[dev.link] cmd/link/internal/loader: add Loader plt/got access methods

Add accessor methods to get at the symbol {plt,got} value for
PE symbols. Fix a bug in the loaders SetPlt/SetGot methods.

Change-Id: I975bd6b86122622b206487c8798f8290ecd25a57
Reviewed-on: https://go-review.googlesource.com/c/go/+/225199
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index e342fbe680..3b77a4bff3 100644
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -1133,24 +1133,40 @@ func (l *Loader) SetSymElfType(i Sym, et elf.SymType) {
 	}
 }
 
+// SymPlt returns the plt value for pe symbols.
+func (l *Loader) SymPlt(s Sym) int32 {
+	if v, ok := l.plt[s]; ok {
+		return v
+	}
+	return -1
+}
+
 // SetPlt sets the plt value for pe symbols.
 func (l *Loader) SetPlt(i Sym, v int32) {
 	if i >= Sym(len(l.objSyms)) || i == 0 {
 		panic("bad symbol for SetPlt")
 	}
-	if v == 0 {
+	if v == -1 {
 		delete(l.plt, i)
 	} else {
 		l.plt[i] = v
 	}
 }
 
+// SymGot returns the got value for pe symbols.
+func (l *Loader) SymGot(s Sym) int32 {
+	if v, ok := l.got[s]; ok {
+		return v
+	}
+	return -1
+}
+
 // SetGot sets the got value for pe symbols.
 func (l *Loader) SetGot(i Sym, v int32) {
 	if i >= Sym(len(l.objSyms)) || i == 0 {
 		panic("bad symbol for SetGot")
 	}
-	if v == 0 {
+	if v == -1 {
 		delete(l.got, i)
 	} else {
 		l.got[i] = v
@@ -1257,11 +1273,11 @@ func (l *Loader) SymLocalentry(i Sym) uint8 {
 	return l.localentry[i]
 }
 
-// SetSymExtname sets the "extname" attribute for a symbol.
+// SetSymLocalentry sets the "local entry" attribute for a symbol.
 func (l *Loader) SetSymLocalentry(i Sym, value uint8) {
 	// reject bad symbols
 	if i >= Sym(len(l.objSyms)) || i == 0 {
-		panic("bad symbol index in SetExtname")
+		panic("bad symbol index in SetSymLocalentry")
 	}
 	if value == 0 {
 		delete(l.localentry, i)