		execvp(file, (char **)argv);
 		exit(fail_code);
 	} else if (pid < 0)
@@ -684,7 +682,7 @@ static void sighandler(int signal)
 static inline void log_append(struct pw_array *buffer, int fd)
 {
 	int r = 0;
-	const int sz = 1024;
+	const int sz = 65536;
 
 	while (true) {
 		r = pw_array_ensure_size(buffer, sz);
@@ -739,6 +737,7 @@ static pid_t start_pwdaemon(struct pwtest_test *t, int stderr_fd, int log_fd)
 	pid_t pid;
 	char pw_remote[64];
 	int status;
+	int r;
 
 	spa_scnprintf(pw_remote, sizeof(pw_remote), "pwtest-pw-%u\n", count++);
 	replace_env(t, "PIPEWIRE_REMOTE", pw_remote);
@@ -752,9 +751,11 @@ static pid_t start_pwdaemon(struct pwtest_test *t, int stderr_fd, int log_fd)
 		setenv("PIPEWIRE_DEBUG", "4", 0);
 		setenv("WIREPLUMBER_DEBUG", "4", 0);
 
-		dup2(stderr_fd, STDERR_FILENO);
-		dup2(stderr_fd, STDOUT_FILENO);
-		setlinebuf(stderr);
+		r = dup2(stderr_fd, STDERR_FILENO);
+		spa_assert_se(r != -1);
+		r = dup2(stderr_fd, STDOUT_FILENO);
+		spa_assert_se(r != -1);
+
 		execl(daemon, daemon, (char*)NULL);
 		return -errno;
 
@@ -814,7 +815,8 @@ static void set_test_env(struct pwtest_context *ctx, struct pwtest_test *t)
 static void close_pipes(int fds[_FD_LAST])
 {
 	for (int i = 0; i < _FD_LAST; i++) {
-		close(fds[i]);
+		if (fds[i] >= 0)
+			close(fds[i]);
 		fds[i] = -1;
 	}
 }
@@ -823,20 +825,40 @@ static int init_pipes(int read_fds[_FD_LAST], int write_fds[_FD_LAST])
 {
 	int r;
 	int i;
+	int pipe_max_size = 4194304;
 
 	for (i = 0; i < _FD_LAST; i++) {
 		read_fds[i] = -1;
 		write_fds[i] = -1;
 	}
 
+#ifdef __linux__
+	{
+		FILE *f;
+		f = fopen("/proc/sys/fs/pipe-max-size", "r");
+		if (f) {
+			if (fscanf(f, "%d", &r) == 1)
+				pipe_max_size = SPA_MIN(r, pipe_max_size);
+			fclose(f);
+		}
+	}
+#endif
+
 	for (i = 0; i < _FD_LAST; i++) {
 		int pipe[2];
 
-		r = pipe2(pipe, O_NONBLOCK);
+		r = pipe2(pipe, O_CLOEXEC | O_NONBLOCK);
 		if (r < 0)
 			goto error;
 		read_fds[i] = pipe[0];
 		write_fds[i] = pipe[1];
+#ifdef __linux__
+		/* Max pipe buffers, to avoid scrambling if reading lags.
+		 * Can't use blocking write fds, since reading too slow
+		 * then affects execution.
+		 */
+		fcntl(write_fds[i], F_SETPIPE_SZ, pipe_max_size);
+#endif
 	}
 
 	return 0;
@@ -1099,7 +1121,14 @@ error:
 
 		kill(-pw_daemon, SIGTERM);
 		remove_cleanup_pid(ctx, -pw_daemon);
-		r = waitpid(pw_daemon, &status, 0);
+
+		/* blocking read. the other end closes when done */
+		close_pipes(write_fds);
+		fcntl(read_fds[FD_DAEMON], F_SETFL, O_CLOEXEC);
+		do {
+			log_append(&t->logs[FD_DAEMON], read_fds[FD_DAEMON]);
+		} while ((r = waitpid(pw_daemon, &status, WNOHANG)) == 0);
+
 		if (r > 0) {
 			/* write_fds are closed in the parent process, so we append directly */
 			char *buf = pw_array_add(&t->logs[FD_DAEMON], 64);