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- // 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.
- //go:build (linux && cgo) || (darwin && cgo) || (freebsd && cgo) || (hurd & 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;
- }
- */
- 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]any{}
- 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 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]any, errstr string)
- // doInit is defined in package runtime
- //go:linkname doInit runtime.doInit
- func doInit(t unsafe.Pointer) // t should be a *runtime.initTask
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