2 files changed, 489 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/staticdata/data.go b/src/cmd/compile/internal/staticdata/data.go
new file mode 100644
index 0000000000..7627aaa11a
--- /dev/null
+++ b/src/cmd/compile/internal/staticdata/data.go
@@ -0,0 +1,296 @@
+// Copyright 2009 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 staticdata
+
+import (
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"sort"
+	"strconv"
+	"sync"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/objw"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+	"cmd/internal/objabi"
+	"cmd/internal/src"
+)
+
+// InitAddr writes the static address of a to n. a must be an ONAME.
+// Neither n nor a is modified.
+func InitAddr(n *ir.Name, noff int64, a *ir.Name, aoff int64) {
+	if n.Op() != ir.ONAME {
+		base.Fatalf("addrsym n op %v", n.Op())
+	}
+	if n.Sym() == nil {
+		base.Fatalf("addrsym nil n sym")
+	}
+	if a.Op() != ir.ONAME {
+		base.Fatalf("addrsym a op %v", a.Op())
+	}
+	s := n.Sym().Linksym()
+	s.WriteAddr(base.Ctxt, noff, types.PtrSize, a.Sym().Linksym(), aoff)
+}
+
+// InitFunc writes the static address of f to n. f must be a global function.
+// Neither n nor f is modified.
+func InitFunc(n *ir.Name, noff int64, f *ir.Name) {
+	if n.Op() != ir.ONAME {
+		base.Fatalf("pfuncsym n op %v", n.Op())
+	}
+	if n.Sym() == nil {
+		base.Fatalf("pfuncsym nil n sym")
+	}
+	if f.Class_ != ir.PFUNC {
+		base.Fatalf("pfuncsym class not PFUNC %d", f.Class_)
+	}
+	s := n.Sym().Linksym()
+	s.WriteAddr(base.Ctxt, noff, types.PtrSize, FuncSym(f.Sym()).Linksym(), 0)
+}
+
+// InitSlice writes a static slice symbol {&arr, lencap, lencap} to n+noff.
+// InitSlice does not modify n.
+func InitSlice(n *ir.Name, noff int64, arr *ir.Name, lencap int64) {
+	s := n.Sym().Linksym()
+	if arr.Op() != ir.ONAME {
+		base.Fatalf("slicesym non-name arr %v", arr)
+	}
+	s.WriteAddr(base.Ctxt, noff, types.PtrSize, arr.Sym().Linksym(), 0)
+	s.WriteInt(base.Ctxt, noff+types.SliceLenOffset, types.PtrSize, lencap)
+	s.WriteInt(base.Ctxt, noff+types.SliceCapOffset, types.PtrSize, lencap)
+}
+
+func InitSliceBytes(nam *ir.Name, off int64, s string) {
+	if nam.Op() != ir.ONAME {
+		base.Fatalf("slicebytes %v", nam)
+	}
+	InitSlice(nam, off, slicedata(nam.Pos(), s), int64(len(s)))
+}
+
+const (
+	stringSymPrefix  = "go.string."
+	stringSymPattern = ".gostring.%d.%x"
+)
+
+// StringSym returns a symbol containing the string s.
+// The symbol contains the string data, not a string header.
+func StringSym(pos src.XPos, s string) (data *obj.LSym) {
+	var symname string
+	if len(s) > 100 {
+		// Huge strings are hashed to avoid long names in object files.
+		// Indulge in some paranoia by writing the length of s, too,
+		// as protection against length extension attacks.
+		// Same pattern is known to fileStringSym below.
+		h := sha256.New()
+		io.WriteString(h, s)
+		symname = fmt.Sprintf(stringSymPattern, len(s), h.Sum(nil))
+	} else {
+		// Small strings get named directly by their contents.
