all: consolidate invokeGo implementations

Over time we have accumulated a disturbing number of ways to run the Go
command, each of which supported slightly different features and
workarounds. Combine all of them.

This unavoidably introduces some changes in debug logging behavior; I
think we should try to fix them incrementally and consistently.

Updates golang/go#37368.

Change-Id: I664ca8685bf247a226be3cb807789c2fcddf233d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/220737
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

1 files changed, 92 insertions, 0 deletions

diff --git a/internal/gocommand/invoke.go b/internal/gocommand/invoke.go
new file mode 100644
index 000000000..26cf7b18e
--- /dev/null
+++ b/internal/gocommand/invoke.go
@@ -0,0 +1,92 @@
+// Package gocommand is a helper for calling the go command.
+package gocommand
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+// An Invocation represents a call to the go command.
+type Invocation struct {
+	Verb       string
+	Args       []string
+	BuildFlags []string
+	Env        []string
+	WorkingDir string
+	Logf       func(format string, args ...interface{})
+}
+
+// Run runs the invocation, returning its stdout and an error suitable for
+// human consumption, including stderr.
+func (i *Invocation) Run(ctx context.Context) (*bytes.Buffer, error) {
+	stdout, _, friendly, _ := i.RunRaw(ctx)
+	return stdout, friendly
+}
+
+// RunRaw is like Run, but also returns the raw stderr and error for callers
+// that want to do low-level error handling/recovery.
+func (i *Invocation) RunRaw(ctx context.Context) (stdout *bytes.Buffer, stderr *bytes.Buffer, friendlyError error, rawError error) {
+	log := i.Logf
+	if log == nil {
+		log = func(string, ...interface{}) {}
+	}
+
+	goArgs := []string{i.Verb}
+	switch i.Verb {
+	case "mod":
+		// mod needs the sub-verb before build flags.
+		goArgs = append(goArgs, i.Args[0])
+		goArgs = append(goArgs, i.BuildFlags...)
+		goArgs = append(goArgs, i.Args[1:]...)
+	case "env":
+		// env doesn't take build flags.
+		goArgs = append(goArgs, i.Args...)
+	default:
+		goArgs = append(goArgs, i.BuildFlags...)
+		goArgs = append(goArgs, i.Args...)
+	}
+	cmd := exec.CommandContext(ctx, "go", goArgs...)
+	stdout = &bytes.Buffer{}
+	stderr = &bytes.Buffer{}
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+	// On darwin the cwd gets resolved to the real path, which breaks anything that
+	// expects the working directory to keep the original path, including the
+	// go command when dealing with modules.
+	// The Go stdlib has a special feature where if the cwd and the PWD are the
+	// same node then it trusts the PWD, so by setting it in the env for the child
+	// process we fix up all the paths returned by the go command.
+	cmd.Env = append(append([]string{}, i.Env...), "PWD="+i.WorkingDir)
+	cmd.Dir = i.WorkingDir
+
+	defer func(start time.Time) { log("%s for %v", time.Since(start), cmdDebugStr(cmd)) }(time.Now())
+
+	rawError = cmd.Run()
+	friendlyError = rawError
+	if rawError != nil {
+		// Check for 'go' executable not being found.
+		if ee, ok := rawError.(*exec.Error); ok && ee.Err == exec.ErrNotFound {
+			friendlyError = fmt.Errorf("go command required, not found: %v", ee)
+		}
+		if ctx.Err() != nil {
+			friendlyError = ctx.Err()
+		}
+		friendlyError = fmt.Errorf("err: %v: stderr: %s", rawError, stderr)
+	}
+	return
+}
+
+func cmdDebugStr(cmd *exec.Cmd) string {
+	env := make(map[string]string)
+	for _, kv := range cmd.Env {
+		split := strings.Split(kv, "=")
+		k, v := split[0], split[1]
+		env[k] = v
+	}
+
+	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v GOPROXY=%v PWD=%v go %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["GOPROXY"], env["PWD"], cmd.Args)
+}