fix #35, add support for package init

dymcode.go

@@ -76,6 +76,7 @@ type Linker struct {
 	pclntable    []byte
 	pcfunc       []findfuncbucket
 	_func        []_func
+	initFuncs    []string
 	Arch         string
 }
 
@@ -133,6 +134,12 @@ func (linker *Linker) addSymbols() error {
 				return err
 			}
 		}
+		if objSym.Kind == SNOPTRDATA {
+			_, err := linker.addSymbol(objSym.Name)
+			if err != nil {
+				return err
+			}
+		}
 	}
 	return nil
 }
@@ -319,6 +326,9 @@ func (linker *Linker) addSymbolMap(symPtr map[string]uintptr, codeModule *CodeMo
 				symbolMap[name] = uintptr(linker.symMap[name].Offset + segment.dataBase)
 			} else {
 				symbolMap[name] = symPtr[name]
+				if isMainInitFunc(name) {
+					symbolMap[name] = uintptr(linker.symMap[name].Offset + segment.dataBase)
+				}
 			}
 		}
 	}
@@ -613,7 +623,9 @@ func Load(linker *Linker, symPtr map[string]uintptr) (codeModule *CodeModule, er
 	if symbolMap, err = linker.addSymbolMap(symPtr, codeModule); err == nil {
 		if err = linker.relocate(codeModule, symbolMap); err == nil {
 			if err = linker.buildModule(codeModule, symbolMap); err == nil {
-				return codeModule, err
+				if err = linker.doInitialize(codeModule, symbolMap); err == nil {
+					return codeModule, err
+				}
 			}
 		}
 	}

init.1.13.go

@@ -0,0 +1,37 @@
+// +build go1.12
+// +build !go1.18
+
+package goloader
+
+import (
+	"unsafe"
+)
+
+const (
+	_MainInitTask   = "main..inittask"
+	_InitTaskSuffix = "..inittask"
+)
+
+func getInitFuncName(packagename string) string {
+	return packagename + _InitTaskSuffix
+}
+
+func isMainInitFunc(name string) bool {
+	if name == _MainInitTask {
+		return true
+	}
+	return false
+}
+
+// doInit is defined in package runtime
+//go:linkname doInit runtime.doInit
+func doInit(t unsafe.Pointer) // t should be a *runtime.initTask
+
+func (linker *Linker) doInitialize(codeModule *CodeModule, symbolMap map[string]uintptr) error {
+	for _, name := range linker.initFuncs {
+		if funcPtr, ok := symbolMap[name]; ok {
+			doInit(adduintptr(funcPtr, 0))
+		}
+	}
+	return nil
+}

init.1.8.go

@@ -0,0 +1,35 @@
+// +build go1.8
+// +build !go1.13
+
+package goloader
+
+import (
+	"unsafe"
+)
+
+const (
+	_MainInitTask   = "main.init"
+	_InitTaskSuffix = ".init"
+)
+
+func getInitFuncName(packagename string) string {
+	return packagename + _InitTaskSuffix
+}
+
+func isMainInitFunc(name string) bool {
+	if name == _MainInitTask {
+		return true
+	}
+	return false
+}
+
+func (linker *Linker) doInitialize(codeModule *CodeModule, symbolMap map[string]uintptr) error {
+	for _, name := range linker.initFuncs {
+		if funcPtr, ok := codeModule.Syms[name]; ok {
+			funcPtrContainer := (uintptr)(unsafe.Pointer(&funcPtr))
+			runFunc := *(*func())(unsafe.Pointer(&funcPtrContainer))
+			runFunc()
+		}
+	}
+	return nil
+}

readobj.go

@@ -55,6 +55,7 @@ func readObj(pkg *Pkg, linker *Linker) error {
 	for _, sym := range pkg.Syms {
 		linker.objsymbolMap[sym.Name] = sym
 	}
+	linker.initFuncs = append(linker.initFuncs, getInitFuncName(pkg.PkgPath))
 	return nil
 }