librclone: factor into gomobile and internal implementation #4891

This was needed because gomobile can't use a main package wheras this
is required to make a normal shared C library.

librclone/README.md

@@ -1,7 +1,13 @@
 # librclone
 
 This directory contains code to build rclone as a C library and the
-shims for accessing rclone from C.
+shims for accessing rclone from C and other languages.
+
+**Note** for the moment, the interfaces defined here are experimental
+and may change in the future. Eventually they will stabilse and this
+notice will be removed.
+
+## C
 
 The shims are a thin wrapper over the rclone RPC.
 
@@ -18,7 +24,7 @@ be `#include`d in `C` programs wishing to use the library.
 
 The library will depend on `libdl` and `libpthread`.
 
-## Documentation
+### Documentation
 
 For documentation see the Go documentation for:
 
@@ -26,6 +32,15 @@ For documentation see the Go documentation for:
 - [RcloneFinalize](https://pkg.go.dev/github.com/rclone/rclone/librclone#RcloneFinalize)
 - [RcloneRPC](https://pkg.go.dev/github.com/rclone/rclone/librclone#RcloneRPC)
 
-## C Example
+### C Example
 
 There is an example program `ctest.c` with Makefile in the `ctest` subdirectory
+
+## gomobile
+
+The gomobile subdirectory contains the equivalent of the C binding but
+suitable for using with gomobile using something like this.
+
+    gomobile bind -v -target=android github.com/rclone/rclone/librclone/gomobile
+
+

librclone/gomobile/gomobile.go

@@ -0,0 +1,40 @@
+// Package gomobile exports shims for gomobile use
+package gomobile
+
+import (
+	"github.com/rclone/rclone/librclone/librclone"
+
+	_ "github.com/rclone/rclone/backend/all" // import all backends
+	_ "github.com/rclone/rclone/lib/plugin"  // import plugins
+)
+
+// RcloneInitialize initializes rclone as a library
+func RcloneInitialize() {
+	librclone.Initialize()
+}
+
+// RcloneFinalize finalizes the library
+func RcloneFinalize() {
+	librclone.Finalize()
+}
+
+// RcloneRPCResult is returned from RcloneRPC
+//
+//   Output will be returned as a serialized JSON object
+//   Status is a HTTP status return (200=OK anything else fail)
+type RcloneRPCResult struct {
+	Output string
+	Status int
+}
+
+// RcloneRPC has an interface optimised for gomobile, in particular
+// the function signature is valid under gobind rules.
+//
+// https://pkg.go.dev/golang.org/x/mobile/cmd/gobind#hdr-Type_restrictions
+func RcloneRPC(method string, input string) (result *RcloneRPCResult) { //nolint:deadcode
+	output, status := librclone.RPC(method, input)
+	return &RcloneRPCResult{
+		Output: output,
+		Status: status,
+	}
+}

librclone/librclone.go

@@ -28,20 +28,7 @@ struct RcloneRPCResult {
 import "C"
 
 import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"net/http"
-	"runtime"
-	"strings"
-
-	"github.com/pkg/errors"
-	"github.com/rclone/rclone/fs"
-	"github.com/rclone/rclone/fs/accounting"
-	"github.com/rclone/rclone/fs/config/configfile"
-	"github.com/rclone/rclone/fs/log"
-	"github.com/rclone/rclone/fs/rc"
-	"github.com/rclone/rclone/fs/rc/jobs"
+	"github.com/rclone/rclone/librclone/librclone"
 
 	_ "github.com/rclone/rclone/backend/all" // import all backends
 	_ "github.com/rclone/rclone/lib/plugin"  // import plugins
@@ -51,28 +38,14 @@ import (
 //
 //export RcloneInitialize
 func RcloneInitialize() {
-	// A subset of initialisation copied from cmd.go
-	// Note that we don't want to pull in anything which depends on pflags
-
-	ctx := context.Background()
-
-	// Start the logger
-	log.InitLogging()
-
-	// Load the config - this may need to be configurable
-	configfile.Install()
-
-	// Start accounting
-	accounting.Start(ctx)
+	librclone.Initialize()
 }
 
