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.
This commit is contained in:
Nick Craig-Wood
parent
62bf63d36f
commit
ba09ee18bb
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@ -1,7 +1,13 @@
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# librclone
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This directory contains code to build rclone as a C library and the
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shims for accessing rclone from C.
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shims for accessing rclone from C and other languages.
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**Note** for the moment, the interfaces defined here are experimental
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and may change in the future. Eventually they will stabilse and this
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notice will be removed.
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## C
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The shims are a thin wrapper over the rclone RPC.
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@ -18,7 +24,7 @@ be `#include`d in `C` programs wishing to use the library.
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The library will depend on `libdl` and `libpthread`.
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## Documentation
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### Documentation
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For documentation see the Go documentation for:
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@ -26,6 +32,15 @@ For documentation see the Go documentation for:
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- [RcloneFinalize](https://pkg.go.dev/github.com/rclone/rclone/librclone#RcloneFinalize)
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- [RcloneRPC](https://pkg.go.dev/github.com/rclone/rclone/librclone#RcloneRPC)
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## C Example
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### C Example
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There is an example program `ctest.c` with Makefile in the `ctest` subdirectory
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## gomobile
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The gomobile subdirectory contains the equivalent of the C binding but
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suitable for using with gomobile using something like this.
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gomobile bind -v -target=android github.com/rclone/rclone/librclone/gomobile
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@ -0,0 +1,40 @@
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// Package gomobile exports shims for gomobile use
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package gomobile
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import (
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"github.com/rclone/rclone/librclone/librclone"
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_ "github.com/rclone/rclone/backend/all" // import all backends
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_ "github.com/rclone/rclone/lib/plugin" // import plugins
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)
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// RcloneInitialize initializes rclone as a library
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func RcloneInitialize() {
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librclone.Initialize()
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}
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// RcloneFinalize finalizes the library
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func RcloneFinalize() {
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librclone.Finalize()
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}
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// RcloneRPCResult is returned from RcloneRPC
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//
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// Output will be returned as a serialized JSON object
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// Status is a HTTP status return (200=OK anything else fail)
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type RcloneRPCResult struct {
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Output string
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Status int
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}
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// RcloneRPC has an interface optimised for gomobile, in particular
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// the function signature is valid under gobind rules.
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//
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// https://pkg.go.dev/golang.org/x/mobile/cmd/gobind#hdr-Type_restrictions
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func RcloneRPC(method string, input string) (result *RcloneRPCResult) { //nolint:deadcode
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output, status := librclone.RPC(method, input)
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return &RcloneRPCResult{
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Output: output,
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Status: status,
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}
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}
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@ -28,20 +28,7 @@ struct RcloneRPCResult {
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import "C"
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"runtime"
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"strings"
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"github.com/pkg/errors"
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"github.com/rclone/rclone/fs"
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"github.com/rclone/rclone/fs/accounting"
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"github.com/rclone/rclone/fs/config/configfile"
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"github.com/rclone/rclone/fs/log"
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"github.com/rclone/rclone/fs/rc"
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"github.com/rclone/rclone/fs/rc/jobs"
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"github.com/rclone/rclone/librclone/librclone"
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_ "github.com/rclone/rclone/backend/all" // import all backends
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_ "github.com/rclone/rclone/lib/plugin" // import plugins
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@ -51,28 +38,14 @@ import (
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//
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//export RcloneInitialize
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func RcloneInitialize() {
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// A subset of initialisation copied from cmd.go
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// Note that we don't want to pull in anything which depends on pflags
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ctx := context.Background()
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// Start the logger
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log.InitLogging()
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// Load the config - this may need to be configurable
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configfile.Install()
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// Start accounting
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accounting.Start(ctx)
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librclone.Initialize()
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}
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// RcloneFinalize finalizes the library
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//
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//export RcloneFinalize
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func RcloneFinalize() {
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// TODO: how to clean up? what happens when rcserver terminates?
