path: root/internal/build/util.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package build

import (
    "bytes"
    "flag"
    "fmt"
    "io"
    "io/ioutil"
    "log"
    "os"
    "os/exec"
    "path/filepath"
    "strings"
    "text/template"
)

var DryRunFlag = flag.Bool("n", false, "dry run, don't execute commands")

// MustRun executes the given command and exits the host process for
// any error.
func MustRun(cmd *exec.Cmd) {
    fmt.Println(">>>", strings.Join(cmd.Args, " "))
    if !*DryRunFlag {
        cmd.Stderr = os.Stderr
        cmd.Stdout = os.Stdout
        if err := cmd.Run(); err != nil {
            log.Fatal(err)
        }
    }
}

func MustRunCommand(cmd string, args ...string) {
    MustRun(exec.Command(cmd, args...))
}

// GOPATH returns the value that the GOPATH environment
// variable should be set to.
func GOPATH() string {
    path := filepath.SplitList(os.Getenv("GOPATH"))
    if len(path) == 0 {
        log.Fatal("GOPATH is not set")
    }
    // Ensure that our internal vendor folder is on GOPATH
    vendor, _ := filepath.Abs(filepath.Join("build", "_vendor"))
    for _, dir := range path {
        if dir == vendor {
            return strings.Join(path, string(filepath.ListSeparator))
        }
    }
    newpath := append(path[:1], append([]string{vendor}, path[1:]...)...)
    return strings.Join(newpath, string(filepath.ListSeparator))
}

// VERSION returns the content of the VERSION file.
func VERSION() string {
    version, err := ioutil.ReadFile("VERSION")
    if err != nil {
        log.Fatal(err)
    }
    return string(bytes.TrimSpace(version))
}

// RunGit runs a git subcommand and returns its output.
// The command must complete successfully.
func RunGit(args ...string) string {
    cmd := exec.Command("git", args...)
    var stdout, stderr bytes.Buffer
    cmd.Stdout, cmd.Stderr = &stdout, &stderr
    if err := cmd.Run(); err == exec.ErrNotFound {
        log.Println("no git in PATH")
        return ""
    } else if err != nil {
        log.Fatal(strings.Join(cmd.Args, " "), ": ", err, "\n", stderr.String())
    }
    return strings.TrimSpace(stdout.String())
}

// Render renders the given template file into outputFile.
func Render(templateFile, outputFile string, outputPerm os.FileMode, x interface{}) {
    tpl := template.Must(template.ParseFiles(templateFile))
    render(tpl, outputFile, outputPerm, x)
}

// RenderString renders the given template string into outputFile.
func RenderString(templateContent, outputFile string, outputPerm os.FileMode, x interface{}) {
    tpl := template.Must(template.New("").Parse(templateContent))
    render(tpl, outputFile, outputPerm, x)
}

func render(tpl *template.Template, outputFile string, outputPerm os.FileMode, x interface{}) {
    if err := os.MkdirAll(filepath.Dir(outputFile), 0755); err != nil {
        log.Fatal(err)
    }
    out, err := os.OpenFile(outputFile, os.O_CREATE|os.O_WRONLY|os.O_EXCL, outputPerm)
    if err != nil {
        log.Fatal(err)
    }
    if err := tpl.Execute(out, x); err != nil {
        log.Fatal(err)
    }
    if err := out.Close(); err != nil {
        log.Fatal(err)
    }
}

// CopyFile copies a file.
func CopyFile(dst, src string, mode os.FileMode) {
    if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
        log.Fatal(err)
    }
    destFile, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode)
    if err != nil {
        log.Fatal(err)
    }
    defer destFile.Close()

    srcFile, err := os.Open(src)
    if err != nil {
        log.Fatal(err)
    }
    defer srcFile.Close()

    if _, err := io.Copy(destFile, srcFile); err != nil {
        log.Fatal(err)
    }
}