[PATCH] selftest: add a test case to check how locks are shown in fdinfo

[Andrey Vagin <avagin@openvz.org>]

The main idea of this test is to check that locks are shown correctly
when they can't be placed in a default seq_file buffer due to its size.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
---
 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/fdinfo/Makefile |  11 +++
 tools/testing/selftests/fdinfo/locks.c  | 119 ++++++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+)
 create mode 100644 tools/testing/selftests/fdinfo/Makefile
 create mode 100644 tools/testing/selftests/fdinfo/locks.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 4e51122..8cd57f6 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -17,6 +17,7 @@ TARGETS += sysctl
 TARGETS += timers
 TARGETS += user
 TARGETS += vm
+TARGETS += fdinfo
 #Please keep the TARGETS list alphabetically sorted
 
 TARGETS_HOTPLUG = cpu-hotplug
diff --git a/tools/testing/selftests/fdinfo/Makefile b/tools/testing/selftests/fdinfo/Makefile
new file mode 100644
index 0000000..83f34ef
--- /dev/null
+++ b/tools/testing/selftests/fdinfo/Makefile
@@ -0,0 +1,11 @@
+CFLAGS += -Wall
+
+all: locks
+
+run_tests: all
+	@./locks || echo "locks: [FAIL]"
+
+locks: locks.c
+
+clean:
+	rm -f locks
diff --git a/tools/testing/selftests/fdinfo/locks.c b/tools/testing/selftests/fdinfo/locks.c
new file mode 100644
index 0000000..93f25c6
--- /dev/null
+++ b/tools/testing/selftests/fdinfo/locks.c
@@ -0,0 +1,119 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define pr_perror(fmt, ...) fprintf(stderr, "%s:%d: " fmt ": %m\n", \
+					__FILE__, __LINE__, ##__VA_ARGS__)
+
+#define FILE_SIZE 4096
+
+int main(int argc, char **argv)
+{
+	int fd, fdinfo, i, ret, size, bsize = 4096;
+	char *buf, *p, fdinfo_path[] = "/proc/self/fdinfo/XXXXXXXXXX";
+
+	fd = open("test_file", O_RDWR | O_CREAT, 0666);
+	if (fd == -1) {
+		pr_perror("Unable to open test_file");
+		return 1;
+	}
+	unlink("test_file");
+	if (ftruncate(fd, FILE_SIZE) == -1) {
+		pr_perror("Unable to truncate test_file");
+		return 1;
+	}
+
+	/*
+	 * Generate FILE_SIZE locks. We are going to exceed the default
+	 * size of seq buffer
+	 */
+	for (i = 0; i < FILE_SIZE; i++) {
+		struct flock lock;
+
+		if (i % 2)
+			lock.l_type = F_WRLCK;
+		else
+			lock.l_type = F_RDLCK;
+		lock.l_whence = SEEK_SET;
+		lock.l_start  = i;
+		lock.l_len    = 1;
+		lock.l_pid    = -1;
+		if (fcntl(fd, F_SETLK, &lock)) {
+			pr_perror("Unable to set lock %d\n", i);
+			return 1;
+		}
+	}
+
+	snprintf(fdinfo_path, sizeof(fdinfo_path), "/proc/self/fdinfo/%d", fd);
+	fdinfo = open(fdinfo_path, O_RDONLY);
+	if (fdinfo < 0) {
+		pr_perror("Unable to open %s", fdinfo_path);
+		return 1;
+	}
+
+	buf = malloc(bsize);
+	if (buf == NULL) {
+		pr_perror("Unable to allocate a buffer");
+		return 1;
+	}
+	size = 0;
+	while (1) {
+		ret = read(fdinfo, buf + size, bsize - 1 - size);
+		if (ret == 0)
+			break;
+		if (ret == -1) {
+			pr_perror("Unable to read %s", fdinfo_path);
+			return 1;
+		}
+		size += ret;
+		if (bsize - size < 4096)
+			bsize += 4096;
+		buf = realloc(buf, bsize);
+		if (buf == NULL) {
+			pr_perror("Unable to allocate a buffer");
+			return 1;
+		}
+	}
+	buf[size] = 0;
+
+	i = 0;
+	for (p = buf - 1; p != NULL; p = strchr(p, '\n')) {
+		char fl_flag[10], fl_type[15], fl_option[10], end[32];
+		int fl_id, fl_owner, maj, min;
+		unsigned long ino;
+		unsigned long long start;
+
+		p++;
+
+		if (strncmp(p, "lock:", 5))
+			continue;
+		ret = sscanf(p, "lock:\t%d:%s %s %s %d %x:%x:%ld %lld %s",
+				&fl_id, fl_flag, fl_type, fl_option,
+				&fl_owner, &maj, &min, &ino,
+				&start, end);
+		if (ret != 10) {
+			pr_perror("Unable to parse");
+			fprintf(stderr, "%s\n", buf);
+			return 1;
+		}
+		i++;
+	}
+
+	close(fdinfo);
+	close(fd);
+
+	if (i == FILE_SIZE)
+		printf("PASS\n");
+	else {
+		fprintf(stderr, "%s\n", buf);
+		return 1;
+	}
+
+	free(buf);
+
+	return 0;
+}
-- 
2.1.0