-
Notifications
You must be signed in to change notification settings - Fork 1
/
plugin_dlopen.go
190 lines (165 loc) · 4.75 KB
/
plugin_dlopen.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
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build linux,cgo darwin,cgo freebsd,cgo
package plugin
/*
#cgo linux LDFLAGS: -ldl
#include <dlfcn.h>
#include <limits.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
static uintptr_t pluginOpen(const char* path, char** err) {
void* h = dlopen(path, RTLD_NOW|RTLD_GLOBAL);
if (h == NULL) {
*err = (char*)dlerror();
}
return (uintptr_t)h;
}
static void* pluginLookup(uintptr_t h, const char* name, char** err) {
void* r = dlsym((void*)h, name);
if (r == NULL) {
*err = (char*)dlerror();
}
return r;
}
static int pluginClose(void* handle, char** err) {
int res = dlclose(handle)
if (res != 0) {
*err = (char*)dlerror();
}
return res;
}
*/
import "C"
import (
"errors"
"sync"
"unsafe"
)
func open(name string) (*Plugin, error) {
cPath := make([]byte, C.PATH_MAX+1)
cRelName := make([]byte, len(name)+1)
copy(cRelName, name)
if C.realpath(
(*C.char)(unsafe.Pointer(&cRelName[0])),
(*C.char)(unsafe.Pointer(&cPath[0]))) == nil {
return nil, errors.New(`plugin.Open("` + name + `"): realpath failed`)
}
filepath := C.GoString((*C.char)(unsafe.Pointer(&cPath[0])))
pluginsMu.Lock()
if p := plugins[filepath]; p != nil {
pluginsMu.Unlock()
if p.err != "" {
return nil, errors.New(`plugin.Open("` + name + `"): ` + p.err + ` (previous failure)`)
}
<-p.loaded
return p, nil
}
var cErr *C.char
h := C.pluginOpen((*C.char)(unsafe.Pointer(&cPath[0])), &cErr)
if h == 0 {
pluginsMu.Unlock()
return nil, errors.New(`plugin.Open("` + name + `"): ` + C.GoString(cErr))
}
// TODO(crawshaw): look for plugin note, confirm it is a Go plugin
// and it was built with the correct toolchain.
if len(name) > 3 && name[len(name)-3:] == ".so" {
name = name[:len(name)-3]
}
if plugins == nil {
plugins = make(map[string]*Plugin)
}
pluginpath, syms, errstr := lastmoduleinit()
if errstr != "" {
plugins[filepath] = &Plugin{
pluginpath: pluginpath,
err: errstr,
}
pluginsMu.Unlock()
return nil, errors.New(`plugin.Open("` + name + `"): ` + errstr)
}
// This function can be called from the init function of a plugin.
// Drop a placeholder in the map so subsequent opens can wait on it.
p := &Plugin{
pluginpath: pluginpath,
loaded: make(chan struct{}),
}
plugins[filepath] = p
pluginsMu.Unlock()
initStr := make([]byte, len(pluginpath)+len("..inittask")+1) // +1 for terminating NUL
copy(initStr, pluginpath)
copy(initStr[len(pluginpath):], "..inittask")
initTask := C.pluginLookup(h, (*C.char)(unsafe.Pointer(&initStr[0])), &cErr)
if initTask != nil {
doInit(initTask)
}
// Fill out the value of each plugin symbol.
updatedSyms := map[string]interface{}{}
for symName, sym := range syms {
isFunc := symName[0] == '.'
if isFunc {
delete(syms, symName)
symName = symName[1:]
}
fullName := pluginpath + "." + symName
cname := make([]byte, len(fullName)+1)
copy(cname, fullName)
p := C.pluginLookup(h, (*C.char)(unsafe.Pointer(&cname[0])), &cErr)
if p == nil {
return nil, errors.New(`plugin.Open("` + name + `"): could not find symbol ` + symName + `: ` + C.GoString(cErr))
}
valp := (*[2]unsafe.Pointer)(unsafe.Pointer(&sym))
if isFunc {
(*valp)[1] = unsafe.Pointer(&p)
} else {
(*valp)[1] = p
}
// we can't add to syms during iteration as we'll end up processing
// some symbols twice with the inability to tell if the symbol is a function
updatedSyms[symName] = sym
}
p.syms = updatedSyms
close(p.loaded)
return p, nil
}
func unload(name string) (error) {
cPath := make([]byte, C.PATH_MAX+1)
cRelName := make([]byte, len(name)+1)
copy(cRelName, name)
if C.realpath(
(*C.char)(unsafe.Pointer(&cRelName[0])),
(*C.char)(unsafe.Pointer(&cPath[0]))) == nil {
return errors.New(`plugin.Close("` + name + `"): realpath failed`)
}
filepath := C.GoString((*C.char)(unsafe.Pointer(&cPath[0])))
pluginsMu.Lock()
p := plugins[filepath]
if p != nil {
delete(plugings, filepath)
}
pluginsMu.Unlock()
if p != nil {
res := C.pluginClose(unsafe.Pointer(p), &cErr)
if res != 0 {
return errors.New(`plugin.Close("` + name + `"): ` + C.GoString(cErr))
}
}
return nil
}
func lookup(p *Plugin, symName string) (Symbol, error) {
if s := p.syms[symName]; s != nil {
return s, nil
}
return nil, errors.New("plugin: symbol " + symName + " not found in plugin " + p.pluginpath)
}
var (
pluginsMu sync.Mutex
plugins map[string]*Plugin
)
// lastmoduleinit is defined in package runtime
func lastmoduleinit() (pluginpath string, syms map[string]interface{}, errstr string)
// doInit is defined in package runtime
//go:linkname doInit runtime.doInit
func doInit(t unsafe.Pointer) // t should be a *runtime.initTask