+		symname = strconv.Quote(s)
+	}
+
+	symdata := base.Ctxt.Lookup(stringSymPrefix + symname)
+	if !symdata.OnList() {
+		off := dstringdata(symdata, 0, s, pos, "string")
+		objw.Global(symdata, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
+		symdata.Set(obj.AttrContentAddressable, true)
+	}
+
+	return symdata
+}
+
+// fileStringSym returns a symbol for the contents and the size of file.
+// If readonly is true, the symbol shares storage with any literal string
+// or other file with the same content and is placed in a read-only section.
+// If readonly is false, the symbol is a read-write copy separate from any other,
+// for use as the backing store of a []byte.
+// The content hash of file is copied into hash. (If hash is nil, nothing is copied.)
+// The returned symbol contains the data itself, not a string header.
+func fileStringSym(pos src.XPos, file string, readonly bool, hash []byte) (*obj.LSym, int64, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer f.Close()
+	info, err := f.Stat()
+	if err != nil {
+		return nil, 0, err
+	}
+	if !info.Mode().IsRegular() {
+		return nil, 0, fmt.Errorf("not a regular file")
+	}
+	size := info.Size()
+	if size <= 1*1024 {
+		data, err := ioutil.ReadAll(f)
+		if err != nil {
+			return nil, 0, err
+		}
+		if int64(len(data)) != size {
+			return nil, 0, fmt.Errorf("file changed between reads")
+		}
+		var sym *obj.LSym
+		if readonly {
+			sym = StringSym(pos, string(data))
+		} else {
+			sym = slicedata(pos, string(data)).Sym().Linksym()
+		}
+		if len(hash) > 0 {
+			sum := sha256.Sum256(data)
+			copy(hash, sum[:])
+		}
+		return sym, size, nil
+	}
+	if size > 2e9 {
+		// ggloblsym takes an int32,
+		// and probably the rest of the toolchain
+		// can't handle such big symbols either.
+		// See golang.org/issue/9862.
+		return nil, 0, fmt.Errorf("file too large")
+	}
+
+	// File is too big to read and keep in memory.
+	// Compute hash if needed for read-only content hashing or if the caller wants it.
+	var sum []byte
+	if readonly || len(hash) > 0 {
+		h := sha256.New()
+		n, err := io.Copy(h, f)
+		if err != nil {
+			return nil, 0, err
+		}
+		if n != size {
+			return nil, 0, fmt.Errorf("file changed between reads")
+		}
+		sum = h.Sum(nil)
+		copy(hash, sum)
+	}
+
+	var symdata *obj.LSym
+	if readonly {
+		symname := fmt.Sprintf(stringSymPattern, size, sum)
+		symdata = base.Ctxt.Lookup(stringSymPrefix + symname)
+		if !symdata.OnList() {
+			info := symdata.NewFileInfo()
+			info.Name = file
+			info.Size = size
+			objw.Global(symdata, int32(size), obj.DUPOK|obj.RODATA|obj.LOCAL)
+			// Note: AttrContentAddressable cannot be set here,
+			// because the content-addressable-handling code
+			// does not know about file symbols.
+		}
+	} else {
+		// Emit a zero-length data symbol
+		// and then fix up length and content to use file.
+		symdata = slicedata(pos, "").Sym().Linksym()
+		symdata.Size = size
+		symdata.Type = objabi.SNOPTRDATA
+		info := symdata.NewFileInfo()
+		info.Name = file
+		info.Size = size
+	}
+
+	return symdata, size, nil
+}
+
+var slicedataGen int
+
+func slicedata(pos src.XPos, s string) *ir.Name {
+	slicedataGen++
+	symname := fmt.Sprintf(".gobytes.%d", slicedataGen)
+	sym := types.LocalPkg.Lookup(symname)
+	symnode := typecheck.NewName(sym)
+	sym.Def = symnode
+
+	lsym := sym.Linksym()
+	off := dstringdata(lsym, 0, s, pos, "slice")
+	objw.Global(lsym, int32(off), obj.NOPTR|obj.LOCAL)
+
+	return symnode
+}
+
+func dstringdata(s *obj.LSym, off int, t string, pos src.XPos, what string) int {
+	// Objects that are too large will cause the data section to overflow right away,
+	// causing a cryptic error message by the linker. Check for oversize objects here
+	// and provide a useful error message instead.