 // RcloneFinalize finalizes the library
 //
 //export RcloneFinalize
 func RcloneFinalize() {
-	// TODO: how to clean up? what happens when rcserver terminates?
-	// what about unfinished async jobs?
-	runtime.GC()
+	librclone.Finalize()
 }
 
 // RcloneRPCResult is returned from RcloneRPC
@@ -98,103 +71,11 @@ type RcloneRPCResult struct { //nolint:deadcode
 //
 //export RcloneRPC
 func RcloneRPC(method *C.char, input *C.char) (result C.struct_RcloneRPCResult) { //nolint:golint
-	output, status := callFunctionJSON(C.GoString(method), C.GoString(input))
+	output, status := librclone.RPC(C.GoString(method), C.GoString(input))
 	result.Output = C.CString(output)
 	result.Status = C.int(status)
 	return result
 }
 
-// RcloneMobileRPCResult is returned from RcloneMobileRPC
-//
-//   Output will be returned as a serialized JSON object
-//   Status is a HTTP status return (200=OK anything else fail)
-type RcloneMobileRPCResult struct {
-	Output string
-	Status int
-}
-
-// RcloneMobileRPC works the same as RcloneRPC but has an interface
-// optimised for gomobile, in particular the function signature is
-// valid under gobind rules.
-//
-// https://pkg.go.dev/golang.org/x/mobile/cmd/gobind#hdr-Type_restrictions
-func RcloneMobileRPC(method string, input string) (result RcloneMobileRPCResult) { //nolint:deadcode
-	output, status := callFunctionJSON(method, input)
-	result.Output = output
-	result.Status = status
-	return result
-}
-
-// writeError returns a formatted error string and the status passed in
-func writeError(path string, in rc.Params, err error, status int) (string, int) {
-	fs.Errorf(nil, "rc: %q: error: %v", path, err)
-	params, status := rc.Error(path, in, err, status)
-	var w strings.Builder
-	err = rc.WriteJSON(&w, params)
-	if err != nil {
-		// ultimate fallback error
-		fs.Errorf(nil, "writeError: failed to write JSON output from %#v: %v", in, err)
-		status = http.StatusInternalServerError
-		w.Reset()
-		fmt.Fprintf(&w, `{
-	"error": %q,
-	"path": %q,
-	"status": %d
-}`, err, path, status)
-
-	}
-	return w.String(), status
-}
-
-// operations/uploadfile and core/command are not supported as they need request or response object
-// modified from handlePost in rcserver.go
-// call a rc function using JSON to input parameters and output the resulted JSON
-func callFunctionJSON(method string, input string) (output string, status int) {
-	// create a buffer to capture the output
-	in := make(rc.Params)
-	err := json.NewDecoder(strings.NewReader(input)).Decode(&in)
-	if err != nil {
-		return writeError(method, in, errors.Wrap(err, "failed to read input JSON"), http.StatusBadRequest)
-	}
-
-	// Find the call
-	call := rc.Calls.Get(method)
-	if call == nil {
-		return writeError(method, in, errors.Errorf("couldn't find method %q", method), http.StatusNotFound)
-	}
-
-	// TODO: handle these cases
-	if call.NeedsRequest {
-		return writeError(method, in, errors.Errorf("method %q needs request, not supported", method), http.StatusNotFound)
-		// Add the request to RC
-		//in["_request"] = r
-	}
-	if call.NeedsResponse {
-		return writeError(method, in, errors.Errorf("method %q need response, not supported", method), http.StatusNotFound)
-		//in["_response"] = w
-	}
-
-	fs.Debugf(nil, "rc: %q: with parameters %+v", method, in)
-
-	_, out, err := jobs.NewJob(context.Background(), call.Fn, in)
-	if err != nil {
-		return writeError(method, in, err, http.StatusInternalServerError)
-	}
-	if out == nil {
-		out = make(rc.Params)
-	}
-
-	fs.Debugf(nil, "rc: %q: reply %+v: %v", method, out, err)
-
-	var w strings.Builder
-	err = rc.WriteJSON(&w, out)
-	if err != nil {
-		fs.Errorf(nil, "rc: failed to write JSON output: %v", err)
-		return writeError(method, in, err, http.StatusInternalServerError)
-	}
-
-	return w.String(), http.StatusOK
-}
-
 // do nothing here - necessary for building into a C library
 func main() {}

