debug/pe: support PE files which contain no symbol table (if NumberOfSymbols is equal...

No longer assume that e_lfanew (in the IMAGE_DOS_HEADER strcuture) is always one byte. It is now regarded as a 4 byte uint32.

Fixes #4177.

R=golang-dev, alex.brainman, dave, minux.ma
CC=golang-dev
https://golang.org/cl/6587048

diff --git a/src/pkg/debug/pe/file.go b/src/pkg/debug/pe/file.go
index c857eca7ce246fbc31c5011dca7de272250109ae..f521566efa7abb5a8c33e172f89afb2618af0b3f 100644 (file)
--- a/src/pkg/debug/pe/file.go
+++ b/src/pkg/debug/pe/file.go
@@ -131,12 +131,13 @@ func NewFile(r io.ReaderAt) (*File, error) {
        }
        var base int64
        if dosheader[0] == 'M' && dosheader[1] == 'Z' {
+               signoff := int64(binary.LittleEndian.Uint32(dosheader[0x3c:]))
                var sign [4]byte
-               r.ReadAt(sign[0:], int64(dosheader[0x3c]))
+               r.ReadAt(sign[:], signoff)
                if !(sign[0] == 'P' && sign[1] == 'E' && sign[2] == 0 && sign[3] == 0) {
                        return nil, errors.New("Invalid PE File Format.")
                }
-               base = int64(dosheader[0x3c]) + 4
+               base = signoff + 4
        } else {
                base = int64(0)
        }
@@ -148,45 +149,48 @@ func NewFile(r io.ReaderAt) (*File, error) {
                return nil, errors.New("Invalid PE File Format.")
        }
 
-       // Get COFF string table, which is located at the end of the COFF symbol table.
-       sr.Seek(int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols), os.SEEK_SET)
-       var l uint32
-       if err := binary.Read(sr, binary.LittleEndian, &l); err != nil {
-               return nil, err
-       }
-       ss := make([]byte, l)
-       if _, err := r.ReadAt(ss, int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols)); err != nil {
-               return nil, err
-       }
-
-       // Process COFF symbol table.
-       sr.Seek(int64(f.FileHeader.PointerToSymbolTable), os.SEEK_SET)
-       aux := uint8(0)
-       for i := 0; i < int(f.FileHeader.NumberOfSymbols); i++ {
-               cs := new(COFFSymbol)
-               if err := binary.Read(sr, binary.LittleEndian, cs); err != nil {
+       var ss []byte
+       if f.FileHeader.NumberOfSymbols > 0 {
+               // Get COFF string table, which is located at the end of the COFF symbol table.
+               sr.Seek(int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols), os.SEEK_SET)
+               var l uint32
+               if err := binary.Read(sr, binary.LittleEndian, &l); err != nil {
                        return nil, err
                }
-               if aux > 0 {
-                       aux--
-                       continue
-               }
-               var name string
-               if cs.Name[0] == 0 && cs.Name[1] == 0 && cs.Name[2] == 0 && cs.Name[3] == 0 {
-                       si := int(binary.LittleEndian.Uint32(cs.Name[4:]))
-                       name, _ = getString(ss, si)
-               } else {
-                       name = cstring(cs.Name[:])
+               ss = make([]byte, l)
+               if _, err := r.ReadAt(ss, int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols)); err != nil {
+                       return nil, err
                }
-               aux = cs.NumberOfAuxSymbols
-               s := &Symbol{
-                       Name:          name,
-                       Value:         cs.Value,
-                       SectionNumber: cs.SectionNumber,
-                       Type:          cs.Type,
-                       StorageClass:  cs.StorageClass,
+
+               // Process COFF symbol table.
+               sr.Seek(int64(f.FileHeader.PointerToSymbolTable), os.SEEK_SET)
+               aux := uint8(0)
+               for i := 0; i < int(f.FileHeader.NumberOfSymbols); i++ {
+                       cs := new(COFFSymbol)
+                       if err := binary.Read(sr, binary.LittleEndian, cs); err != nil {
+                               return nil, err
+                       }
+                       if aux > 0 {
+                               aux--
+                               continue
+                       }
+                       var name string
+                       if cs.Name[0] == 0 && cs.Name[1] == 0 && cs.Name[2] == 0 && cs.Name[3] == 0 {
+                               si := int(binary.LittleEndian.Uint32(cs.Name[4:]))
+                               name, _ = getString(ss, si)
+                       } else {
+                               name = cstring(cs.Name[:])
+                       }
+                       aux = cs.NumberOfAuxSymbols
+                       s := &Symbol{
+                               Name:          name,
+                               Value:         cs.Value,
+                               SectionNumber: cs.SectionNumber,
+                               Type:          cs.Type,
+                               StorageClass:  cs.StorageClass,
+                       }
+                       f.Symbols = append(f.Symbols, s)
                }
-               f.Symbols = append(f.Symbols, s)
        }
 
        // Process sections.