proc,proc/native,proc/gdbserial: initial plugin support (go-delve#1413)

Adds initial support for plugins, this is only the code needed to keep
track of loaded plugins on linux (both native and gdbserial backend).

It does not actually implement support for debugging plugins on linux.

Updates go-delve#865

Documentation/cli/README.md

@@ -24,6 +24,7 @@ Command | Description
 [goroutine](#goroutine) | Shows or changes current goroutine
 [goroutines](#goroutines) | List program goroutines.
 [help](#help) | Prints the help message.
+[libraries](#libraries) | List loaded dynamic libraries
 [list](#list) | Show source code.
 [locals](#locals) | Print local variables.
 [next](#next) | Step over to next source line.
@@ -266,6 +267,10 @@ Type "help" followed by the name of a command for more information about it.
 
 Aliases: h
 
+## libraries
+List loaded dynamic libraries
+
+
 ## list
 Show source code.
 

_fixtures/internal/pluginsupport/pluginsupport.go

@@ -0,0 +1,9 @@
+package pluginsupport
+
+type Something interface {
+	Callback(int) int
+}
+
+type SomethingElse interface {
+	Callback2(int, int) float64
+}

_fixtures/plugin1/plugin1.go

@@ -0,0 +1,13 @@
+package main
+
+import "fmt"
+
+func Fn1() string {
+	return "hello"
+}
+
+func HelloFn(n int) string {
+	n++
+	s := fmt.Sprintf("hello%d", n)
+	return s
+}

_fixtures/plugin2/plugin2.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"github.com/go-delve/delve/_fixtures/internal/pluginsupport"
+)
+
+func Fn2() string {
+	return "world"
+}
+
+type asomethingelse struct {
+	x, y float64
+}
+
+func (a *asomethingelse) Callback2(n, m int) float64 {
+	r := a.x + 2*a.y
+	r += float64(n) / float64(m)
+	return r
+}
+
+func TypesTest(s pluginsupport.Something) pluginsupport.SomethingElse {
+	if A != nil {
+		aIsNotNil(fmt.Sprintf("%s", A))
+	}
+	return &asomethingelse{1.0, float64(s.Callback(2))}
+}
+
+var A interface{}
+
+func aIsNotNil(str string) {
+	// nothing here
+}

_fixtures/plugintest.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"plugin"
+	"runtime"
+)
+
+func must(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	plug1, err := plugin.Open(os.Args[1])
+	must(err)
+
+	runtime.Breakpoint()
+
+	plug2, err := plugin.Open(os.Args[2])
+	must(err)
+
+	runtime.Breakpoint()
+
+	fn1, err := plug1.Lookup("Fn1")
+	must(err)
+	fn2, err := plug2.Lookup("Fn2")
+	must(err)
+
+	a := fn1.(func() string)()
+	b := fn2.(func() string)()
+
+	fmt.Println(plug1, plug2, fn1, fn2, a, b)
+}

_fixtures/plugintest2.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+	"github.com/go-delve/delve/_fixtures/internal/pluginsupport"
+	"os"
+	"plugin"
+)
+
+type asomething struct {
+	n int
+}
+
+func (a *asomething) Callback(n int) int {
+	return a.n + n
+}
+
+func (a *asomething) String() string {
+	return "success"
+}
+
+var ExeGlobal = &asomething{2}
+
+func must(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	plug1, err := plugin.Open(os.Args[1])
+	must(err)
+	plug2, err := plugin.Open(os.Args[2])
+	must(err)
+	fn1iface, err := plug1.Lookup("HelloFn")
+	must(err)
+	fn2iface, err := plug2.Lookup("TypesTest")
+	must(err)
+	fn1 := fn1iface.(func(int) string)
+	fn2 := fn2iface.(func(pluginsupport.Something) pluginsupport.SomethingElse)
+	a := fn1(3)
+	b := fn2(&asomething{2})
+	fmt.Println(a, b, ExeGlobal)
+}

pkg/proc/bininfo.go

@@ -26,7 +26,8 @@ import (
 	"github.com/go-delve/delve/pkg/goversion"
 )
 
-// BinaryInfo holds information on the binary being executed.
+// BinaryInfo holds information on the binaries being executed (this
+// includes both the executable and also any loaded libraries).
 type BinaryInfo struct {
 	// Path on disk of the binary being executed.
 	Path string
@@ -43,6 +44,12 @@ type BinaryInfo struct {
 	// LookupFunc maps function names to a description of the function.
 	LookupFunc map[string]*Function
 
+	// Images is a list of loaded shared libraries (also known as
+	// shared objects on linux or DLLs on windws).
+	Images []*Image
+
+	ElfDynamicSection ElfDynamicSection
+
 	lastModified time.Time // Time the executable of this process was last modified
 
 	closer         io.Closer
@@ -289,6 +296,12 @@ type buildIDHeader struct {
 	Type   uint32
 }
 
+// ElfDynamicSection describes the .dynamic section of an ELF executable.
+type ElfDynamicSection struct {
+	Addr uint64 // relocated address of where the .dynamic section is mapped in memory
+	Size uint64 // size of the .dynamic section of the executable
+}
+
 // NewBinaryInfo returns an initialized but unloaded BinaryInfo struct.
 func NewBinaryInfo(goos, goarch string) *BinaryInfo {
 	r := &BinaryInfo{GOOS: goos, nameOfRuntimeType: make(map[uintptr]nameOfRuntimeTypeEntry), typeCache: make(map[dwarf.Offset]godwarf.Type)}
@@ -412,6 +425,26 @@ func (bi *BinaryInfo) PCToFunc(pc uint64) *Function {
 	return nil
 }
 
+// Image represents a loaded library file (shared object on linux, DLL on windows).
+type Image struct {
+	Path string
+	addr uint64
+}
+
+// AddImage adds the specified image to bi.
+func (bi *BinaryInfo) AddImage(path string, addr uint64) {
+	if !strings.HasPrefix(path, "/") {
+		return
+	}
+	for _, image := range bi.Images {
+		if image.Path == path && image.addr == addr {
+			return
+		}
+	}
+	//TODO(aarzilli): actually load informations about the image here
+	bi.Images = append(bi.Images, &Image{Path: path, addr: addr})
+}
+
 // Close closes all internal readers.
 func (bi *BinaryInfo) Close() error {
 	if bi.sepDebugCloser != nil {
@@ -671,6 +704,11 @@ func (bi *BinaryInfo) LoadBinaryInfoElf(path string, entryPoint uint64, debugInf
 		}
 	}
 
+	if dynsec := elfFile.Section(".dynamic"); dynsec != nil {
+		bi.ElfDynamicSection.Addr = dynsec.Addr + bi.staticBase
+		bi.ElfDynamicSection.Size = dynsec.Size
+	}
+
 	dwarfFile := elfFile
 
 	bi.dwarf, err = elfFile.DWARF()

pkg/proc/gdbserial/gdbserver.go

@@ -702,6 +702,12 @@ continueLoop:
 		return nil, err
 	}
 
+	if p.BinInfo().GOOS == "linux" {
+		if err := linutil.ElfUpdateSharedObjects(p); err != nil {
+			return nil, err
+		}
+	}
+
 	if err := p.setCurrentBreakpoints(); err != nil {
 		return nil, err
 	}