1// Copyright 2019 the Go-FUSE Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package fs
6
7import (
8	"context"
9	"sync"
10	"syscall"
11
12	"github.com/hanwen/go-fuse/v2/fuse"
13)
14
15// MemRegularFile is a filesystem node that holds a read-only data
16// slice in memory.
17type MemRegularFile struct {
18	Inode
19
20	mu   sync.Mutex
21	Data []byte
22	Attr fuse.Attr
23}
24
25var _ = (NodeOpener)((*MemRegularFile)(nil))
26var _ = (NodeReader)((*MemRegularFile)(nil))
27var _ = (NodeWriter)((*MemRegularFile)(nil))
28var _ = (NodeSetattrer)((*MemRegularFile)(nil))
29var _ = (NodeFlusher)((*MemRegularFile)(nil))
30
31func (f *MemRegularFile) Open(ctx context.Context, flags uint32) (fh FileHandle, fuseFlags uint32, errno syscall.Errno) {
32	return nil, fuse.FOPEN_KEEP_CACHE, OK
33}
34
35func (f *MemRegularFile) Write(ctx context.Context, fh FileHandle, data []byte, off int64) (uint32, syscall.Errno) {
36	f.mu.Lock()
37	defer f.mu.Unlock()
38	end := int64(len(data)) + off
39	if int64(len(f.Data)) < end {
40		n := make([]byte, end)
41		copy(n, f.Data)
42		f.Data = n
43	}
44
45	copy(f.Data[off:off+int64(len(data))], data)
46
47	return uint32(len(data)), 0
48}
49
50var _ = (NodeGetattrer)((*MemRegularFile)(nil))
51
52func (f *MemRegularFile) Getattr(ctx context.Context, fh FileHandle, out *fuse.AttrOut) syscall.Errno {
53	f.mu.Lock()
54	defer f.mu.Unlock()
55	out.Attr = f.Attr
56	out.Attr.Size = uint64(len(f.Data))
57	return OK
58}
59
60func (f *MemRegularFile) Setattr(ctx context.Context, fh FileHandle, in *fuse.SetAttrIn, out *fuse.AttrOut) syscall.Errno {
61	f.mu.Lock()
62	defer f.mu.Unlock()
63	if sz, ok := in.GetSize(); ok {
64		f.Data = f.Data[:sz]
65	}
66	out.Attr = f.Attr
67	out.Size = uint64(len(f.Data))
68	return OK
69}
70
71func (f *MemRegularFile) Flush(ctx context.Context, fh FileHandle) syscall.Errno {
72	return 0
73}
74
75func (f *MemRegularFile) Read(ctx context.Context, fh FileHandle, dest []byte, off int64) (fuse.ReadResult, syscall.Errno) {
76	f.mu.Lock()
77	defer f.mu.Unlock()
78	end := int(off) + len(dest)
79	if end > len(f.Data) {
80		end = len(f.Data)
81	}
82	return fuse.ReadResultData(f.Data[off:end]), OK
83}
84
85// MemSymlink is an inode holding a symlink in memory.
86type MemSymlink struct {
87	Inode
88	Attr fuse.Attr
89	Data []byte
90}
91
92var _ = (NodeReadlinker)((*MemSymlink)(nil))
93
94func (l *MemSymlink) Readlink(ctx context.Context) ([]byte, syscall.Errno) {
95	return l.Data, OK
96}
97
98var _ = (NodeGetattrer)((*MemSymlink)(nil))
99
100func (l *MemSymlink) Getattr(ctx context.Context, fh FileHandle, out *fuse.AttrOut) syscall.Errno {
101	out.Attr = l.Attr
102	return OK
103}
104