1 files changed, 146 insertions, 0 deletions
diff --git a/tools/testing/selftests/filesystems/fuse/fuse_mnt.c b/tools/testing/selftests/filesystems/fuse/fuse_mnt.c
new file mode 100644
index 000000000000..d12b17f30fad
--- /dev/null
+++ b/tools/testing/selftests/filesystems/fuse/fuse_mnt.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fusectl test file-system
+ * Creates a simple FUSE filesystem with a single read-write file (/test)
+ */
+
+#define FUSE_USE_VERSION 26
+
+#include <fuse.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+static char *content;
+static size_t content_size = 0;
+static const char test_path[] = "/test";
+
+static int test_getattr(const char *path, struct stat *st)
+{
+	memset(st, 0, sizeof(*st));
+
+	if (!strcmp(path, "/")) {
+		st->st_mode = S_IFDIR | 0755;
+		st->st_nlink = 2;
+		return 0;
+	}
+
+	if (!strcmp(path, test_path)) {
+		st->st_mode = S_IFREG | 0664;
+		st->st_nlink = 1;
+		st->st_size = content_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static int test_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+			off_t offset, struct fuse_file_info *fi)
+{
+	if (strcmp(path, "/"))
+		return -ENOENT;
+
+	filler(buf, ".", NULL, 0);
+	filler(buf, "..", NULL, 0);
+	filler(buf, test_path + 1, NULL, 0);
+
+	return 0;
+}
+
+static int test_open(const char *path, struct fuse_file_info *fi)
+{
+	if (strcmp(path, test_path))
+		return -ENOENT;
+
+	return 0;
+}
+
+static int test_read(const char *path, char *buf, size_t size, off_t offset,
+		     struct fuse_file_info *fi)
+{
+	if (strcmp(path, test_path) != 0)
+		return -ENOENT;
+
+	if (!content || content_size == 0)
+		return 0;
+
+	if (offset >= content_size)
+		return 0;
+
+	if (offset + size > content_size)
+		size = content_size - offset;
+
+	memcpy(buf, content + offset, size);
+
+	return size;
+}
+
+static int test_write(const char *path, const char *buf, size_t size,
+		      off_t offset, struct fuse_file_info *fi)
+{
+	size_t new_size;
+
+	if (strcmp(path, test_path) != 0)
+		return -ENOENT;
+
+	if(offset > content_size)
+		return -EINVAL;
+
+	new_size = MAX(offset + size, content_size);
+
+	if (new_size > content_size)
+		content = realloc(content, new_size);
+
+	content_size = new_size;
+
+	if (!content)
+		return -ENOMEM;
+
+	memcpy(content + offset, buf, size);
+
+	return size;
+}
+
+static int test_truncate(const char *path, off_t size)
+{
+	if (strcmp(path, test_path) != 0)
+		return -ENOENT;
+
+	if (size == 0) {
+		free(content);
+		content = NULL;
+		content_size = 0;
+		return 0;
+	}
+
+	content = realloc(content, size);
+
+	if (!content)
+		return -ENOMEM;
+
+	if (size > content_size)
+		memset(content + content_size, 0, size - content_size);
+
+	content_size = size;
+	return 0;
+}
+
+static struct fuse_operations memfd_ops = {
+	.getattr = test_getattr,
+	.readdir = test_readdir,
+	.open = test_open,
+	.read = test_read,
+	.write = test_write,
+	.truncate = test_truncate,
+};
+
+int main(int argc, char *argv[])
+{
+	return fuse_main(argc, argv, &memfd_ops, NULL);
+}