+	if int64(len(t)) > 2e9 {
+		base.ErrorfAt(pos, "%v with length %v is too big", what, len(t))
+		return 0
+	}
+
+	s.WriteString(base.Ctxt, int64(off), len(t), t)
+	return off + len(t)
+}
+
+var (
+	funcsymsmu sync.Mutex // protects funcsyms and associated package lookups (see func funcsym)
+	funcsyms   []*types.Sym
+)
+
+// FuncSym returns s·f.
+func FuncSym(s *types.Sym) *types.Sym {
+	// funcsymsmu here serves to protect not just mutations of funcsyms (below),
+	// but also the package lookup of the func sym name,
+	// since this function gets called concurrently from the backend.
+	// There are no other concurrent package lookups in the backend,
+	// except for the types package, which is protected separately.
+	// Reusing funcsymsmu to also cover this package lookup
+	// avoids a general, broader, expensive package lookup mutex.
+	// Note makefuncsym also does package look-up of func sym names,
+	// but that it is only called serially, from the front end.
+	funcsymsmu.Lock()
+	sf, existed := s.Pkg.LookupOK(ir.FuncSymName(s))
+	// Don't export s·f when compiling for dynamic linking.
+	// When dynamically linking, the necessary function
+	// symbols will be created explicitly with makefuncsym.
+	// See the makefuncsym comment for details.
+	if !base.Ctxt.Flag_dynlink && !existed {
+		funcsyms = append(funcsyms, s)
+	}
+	funcsymsmu.Unlock()
+	return sf
+}
+
+// NeedFuncSym ensures that s·f is exported.
+// It is only used with -dynlink.
+// When not compiling for dynamic linking,
+// the funcsyms are created as needed by
+// the packages that use them.
+// Normally we emit the s·f stubs as DUPOK syms,
+// but DUPOK doesn't work across shared library boundaries.
+// So instead, when dynamic linking, we only create
+// the s·f stubs in s's package.
+func NeedFuncSym(s *types.Sym) {
+	if !base.Ctxt.Flag_dynlink {
+		base.Fatalf("makefuncsym dynlink")
+	}
+	if s.IsBlank() {
+		return
+	}
+	if base.Flag.CompilingRuntime && (s.Name == "getg" || s.Name == "getclosureptr" || s.Name == "getcallerpc" || s.Name == "getcallersp") {
+		// runtime.getg(), getclosureptr(), getcallerpc(), and
+		// getcallersp() are not real functions and so do not
+		// get funcsyms.
+		return
+	}
+	if _, existed := s.Pkg.LookupOK(ir.FuncSymName(s)); !existed {
+		funcsyms = append(funcsyms, s)
+	}
+}
+
+func WriteFuncSyms() {
+	sort.Slice(funcsyms, func(i, j int) bool {
+		return funcsyms[i].LinksymName() < funcsyms[j].LinksymName()
+	})
+	for _, s := range funcsyms {
+		sf := s.Pkg.Lookup(ir.FuncSymName(s)).Linksym()
+		objw.SymPtr(sf, 0, s.Linksym(), 0)
+		objw.Global(sf, int32(types.PtrSize), obj.DUPOK|obj.RODATA)
+	}
+}
diff --git a/src/cmd/compile/internal/staticdata/embed.go b/src/cmd/compile/internal/staticdata/embed.go
new file mode 100644
index 0000000000..55c9a3356e
--- /dev/null
+++ b/src/cmd/compile/internal/staticdata/embed.go
@@ -0,0 +1,193 @@
+// 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 staticdata
+
+import (
+	"path"
+	"sort"
+	"strings"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/objw"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+)
+
+const (
+	embedUnknown = iota
+	embedBytes
+	embedString
+	embedFiles
+)
+
+func embedFileList(v *ir.Name) []string {
+	kind := embedKind(v.Type())
+	if kind == embedUnknown {
+		base.ErrorfAt(v.Pos(), "go:embed cannot apply to var of type %v", v.Type())
+		return nil
+	}
+
+	// Build list of files to store.
