Add git utils

internal/util/git.go

@@ -0,0 +1,183 @@
+// Copyright 2019 Sorint.lab
+//
+// 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 util
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net/url"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+	"syscall"
+
+	"github.com/pkg/errors"
+)
+
+// scpSyntaxRe matches the SCP-like addresses used by Git to access repositories
+// by SSH.
+var scpSyntaxRe = regexp.MustCompile(`^([a-zA-Z0-9_]+)@([a-zA-Z0-9._-]+):(.*)$`)
+
+func ParseGitURL(u string) (*url.URL, error) {
+	if m := scpSyntaxRe.FindStringSubmatch(u); m != nil {
+		// Match SCP-like syntax and convert it to a URL.
+		// Eg, "git@github.com:user/repo" becomes
+		// "ssh://git@github.com/user/repo".
+		return &url.URL{
+			Scheme: "ssh",
+			User:   url.User(m[1]),
+			Host:   m[2],
+			Path:   m[3],
+		}, nil
+	}
+	return url.Parse(u)
+}
+
+type Git struct {
+	cmd    *exec.Cmd
+	GitDir string
+	Env    []string
+}
+
+func (g *Git) gitCmd(ctx context.Context, args ...string) *exec.Cmd {
+	cmd := exec.CommandContext(ctx, "git", args...)
+	// only keep the PATH, HOME and other useful env vars
+	cmdEnv := []string{}
+	cmdEnv = append(cmdEnv, "PATH="+os.Getenv("PATH"))
+	cmdEnv = append(cmdEnv, "HOME="+os.Getenv("HOME"))
+	cmdEnv = append(cmdEnv, "USER="+os.Getenv("USER"))
+	if g.GitDir != "" {
+		cmdEnv = append(cmdEnv, "GIT_DIR="+g.GitDir)
+	}
+	cmdEnv = append(cmdEnv, g.Env...)
+	cmd.Env = cmdEnv
+
+	return cmd
+}
+
+func (g *Git) Output(ctx context.Context, stdin io.Reader, args ...string) ([]byte, error) {
+	cmd := g.gitCmd(ctx, args...)
+
+	if stdin != nil {
+		cmd.Stdin = stdin
+	}
+
+	stderr := &bytes.Buffer{}
+	cmd.Stderr = stderr
+
+	out, err := cmd.Output()
+	if err != nil {
+		gitErr := stderr.String()
+		if len(gitErr) > 0 {
+			return nil, errors.New(stderr.String())
+		} else {
+			return nil, err
+		}
+	}
+
+	return out, err
+}
+
+func (g *Git) OutputLines(ctx context.Context, stdin io.Reader, args ...string) ([]string, error) {
+	out, err := g.Output(ctx, stdin, args...)
+	if err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(bytes.NewReader(out))
+	lines := []string{}
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return lines, nil
+}
+
+func (g *Git) Pipe(ctx context.Context, w io.Writer, r io.Reader, args ...string) error {
+	cmd := g.gitCmd(ctx, args...)
+
+	cmd.Stdin = r
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+
+	stderr := &bytes.Buffer{}
+	cmd.Stderr = stderr
+
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	if _, err := io.Copy(w, stdout); err != nil {
+		return err
+	}
+
+	if err := cmd.Wait(); err != nil {
+		gitErr := stderr.String()
+		if len(gitErr) > 0 {
+			return errors.New(stderr.String())
+		} else {
+			return err
+		}
+	}
+	return nil
+}
+
+type ErrNotFound struct {
+	Key string
+}
+
+func (e *ErrNotFound) Error() string {
+	return fmt.Sprintf("key `%q` was not found", e.Key)
+}
+
+func (g *Git) ConfigGet(ctx context.Context, args ...string) (string, error) {
+	args = append([]string{"config", "--get", "--null"}, args...)
+	out, err := g.Output(ctx, nil, args...)
+
+	if exitError, ok := err.(*exec.ExitError); ok {
+		if waitStatus, ok := exitError.Sys().(syscall.WaitStatus); ok {
+			if waitStatus.ExitStatus() == 1 {
+				return "", &ErrNotFound{Key: args[len(args)-1]}
+			}
+		}
+		return "", err
+	}
+
+	return strings.TrimRight(string(out), "\000"), nil
+}
+
+func (g *Git) ConfigSet(ctx context.Context, args ...string) (string, error) {
+	args = append([]string{"config", "--null"}, args...)
+	out, err := g.Output(ctx, nil, args...)
+
+	if exitError, ok := err.(*exec.ExitError); ok {
+		if waitStatus, ok := exitError.Sys().(syscall.WaitStatus); ok {
+			if waitStatus.ExitStatus() == 1 {
+				return "", &ErrNotFound{Key: args[len(args)-1]}
+			}
+		}
+		return "", err
+	}
+
+	return strings.TrimRight(string(out), "\000"), nil
+}