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tailscale/tool/gocross/gocross.go

129 lines
3.4 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// gocross is a wrapper around the `go` tool that invokes `go` from Tailscale's
// custom toolchain, with the right build parameters injected based on the
// native+target GOOS/GOARCH.
//
// In short, when aliased to `go`, using `go build`, `go test` behave like the
// upstream Go tools, but produce correctly configured, correctly linked
// binaries stamped with version information.
package main
import (
_ "embed"
"fmt"
"os"
"path/filepath"
"tailscale.com/atomicfile"
"tailscale.com/version"
)
func main() {
if len(os.Args) > 1 {
// These additional subcommands are various support commands to handle
// integration with Tailscale's existing build system. Unless otherwise
// specified, these are not stable APIs, and may change or go away at
// any time.
switch os.Args[1] {
case "gocross-version":
fmt.Println(version.GetMeta().GitCommit)
os.Exit(0)
case "is-gocross":
// This subcommand exits with an error code when called on a
// regular go binary, so it can be used to detect when `go` is
// actually gocross.
os.Exit(0)
case "make-goroot":
_, gorootDir, err := getToolchain()
if err != nil {
fmt.Fprintf(os.Stderr, "getting toolchain: %v\n", err)
os.Exit(1)
}
fmt.Println(gorootDir)
os.Exit(0)
case "gocross-get-toolchain-go":
toolchain, _, err := getToolchain()
if err != nil {
fmt.Fprintf(os.Stderr, "getting toolchain: %v\n", err)
os.Exit(1)
}
fmt.Println(filepath.Join(toolchain, "bin/go"))
os.Exit(0)
case "gocross-write-wrapper-script":
if len(os.Args) != 3 {
fmt.Fprintf(os.Stderr, "usage: gocross write-wrapper-script <path>\n")
os.Exit(1)
}
if err := atomicfile.WriteFile(os.Args[2], wrapperScript, 0755); err != nil {
fmt.Fprintf(os.Stderr, "writing wrapper script: %v\n", err)
os.Exit(1)
}
os.Exit(0)
}
}
toolchain, goroot, err := getToolchain()
if err != nil {
fmt.Fprintf(os.Stderr, "getting toolchain: %v\n", err)
os.Exit(1)
}
args := os.Args
if os.Getenv("GOCROSS_BYPASS") == "" {
newArgv, env, err := Autoflags(os.Args, goroot)
if err != nil {
fmt.Fprintf(os.Stderr, "computing flags: %v\n", err)
os.Exit(1)
}
// Make sure the right version of cmd/go is the first thing in the PATH
// for tests that execute `go build` or `go test`.
// TODO: if we really need to do this, do it inside Autoflags, not here.
path := filepath.Join(toolchain, "bin") + string(os.PathListSeparator) + os.Getenv("PATH")
env.Set("PATH", path)
debug("Input: %s\n", formatArgv(os.Args))
debug("Command: %s\n", formatArgv(newArgv))
debug("Set the following flags/envvars:\n%s\n", env.Diff())
args = newArgv
if err := env.Apply(); err != nil {
fmt.Fprintf(os.Stderr, "modifying environment: %v\n", err)
os.Exit(1)
}
}
doExec(filepath.Join(toolchain, "bin/go"), args, os.Environ())
}
//go:embed gocross-wrapper.sh
var wrapperScript []byte
func debug(format string, args ...any) {
debug := os.Getenv("GOCROSS_DEBUG")
var (
out *os.File
err error
)
switch debug {
case "0", "":
return
case "1":
out = os.Stderr
default:
out, err = os.OpenFile(debug, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0640)
if err != nil {
fmt.Fprintf(os.Stderr, "opening debug file %q: %v", debug, err)
out = os.Stderr
} else {
defer out.Close() // May lose some write errors, but we don't care.
}
}
fmt.Fprintf(out, format, args...)
}