// SPDX-License-Identifier: GPL-2.0
/*
 * Simple filesystem to test FUSE readdir cache
 *
 * It will simply perform readdir operations on a directory checking how many
 * times a request is sent to user-space using all the possible caching
 * combination setting (FOPEN_KEEP_CACHE and FOPEN_CACHE_DIR flags).
 */

#include <stdio.h>
#include <dirent.h>

#include "kselftest_harness.h"

#include "fuse_common.h"

#define DIRNAME "mydir"
#define FILENAME "myfile"

#define DIR_INO 42
#define FILE_INO 43
#define DOT_INO 40
#define DOTDOT_INO 41

#define TIMEOUT	86400.0f

struct test_state {
	pthread_mutex_t lock;
	time_t mtime;
	int readdir_counter;
	bool cache_readdir;
	bool keep_cache;
} test_state = {
	.lock = PTHREAD_MUTEX_INITIALIZER,
};

static void fs_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
{
	struct fuse_entry_param e = {};

	if (parent != FUSE_ROOT_ID || strcmp(name, DIRNAME) != 0) {
		fuse_reply_err(req, ENOENT);
		return;
	}

	e.ino = DIR_INO;
	e.attr.st_mode = S_IFDIR | 0755;
	e.attr.st_nlink = 1;
	pthread_mutex_lock(&test_state.lock);
	e.attr.st_mtime = test_state.mtime;
	pthread_mutex_unlock(&test_state.lock);
	e.attr_timeout = TIMEOUT;
	e.entry_timeout = TIMEOUT;

	fuse_reply_entry(req, &e);
}

static int fill_stat(fuse_ino_t ino, struct stat *st)
{
	int ret = 0;

	st->st_ino = ino;
	pthread_mutex_lock(&test_state.lock);
	st->st_mtime = test_state.mtime;
	pthread_mutex_unlock(&test_state.lock);

	switch (ino) {
	case FUSE_ROOT_ID:
		st->st_mode = S_IFDIR | 0755;
		st->st_nlink = 2;
		break;
	case DOT_INO:
	case DOTDOT_INO:
	case DIR_INO:
		st->st_mode = S_IFDIR | 0755;
		st->st_nlink = 1;
		break;
	case FILE_INO:
		st->st_mode = S_IFREG | 0444;
		st->st_nlink = 1;
		break;
	default:
		ret = -1;
		break;
	}

	return ret;
}

static void fs_getattr(fuse_req_t req, fuse_ino_t ino,
		       struct fuse_file_info *fi)
{
	struct stat st = {};

	if (fill_stat(ino, &st) < 0)
		fuse_reply_err(req, ENOENT);
	else
		fuse_reply_attr(req, &st, TIMEOUT);
}

static void fs_opendir(fuse_req_t req, fuse_ino_t ino,
		       struct fuse_file_info *fi)
{
	pthread_mutex_lock(&test_state.lock);
	fi->keep_cache = test_state.keep_cache;
	fi->cache_readdir = test_state.cache_readdir;
	pthread_mutex_unlock(&test_state.lock);
	fuse_reply_open(req, fi);
}

static void fs_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
		       off_t offset, struct fuse_file_info *fi)
{
	struct stat st = {};
	char buf[1024];
	char *pbuf;
	size_t rem = size;
	size_t sz;
	int nextoff = 0;

	if (ino != DIR_INO) {
		fuse_reply_err(req, ENOTDIR);
		return;
	}
	if (offset) {
		fuse_reply_buf(req, NULL, 0);
		return;
	}
	pbuf = buf;
	fill_stat(DOT_INO, &st);
	sz = fuse_add_direntry(req, pbuf, rem, ".", &st, nextoff++);
	rem -= sz;
	pbuf += sz;
	fill_stat(DOTDOT_INO, &st);
	sz = fuse_add_direntry(req, pbuf, rem, "..", &st, nextoff++);
	rem -= sz;
	pbuf += sz;
	fill_stat(FILE_INO, &st);
	sz = fuse_add_direntry(req, pbuf, rem, FILENAME, &st, nextoff++);
	rem -= sz;

	fuse_reply_buf(req, buf, size - rem);

	pthread_mutex_lock(&test_state.lock);
	test_state.readdir_counter++;
	pthread_mutex_unlock(&test_state.lock);
}

static const struct fuse_lowlevel_ops fs_ops = {
	.lookup		= fs_lookup,
	.getattr	= fs_getattr,
	.opendir	= fs_opendir,
	.readdir	= fs_readdir,
};

