1 files changed, 273 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/embed.go b/src/cmd/compile/internal/gc/embed.go
new file mode 100644
index 0000000000..103949c1f9
--- /dev/null
+++ b/src/cmd/compile/internal/gc/embed.go
@@ -0,0 +1,273 @@
+// Copyright 2020 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 gc
+
+import (
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"path"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+var embedlist []*Node
+
+var embedCfg struct {
+	Patterns map[string][]string
+	Files    map[string]string
+}
+
+func readEmbedCfg(file string) {
+	data, err := ioutil.ReadFile(file)
+	if err != nil {
+		log.Fatalf("-embedcfg: %v", err)
+	}
+	if err := json.Unmarshal(data, &embedCfg); err != nil {
+		log.Fatalf("%s: %v", file, err)
+	}
+	if embedCfg.Patterns == nil {
+		log.Fatalf("%s: invalid embedcfg: missing Patterns", file)
+	}
+	if embedCfg.Files == nil {
+		log.Fatalf("%s: invalid embedcfg: missing Files", file)
+	}
+}
+
+const (
+	embedUnknown = iota
+	embedBytes
+	embedString
+	embedFiles
+)
+
+var numLocalEmbed int
+
+func varEmbed(p *noder, names []*Node, typ *Node, exprs []*Node, embeds []PragmaEmbed) (newExprs []*Node) {
+	haveEmbed := false
+	for _, decl := range p.file.DeclList {
+		imp, ok := decl.(*syntax.ImportDecl)
+		if !ok {
+			// imports always come first
+			break
+		}
+		path, _ := strconv.Unquote(imp.Path.Value)
+		if path == "embed" {
+			haveEmbed = true
+			break
+		}
+	}
+
+	pos := embeds[0].Pos
+	if !haveEmbed {
+		p.yyerrorpos(pos, "invalid go:embed: missing import \"embed\"")
+		return exprs
+	}
+	if embedCfg.Patterns == nil {
+		p.yyerrorpos(pos, "invalid go:embed: build system did not supply embed configuration")
+		return exprs
+	}
+	if len(names) > 1 {
+		p.yyerrorpos(pos, "go:embed cannot apply to multiple vars")
+		return exprs
+	}
+	if len(exprs) > 0 {
+		p.yyerrorpos(pos, "go:embed cannot apply to var with initializer")
+		return exprs
+	}
+	if typ == nil {
+		// Should not happen, since len(exprs) == 0 now.
+		p.yyerrorpos(pos, "go:embed cannot apply to var without type")
+		return exprs
+	}
+
+	kind := embedKindApprox(typ)
+	if kind == embedUnknown {
+		p.yyerrorpos(pos, "go:embed cannot apply to var of type %v", typ)
+		return exprs
+	}
+
+	// Build list of files to store.
+	have := make(map[string]bool)
+	var list []string
+	for _, e := range embeds {
+		for _, pattern := range e.Patterns {
+			files, ok := embedCfg.Patterns[pattern]
+			if !ok {
+				p.yyerrorpos(e.Pos, "invalid go:embed: build system did not map pattern: %s", pattern)
+			}
+			for _, file := range files {
+				if embedCfg.Files[file] == "" {
+					p.yyerrorpos(e.Pos, "invalid go:embed: build system did not map file: %s", file)
+					continue
+				}
+				if !have[file] {
+					have[file] = true
+					list = append(list, file)
+				}
+				if kind == embedFiles {
+					for dir := path.Dir(file); dir != "." && !have[dir]; dir = path.Dir(dir) {
+						have[dir] = true
+						list = append(list, dir+"/")
+					}
+				}
+			}
+		}
+	}
+	sort.Slice(list, func(i, j int) bool {
+		return embedFileLess(list[i], list[j])
+	})
+
+	if kind == embedString || kind == embedBytes {
+		if len(list) > 1 {
+			p.yyerrorpos(pos, "invalid go:embed: multiple files for type %v", typ)
+			return exprs
+		}
+	}
+
+	v := names[0]
+	if dclcontext != PEXTERN {
+		numLocalEmbed++
+		v = newnamel(v.Pos, lookupN("embed.", numLocalEmbed))
+		v.Sym.Def = asTypesNode(v)
+		v.Name.Param.Ntype = typ
+		v.SetClass(PEXTERN)
+		externdcl = append(externdcl, v)
+		exprs = []*Node{v}
+	}
+
+	v.Name.Param.SetEmbedFiles(list)
+	embedlist = append(embedlist, v)
+	return exprs
+}
+
+// embedKindApprox determines the kind of embedding variable, approximately.
+// The match is approximate because we haven't done scope resolution yet and
+// can't tell whether "string" and "byte" really mean "string" and "byte".
+// The result must be confirmed later, after type checking, using embedKind.