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// what about unfinished async jobs?
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runtime.GC()
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librclone.Finalize()
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}
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// RcloneRPCResult is returned from RcloneRPC
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@ -98,103 +71,11 @@ type RcloneRPCResult struct { //nolint:deadcode
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//
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//export RcloneRPC
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func RcloneRPC(method *C.char, input *C.char) (result C.struct_RcloneRPCResult) { //nolint:golint
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output, status := callFunctionJSON(C.GoString(method), C.GoString(input))
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output, status := librclone.RPC(C.GoString(method), C.GoString(input))
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result.Output = C.CString(output)
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result.Status = C.int(status)
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return result
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}
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// RcloneMobileRPCResult is returned from RcloneMobileRPC
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//
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// Output will be returned as a serialized JSON object
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// Status is a HTTP status return (200=OK anything else fail)
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type RcloneMobileRPCResult struct {
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Output string
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Status int
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}
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// RcloneMobileRPC works the same as RcloneRPC but has an interface
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// optimised for gomobile, in particular the function signature is
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// valid under gobind rules.
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//
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// https://pkg.go.dev/golang.org/x/mobile/cmd/gobind#hdr-Type_restrictions
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func RcloneMobileRPC(method string, input string) (result RcloneMobileRPCResult) { //nolint:deadcode
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output, status := callFunctionJSON(method, input)
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result.Output = output
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result.Status = status
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return result
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}
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// writeError returns a formatted error string and the status passed in
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func writeError(path string, in rc.Params, err error, status int) (string, int) {
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fs.Errorf(nil, "rc: %q: error: %v", path, err)
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params, status := rc.Error(path, in, err, status)
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var w strings.Builder
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err = rc.WriteJSON(&w, params)
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if err != nil {
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// ultimate fallback error
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fs.Errorf(nil, "writeError: failed to write JSON output from %#v: %v", in, err)
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status = http.StatusInternalServerError
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w.Reset()
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fmt.Fprintf(&w, `{
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"error": %q,
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"path": %q,
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"status": %d
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}`, err, path, status)
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}
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return w.String(), status
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}
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// operations/uploadfile and core/command are not supported as they need request or response object
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// modified from handlePost in rcserver.go
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// call a rc function using JSON to input parameters and output the resulted JSON
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func callFunctionJSON(method string, input string) (output string, status int) {
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// create a buffer to capture the output
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in := make(rc.Params)
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err := json.NewDecoder(strings.NewReader(input)).Decode(&in)
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if err != nil {
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return writeError(method, in, errors.Wrap(err, "failed to read input JSON"), http.StatusBadRequest)
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}
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// Find the call
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call := rc.Calls.Get(method)
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if call == nil {
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return writeError(method, in, errors.Errorf("couldn't find method %q", method), http.StatusNotFound)
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}
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// TODO: handle these cases
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if call.NeedsRequest {
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return writeError(method, in, errors.Errorf("method %q needs request, not supported", method), http.StatusNotFound)
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// Add the request to RC
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//in["_request"] = r
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}
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if call.NeedsResponse {
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return writeError(method, in, errors.Errorf("method %q need response, not supported", method), http.StatusNotFound)
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//in["_response"] = w
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}
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fs.Debugf(nil, "rc: %q: with parameters %+v", method, in)
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_, out, err := jobs.NewJob(context.Background(), call.Fn, in)
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if err != nil {
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return writeError(method, in, err, http.StatusInternalServerError)
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}
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if out == nil {
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out = make(rc.Params)
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}
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fs.Debugf(nil, "rc: %q: reply %+v: %v", method, out, err)
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var w strings.Builder
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err = rc.WriteJSON(&w, out)
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if err != nil {
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fs.Errorf(nil, "rc: failed to write JSON output: %v", err)
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return writeError(method, in, err, http.StatusInternalServerError)
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}
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return w.String(), http.StatusOK
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}
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// do nothing here - necessary for building into a C library
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func main() {}
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@ -0,0 +1,124 @@
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// Package librclone exports shims for library use
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//
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// This is the internal implementation which is used for C and
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// Gomobile libaries which need slightly different export styles.
