tests: support testing fd inheritance over exec

Add facility for testing how (many) file descriptors survive an exec.
This allows implementing O_CLOEXEC tests.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

tests/Makefile.am

@@ -1,7 +1,4 @@
-TESTS = $(check_PROGRAMS)
-
-
-check_PROGRAMS =				\
+my_check_programs =				\
 	sanity-test				\
 	array-test				\
 	map-test				\
@@ -10,6 +7,12 @@ check_PROGRAMS =				\
 	event-loop-test				\
 	client-test
 
+TESTS = $(my_check_programs)
+
+check_PROGRAMS =				\
+	$(my_check_programs)			\
+	exec-fd-leak-checker
+
 test_runner_src = test-runner.c test-runner.h test-helpers.c
 
 sanity_test_SOURCES = sanity-test.c $(test_runner_src)
@@ -25,3 +28,8 @@ LDADD = $(top_builddir)/src/libwayland-util.la \
 	$(top_builddir)/src/libwayland-server.la \
 	-lrt -ldl $(FFI_LIBS)
 
+exec_fd_leak_checker_SOURCES =			\
+	exec-fd-leak-checker.c			\
+	test-runner.h				\
+	test-helpers.c
+exec_fd_leak_checker_LDADD =

tests/exec-fd-leak-checker.c

@@ -0,0 +1,75 @@
+/*
+ * Copyright © 2012 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <limits.h>
+
+#include "test-runner.h"
+
+static int
+parse_count(const char *str, int *value)
+{
+	char *end;
+	long v;
+
+	errno = 0;
+	v = strtol(str, &end, 0);
+	if ((errno == ERANGE && (v == LONG_MAX || v == LONG_MIN)) ||
+	    (errno != 0 && v == 0) ||
+	    (end == str) ||
+	    (*end != '\0')) {
+		return -1;
+	}
+
+	if (v < 0 || v > INT_MAX) {
+		return -1;
+	}
+
+	*value = v;
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int expected;
+
+	if (argc != 2)
+		goto help_out;
+
+	if (parse_count(argv[1], &expected) < 0)
+		goto help_out;
+
+	if (count_open_fds() == expected)
+		return EXIT_SUCCESS;
+	else
+		return EXIT_FAILURE;
+
+help_out:
+	fprintf(stderr, "Usage: %s N\n"
+		"where N is the expected number of open file descriptors.\n"
+		"This program exits with a failure if the number "
+		"does not match exactly.\n", argv[0]);
+
+	return EXIT_FAILURE;
+}

tests/sanity-test.c

@@ -93,3 +93,25 @@ FAIL_TEST(sanity_fd_leak)
 	/* leak 2 file descriptors */
 	pipe(fd);
 }
+
+FAIL_TEST(sanity_fd_leak_exec)
+{
+	int fd[2];
+	int nr_fds = count_open_fds();
+
+	/* leak 2 file descriptors */
+	pipe(fd);
+
+	exec_fd_leak_check(nr_fds);
+}
+
+TEST(sanity_fd_exec)
+{
+	int fd[2];
+	int nr_fds = count_open_fds();
+
+	/* create 2 file descriptors, that should pass over exec */
+	pipe(fd);
+
+	exec_fd_leak_check(nr_fds + 2);
+}

tests/test-helpers.c

@@ -23,6 +23,8 @@
 #include <assert.h>
 #include <errno.h>
 #include <dirent.h>
+#include <stdio.h>
+#include <unistd.h>
 
 #include "test-runner.h"
 
@@ -50,3 +52,13 @@ count_open_fds(void)
 	return count;
 }
 
+void
+exec_fd_leak_check(int nr_expected_fds)
+{
+	const char *exe = "./exec-fd-leak-checker";
+	char number[16] = { 0 };
+
+	snprintf(number, sizeof number - 1, "%d", nr_expected_fds);
+	execl(exe, exe, number, (char *)NULL);
+	assert(0 && "execing fd leak checker failed");
+}

tests/test-runner.h

@@ -34,4 +34,7 @@ struct test {
 int
 count_open_fds(void);
 
+void
+exec_fd_leak_check(int nr_expected_fds); /* never returns */
+
 #endif