// Copyright 2023 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.

package linux

import (
	"io/fs"
	"testing"
	"testing/fstest"

	"github.com/google/syzkaller/pkg/subsystem"
	"github.com/stretchr/testify/assert"
)

func TestGroupLinuxSubsystems(t *testing.T) {
	subsystems, err := listFromRepoInner(
		prepareTestLinuxRepo(t, []byte(testMaintainers)),
		nil)
	if err != nil {
		t.Fatal(err)
	}
	for _, s := range subsystems {
		// The regexps used for matching rules may change later, so let's not compare them here.
		s.PathRules = nil
		// It complicates the test, so let's skip it here.
		s.Parents = nil
	}
	expected := []*subsystem.Subsystem{
		{
			Name:  "fs",
			Lists: []string{"linux-fsdevel@vger.kernel.org"},
			// Two different subsystems point to linux-fsdevel@vger.kernel.org, so
			// we do not include maintainers.
		},
		{
			Name:        "ext4",
			Lists:       []string{"linux-ext4@vger.kernel.org"},
			Maintainers: []string{"email_ext4@email.com", "email_ext4_2@email.com"},
		},
		{
			Name:        "mm",
			Lists:       []string{"linux-mm@kvack.org"},
			Maintainers: []string{"email_mm@email.com"},
		},
		{
			Name:        "tmpfs",
			Lists:       []string{"tmpfs@kvack.org"},
			Maintainers: []string{"email_shmem@email.com"},
		},
		{
			Name:        "kernel",
			Lists:       []string{"linux-kernel@vger.kernel.org"},
			Maintainers: []string{"email_rest@email.com"},
		},
	}
	assert.ElementsMatch(t, subsystems, expected)
}

func TestCustomCallRules(t *testing.T) {
	subsystems, err := listFromRepoInner(
		prepareTestLinuxRepo(t, []byte(testMaintainers)),
		testRules,
	)
	if err != nil {
		t.Fatal(err)
	}
	for _, s := range subsystems {
		// The regexps used for matching rules may change later, so let's not compare them here.
		s.PathRules = nil
		// It complicates the test, so let's skip it here.
		s.Parents = nil
	}
	// Ensure that the subsystem from the custom rule is present.
	assert.Contains(t, subsystems, &subsystem.Subsystem{
		Name:        "udf",
		Maintainers: []string{"email_udf@email.com"},
		Lists:       []string{"linux-fsdevel@vger.kernel.org"},
	})
	// Now that udf is excluded, it becomes possible to generate a maintainer list for vfs.
	assert.Contains(t, subsystems, &subsystem.Subsystem{
		Name:        "fs",
		Lists:       []string{"linux-fsdevel@vger.kernel.org"},
		Maintainers: []string{"email_vfs@email.com"},
	})

	expectCalls := map[string][]string{
		"ext4":  {"syz_mount_image$ext4"},
		"tmpfs": {"syz_mount_image$tmpfs"},
	}
	gotCalls := map[string][]string{}
	for _, s := range subsystems {
		if len(s.Syscalls) > 0 {
			gotCalls[s.Name] = s.Syscalls
		}
	}
	assert.Equal(t, len(expectCalls), len(gotCalls))
	for name, expect := range expectCalls {
		assert.ElementsMatchf(t, expect, gotCalls[name], "syscalls of %s", name)
	}
}

func TestLinuxSubsystemPaths(t *testing.T) {
	// For the list of subsystems, see TestLinuxSubsystemsList.
	// Here we rely on the same ones.
	repo := prepareTestLinuxRepo(t, []byte(testMaintainers))
	subsystems, err := listFromRepoInner(repo, nil)
	if err != nil {
		t.Fatal(err)
	}
	matcher := subsystem.MakePathMatcher(subsystems)
	tests := []struct {
		path string
		list []string
	}{
		{
			path: `fs/internal.h`,
			list: []string{"kernel", "fs"},
		},
		{
			path: `fs/ext4/mmp.c`,
			list: []string{"kernel", "fs", "ext4"},
		},
		{
			// The subsystem is not present in our test MAINTAINERS.
			path: `fs/fat/inode.c`,
			list: []string{"kernel", "fs"},
		},
		{
			path: `fs/freevxfs/vxfs_olt.c`,
			list: []string{"kernel", "fs"},
		},
		{
			path: `mm/memory.c`,
			list: []string{"kernel", "mm"},
		},
		{
			path: `mm/shmem.c`,
			list: []string{"kernel", "mm", "tmpfs"},
		},
		{
			path: `include/net/ah.h`,
			list: []string{"kernel"},
		},
		{
			path: `include/linux/mm.h`,
			list: []string{"kernel", "mm"},
		},
		{
			path: `include/linux/fs.h`,
			list: []string{"kernel", "fs"},
		},
	}
	for _, test := range tests {
		retList := []string{}
		for _, s := range matcher.Match(test.path) {
			retList = append(retList, s.Name)
		}
		assert.ElementsMatchf(t, retList, test.list,
			"invalid subsystems for %#v", test.path)
	}
}

func TestLinuxSubsystemParents(t *testing.T) {
	// For the list of subsystems, see TestLinuxSubsystemsList.
	// Here we rely on the same ones.
	repo := prepareTestLinuxRepo(t, []byte(testMaintainers))
	subsystems, err := listFromRepoInner(repo, nil)
	if err != nil {
		t.Fatal(err)
	}
	ensureParents(t, subsystems, map[string][]string{
		"ext4":     {"fs"},
		"mm":       {"kernel"},
		"fs":       {"kernel"},
		"tmpfs":    {"mm"},
		"freevxfs": {"fs"},
	})