+func embedKindApprox(typ *Node) int {
+	if typ.Sym != nil && typ.Sym.Name == "FS" && (typ.Sym.Pkg.Path == "embed" || (typ.Sym.Pkg == localpkg && myimportpath == "embed")) {
+		return embedFiles
+	}
+	// These are not guaranteed to match only string and []byte -
+	// maybe the local package has redefined one of those words.
+	// But it's the best we can do now during the noder.
+	// The stricter check happens later, in initEmbed calling embedKind.
+	if typ.Sym != nil && typ.Sym.Name == "string" && typ.Sym.Pkg == localpkg {
+		return embedString
+	}
+	if typ.Op == OTARRAY && typ.Left == nil && typ.Right.Sym != nil && typ.Right.Sym.Name == "byte" && typ.Right.Sym.Pkg == localpkg {
+		return embedBytes
+	}
+	return embedUnknown
+}
+
+// embedKind determines the kind of embedding variable.
+func embedKind(typ *types.Type) int {
+	if typ.Sym != nil && typ.Sym.Name == "FS" && (typ.Sym.Pkg.Path == "embed" || (typ.Sym.Pkg == localpkg && myimportpath == "embed")) {
+		return embedFiles
+	}
+	if typ == types.Types[TSTRING] {
+		return embedString
+	}
+	if typ.Sym == nil && typ.IsSlice() && typ.Elem() == types.Bytetype {
+		return embedBytes
+	}
+	return embedUnknown
+}
+
+func embedFileNameSplit(name string) (dir, elem string, isDir bool) {
+	if name[len(name)-1] == '/' {
+		isDir = true
+		name = name[:len(name)-1]
+	}
+	i := len(name) - 1
+	for i >= 0 && name[i] != '/' {
+		i--
+	}
+	if i < 0 {
+		return ".", name, isDir
+	}
+	return name[:i], name[i+1:], isDir
+}
+
+// embedFileLess implements the sort order for a list of embedded files.
+// See the comment inside ../../../../embed/embed.go's Files struct for rationale.
+func embedFileLess(x, y string) bool {
+	xdir, xelem, _ := embedFileNameSplit(x)
+	ydir, yelem, _ := embedFileNameSplit(y)
+	return xdir < ydir || xdir == ydir && xelem < yelem
+}
+
+func dumpembeds() {
+	for _, v := range embedlist {
+		initEmbed(v)
+	}
+}
+
+// initEmbed emits the init data for a //go:embed variable,
+// which is either a string, a []byte, or an embed.FS.
+func initEmbed(v *Node) {
+	files := v.Name.Param.EmbedFiles()
+	switch kind := embedKind(v.Type); kind {
+	case embedUnknown:
+		yyerrorl(v.Pos, "go:embed cannot apply to var of type %v", v.Type)
+
+	case embedString, embedBytes:
+		file := files[0]
+		fsym, size, err := fileStringSym(v.Pos, embedCfg.Files[file], kind == embedString, nil)
+		if err != nil {
+			yyerrorl(v.Pos, "embed %s: %v", file, err)
+		}
+		sym := v.Sym.Linksym()
+		off := 0
+		off = dsymptr(sym, off, fsym, 0)       // data string
+		off = duintptr(sym, off, uint64(size)) // len
+		if kind == embedBytes {
+			duintptr(sym, off, uint64(size)) // cap for slice
+		}
+
+	case embedFiles:
+		slicedata := Ctxt.Lookup(`"".` + v.Sym.Name + `.files`)
+		off := 0
+		// []files pointed at by Files
+		off = dsymptr(slicedata, off, slicedata, 3*Widthptr) // []file, pointing just past slice
+		off = duintptr(slicedata, off, uint64(len(files)))
+		off = duintptr(slicedata, off, uint64(len(files)))
+
+		// embed/embed.go type file is:
+		//	name string
+		//	data string
+		//	hash [16]byte
+		// Emit one of these per file in the set.
+		const hashSize = 16
+		hash := make([]byte, hashSize)
+		for _, file := range files {
+			off = dsymptr(slicedata, off, stringsym(v.Pos, file), 0) // file string
+			off = duintptr(slicedata, off, uint64(len(file)))
+			if strings.HasSuffix(file, "/") {
+				// entry for directory - no data
+				off = duintptr(slicedata, off, 0)
+				off = duintptr(slicedata, off, 0)
+				off += hashSize
+			} else {
+				fsym, size, err := fileStringSym(v.Pos, embedCfg.Files[file], true, hash)
+				if err != nil {
+					yyerrorl(v.Pos, "embed %s: %v", file, err)
+				}
+				off = dsymptr(slicedata, off, fsym, 0) // data string
+				off = duintptr(slicedata, off, uint64(size))
+				off = int(slicedata.WriteBytes(Ctxt, int64(off), hash))
+			}
+		}
+		ggloblsym(slicedata, int32(off), obj.RODATA|obj.LOCAL)
+		sym := v.Sym.Linksym()
+		dsymptr(sym, 0, slicedata, 0)
+	}
+}