librclone/librclone/librclone.go

@@ -0,0 +1,124 @@
+// Package librclone exports shims for library use
+//
+// This is the internal implementation which is used for C and
+// Gomobile libaries which need slightly different export styles.
+//
+// The shims are a thin wrapper over the rclone RPC.
+package librclone
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"runtime"
+	"strings"
+
+	"github.com/pkg/errors"
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/accounting"
+	"github.com/rclone/rclone/fs/config/configfile"
+	"github.com/rclone/rclone/fs/log"
+	"github.com/rclone/rclone/fs/rc"
+	"github.com/rclone/rclone/fs/rc/jobs"
+)
+
+// Initialize initializes rclone as a library
+//
+//export Initialize
+func Initialize() {
+	// A subset of initialisation copied from cmd.go
+	// Note that we don't want to pull in anything which depends on pflags
+
+	ctx := context.Background()
+
+	// Start the logger
+	log.InitLogging()
+
+	// Load the config - this may need to be configurable
+	configfile.Install()
+
+	// Start accounting
+	accounting.Start(ctx)
+}
+
+// Finalize finalizes the library
+func Finalize() {
+	// TODO: how to clean up? what happens when rcserver terminates?
+	// what about unfinished async jobs?
+	runtime.GC()
+}
+
+// writeError returns a formatted error string and the status passed in
+func writeError(path string, in rc.Params, err error, status int) (string, int) {
+	fs.Errorf(nil, "rc: %q: error: %v", path, err)
+	params, status := rc.Error(path, in, err, status)
+	var w strings.Builder
+	err = rc.WriteJSON(&w, params)
+	if err != nil {
+		// ultimate fallback error
+		fs.Errorf(nil, "writeError: failed to write JSON output from %#v: %v", in, err)
+		status = http.StatusInternalServerError
+		w.Reset()
+		fmt.Fprintf(&w, `{
+	"error": %q,
+	"path": %q,
+	"status": %d
+}`, err, path, status)
+
+	}
+	return w.String(), status
+}
+
+// RPC runs a transaction over the RC
+//
+// Calling an rc function using JSON to input parameters and output the resulted JSON
+//
+// operations/uploadfile and core/command are not supported as they need request or response object
+// modified from handlePost in rcserver.go
+func RPC(method string, input string) (output string, status int) {
+	// create a buffer to capture the output
+	in := make(rc.Params)
+	err := json.NewDecoder(strings.NewReader(input)).Decode(&in)
+	if err != nil {
+		return writeError(method, in, errors.Wrap(err, "failed to read input JSON"), http.StatusBadRequest)
+	}
+
+	// Find the call
+	call := rc.Calls.Get(method)
+	if call == nil {
+		return writeError(method, in, errors.Errorf("couldn't find method %q", method), http.StatusNotFound)
+	}
+
+	// TODO: handle these cases
+	if call.NeedsRequest {
+		return writeError(method, in, errors.Errorf("method %q needs request, not supported", method), http.StatusNotFound)
+		// Add the request to RC
+		//in["_request"] = r
+	}
+	if call.NeedsResponse {
+		return writeError(method, in, errors.Errorf("method %q need response, not supported", method), http.StatusNotFound)
+		//in["_response"] = w
+	}
+
+	fs.Debugf(nil, "rc: %q: with parameters %+v", method, in)
+
+	_, out, err := jobs.NewJob(context.Background(), call.Fn, in)
+	if err != nil {
+		return writeError(method, in, err, http.StatusInternalServerError)
+	}
+	if out == nil {
+		out = make(rc.Params)
+	}
+
+	fs.Debugf(nil, "rc: %q: reply %+v: %v", method, out, err)
+
+	var w strings.Builder
+	err = rc.WriteJSON(&w, out)
+	if err != nil {
+		fs.Errorf(nil, "rc: failed to write JSON output: %v", err)
+		return writeError(method, in, err, http.StatusInternalServerError)
+	}
+
+	return w.String(), http.StatusOK
+}