Implement the API backend and minor tweaks for the native one

Makefile

@@ -1,5 +1,7 @@
 all:
 	go test
+
+ex:
 	cd example ; go run example.go
 
 sync:

api.go

@@ -0,0 +1,48 @@
+// radare - LGPL - Copyright 2021 - pancake
+
+package r2pipe
+
+// #cgo CFLAGS: -I/usr/local/include/libr
+// #cgo CFLAGS: -I/usr/local/include/libr/sdb
+// #cgo LDFLAGS: -L/usr/local/lib -lr_core
+// #include <stdio.h>
+// #include <stdlib.h>
+// extern void r_core_free(void *);
+// extern void *r_core_new(void);
+// extern char *r_core_cmd_str(void*, const char *);
+//
+import "C"
+
+import (
+	"unsafe"
+)
+
+
+func (r2p *Pipe) ApiCmd(cmd string) (string, error) {
+	res := C.r_core_cmd_str(r2p.Core, C.CString(cmd))
+	return C.GoString(res), nil
+}
+
+func (r2p *Pipe) ApiClose() error {
+	C.r_core_free(unsafe.Pointer(r2p.Core))
+	r2p.Core = nil
+	return nil
+}
+
+func NewApiPipe(file string) (*Pipe, error) {
+	r2 := C.r_core_new()
+	r2p := &Pipe{
+		File: file,
+		Core: r2,
+		cmd: func(r2p *Pipe, cmd string) (string, error) {
+			return r2p.ApiCmd(cmd)
+		},
+		close: func(r2p *Pipe) error {
+			return r2p.ApiClose()
+		},
+	}
+	if file != "" {
+		r2p.ApiCmd("o " + file)
+	}
+	return r2p, nil
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/radareorg/r2pipe-go
+
+go 1.13

native.go

@@ -2,22 +2,23 @@
 
 package r2pipe
 
+//#cgo linux LDFLAGS: -ldl
 //#include <stdio.h>
 //#include <dlfcn.h>
 // #include <stdlib.h>
-// void *r_core_new(void *f) {
+// void *gor_core_new(void *f) {
 // 	void *(*rcn)();
 // 	rcn = (void *(*)())f;
 // 	return rcn();
 // }
 //
-// void r_core_free(void *f, void *arg) {
+// void gor_core_free(void *f, void *arg) {
 // 	void (*fr)(void *);
 // 	fr = (void (*)(void *))f;
 // 	fr(arg);
 // }
 //
-// char *r_core_cmd_str(void *f, void *arg, char *arg2) {
+// char *gor_core_cmd_str(void *f, void *arg, char *arg2) {
 // 	char *(*cmdstr)(void *, char *);
 // 	cmdstr = (char *(*)(void *, char *))f;
 // 	return cmdstr(arg, arg2);
@@ -25,12 +26,14 @@ package r2pipe
 import "C"
 
 import (
+	"fmt"
 	"errors"
 	"runtime"
 	"unsafe"
 )
 
-type Ptr = *struct{}
+type Ptr = unsafe.Pointer
+// *struct{}
 
 var (
 	lib            Ptr = nil
@@ -63,7 +66,7 @@ func dlOpen(path string) (*DL, error) {
 	ret.name = path
 	C.free(unsafe.Pointer(cpath))
 	if ret.handle == nil {
-		return nil, errors.New("Failed to open dl")
+		return nil, errors.New(fmt.Sprintf("Failed to open %s", path))
 	}
 	return &ret, nil
 }
@@ -92,17 +95,17 @@ func NativeLoad() error {
 	}
 	handle, _ := dlSym(lib, "r_core_new")
 	r_core_new = func() Ptr {
-		a := (Ptr)(C.r_core_new(handle))
+		a := (Ptr)(C.gor_core_new(handle))
 		return a
 	}
 	handle, _ = dlSym(lib, "r_core_free")
 	r_core_free = func(p Ptr) {
-		C.r_core_free(handle, unsafe.Pointer(p))
+		C.gor_core_free(handle, unsafe.Pointer(p))
 	}
 	handle, _ = dlSym(lib, "r_core_cmd_str")
 	r_core_cmd_str = func(p Ptr, s string) string {
 		a := C.CString(s)
-		b := C.r_core_cmd_str(handle, unsafe.Pointer(p), a)
+		b := C.gor_core_cmd_str(handle, unsafe.Pointer(p), a)
 		C.free(unsafe.Pointer(a))
 		return C.GoString(b)
 	}

r2pipe.go

@@ -34,6 +34,7 @@ package r2pipe
 
 import (
 	"bufio"
+	"unsafe"
 	"bytes"
 	"encoding/json"
 	"fmt"
@@ -51,7 +52,7 @@ type Pipe struct {
 	r2cmd  *exec.Cmd
 	stdin  io.WriteCloser
 	stdout io.ReadCloser
-	Core   *struct{}
+	Core   unsafe.Pointer
 	cmd    CmdDelegate
 	close  CloseDelegate
 }