cmd: stop looking for __.(GO)?SYMDEF entries in archives

The Go toolchain stopped creating them before Go 1.3, so no point in
worrying about them today.

History:

- Git commit 250a091 added cmd/ar, which wrote Plan 9 __.SYMDEF
entries into archive files.

- golang.org/cl/6500117 renamed __.SYMDEF to __.GOSYMDEF.  (Notably,
the commit message suggests users need to use Go nm to read symbols,
but even back then the toolchain did nothing with __.(GO)?SYMDEF files
except skip over them.)

- golang.org/cl/42880043 added the -pack flag to cmd/gc to directly
produce archives by the Go compiler, and did not write __.GOSYMDEF
entries.

- golang.org/cl/52310044 rewrote cmd/pack in Go, and removed support
for producing __.GOSYMDEF entries.

Change-Id: I255edf40d0d3690e3447e488039fcdef73c6d6b1
Reviewed-on: https://go-review.googlesource.com/19924
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/cmd/compile/internal/gc/lex.go b/src/cmd/compile/internal/gc/lex.go
index a051214b9c682f13f53bc302df393740768ba9ec..01423000630140d2c00655d4a8cac907f8bc8daf 100644 (file)
--- a/src/cmd/compile/internal/gc/lex.go
+++ b/src/cmd/compile/internal/gc/lex.go
@@ -549,22 +549,9 @@ func skiptopkgdef(b *obj.Biobuf) bool {
                return false
        }
 
-       // symbol table may be first; skip it
-       sz := arsize(b, "__.GOSYMDEF")
-
-       if sz >= 0 {
-               obj.Bseek(b, int64(sz), 1)
-       } else {
-               obj.Bseek(b, 8, 0)
-       }
-
-       // package export block is next
-       sz = arsize(b, "__.PKGDEF")
-
-       if sz <= 0 {
-               return false
-       }
-       return true
+       // package export block should be first
+       sz := arsize(b, "__.PKGDEF")
+       return sz > 0
 }
 
 var idirs []string

diff --git a/src/cmd/internal/goobj/read.go b/src/cmd/internal/goobj/read.go
index 7fdaf557c81500a11bf63a81ebcf6efc5cdbae7b..dff6224d850355912a1de46c3aa7b490f9449801 100644 (file)
--- a/src/cmd/internal/goobj/read.go
+++ b/src/cmd/internal/goobj/read.go
@@ -530,7 +530,7 @@ func (r *objReader) parseArchive() error {
                        return errCorruptArchive
                }
                switch name {
-               case "__.SYMDEF", "__.GOSYMDEF", "__.PKGDEF":
+               case "__.PKGDEF":
                        r.skip(size)
                default:
                        oldLimit := r.limit

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index bdfa0563c3d269c659ccb628944883c5486361e7..461ebf8db1fd15bfdb61b805a1fdd24b9fc62673 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -255,10 +255,7 @@ var coutbuf struct {
        f *os.File
 }
 
-const (
-       symname = "__.GOSYMDEF"
-       pkgname = "__.PKGDEF"
-)
+const pkgname = "__.PKGDEF"
 
 var (
        // Set if we see an object compiled by the host compiler that is not
@@ -781,7 +778,7 @@ func objfile(lib *Library) {
                return
        }
 
-       /* skip over optional __.GOSYMDEF and process __.PKGDEF */
+       /* process __.PKGDEF */
        off := obj.Boffset(f)
 
        var arhdr ArHdr
@@ -792,15 +789,6 @@ func objfile(lib *Library) {
                goto out
        }
 
-       if strings.HasPrefix(arhdr.name, symname) {
-               off += l
-               l = nextar(f, off, &arhdr)
-               if l <= 0 {
-                       Diag("%s: short read on archive file symbol header", lib.File)
-                       goto out
-               }
-       }
-
        if !strings.HasPrefix(arhdr.name, pkgname) {
                Diag("%s: cannot find package header", lib.File)
                goto out
@@ -829,7 +817,7 @@ func objfile(lib *Library) {
         * the individual symbols that are unused.
         *
         * loading every object will also make it possible to
-        * load foreign objects not referenced by __.GOSYMDEF.
+        * load foreign objects not referenced by __.PKGDEF.
         */
        for {
                l = nextar(f, off, &arhdr)

diff --git a/src/go/internal/gcimporter/exportdata.go b/src/go/internal/gcimporter/exportdata.go
index 18bea415ae49695174ab95be4dc2dec72cacf897..4c0d2fe7616588859cd4792017341909242bc462 100644 (file)
--- a/src/go/internal/gcimporter/exportdata.go
+++ b/src/go/internal/gcimporter/exportdata.go
@@ -52,33 +52,11 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
        if string(line) == "!<arch>\n" {
                // Archive file. Scan to __.PKGDEF.
                var name string
-               var size int
-               if name, size, err = readGopackHeader(r); err != nil {
+               if name, _, err = readGopackHeader(r); err != nil {
                        return
                }
 
-               // Optional leading __.GOSYMDEF or __.SYMDEF.
-               // Read and discard.
-               if name == "__.SYMDEF" || name == "__.GOSYMDEF" {
-                       const block = 4096
-                       tmp := make([]byte, block)
-                       for size > 0 {
-                               n := size
-                               if n > block {
-                                       n = block
-                               }
-                               if _, err = io.ReadFull(r, tmp[:n]); err != nil {
-                                       return
-                               }
-                               size -= n
-                       }
-
-                       if name, _, err = readGopackHeader(r); err != nil {
-                               return
-                       }
-               }
-
-               // First real entry should be __.PKGDEF.
+               // First entry should be __.PKGDEF.
                if name != "__.PKGDEF" {
                        err = errors.New("go archive is missing __.PKGDEF")
                        return