435c0d9fc8
This PR switches the Nomad repository from using govendor to Go modules for managing dependencies. Aspects of the Nomad workflow remain pretty much the same. The usual Makefile targets should continue to work as they always did. The API submodule simply defers to the parent Nomad version on the repository, keeping the semantics of API versioning that currently exists.
102 lines
3.4 KiB
Go
102 lines
3.4 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file enables an external tool to intercept package requests.
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// If the tool is present then its results are used in preference to
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// the go list command.
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package packages
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"os"
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"os/exec"
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"strings"
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)
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// The Driver Protocol
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//
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// The driver, given the inputs to a call to Load, returns metadata about the packages specified.
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// This allows for different build systems to support go/packages by telling go/packages how the
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// packages' source is organized.
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// The driver is a binary, either specified by the GOPACKAGESDRIVER environment variable or in
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// the path as gopackagesdriver. It's given the inputs to load in its argv. See the package
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// documentation in doc.go for the full description of the patterns that need to be supported.
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// A driver receives as a JSON-serialized driverRequest struct in standard input and will
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// produce a JSON-serialized driverResponse (see definition in packages.go) in its standard output.
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// driverRequest is used to provide the portion of Load's Config that is needed by a driver.
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type driverRequest struct {
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Mode LoadMode `json:"mode"`
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// Env specifies the environment the underlying build system should be run in.
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Env []string `json:"env"`
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// BuildFlags are flags that should be passed to the underlying build system.
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BuildFlags []string `json:"build_flags"`
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// Tests specifies whether the patterns should also return test packages.
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Tests bool `json:"tests"`
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// Overlay maps file paths (relative to the driver's working directory) to the byte contents
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// of overlay files.
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Overlay map[string][]byte `json:"overlay"`
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}
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// findExternalDriver returns the file path of a tool that supplies
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// the build system package structure, or "" if not found."
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// If GOPACKAGESDRIVER is set in the environment findExternalTool returns its
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// value, otherwise it searches for a binary named gopackagesdriver on the PATH.
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func findExternalDriver(cfg *Config) driver {
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const toolPrefix = "GOPACKAGESDRIVER="
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tool := ""
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for _, env := range cfg.Env {
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if val := strings.TrimPrefix(env, toolPrefix); val != env {
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tool = val
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}
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}
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if tool != "" && tool == "off" {
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return nil
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}
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if tool == "" {
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var err error
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tool, err = exec.LookPath("gopackagesdriver")
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if err != nil {
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return nil
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}
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}
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return func(cfg *Config, words ...string) (*driverResponse, error) {
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req, err := json.Marshal(driverRequest{
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Mode: cfg.Mode,
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Env: cfg.Env,
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BuildFlags: cfg.BuildFlags,
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Tests: cfg.Tests,
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Overlay: cfg.Overlay,
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})
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if err != nil {
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return nil, fmt.Errorf("failed to encode message to driver tool: %v", err)
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}
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buf := new(bytes.Buffer)
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stderr := new(bytes.Buffer)
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cmd := exec.CommandContext(cfg.Context, tool, words...)
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cmd.Dir = cfg.Dir
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cmd.Env = cfg.Env
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cmd.Stdin = bytes.NewReader(req)
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cmd.Stdout = buf
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cmd.Stderr = stderr
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if err := cmd.Run(); err != nil {
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return nil, fmt.Errorf("%v: %v: %s", tool, err, cmd.Stderr)
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}
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if len(stderr.Bytes()) != 0 && os.Getenv("GOPACKAGESPRINTDRIVERERRORS") != "" {
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fmt.Fprintf(os.Stderr, "%s stderr: <<%s>>\n", cmdDebugStr(cmd, words...), stderr)
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}
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var response driverResponse
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if err := json.Unmarshal(buf.Bytes(), &response); err != nil {
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return nil, err
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}
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return &response, nil
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}
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}
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