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//
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// The shims are a thin wrapper over the rclone RPC.
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package librclone
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"runtime"
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"strings"
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"github.com/pkg/errors"
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"github.com/rclone/rclone/fs"
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"github.com/rclone/rclone/fs/accounting"
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"github.com/rclone/rclone/fs/config/configfile"
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"github.com/rclone/rclone/fs/log"
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"github.com/rclone/rclone/fs/rc"
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"github.com/rclone/rclone/fs/rc/jobs"
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)
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// Initialize initializes rclone as a library
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//
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//export Initialize
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func Initialize() {
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// A subset of initialisation copied from cmd.go
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// Note that we don't want to pull in anything which depends on pflags
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ctx := context.Background()
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// Start the logger
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log.InitLogging()
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// Load the config - this may need to be configurable
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configfile.Install()
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// Start accounting
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accounting.Start(ctx)
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}
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// Finalize finalizes the library
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func Finalize() {
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// TODO: how to clean up? what happens when rcserver terminates?
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// what about unfinished async jobs?
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runtime.GC()
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}
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// writeError returns a formatted error string and the status passed in
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func writeError(path string, in rc.Params, err error, status int) (string, int) {
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fs.Errorf(nil, "rc: %q: error: %v", path, err)
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params, status := rc.Error(path, in, err, status)
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var w strings.Builder
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err = rc.WriteJSON(&w, params)
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if err != nil {
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// ultimate fallback error
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fs.Errorf(nil, "writeError: failed to write JSON output from %#v: %v", in, err)
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status = http.StatusInternalServerError
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w.Reset()
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fmt.Fprintf(&w, `{
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"error": %q,
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"path": %q,
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"status": %d
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}`, err, path, status)
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}
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return w.String(), status
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}
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// RPC runs a transaction over the RC
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//
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// Calling an rc function using JSON to input parameters and output the resulted JSON
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//
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// operations/uploadfile and core/command are not supported as they need request or response object
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// modified from handlePost in rcserver.go
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func RPC(method string, input string) (output string, status int) {
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// create a buffer to capture the output
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in := make(rc.Params)
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err := json.NewDecoder(strings.NewReader(input)).Decode(&in)
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if err != nil {
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return writeError(method, in, errors.Wrap(err, "failed to read input JSON"), http.StatusBadRequest)
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}
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// Find the call
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call := rc.Calls.Get(method)
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if call == nil {
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return writeError(method, in, errors.Errorf("couldn't find method %q", method), http.StatusNotFound)
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}
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// TODO: handle these cases
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if call.NeedsRequest {
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return writeError(method, in, errors.Errorf("method %q needs request, not supported", method), http.StatusNotFound)
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// Add the request to RC
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//in["_request"] = r
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}
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if call.NeedsResponse {
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return writeError(method, in, errors.Errorf("method %q need response, not supported", method), http.StatusNotFound)
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//in["_response"] = w
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}
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fs.Debugf(nil, "rc: %q: with parameters %+v", method, in)
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_, out, err := jobs.NewJob(context.Background(), call.Fn, in)
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if err != nil {
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return writeError(method, in, err, http.StatusInternalServerError)
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}
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if out == nil {
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out = make(rc.Params)
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}
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fs.Debugf(nil, "rc: %q: reply %+v: %v", method, out, err)
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var w strings.Builder
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err = rc.WriteJSON(&w, out)
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if err != nil {
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fs.Errorf(nil, "rc: failed to write JSON output: %v", err)
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return writeError(method, in, err, http.StatusInternalServerError)
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}
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return w.String(), http.StatusOK
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}
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