Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 120 insertions, 0 deletions

diff --git a/src/plugin/plugin.go b/src/plugin/plugin.go
new file mode 100644
index 0000000..187d127
--- /dev/null
+++ b/src/plugin/plugin.go
@@ -0,0 +1,120 @@
+// 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.
+
+// Package plugin implements loading and symbol resolution of Go plugins.
+//
+// A plugin is a Go main package with exported functions and variables that
+// has been built with:
+//
+//	go build -buildmode=plugin
+//
+// When a plugin is first opened, the init functions of all packages not
+// already part of the program are called. The main function is not run.
+// A plugin is only initialized once, and cannot be closed.
+//
+// # Warnings
+//
+// The ability to dynamically load parts of an application during
+// execution, perhaps based on user-defined configuration, may be a
+// useful building block in some designs. In particular, because
+// applications and dynamically loaded functions can share data
+// structures directly, plugins may enable very high-performance
+// integration of separate parts.
+//
+// However, the plugin mechanism has many significant drawbacks that
+// should be considered carefully during the design. For example:
+//
+//   - Plugins are currently supported only on Linux, FreeBSD, and
+//     macOS, making them unsuitable for applications intended to be
+//     portable.
+//
+//   - Applications that use plugins may require careful configuration
+//     to ensure that the various parts of the program be made available
+//     in the correct location in the file system (or container image).
+//     By contrast, deploying an application consisting of a single static
+//     executable is straightforward.
+//
+//   - Reasoning about program initialization is more difficult when
+//     some packages may not be initialized until long after the
+//     application has started running.
+//
+//   - Bugs in applications that load plugins could be exploited by
+//     an attacker to load dangerous or untrusted libraries.
+//
+//   - Runtime crashes are likely to occur unless all parts of the
+//     program (the application and all its plugins) are compiled
+//     using exactly the same version of the toolchain, the same build
+//     tags, and the same values of certain flags and environment
+//     variables.
+//
+//   - Similar crashing problems are likely to arise unless all common
+//     dependencies of the application and its plugins are built from
+//     exactly the same source code.
+//
+//   - Together, these restrictions mean that, in practice, the
+//     application and its plugins must all be built together by a
+//     single person or component of a system. In that case, it may
+//     be simpler for that person or component to generate Go source
+//     files that blank-import the desired set of plugins and then
+//     compile a static executable in the usual way.
+//
+// For these reasons, many users decide that traditional interprocess
+// communication (IPC) mechanisms such as sockets, pipes, remote
+// procedure call (RPC), shared memory mappings, or file system
+// operations may be more suitable despite the performance overheads.
+package plugin
+
+// Plugin is a loaded Go plugin.
+type Plugin struct {
+	pluginpath string
+	err        string        // set if plugin failed to load
+	loaded     chan struct{} // closed when loaded
+	syms       map[string]any
+}
+
+// Open opens a Go plugin.
+// If a path has already been opened, then the existing *Plugin is returned.
+// It is safe for concurrent use by multiple goroutines.
+func Open(path string) (*Plugin, error) {
+	return open(path)
+}
+
+// Lookup searches for a symbol named symName in plugin p.
+// A symbol is any exported variable or function.
+// It reports an error if the symbol is not found.
+// It is safe for concurrent use by multiple goroutines.
+func (p *Plugin) Lookup(symName string) (Symbol, error) {
+	return lookup(p, symName)
+}
+
+// A Symbol is a pointer to a variable or function.
+//
+// For example, a plugin defined as
+//
+//	package main
+//
+//	import "fmt"
+//
+//	var V int
+//
+//	func F() { fmt.Printf("Hello, number %d\n", V) }
+//
+// may be loaded with the Open function and then the exported package
+// symbols V and F can be accessed
+//
+//	p, err := plugin.Open("plugin_name.so")
+//	if err != nil {
+//		panic(err)
+//	}
+//	v, err := p.Lookup("V")
+//	if err != nil {
+//		panic(err)
+//	}
+//	f, err := p.Lookup("F")
+//	if err != nil {
+//		panic(err)
+//	}
+//	*v.(*int) = 7
+//	f.(func())() // prints "Hello, number 7"
+type Symbol any