157 lines
4.0 KiB
Go
157 lines
4.0 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package fuseops
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import (
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"fmt"
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"reflect"
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"strings"
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"github.com/jacobsa/bazilfuse"
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"github.com/jacobsa/reqtrace"
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"golang.org/x/net/context"
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)
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// An interface that all ops inside which commonOp is embedded must
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// implement.
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type internalOp interface {
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Op
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// Convert to a bazilfuse response compatible with the Respond method on the
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// wrapped bazilfuse request. If that Respond method takes no arguments,
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// return nil.
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toBazilfuseResponse() interface{}
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}
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// A helper for embedding common behavior.
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type commonOp struct {
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// The context exposed to the user.
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ctx context.Context
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// The op in which this struct is embedded.
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op internalOp
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// The underlying bazilfuse request for this op.
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bazilReq bazilfuse.Request
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// A function that can be used to log information about the op. The first
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// argument is a call depth.
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log func(int, string, ...interface{})
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// A function that is invoked with the error given to Respond, for use in
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// closing off traces and reporting back to the connection.
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finished func(error)
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}
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func (o *commonOp) ShortDesc() (desc string) {
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opName := reflect.TypeOf(o.op).String()
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// Attempt to better handle the usual case: a string that looks like
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// "*fuseops.GetInodeAttributesOp".
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const prefix = "*fuseops."
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const suffix = "Op"
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if strings.HasPrefix(opName, prefix) && strings.HasSuffix(opName, suffix) {
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opName = opName[len(prefix) : len(opName)-len(suffix)]
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}
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// Include the inode number to which the op applies.
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desc = fmt.Sprintf("%s(inode=%v)", opName, o.bazilReq.Hdr().Node)
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return
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}
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func (o *commonOp) init(
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ctx context.Context,
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op internalOp,
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bazilReq bazilfuse.Request,
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log func(int, string, ...interface{}),
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finished func(error)) {
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// Initialize basic fields.
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o.ctx = ctx
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o.op = op
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o.bazilReq = bazilReq
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o.log = log
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o.finished = finished
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// Set up a trace span for this op.
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var reportForTrace reqtrace.ReportFunc
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o.ctx, reportForTrace = reqtrace.StartSpan(o.ctx, o.op.ShortDesc())
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// When the op is finished, report to both reqtrace and the connection.
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prevFinish := o.finished
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o.finished = func(err error) {
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reportForTrace(err)
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prevFinish(err)
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}
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}
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func (o *commonOp) Header() OpHeader {
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bh := o.bazilReq.Hdr()
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return OpHeader{
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Uid: bh.Uid,
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Gid: bh.Gid,
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}
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}
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func (o *commonOp) Context() context.Context {
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return o.ctx
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}
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func (o *commonOp) Logf(format string, v ...interface{}) {
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const calldepth = 2
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o.log(calldepth, format, v...)
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}
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func (o *commonOp) Respond(err error) {
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// Report that the user is responding.
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o.finished(err)
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// If successful, we should respond to bazilfuse with the appropriate struct.
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if err == nil {
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o.sendBazilfuseResponse(o.op.toBazilfuseResponse())
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return
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}
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// Log the error.
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o.Logf(
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"-> (%s) error: %v",
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o.op.ShortDesc(),
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err)
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// Send a response to the kernel.
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o.bazilReq.RespondError(err)
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}
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// Respond with the supplied response struct, which must be accepted by a
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// method called Respond on o.bazilReq.
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//
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// Special case: nil means o.bazilReq.Respond accepts no parameters.
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func (o *commonOp) sendBazilfuseResponse(resp interface{}) {
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// Find the Respond method.
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v := reflect.ValueOf(o.bazilReq)
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respond := v.MethodByName("Respond")
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// Special case: handle successful ops with no response struct.
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if resp == nil {
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o.Logf("-> (%s) OK", o.op.ShortDesc())
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respond.Call([]reflect.Value{})
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return
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}
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// Otherwise, send the response struct to the kernel.
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o.Logf("-> %v", resp)
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respond.Call([]reflect.Value{reflect.ValueOf(resp)})
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}
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