new test taken from stat issue with new tar

test/stat/memcmp-stat.c

@@ -0,0 +1,104 @@
+/* Distilled from issue found with tar and symlinks.
+ * Make sure that the whole stat struct between runs
+ * is agreeable.
+ */
+
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+#include <time.h>
+
+void show_stat(struct stat *st)
+{
+	printf(
+		"------------------\n"
+		"st_dev     = %li\n"
+		"st_ino     = %li\n"
+		"st_mode    = %li\n"
+		"st_nlink   = %li\n"
+		"st_uid     = %li\n"
+		"st_gid     = %li\n"
+		"st_rdev    = %li\n"
+		"st_size    = %li\n"
+		"st_blksize = %li\n"
+		"st_blocks  = %li\n"
+		"st_atime   = %li\n"
+		"st_ansec   = %li\n"
+		"st_mtime   = %li\n"
+		"st_mnsec   = %li\n"
+		"st_ctime   = %li\n"
+		"st_cnsec   = %li\n",
+		(long int)st->st_dev,
+		(long int)st->st_ino,
+		(long int)st->st_mode,
+		(long int)st->st_nlink,
+		(long int)st->st_uid,
+		(long int)st->st_gid,
+		(long int)st->st_rdev,
+		(long int)st->st_size,
+		(long int)st->st_blksize,
+		(long int)st->st_blocks,
+#ifndef __UCLIBC__
+		(long int)st->st_atime,
+		(long int)st->st_atim.tv_nsec,
+		(long int)st->st_mtime,
+		(long int)st->st_mtim.tv_nsec,
+		(long int)st->st_ctime,
+		(long int)st->st_ctim.tv_nsec
+#else
+		(long int)st->st_atime,
+		(long int)st->st_atimensec,
+		(long int)st->st_mtime,
+		(long int)st->st_mtimensec,
+		(long int)st->st_ctime,
+		(long int)st->st_ctimensec
+#endif
+	);
+}
+
+int main()
+{
+	int ret;
+	int fd;
+	struct stat fst, st;
+
+	unlink(".testfile");
+	fd = open(".testfile", O_WRONLY | O_CREAT | O_EXCL, 0);
+	if (fd < 0) {
+		perror("open(.testfile) failed");
+		return 1;
+	}
+	ret = fstat(fd, &fst);
+	if (ret != 0) {
+		perror("fstat(.testfile) failed");
+		return 1;
+	}
+	close(fd);
+
+	ret = stat(".testfile", &st);
+	if (ret != 0) {
+		perror("stat(.testfile) failed");
+		return 1;
+	}
+
+	ret = memcmp(&fst, &st, sizeof(fst));
+	if (ret != 0) {
+		printf("FAILED: memcmp() = %i\n", ret);
+		show_stat(&fst);
+		show_stat(&st);
+	}
+
+	unlink(".testfile");
+
+	return ret;
+}