+	have := make(map[string]bool)
+	var list []string
+	for _, e := range *v.Embed {
+		for _, pattern := range e.Patterns {
+			files, ok := base.Flag.Cfg.Embed.Patterns[pattern]
+			if !ok {
+				base.ErrorfAt(e.Pos, "invalid go:embed: build system did not map pattern: %s", pattern)
+			}
+			for _, file := range files {
+				if base.Flag.Cfg.Embed.Files[file] == "" {
+					base.ErrorfAt(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 {
+			base.ErrorfAt(v.Pos(), "invalid go:embed: multiple files for type %v", v.Type())
+			return nil
+		}
+	}
+
+	return list
+}
+
+// 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 ir.Node) int {
+	if typ.Sym() != nil && typ.Sym().Name == "FS" && (typ.Sym().Pkg.Path == "embed" || (typ.Sym().Pkg == types.LocalPkg && base.Ctxt.Pkgpath == "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 == types.LocalPkg {
+		return embedString
+	}
+	if typ, ok := typ.(*ir.SliceType); ok {
+		if sym := typ.Elem.Sym(); sym != nil && sym.Name == "byte" && sym.Pkg == types.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 == types.LocalPkg && base.Ctxt.Pkgpath == "embed")) {
+		return embedFiles
+	}
+	if typ == types.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
+}
+
+// WriteEmbed emits the init data for a //go:embed variable,
+// which is either a string, a []byte, or an embed.FS.
+func WriteEmbed(v *ir.Name) {
+	files := embedFileList(v)
+	switch kind := embedKind(v.Type()); kind {
+	case embedUnknown:
+		base.ErrorfAt(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(), base.Flag.Cfg.Embed.Files[file], kind == embedString, nil)
+		if err != nil {
+			base.ErrorfAt(v.Pos(), "embed %s: %v", file, err)
+		}
+		sym := v.Sym().Linksym()
+		off := 0
+		off = objw.SymPtr(sym, off, fsym, 0)       // data string
+		off = objw.Uintptr(sym, off, uint64(size)) // len
+		if kind == embedBytes {
+			objw.Uintptr(sym, off, uint64(size)) // cap for slice
+		}
+
+	case embedFiles:
+		slicedata := base.Ctxt.Lookup(`"".` + v.Sym().Name + `.files`)
+		off := 0
+		// []files pointed at by Files
+		off = objw.SymPtr(slicedata, off, slicedata, 3*types.PtrSize) // []file, pointing just past slice
+		off = objw.Uintptr(slicedata, off, uint64(len(files)))
+		off = objw.Uintptr(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 = objw.SymPtr(slicedata, off, StringSym(v.Pos(), file), 0) // file string
+			off = objw.Uintptr(slicedata, off, uint64(len(file)))
+			if strings.HasSuffix(file, "/") {
+				// entry for directory - no data
+				off = objw.Uintptr(slicedata, off, 0)
+				off = objw.Uintptr(slicedata, off, 0)
+				off += hashSize
+			} else {
+				fsym, size, err := fileStringSym(v.Pos(), base.Flag.Cfg.Embed.Files[file], true, hash)
+				if err != nil {
+					base.ErrorfAt(v.Pos(), "embed %s: %v", file, err)
+				}
+				off = objw.SymPtr(slicedata, off, fsym, 0) // data string
+				off = objw.Uintptr(slicedata, off, uint64(size))
+				off = int(slicedata.WriteBytes(base.Ctxt, int64(off), hash))
+			}
+		}
+		objw.Global(slicedata, int32(off), obj.RODATA|obj.LOCAL)
+		sym := v.Sym().Linksym()
+		objw.SymPtr(sym, 0, slicedata, 0)
+	}
+}