	// Now check that our custom parent rules work.
	subsystems2, err := listFromRepoInner(repo, &customRules{
		addParents: map[string][]string{
			// Just for the sake of testing.
			"fs": {"mm"},
		},
	})
	if err != nil {
		t.Fatal(err)
	}
	ensureParents(t, subsystems2, map[string][]string{
		"ext4":     {"fs"},
		"mm":       {"kernel"},
		"fs":       {"mm"}, // We test for this change.
		"tmpfs":    {"mm"},
		"freevxfs": {"fs"},
	})
}

func ensureParents(t *testing.T, subsystems []*subsystem.Subsystem,
	expectParents map[string][]string) {
	for _, s := range subsystems {
		names := []string{}
		for _, p := range s.Parents {
			names = append(names, p.Name)
		}
		assert.ElementsMatch(t, names, expectParents[s.Name],
			"wrong parents for %#v", s.Name)
	}
}

func prepareTestLinuxRepo(t *testing.T, maintainers []byte) fs.FS {
	return fstest.MapFS{
		`fs/ext4/fsync.c`:          {},
		`fs/ext4/fsync.h`:          {},
		`fs/ext4/mmp.c`:            {},
		`fs/ext4/mmp.h`:            {},
		`fs/freevxfs/vxfs_olt.c`:   {},
		`fs/freevxfs/vxfs_olt.h`:   {},
		`fs/freevxfs/file.c`:       {},
		`fs/udf/file.c`:            {},
		`fs/udf/file2.c`:           {},
		`fs/udf/file3.c`:           {},
		`fs/file.c`:                {},
		`fs/internal.h`:            {},
		`include/linux/fs.h`:       {},
		`include/linux/mm.h`:       {},
		`include/linux/shmem_fs.h`: {},
		`include/net/ah.h`:         {},
		`mm/memory.c`:              {},
		`mm/shmem.c`:               {},
		`mm/shmem2.c`:              {},
		`MAINTAINERS`:              {Data: maintainers},
	}
}

var (
	testRules = &customRules{
		subsystemCalls: map[string][]string{
			"ext4":  {"syz_mount_image$ext4"},
			"tmpfs": {"syz_mount_image$tmpfs"},
		},
		extraSubsystems: map[string][]string{
			"udf": {"UDF FILESYSTEM"},
		},
	}
	testMaintainers = `
Maintainers List
----------------

.. note:: When reading this list, please look for the most precise areas
          first. When adding to this list, please keep the entries in
          alphabetical order.

FILESYSTEMS (VFS and infrastructure)
M:	Developer <email_vfs@email.com>
L:	linux-fsdevel@vger.kernel.org
S:	Maintained
F:	fs/*
F:	include/linux/fs.h
F:	include/linux/fs_types.h
F:	include/uapi/linux/fs.h
F:	include/uapi/linux/openat2.h

EXT4 FILE SYSTEM
M:	Developer <email_ext4@email.com>
M:	Developer <email_ext4_2@email.com>
L:	linux-ext4@vger.kernel.org
S:	Maintained
W:	http://ext4.wiki.kernel.org
Q:	http://patchwork.ozlabs.org/project/linux-ext4/list/
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
F:	Documentation/filesystems/ext4/
F:	fs/ext4/
F:	include/trace/events/ext4.h

FREEVXFS FILESYSTEM
M:	Developer <email_vxfs@email.com>
S:	Maintained
W:	ftp://ftp.openlinux.org/pub/people/hch/vxfs
F:	fs/freevxfs/

MEMORY MANAGEMENT
M:	Developer <email_mm@email.com>
L:	linux-mm@kvack.org
S:	Maintained
W:	http://www.linux-mm.org
T:	git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
T:	quilt git://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new
F:	include/linux/gfp.h
F:	include/linux/gfp_types.h
F:	include/linux/memory_hotplug.h
F:	include/linux/mm.h
F:	include/linux/mmzone.h
F:	include/linux/pagewalk.h
F:	include/linux/vmalloc.h
F:	mm/
F:	tools/testing/selftests/vm/

TMPFS (SHMEM FILESYSTEM)
M:	Developer <email_shmem@email.com>
L:	tmpfs@kvack.org
S:	Maintained
F:	include/linux/shmem_fs.h
F:	mm/shmem*

UDF FILESYSTEM
M:	email_udf <email_udf@email.com>
L:	linux-fsdevel@vger.kernel.org
S:	Maintained
F:	Documentation/filesystems/udf.rst
F:	fs/udf/

THE REST
M:	Developer <email_rest@email.com>
L:	linux-kernel@vger.kernel.org
S:	Buried alive in reporters
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
F:	*
F:	*/

`
)