[dev.link] cmd/link: use fingerprint as package hash
Now the compiler-generated fingerprint is a hash of the export
data. We don't need to hash it ourselves in the linker. And the
linker doesn't need to read export data at all.
Fixes #33820.
Change-Id: I54bf3ebfd0f0c72aa43a352d7b2e0575dd62970d
Reviewed-on: https://go-review.googlesource.com/c/go/+/236119
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
diff --git a/src/cmd/link/internal/ld/elf.go b/src/cmd/link/internal/ld/elf.go
index eaa3ffd..b100d07 100644
--- a/src/cmd/link/internal/ld/elf.go
+++ b/src/cmd/link/internal/ld/elf.go
@@ -12,7 +12,6 @@
"crypto/sha1"
"encoding/binary"
"encoding/hex"
- "io"
"path/filepath"
"sort"
"strings"
@@ -1713,7 +1712,7 @@
sort.Sort(byPkg(ctxt.Library))
h := sha1.New()
for _, l := range ctxt.Library {
- io.WriteString(h, l.Hash)
+ h.Write(l.Fingerprint[:])
}
addgonote(ctxt, ".note.go.abihash", ELF_NOTE_GOABIHASH_TAG, h.Sum([]byte{}))
addgonote(ctxt, ".note.go.pkg-list", ELF_NOTE_GOPKGLIST_TAG, pkglistfornote)
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 93524f0..dcb5f79 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -48,7 +48,6 @@
"debug/macho"
"encoding/base64"
"encoding/binary"
- "encoding/hex"
"fmt"
"io"
"io/ioutil"
@@ -785,16 +784,6 @@
ctxt.loader.SetAttrReachable(moduledata, true)
ctxt.Moduledata = moduledata
- // If package versioning is required, generate a hash of the
- // packages used in the link.
- if ctxt.BuildMode == BuildModeShared || ctxt.BuildMode == BuildModePlugin || ctxt.CanUsePlugins() {
- for _, lib := range ctxt.Library {
- if lib.Shlib == "" {
- genhash(ctxt, lib)
- }
- }
- }
-
if ctxt.Arch == sys.Arch386 && ctxt.HeadType != objabi.Hwindows {
if (ctxt.BuildMode == BuildModeCArchive && ctxt.IsELF) || ctxt.BuildMode == BuildModeCShared || ctxt.BuildMode == BuildModePIE || ctxt.DynlinkingGo() {
got := ctxt.loader.LookupOrCreateSym("_GLOBAL_OFFSET_TABLE_", 0)
@@ -919,67 +908,6 @@
return arsize + SAR_HDR
}
-func genhash(ctxt *Link, lib *sym.Library) {
- f, err := bio.Open(lib.File)
- if err != nil {
- Errorf(nil, "cannot open file %s for hash generation: %v", lib.File, err)
- return
- }
- defer f.Close()
-
- var magbuf [len(ARMAG)]byte
- if _, err := io.ReadFull(f, magbuf[:]); err != nil {
- Exitf("file %s too short", lib.File)
- }
-
- if string(magbuf[:]) != ARMAG {
- Exitf("%s is not an archive file", lib.File)
- }
-
- var arhdr ArHdr
- l := nextar(f, f.Offset(), &arhdr)
- if l <= 0 {
- Errorf(nil, "%s: short read on archive file symbol header", lib.File)
- return
- }
- if arhdr.name != pkgdef {
- Errorf(nil, "%s: missing package data entry", lib.File)
- return
- }
-
- h := sha1.New()
-
- // To compute the hash of a package, we hash the first line of
- // __.PKGDEF (which contains the toolchain version and any
- // GOEXPERIMENT flags) and the export data (which is between
- // the first two occurrences of "\n$$").
-
- pkgDefBytes := make([]byte, atolwhex(arhdr.size))
- _, err = io.ReadFull(f, pkgDefBytes)
- if err != nil {
- Errorf(nil, "%s: error reading package data: %v", lib.File, err)
- return
- }
- firstEOL := bytes.IndexByte(pkgDefBytes, '\n')
- if firstEOL < 0 {
- Errorf(nil, "cannot parse package data of %s for hash generation, no newline found", lib.File)
- return
- }
- firstDoubleDollar := bytes.Index(pkgDefBytes, []byte("\n$$"))
- if firstDoubleDollar < 0 {
- Errorf(nil, "cannot parse package data of %s for hash generation, no \\n$$ found", lib.File)
- return
- }
- secondDoubleDollar := bytes.Index(pkgDefBytes[firstDoubleDollar+1:], []byte("\n$$"))
- if secondDoubleDollar < 0 {
- Errorf(nil, "cannot parse package data of %s for hash generation, only one \\n$$ found", lib.File)
- return
- }
- h.Write(pkgDefBytes[0:firstEOL])
- h.Write(pkgDefBytes[firstDoubleDollar : firstDoubleDollar+secondDoubleDollar])
- lib.Hash = hex.EncodeToString(h.Sum(nil))
-}
-
func loadobjfile(ctxt *Link, lib *sym.Library) {
pkg := objabi.PathToPrefix(lib.Pkg)
diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index a448244..4363939 100644
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -591,13 +591,13 @@
s := ldr.CreateSymForUpdate("go.link.pkghashbytes."+l.Pkg, 0)
s.SetReachable(true)
s.SetType(sym.SRODATA)
- s.SetSize(int64(len(l.Hash)))
- s.SetData([]byte(l.Hash))
+ s.SetSize(int64(len(l.Fingerprint)))
+ s.SetData(l.Fingerprint[:])
str := ldr.CreateSymForUpdate("go.link.pkghash."+l.Pkg, 0)
str.SetReachable(true)
str.SetType(sym.SRODATA)
str.AddAddr(ctxt.Arch, s.Sym())
- str.AddUint(ctxt.Arch, uint64(len(l.Hash)))
+ str.AddUint(ctxt.Arch, uint64(len(l.Fingerprint)))
}
}
@@ -698,7 +698,7 @@
// pkghashes[i].name
addgostring(ctxt, ldr, pkghashes, fmt.Sprintf("go.link.pkgname.%d", i), l.Pkg)
// pkghashes[i].linktimehash
- addgostring(ctxt, ldr, pkghashes, fmt.Sprintf("go.link.pkglinkhash.%d", i), l.Hash)
+ addgostring(ctxt, ldr, pkghashes, fmt.Sprintf("go.link.pkglinkhash.%d", i), string(l.Fingerprint[:]))
// pkghashes[i].runtimehash
hash := ldr.Lookup("go.link.pkghash."+l.Pkg, 0)
pkghashes.AddAddr(ctxt.Arch, hash)
diff --git a/src/cmd/link/internal/sym/library.go b/src/cmd/link/internal/sym/library.go
index 18e1380..7f6e63c 100644
--- a/src/cmd/link/internal/sym/library.go
+++ b/src/cmd/link/internal/sym/library.go
@@ -12,7 +12,6 @@
File string
Pkg string
Shlib string
- Hash string
Fingerprint goobj2.FingerprintType
Autolib []goobj2.ImportedPkg
Imports []*Library
