1 files changed, 296 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)
+	}
+}