Add git save implementation

internal/git-save/save.go

@@ -0,0 +1,224 @@
+// 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 gitsave
+
+import (
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/sorintlab/agola/internal/util"
+
+	"github.com/pkg/errors"
+	"go.uber.org/zap"
+)
+
+const (
+	gitIndexFile  = "index"
+	gitRefsPrefix = "refs/gitsave"
+)
+
+func copyFile(src, dest string) error {
+	srcf, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer srcf.Close()
+
+	destf, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer destf.Close()
+
+	_, err = io.Copy(destf, srcf)
+	return err
+}
+
+func fileExists(path string) (bool, error) {
+	_, err := os.Stat(path)
+	if err != nil && !os.IsNotExist(err) {
+		return false, err
+	}
+	return !os.IsNotExist(err), nil
+}
+
+// GitDir returns the git dir relative to the working dir
+func GitDir() (string, error) {
+	git := &util.Git{}
+	lines, err := git.OutputLines(context.Background(), nil, "rev-parse", "--git-dir")
+	if err != nil {
+		return "", err
+	}
+	if len(lines) != 1 {
+		return "", errors.Errorf("received %d lines, expected one line", len(lines))
+	}
+	return lines[0], err
+}
+
+func currentGitBranch() (string, error) {
+	git := &util.Git{}
+	lines, err := git.OutputLines(context.Background(), nil, "symbolic-ref", "--short", "HEAD")
+	if err != nil {
+		return "", err
+	}
+	if len(lines) != 1 {
+		return "", errors.Errorf("received %d lines, expected one line", len(lines))
+	}
+	return lines[0], err
+}
+
+// gitDir returns the git dir relative to the working dir
+func gitWriteTree(indexPath string) (string, error) {
+	git := &util.Git{Env: []string{"GIT_INDEX_FILE=" + indexPath}}
+	lines, err := git.OutputLines(context.Background(), nil, "write-tree")
+	if err != nil {
+		return "", err
+	}
+	if len(lines) != 1 {
+		return "", errors.Errorf("received %d lines, expected  one line", len(lines))
+	}
+	return lines[0], err
+}
+
+func gitCommitTree(message, treeSHA string) (string, error) {
+	git := &util.Git{}
+	lines, err := git.OutputLines(context.Background(), nil, "commit-tree", "-m", message, treeSHA)
+	if err != nil {
+		return "", err
+	}
+	if len(lines) != 1 {
+		return "", errors.Errorf("received %d lines, expected one line", len(lines))
+	}
+	return lines[0], err
+}
+
+func gitUpdateRef(message, ref, commitSHA string) error {
+	git := &util.Git{}
+	_, err := git.Output(context.Background(), nil, "update-ref", "-m", message, ref, commitSHA)
+	return err
+}
+
+func gitAddUntrackedFiles(indexPath string) error {
+	git := &util.Git{Env: []string{"GIT_INDEX_FILE=" + indexPath}}
+	_, err := git.Output(context.Background(), nil, "add", ".")
+	return err
+}
+
+func gitAddIgnoredFiles(indexPath string) error {
+	git := &util.Git{Env: []string{"GIT_INDEX_FILE=" + indexPath}}
+	_, err := git.Output(context.Background(), nil, "add", "-f", "-A", ".")
+	return err
+}
+
+func GitAddRemote(configPath, name, url string) error {
+	git := &util.Git{}
+	_, err := git.Output(context.Background(), nil, "remote", "add", name, url)
+	return err
+}
+
+func GitPush(configPath, remote, branch string) error {
+	git := &util.Git{}
+	_, err := git.Output(context.Background(), nil, "push", remote, branch, "-f")
+	return err
+}
+
+type GitSaveConfig struct {
+	AddUntracked bool
+	AddIgnored   bool
+}
+
+type GitSave struct {
+	log  *zap.SugaredLogger
+	conf *GitSaveConfig
+}
+
+func NewGitSave(logger *zap.Logger, conf *GitSaveConfig) *GitSave {
+	return &GitSave{log: logger.Sugar(), conf: conf}
+}
+
+// Save adds files to the provided index, creates a tree and a commit pointing to
+// that tree, finally it creates a branch poiting to that commit
+// Save will use the current worktree index if available to speed the index generation
+func (s *GitSave) Save(tmpIndexPath, message, branchName string) error {
+	gitdir, err := GitDir()
+	if err != nil {
+		return err
+	}
+
+	indexPath := filepath.Join(gitdir, gitIndexFile)
+
+	curBranch, err := currentGitBranch()
+	if err != nil {
+		return err
+	}
+
+	indexExists, err := fileExists(indexPath)
+	if err != nil {
+		return err
+	}
+
+	if indexExists {
+		// copy current git index to a temporary index
+		if err := copyFile(indexPath, tmpIndexPath); err != nil {
+			return err
+		}
+		s.log.Infof("created temporary index: %s", tmpIndexPath)
+		// read the current branch tree information into the index
+		git := &util.Git{Env: []string{"GIT_INDEX_FILE=" + tmpIndexPath}}
+		_, err = git.Output(context.Background(), nil, "read-tree", curBranch)
+		if err != nil {
+			return err
+		}
+	} else {
+		s.log.Infof("index %s does not exist", indexPath)
+	}
+
+	if s.conf.AddUntracked {
+		s.log.Infof("adding untracked files")
+		if err := gitAddUntrackedFiles(tmpIndexPath); err != nil {
+			return err
+		}
+	}
+
+	if s.conf.AddIgnored {
+		s.log.Infof("adding ignored files")
+		if err := gitAddIgnoredFiles(tmpIndexPath); err != nil {
+			return err
+		}
+	}
+
+	s.log.Infof("writing tree file")
+	treeSHA, err := gitWriteTree(tmpIndexPath)
+	if err != nil {
+		return err
+	}
+	s.log.Infof("tree: %s", treeSHA)
+
+	s.log.Infof("committing tree")
+	commitSHA, err := gitCommitTree("git-save", treeSHA)
+	if err != nil {
+		return err
+	}
+	s.log.Infof("commit: %s", commitSHA)
+
+	s.log.Infof("updating ref")
+	if err = gitUpdateRef("git-save", filepath.Join(gitRefsPrefix, branchName), commitSHA); err != nil {
+		return err
+	}
+
+	return nil
+}