1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package fs
import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/memmap"
"gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
// SpliceOpts define how a splice works.
type SpliceOpts struct {
// Length is the length of the splice operation.
Length int64
// SrcOffset indicates whether the existing source file offset should
// be used. If this is true, then the Start value below is used.
//
// When passed to FileOperations object, this should always be true as
// the offset will be provided by a layer above, unless the object in
// question is a pipe or socket. This value can be relied upon for such
// an indicator.
SrcOffset bool
// SrcStart is the start of the source file. This is used only if
// SrcOffset is false.
SrcStart int64
// Dup indicates that the contents should not be consumed from the
// source (e.g. in the case of a socket or a pipe), but duplicated.
Dup bool
// DstOffset indicates that the destination file offset should be used.
//
// See SrcOffset for additional information.
DstOffset bool
// DstStart is the start of the destination file. This is used only if
// DstOffset is false.
DstStart int64
}
// FileOperations are operations on a File that diverge per file system.
//
// Operations that take a *File may use only the following interfaces:
//
// - File.UniqueID: Operations may only read this value.
// - File.Dirent: Operations must not take or drop a reference.
// - File.Offset(): This value is guaranteed to not change for the
// duration of the operation.
// - File.Flags(): This value may change during the operation.
type FileOperations interface {
// Release release resources held by FileOperations.
Release()
// Waitable defines how this File can be waited on for read and
// write readiness.
waiter.Waitable
// Seek seeks to offset based on SeekWhence. Returns the new
// offset or no change in the offset and an error.
Seek(ctx context.Context, file *File, whence SeekWhence, offset int64) (int64, error)
// Readdir reads the directory entries of file and serializes them
// using serializer.
//
// Returns the new directory offset or no change in the offset and
// an error. The offset returned must not be less than file.Offset().
//
// Serialization of directory entries must not happen asynchronously.
Readdir(ctx context.Context, file *File, serializer DentrySerializer) (int64, error)
// Read reads from file into dst at offset and returns the number
// of bytes read which must be greater than or equal to 0. File
// systems that do not support reading at an offset, (i.e. pipefs,
// sockfs) may ignore the offset. These file systems are expected
// to construct Files with !FileFlags.Pread.
//
// Read may return a nil error and only partially fill dst (at or
// before EOF). If the file represents a symlink, Read reads the target
// value of the symlink.
//
// Read does not check permissions nor flags.
//
// Read must not be called if !FileFlags.Read.
Read(ctx context.Context, file *File, dst usermem.IOSequence, offset int64) (int64, error)
// WriteTo is a variant of read that takes another file as a
// destination. For a splice (copy or move from one file to another),
// first a WriteTo on the source is attempted, followed by a ReadFrom
// on the destination, following by a buffered copy with standard Read
// and Write operations.
//
// The same preconditions as Read apply.
WriteTo(ctx context.Context, file *File, dst *File, opts SpliceOpts) (int64, error)
// Write writes src to file at offset and returns the number of bytes
// written which must be greater than or equal to 0. Like Read, file
// systems that do not support writing at an offset (i.e. pipefs, sockfs)
// may ignore the offset. These file systems are expected to construct
// Files with !FileFlags.Pwrite.
//
// If only part of src could be written, Write must return an error
// indicating why (e.g. syserror.ErrWouldBlock).
//
// Write does not check permissions nor flags.
//
// Write must not be called if !FileFlags.Write.
Write(ctx context.Context, file *File, src usermem.IOSequence, offset int64) (int64, error)
// ReadFrom is a variant of write that takes a another file as a
// source. See WriteTo for details regarding how this is called.
//
// The same preconditions as Write apply; FileFlags.Write must be set.
ReadFrom(ctx context.Context, file *File, src *File, opts SpliceOpts) (int64, error)
// Fsync writes buffered modifications of file and/or flushes in-flight
// operations to backing storage based on syncType. The range to sync is
// [start, end]. The end is inclusive so that the last byte of a maximally
// sized file can be synced.
Fsync(ctx context.Context, file *File, start, end int64, syncType SyncType) error
// Flush this file's buffers/state (on close(2)).
Flush(ctx context.Context, file *File) error
// ConfigureMMap mutates opts to implement mmap(2) for the file. Most
// implementations can either embed fsutil.FileNoMMap (if they don't support
// memory mapping) or call fsutil.GenericConfigureMMap with the appropriate
// memmap.Mappable.
ConfigureMMap(ctx context.Context, file *File, opts *memmap.MMapOpts) error
// UnstableAttr returns the "unstable" attributes of the inode represented
// by the file. Most implementations can embed
// fsutil.FileUseInodeUnstableAttr, which delegates to
// InodeOperations.UnstableAttr.
UnstableAttr(ctx context.Context, file *File) (UnstableAttr, error)
// Ioctl implements the ioctl(2) linux syscall.
//
// io provides access to the virtual memory space to which pointers in args
// refer.
//
// Preconditions: The AddressSpace (if any) that io refers to is activated.
Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error)
}
|
