test: Check that overlapping locks work

If we open a file, lock one, fork, then close and
open the file in parent again, lock should 'slide'
to the child process anyway.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -117,6 +117,7 @@ static/file_locks00
 static/file_locks01
 static/file_locks02
 static/file_locks03
+static/file_locks04
 static/sigpending
 static/sigaltstack
 static/sk-netlink

test/zdtm/live/static/Makefile

@@ -151,6 +151,7 @@ TST_FILE	=				\
 		file_locks01			\
 		file_locks02			\
 		file_locks03			\
+		file_locks04			\
 		netns-nf			\
 		maps_file_prot			\
 

test/zdtm/live/static/file_locks04.c

+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/file.h>
+#include <string.h>
+#include <sys/wait.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Check that 'overlapping' flocks work";
+const char *test_author	= "Pavel Emelyanov <xemul@parallels.com>";
+
+char *filename;
+TEST_OPTION(filename, string, "file name", 1);
+
+static int check_file_locks(int alt_pid, int fd)
+{
+	FILE		*fp_locks = NULL;
+	char		buf[100], fl_flag[16], fl_type[16], fl_option[16];
+	pid_t		pid = getpid();
+	int		found = 0, num, fl_owner;
+
+	fp_locks = fopen("/proc/locks", "r");
+	if (!fp_locks)
+		return -1;
+
+	while (fgets(buf, sizeof(buf), fp_locks)) {
+		if (strstr(buf, "->"))
+			continue;
+
+		num = sscanf(buf,
+			"%*d:%s %s %s %d %*02x:%*02x:%*d %*d %*s",
+			fl_flag, fl_type, fl_option, &fl_owner);
+
+		if (num < 4) {
+			err("Invalid lock info.\n");
+			break;
+		}
+
+		if (fl_owner != pid && fl_owner != alt_pid)
+			continue;
+
+		if (!strcmp(fl_flag, "FLOCK") &&
+				!strcmp(fl_type, "ADVISORY") &&
+				!strcmp(fl_option, "WRITE"))
+			found++;
+
+		memset(fl_flag, 0, sizeof(fl_flag));
+		memset(fl_type, 0, sizeof(fl_type));
+		memset(fl_option, 0, sizeof(fl_option));
+	}
+
+	fclose(fp_locks);
+
+	if (flock(fd, LOCK_EX | LOCK_NB) == 0)
+		return 0;
+
+	return found == 1;
+}
+
+int main(int argc, char **argv)
+{
+	int fd, pf[2], pid;
+
+	test_init(argc, argv);
+
+	pipe(pf);
+
+	fd = open(filename, O_CREAT | O_RDWR, 0600);
+	if (fd < 0) {
+		err("No file");
+		return -1;
+	}
+
+	flock(fd, LOCK_EX);
+
+	pid = fork();
+	if (pid == 0) {
+		close(pf[1]);
+		read(pf[0], &pid, sizeof(pid));
+		exit(0);
+	}
+
+	close(pf[0]);
+	close(fd);
+
+	fd = open(filename, O_RDONLY);
+	if (fd < 0) {
+		err("No file 2");
+		close(pf[1]);
+		waitpid(pid, NULL, 0);
+		return -1;
+	}
+
+	if (flock(fd, LOCK_EX | LOCK_NB) == 0) {
+		err("Bogus locks");
+		close(pf[1]);
+		waitpid(pid, NULL, 0);
+		return -1;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	if (check_file_locks(pid, fd))
+		pass();
+	else
+		fail("Flock file locks check failed");
+
+	close(pf[1]);
+	waitpid(pid, NULL, 0);
+	close(fd);
+	unlink(filename);
+
+	return 0;
+}

test/zdtm/live/static/file_locks04.opts

+--file-locks