zdtm: Check that O_APPEND is preserved properly

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -24,6 +24,7 @@ static/vdso00
 static/sched_prio00
 static/sched_policy00
 static/file_shared
+static/file_append
 static/timers
 static/posix_timers
 static/futex

test/zdtm/live/static/Makefile

@@ -127,6 +127,7 @@ TST_FILE	=				\
 		unlink_fifo			\
 		unlink_fifo_wronly		\
 		file_shared			\
+		file_append			\
 		cow01				\
 		fdt_shared			\
 		sockets00			\

test/zdtm/live/static/file_append.c

+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Check O_APPEND preserved";
+const char *test_author	= "Pavel Emelyanov <xemul@parallels.com>";
+
+char *filename;
+TEST_OPTION(filename, string, "file name", 1);
+
+int main(int argc, char **argv)
+{
+	int fd, fd2, ret;
+	char tmp[3];
+
+	test_init(argc, argv);
+
+	fd = open(filename, O_RDWR | O_CREAT | O_APPEND, 0644);
+	if (fd == -1)
+		return 1;
+
+	fd2 = open(filename, O_RDWR, 0644);
+	if (fd2 == -1)
+		return 1;
+
+	test_daemon();
+	test_waitsig();
+
+	if (write(fd2, "x", 1) != 1) {
+		err("Can't write x");
+		return 1;
+	}
+
+	if (write(fd, "y", 1) != 1) {
+		err("Can't write y");
+		return 1;
+	}
+
+	lseek(fd2, 0, SEEK_SET);
+	ret = read(fd2, tmp, 3);
+	if (ret != 2) {
+		fail("Smth's wrong with file size");
+		return 1;
+	}
+	tmp[2] = '\0';
+	if (strcmp(tmp, "xy")) {
+		fail("Smth's wron with file contents (%s)", tmp);
+		return 1;
+	}
+
+	pass();
+
+	return 0;
+}