Add linkat test case

Tests success, EEXISTS, ENOENT (no parent dir).

Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Link: https://lore.kernel.org/r/20210603052906.2616489-9-dkadashev@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 136 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 0b336d6..7a6f75c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -57,6 +57,7 @@
 /test/files-exit-hang-timeout
 /test/fixed-link
 /test/fsync
+/test/hardlink
 /test/io-cancel
 /test/io_uring_enter
 /test/io_uring_register
diff --git a/test/Makefile b/test/Makefile
index 4fc78ea..2f0a694 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -54,6 +54,7 @@ test_targets += \
 	files-exit-hang-timeout \
 	fixed-link \
 	fsync \
+	hardlink \
 	io-cancel \
 	io_uring_enter \
 	io_uring_register \
@@ -193,6 +194,7 @@ test_srcs := \
 	files-exit-hang-timeout.c \
 	fixed-link.c \
 	fsync.c \
+	hardlink.c \
 	io-cancel.c \
 	io_uring_enter.c \
 	io_uring_register.c \
diff --git a/test/hardlink.c b/test/hardlink.c
new file mode 100644
index 0000000..1c73424
--- /dev/null
+++ b/test/hardlink.c
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Description: test io_uring linkat handling
+ */
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "liburing.h"
+
+
+static int do_linkat(struct io_uring *ring, const char *oldname, const char *newname)
+{
+	int ret;
+	struct io_uring_sqe *sqe;
+	struct io_uring_cqe *cqe;
+
+	sqe = io_uring_get_sqe(ring);
+	if (!sqe) {
+		fprintf(stderr, "sqe get failed\n");
+		goto err;
+	}
+	io_uring_prep_linkat(sqe, AT_FDCWD, oldname, AT_FDCWD, newname, 0);
+
+	ret = io_uring_submit(ring);
+	if (ret != 1) {
+		fprintf(stderr, "submit failed: %d\n", ret);
+		goto err;
+	}
+
+	ret = io_uring_wait_cqes(ring, &cqe, 1, 0, 0);
+	if (ret) {
+		fprintf(stderr, "wait_cqe failed: %d\n", ret);
+		goto err;
+	}
+	ret = cqe->res;
+	io_uring_cqe_seen(ring, cqe);
+	return ret;
+err:
+	return 1;
+}
+
+int files_linked_ok(const char* fn1, const char *fn2)
+{
+	struct stat s1, s2;
+
+	if (stat(fn1, &s1)) {
+		fprintf(stderr, "stat(%s): %s\n", fn1, strerror(errno));
+		return 0;
+	}
+	if (stat(fn2, &s2)) {
+		fprintf(stderr, "stat(%s): %s\n", fn2, strerror(errno));
+		return 0;
+	}
+	if (s1.st_dev != s2.st_dev || s1.st_ino != s2.st_ino) {
+		fprintf(stderr, "linked files have different device / inode numbers\n");
+		return 0;
+	}
+	if (s1.st_nlink != 2 || s2.st_nlink != 2) {
+		fprintf(stderr, "linked files have unexpected links count\n");
+		return 0;
+	}
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	static const char target[] = "io_uring-linkat-test-target";
+	static const char linkname[] = "io_uring-linkat-test-link";
+	int ret;
+	struct io_uring ring;
+
+	ret = io_uring_queue_init(8, &ring, 0);
+	if (ret) {
+		fprintf(stderr, "queue init failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = open(target, O_CREAT | O_RDWR | O_EXCL, 0600);
+	if (ret < 0) {
+		perror("open");
+		goto err;
+	}
+	if (write(ret, "linktest", 8) != 8) {
+		close(ret);
+		goto err1;
+	}
+	close(ret);
+
+	ret = do_linkat(&ring, target, linkname);
+	if (ret < 0) {
+		if (ret == -EBADF || ret == -EINVAL) {
+			fprintf(stdout, "linkat not supported, skipping\n");
+			goto out;
+		}
+		fprintf(stderr, "linkat: %s\n", strerror(-ret));
+		goto err1;
+	} else if (ret) {
+		goto err1;
+	}
+
+	if (!files_linked_ok(linkname, target))
+		goto err2;
+
+	ret = do_linkat(&ring, target, linkname);
+	if (ret != -EEXIST) {
+		fprintf(stderr, "test_linkat linkname already exists failed: %d\n", ret);
+		goto err2;
+	}
+
+	ret = do_linkat(&ring, target, "surely/this/does/not/exist");
+	if (ret != -ENOENT) {
+		fprintf(stderr, "test_linkat no parent failed: %d\n", ret);
+		goto err2;
+	}
+
+out:
+	unlinkat(AT_FDCWD, linkname, 0);
+	unlinkat(AT_FDCWD, target, 0);
+	io_uring_queue_exit(&ring);
+	return 0;
+err2:
+	unlinkat(AT_FDCWD, linkname, 0);
+err1:
+	unlinkat(AT_FDCWD, target, 0);
+err:
+	io_uring_queue_exit(&ring);
+	return 1;
+}
+