1// Copyright 2021 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
5package base
6
7import (
8	"cmd/internal/obj"
9)
10
11// ReservedImports are import paths used internally for generated
12// symbols by the compiler.
13//
14// The linker uses the magic symbol prefixes "go:" and "type:".
15// Avoid potential confusion between import paths and symbols
16// by rejecting these reserved imports for now. Also, people
17// "can do weird things in GOPATH and we'd prefer they didn't
18// do _that_ weird thing" (per rsc). See also #4257.
19var ReservedImports = map[string]bool{
20	"go":   true,
21	"type": true,
22}
23
24var Ctxt *obj.Link
25
26// TODO(mdempsky): These should probably be obj.Link methods.
27
28// PkgLinksym returns the linker symbol for name within the given
29// package prefix. For user packages, prefix should be the package
30// path encoded with objabi.PathToPrefix.
31func PkgLinksym(prefix, name string, abi obj.ABI) *obj.LSym {
32	if name == "_" {
33		// TODO(mdempsky): Cleanup callers and Fatalf instead.
34		return linksym(prefix, "_", abi)
35	}
36	sep := "."
37	if ReservedImports[prefix] {
38		sep = ":"
39	}
40	return linksym(prefix, prefix+sep+name, abi)
41}
42
43// Linkname returns the linker symbol for the given name as it might
44// appear within a //go:linkname directive.
45func Linkname(name string, abi obj.ABI) *obj.LSym {
46	return linksym("_", name, abi)
47}
48
49// linksym is an internal helper function for implementing the above
50// exported APIs.
51func linksym(pkg, name string, abi obj.ABI) *obj.LSym {
52	return Ctxt.LookupABIInit(name, abi, func(r *obj.LSym) { r.Pkg = pkg })
53}
54