1 // Copyright 2016 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package plugin implements loading and symbol resolution of Go plugins. 6 // 7 // Currently plugins only work on Linux. 8 // 9 // A plugin is a Go main package with exported functions and variables that 10 // has been built with: 11 // 12 // go build -buildmode=plugin 13 // 14 // When a plugin is first opened, the init functions of all packages not 15 // already part of the program are called. The main function is not run. 16 // A plugin is only initialized once, and cannot be closed. 17 package plugin 18 19 // Plugin is a loaded Go plugin. 20 type Plugin struct { 21 pluginpath string 22 loaded chan struct{} // closed when loaded 23 syms map[string]interface{} 24 } 25 26 // Open opens a Go plugin. 27 // If a path has already been opened, then the existing *Plugin is returned. 28 // It is safe for concurrent use by multiple goroutines. 29 func Open(path string) (*Plugin, error) { 30 return open(path) 31 } 32 33 // Lookup searches for a symbol named symName in plugin p. 34 // A symbol is any exported variable or function. 35 // It reports an error if the symbol is not found. 36 // It is safe for concurrent use by multiple goroutines. 37 func (p *Plugin) Lookup(symName string) (Symbol, error) { 38 return lookup(p, symName) 39 } 40 41 // A Symbol is a pointer to a variable or function. 42 // 43 // For example, a plugin defined as 44 // 45 // package main 46 // 47 // // // No C code needed. 48 // import "C" 49 // 50 // import "fmt" 51 // 52 // var V int 53 // 54 // func F() { fmt.Printf("Hello, number %d\n", V) } 55 // 56 // may be loaded with the Open function and then the exported package 57 // symbols V and F can be accessed 58 // 59 // p, err := plugin.Open("plugin_name.so") 60 // if err != nil { 61 // panic(err) 62 // } 63 // v, err := p.Lookup("V") 64 // if err != nil { 65 // panic(err) 66 // } 67 // f, err := p.Lookup("F") 68 // if err != nil { 69 // panic(err) 70 // } 71 // *v.(*int) = 7 72 // f.(func())() // prints "Hello, number 7" 73 type Symbol interface{} 74
