cloudflared-mirror/vendor/go.uber.org/mock/mockgen/reflect.go

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// Copyright 2012 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
// This file contains the model construction by reflection.
import (
"bytes"
"encoding/gob"
"flag"
"fmt"
"go/build"
"io"
"log"
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"text/template"
"go.uber.org/mock/mockgen/model"
)
var (
progOnly = flag.Bool("prog_only", false, "(reflect mode) Only generate the reflection program; write it to stdout and exit.")
execOnly = flag.String("exec_only", "", "(reflect mode) If set, execute this reflection program.")
buildFlags = flag.String("build_flags", "", "(reflect mode) Additional flags for go build.")
)
// reflectMode generates mocks via reflection on an interface.
func reflectMode(importPath string, symbols []string) (*model.Package, error) {
if *execOnly != "" {
return run(*execOnly)
}
program, err := writeProgram(importPath, symbols)
if err != nil {
return nil, err
}
if *progOnly {
if _, err := os.Stdout.Write(program); err != nil {
return nil, err
}
os.Exit(0)
}
wd, _ := os.Getwd()
// Try to run the reflection program in the current working directory.
if p, err := runInDir(program, wd); err == nil {
return p, nil
}
// Try to run the program in the same directory as the input package.
if p, err := build.Import(importPath, wd, build.FindOnly); err == nil {
dir := p.Dir
if p, err := runInDir(program, dir); err == nil {
return p, nil
}
}
// Try to run it in a standard temp directory.
return runInDir(program, "")
}
func writeProgram(importPath string, symbols []string) ([]byte, error) {
var program bytes.Buffer
data := reflectData{
ImportPath: importPath,
Symbols: symbols,
}
if err := reflectProgram.Execute(&program, &data); err != nil {
return nil, err
}
return program.Bytes(), nil
}
// run the given program and parse the output as a model.Package.
func run(program string) (*model.Package, error) {
f, err := os.CreateTemp("", "")
if err != nil {
return nil, err
}
filename := f.Name()
defer os.Remove(filename)
if err := f.Close(); err != nil {
return nil, err
}
// Run the program.
cmd := exec.Command(program, "-output", filename)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
if err := cmd.Run(); err != nil {
return nil, err
}
f, err = os.Open(filename)
if err != nil {
return nil, err
}
// Process output.
var pkg model.Package
if err := gob.NewDecoder(f).Decode(&pkg); err != nil {
return nil, err
}
if err := f.Close(); err != nil {
return nil, err
}
return &pkg, nil
}
// runInDir writes the given program into the given dir, runs it there, and
// parses the output as a model.Package.
func runInDir(program []byte, dir string) (*model.Package, error) {
// We use TempDir instead of TempFile so we can control the filename.
tmpDir, err := os.MkdirTemp(dir, "gomock_reflect_")
if err != nil {
return nil, err
}
defer func() {
if err := os.RemoveAll(tmpDir); err != nil {
log.Printf("failed to remove temp directory: %s", err)
}
}()
const progSource = "prog.go"
var progBinary = "prog.bin"
if runtime.GOOS == "windows" {
// Windows won't execute a program unless it has a ".exe" suffix.
progBinary += ".exe"
}
if err := os.WriteFile(filepath.Join(tmpDir, progSource), program, 0600); err != nil {
return nil, err
}
cmdArgs := []string{}
cmdArgs = append(cmdArgs, "build")
if *buildFlags != "" {
cmdArgs = append(cmdArgs, strings.Split(*buildFlags, " ")...)
}
cmdArgs = append(cmdArgs, "-o", progBinary, progSource)
// Build the program.
buf := bytes.NewBuffer(nil)
cmd := exec.Command("go", cmdArgs...)
cmd.Dir = tmpDir
cmd.Stdout = os.Stdout
cmd.Stderr = io.MultiWriter(os.Stderr, buf)
if err := cmd.Run(); err != nil {
sErr := buf.String()
if strings.Contains(sErr, `cannot find package "."`) &&
strings.Contains(sErr, "go.uber.org/mock/mockgen/model") {
fmt.Fprint(os.Stderr, "Please reference the steps in the README to fix this error:\n\thttps://go.uber.org/mock#reflect-vendoring-error.\n")
return nil, err
}
return nil, err
}
return run(filepath.Join(tmpDir, progBinary))
}
type reflectData struct {
ImportPath string
Symbols []string
}
// This program reflects on an interface value, and prints the
// gob encoding of a model.Package to standard output.
// JSON doesn't work because of the model.Type interface.
var reflectProgram = template.Must(template.New("program").Parse(`
package main
import (
"encoding/gob"
"flag"
"fmt"
"os"
"path"
"reflect"
"go.uber.org/mock/mockgen/model"
pkg_ {{printf "%q" .ImportPath}}
)
var output = flag.String("output", "", "The output file name, or empty to use stdout.")
func main() {
flag.Parse()
its := []struct{
sym string
typ reflect.Type
}{
{{range .Symbols}}
{ {{printf "%q" .}}, reflect.TypeOf((*pkg_.{{.}})(nil)).Elem()},
{{end}}
}
pkg := &model.Package{
// NOTE: This behaves contrary to documented behaviour if the
// package name is not the final component of the import path.
// The reflect package doesn't expose the package name, though.
Name: path.Base({{printf "%q" .ImportPath}}),
}
for _, it := range its {
intf, err := model.InterfaceFromInterfaceType(it.typ)
if err != nil {
fmt.Fprintf(os.Stderr, "Reflection: %v\n", err)
os.Exit(1)
}
intf.Name = it.sym
pkg.Interfaces = append(pkg.Interfaces, intf)
}
outfile := os.Stdout
if len(*output) != 0 {
var err error
outfile, err = os.Create(*output)
if err != nil {
fmt.Fprintf(os.Stderr, "failed to open output file %q", *output)
}
defer func() {
if err := outfile.Close(); err != nil {
fmt.Fprintf(os.Stderr, "failed to close output file %q", *output)
os.Exit(1)
}
}()
}
if err := gob.NewEncoder(outfile).Encode(pkg); err != nil {
fmt.Fprintf(os.Stderr, "gob encode: %v\n", err)
os.Exit(1)
}
}
`))