/
system.go
213 lines (173 loc) · 4.32 KB
/
system.go
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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
package ssh
import (
"bytes"
"context"
"fmt"
"github.com/neuspaces/terraform-provider-system/internal/cmd"
"github.com/neuspaces/terraform-provider-system/internal/lib/stat"
"github.com/neuspaces/terraform-provider-system/internal/sshclient"
"github.com/neuspaces/terraform-provider-system/internal/system"
"golang.org/x/crypto/ssh"
"golang.org/x/sync/semaphore"
"io/fs"
"sync"
)
type System struct {
sshClient *sshclient.Client
sshClientM sync.Mutex
cmdM cmd.Middleware
sessions *semaphore.Weighted
}
// System implements system.System
var _ system.System = &System{}
type SystemOption func(*System) error
// Sessions is a SystemOption which defines the maximum number of concurrent ssh sessions to the remote
// Set Sessions to 0 to not limit the number of concurrent ssh sessions.
func Sessions(c int) SystemOption {
return func(s *System) error {
if c > 0 {
s.sessions = semaphore.NewWeighted(int64(c))
} else if c == 0 {
s.sessions = nil
} else {
return fmt.Errorf("invalid connections value: %d", c)
}
return nil
}
}
func CommandMiddleware(m cmd.Middleware) SystemOption {
return func(s *System) error {
s.cmdM = m
return nil
}
}
func NewSystem(sshClient *sshclient.Client, opts ...SystemOption) (*System, error) {
var err error
s := &System{
sshClient: sshClient,
}
// Apply options
for _, opt := range opts {
err = opt(s)
if err != nil {
return nil, err
}
}
return s, nil
}
// Close closes the underlying ssh client
func (s *System) Close() error {
s.sshClientM.Lock()
defer s.sshClientM.Unlock()
if s.sshClient != nil {
return s.sshClient.Close()
}
return nil
}
// Open returns a fs.File
// Open fetches fs.FileInfo immediately when invoked
func (s *System) Open(ctx context.Context, name string) (fs.File, error) {
// Retrieve file info
fileInfo, err := s.Stat(ctx, name)
if err != nil {
return nil, err
}
// Return readFile with file info and reader based on `cat` command
file := &readFile{
fileInfo: fileInfo,
readCloser: newCatFileReader(ctx, s, name),
}
return file, nil
}
func (s *System) Create(ctx context.Context, fileInfo fs.FileInfo) (system.WriteFile, error) {
return nil, fmt.Errorf("create is not supported by ssh.System")
}
func (s *System) Stat(ctx context.Context, name string) (fs.FileInfo, error) {
statOut := &bytes.Buffer{}
statCmd := cmd.NewCommand(fmt.Sprintf(`stat -t '%s'`, name), cmd.Stdout(statOut))
statCmdResult, err := s.Execute(ctx, statCmd)
if err != nil {
return nil, err
}
if statCmdResult.ExitCode() != 0 {
return nil, fs.ErrNotExist
}
fileInfo, err := stat.ParseTerseFormat(statOut.Bytes())
if err != nil {
return nil, err
}
return fileInfo.ToFsFileInfo(), nil
}
func (s *System) Execute(ctx context.Context, c cmd.Command) (cmd.Result, error) {
var err error
if s.sessions != nil {
err := s.sessions.Acquire(ctx, 1)
if err != nil {
return nil, err
}
defer s.sessions.Release(1)
}
// Apply command middleware
if s.cmdM != nil {
c = s.cmdM(c)
}
// Ensure connection
s.sshClientM.Lock()
err = s.sshClient.Connected(ctx)
s.sshClientM.Unlock()
if err != nil {
return nil, err
}
// Create session
sess, err := s.sshClient.NewSession()
if err != nil {
return nil, err
}
defer func() {
// Close session
_ = sess.Close()
}()
// Connect inputs/outputs
sess.Stdin = c.Stdin()
sess.Stdout = c.Stdout()
sess.Stderr = c.Stderr()
// Completed channel is closed after sess.Wait returned
completed := make(chan struct{})
// Start command
err = sess.Start(c.Command())
if err != nil {
return nil, err
}
// Handle context cancellation
var signalErr error
go func() {
select {
case <-ctx.Done():
// Parent context has been cancelled
// Send interrupt (SIGINT) when context is cancelled
err := sess.Signal(ssh.SIGINT)
if err != nil {
signalErr = fmt.Errorf("ssh.System: failed to send singal SIGINT: %w", err)
}
// Close session (will lead sess.Wait to return)
_ = sess.Close()
return
case <-completed:
// Command completed
return
}
}()
// Wait for command to complete
err = sess.Wait()
if signalErr != nil {
return nil, signalErr
} else if err != nil {
if exitErr, isExitErr := err.(*ssh.ExitError); isExitErr {
return cmd.NewResult(exitErr.ExitStatus()), nil
} else {
return nil, err
}
}
close(completed)
return cmd.NewResult(0), nil
}