FIXTURE(readdir_cache)
{
	struct fuse_common_ctx ctx;
};

FIXTURE_VARIANT(readdir_cache)
{
	bool cache_readdir;
	bool keep_cache;
};
FIXTURE_VARIANT_ADD(readdir_cache, nocache)
{
	.cache_readdir = false,
	.keep_cache = false,
};
FIXTURE_VARIANT_ADD(readdir_cache, cache_readdir)
{
	.cache_readdir = true,
	.keep_cache = false,
};
FIXTURE_VARIANT_ADD(readdir_cache, keep_cache)
{
	.cache_readdir = false,
	.keep_cache = true,
};
FIXTURE_VARIANT_ADD(readdir_cache, cache)
{
	.cache_readdir = true,
	.keep_cache = true,
};

FIXTURE_SETUP(readdir_cache)
{
	char err[MAX_ERR_MSG];

	pthread_mutex_lock(&test_state.lock);
	test_state.mtime = time(NULL);
	test_state.readdir_counter = 0;
	test_state.cache_readdir = variant->cache_readdir;
	test_state.keep_cache = variant->keep_cache;
	pthread_mutex_unlock(&test_state.lock);

	if (fs_setup(&fs_ops, &self->ctx, err))
		SKIP(return, err);
}

FIXTURE_TEARDOWN(readdir_cache)
{
	fs_teardown(&self->ctx);
}

TEST_F(readdir_cache, test_readdir_cache)
{
	struct dirent *dentry;
	DIR *dir;
	char pathname[PATH_MAX];
	int total_counter, rewind_counter;
	int dentrycount;

	sprintf(pathname, "%s/%s", self->ctx.mountpoint, DIRNAME);

	dir = opendir(pathname);
	if (dir == NULL)
		TH_LOG("opendir(): %s", strerror(errno));
	ASSERT_NE(dir, NULL);

	errno = 0;
	dentrycount = 0;
	while ((dentry = readdir(dir)))
		dentrycount++;
	ASSERT_EQ(errno, 0);
	ASSERT_EQ(dentrycount, 3);

	rewinddir(dir);
	errno = 0;
	dentrycount = 0;
	while ((dentry = readdir(dir)))
		dentrycount++;
	ASSERT_EQ(errno, 0);
	ASSERT_EQ(dentrycount, 3);

	ASSERT_EQ(closedir(dir), 0);

	pthread_mutex_lock(&test_state.lock);
	rewind_counter = test_state.readdir_counter;
	pthread_mutex_unlock(&test_state.lock);

	dir = opendir(pathname);
	if (dir == NULL)
		TH_LOG("opendir(): %s", strerror(errno));
	ASSERT_NE(dir, NULL);

	errno = 0;
	dentrycount = 0;
	while ((dentry = readdir(dir)))
		dentrycount++;
	ASSERT_EQ(errno, 0);
	ASSERT_EQ(dentrycount, 3);

	ASSERT_EQ(closedir(dir), 0);

	pthread_mutex_lock(&test_state.lock);
	total_counter = test_state.readdir_counter;
	pthread_mutex_unlock(&test_state.lock);

	if (!variant->cache_readdir) {
		ASSERT_EQ(rewind_counter, 2);
		ASSERT_EQ(total_counter, 3);
	} else if (!variant->keep_cache) {
		ASSERT_EQ(rewind_counter, 1);
		ASSERT_EQ(total_counter, 2);
	} else {
		ASSERT_EQ(rewind_counter, 1);
		ASSERT_EQ(total_counter, 1);
	}
}

TEST_HARNESS_MAIN