-
-
Notifications
You must be signed in to change notification settings - Fork 108
/
capnptool.go
76 lines (67 loc) · 1.82 KB
/
capnptool.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
// Package capnptool provides an API for calling the capnp tool in tests.
package capnptool
import (
"bytes"
"fmt"
"io"
"os/exec"
"strings"
"sync"
)
// Tool is the path to the capnp command-line tool.
// It can be used from multiple goroutines.
type Tool string
var cache struct {
init sync.Once
tool Tool
err error
}
// Find searches PATH for the capnp tool.
func Find() (Tool, error) {
cache.init.Do(func() {
path, err := exec.LookPath("capnp")
if err != nil {
cache.err = err
return
}
cache.tool = Tool(path)
})
return cache.tool, cache.err
}
// Run executes the tool with the given stdin and arguments returns the stdout.
func (tool Tool) Run(stdin io.Reader, args ...string) ([]byte, error) {
c := exec.Command(string(tool), args...)
c.Stdin = stdin
stderr := new(bytes.Buffer)
c.Stderr = stderr
out, err := c.Output()
if err != nil {
return nil, fmt.Errorf("run `%s`: %v; stderr:\n%s", strings.Join(c.Args, " "), err, stderr)
}
return out, nil
}
// Encode encodes Cap'n Proto text into the binary representation.
func (tool Tool) Encode(typ Type, text string) ([]byte, error) {
return tool.Run(strings.NewReader(text), "encode", typ.SchemaPath, typ.Name)
}
// Decode decodes a Cap'n Proto message into text.
func (tool Tool) Decode(typ Type, r io.Reader) (string, error) {
out, err := tool.Run(r, "decode", "--short", typ.SchemaPath, typ.Name)
if err != nil {
return "", err
}
return string(out), nil
}
// DecodePacked decodes a packed Cap'n Proto message into text.
func (tool Tool) DecodePacked(typ Type, r io.Reader) (string, error) {
out, err := tool.Run(r, "decode", "--short", "--packed", typ.SchemaPath, typ.Name)
if err != nil {
return "", err
}
return string(out), nil
}
// Type is a reference to a Cap'n Proto type in a schema.
type Type struct {
SchemaPath string
Name string
}