[PATCH v2 2/2] selftests/nolibc: add testcase for pipe

[Yuan Tan]

Add a testcase of pipe that child process sends message to parent
process.

Here we use memcmp() to avoid the output buffer issue.

Suggested-by: Thomas Weißschuh <thomas@xxxxxxxx>
Suggested-by: Willy Tarreau <w@xxxxxx>
Link: https://lore.kernel.org/all/c5de2d13-3752-4e1b-90d9-f58cca99c702@xxxxxxxx/
Signed-off-by: Yuan Tan <tanyuan@xxxxxxxxxxx>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 35 ++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 03b1d30f5507..2653ab8d5124 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -767,6 +767,41 @@ int test_mmap_munmap(void)
 	return ret;
 }
 
+int test_pipe(void)
+{
+	const char *const msg = "hello, nolibc";
+	int pipefd[2];
+	char buf[32];
+	pid_t pid;
+	ssize_t len;
+
+	if (pipe(pipefd) == -1)
+		return 1;
+
+	pid = fork();
+
+	switch (pid) {
+	case -1:
+		return 1;
+
+	case 0:
+		close(pipefd[0]);
+		write(pipefd[1], msg, strlen(msg));
+		close(pipefd[1]);
+		exit(EXIT_SUCCESS);
+
+	default:
+		close(pipefd[1]);
+		len = read(pipefd[0], buf, sizeof(buf));
+		close(pipefd[0]);
+		waitpid(pid, NULL, 0);
+
+		if (len != strlen(msg))
+			return 1;
+		return !!memcmp(buf, msg, len);
+	}
+}
+
 
 /* Run syscall tests between IDs <min> and <max>.
  * Return 0 on success, non-zero on failure.
-- 
2.34.1