feat: add checksum for git downloader

pkg/dl/git.go

@@ -0,0 +1,238 @@
+// This file was originally part of the project "LURE - Linux User REpository", created by Elara Musayelyan.
+// It has been modified as part of "ALR - Any Linux Repository" by the ALR Authors.
+//
+// ALR - Any Linux Repository
+// Copyright (C) 2025 The ALR Authors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package dl
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"errors"
+	"log/slog"
+	"net/url"
+	"path"
+	"strconv"
+	"strings"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/config"
+	"github.com/go-git/go-git/v5/plumbing"
+)
+
+// GitDownloader downloads Git repositories
+type GitDownloader struct{}
+
+// Name always returns "git"
+func (GitDownloader) Name() string {
+	return "git"
+}
+
+// MatchURL matches any URLs that start with "git+"
+func (GitDownloader) MatchURL(u string) bool {
+	return strings.HasPrefix(u, "git+")
+}
+
+// Download uses git to clone the repository from the specified URL.
+// It allows specifying the revision, depth and recursion options
+// via query string
+func (d *GitDownloader) Download(ctx context.Context, opts Options) (Type, string, error) {
+	u, err := url.Parse(opts.URL)
+	if err != nil {
+		return 0, "", err
+	}
+	u.Scheme = strings.TrimPrefix(u.Scheme, "git+")
+
+	query := u.Query()
+
+	rev := query.Get("~rev")
+	query.Del("~rev")
+
+	// Right now, this only affects the return value of name,
+	// which will be used by dl_cache.
+	// It seems wrong, but for now it's better to leave it as it is.
+	name := query.Get("~name")
+	query.Del("~name")
+
+	depthStr := query.Get("~depth")
+	query.Del("~depth")
+
+	recursive := query.Get("~recursive")
+	query.Del("~recursive")
+
+	u.RawQuery = query.Encode()
+
+	depth := 0
+	if depthStr != "" {
+		depth, err = strconv.Atoi(depthStr)
+		if err != nil {
+			return 0, "", err
+		}
+	}
+
+	co := &git.CloneOptions{
+		URL:               u.String(),
+		Depth:             depth,
+		Progress:          opts.Progress,
+		RecurseSubmodules: git.NoRecurseSubmodules,
+	}
+
+	if recursive == "true" {
+		co.RecurseSubmodules = git.DefaultSubmoduleRecursionDepth
+	}
+
+	r, err := git.PlainCloneContext(ctx, opts.Destination, false, co)
+	if err != nil {
+		return 0, "", err
+	}
+
+	err = r.Fetch(&git.FetchOptions{
+		RefSpecs: []config.RefSpec{"+refs/*:refs/*"},
+	})
+	if err != git.NoErrAlreadyUpToDate && err != nil {
+		return 0, "", err
+	}
+
+	if rev != "" {
+		h, err := r.ResolveRevision(plumbing.Revision(rev))
+		if err != nil {
+			return 0, "", err
+		}
+
+		w, err := r.Worktree()
+		if err != nil {
+			return 0, "", err
+		}
+
+		err = w.Checkout(&git.CheckoutOptions{
+			Hash: *h,
+		})
+		if err != nil {
+			return 0, "", err
+		}
+	}
+
+	err = d.verifyHash(opts)
+	if err != nil {
+		return 0, "", err
+	}
+
+	if name == "" {
+		name = strings.TrimSuffix(path.Base(u.Path), ".git")
+	}
+
+	return TypeDir, name, nil
+}
+
+func (GitDownloader) verifyHash(opts Options) error {
+	if opts.Hash != nil {
+		h, err := opts.NewHash()
+		if err != nil {
+			return err
+		}
+
+		err = HashDir(opts.Destination, h)
+		if err != nil {
+			return err
+		}
+
+		sum := h.Sum(nil)
+
+		slog.Warn("validate checksum", "real", hex.EncodeToString(sum), "expected", hex.EncodeToString(opts.Hash))
+
+		if !bytes.Equal(sum, opts.Hash) {
+			return ErrChecksumMismatch
+		}
+	}
+
+	return nil
+}
+
+// Update uses git to pull the repository and update it
+// to the latest revision. It allows specifying the depth
+// and recursion options via query string. It returns
+// true if update was successful and false if the
+// repository is already up-to-date
+func (d *GitDownloader) Update(opts Options) (bool, error) {
+	u, err := url.Parse(opts.URL)
+	if err != nil {
+		return false, err
+	}
+	u.Scheme = strings.TrimPrefix(u.Scheme, "git+")
+
+	query := u.Query()
+	query.Del("~rev")
+
+	depthStr := query.Get("~depth")
+	query.Del("~depth")
+
+	recursive := query.Get("~recursive")
+	query.Del("~recursive")
+
+	u.RawQuery = query.Encode()
+
+	r, err := git.PlainOpen(opts.Destination)
+	if err != nil {
+		return false, err
+	}
+
+	w, err := r.Worktree()
+	if err != nil {
+		return false, err
+	}
+
+	depth := 0
+	if depthStr != "" {
+		depth, err = strconv.Atoi(depthStr)
+		if err != nil {
+			return false, err
+		}
+	}
+
+	po := &git.PullOptions{
+		Depth:             depth,
+		Progress:          opts.Progress,
+		RecurseSubmodules: git.NoRecurseSubmodules,
+	}
+
+	if recursive == "true" {
+		po.RecurseSubmodules = git.DefaultSubmoduleRecursionDepth
+	}
+
+	m, err := getManifest(opts.Destination)
+	manifestOK := err == nil
+
+	err = w.Pull(po)
+	if err != nil {
+		if errors.Is(err, git.NoErrAlreadyUpToDate) {
+			return false, nil
+		}
+		return false, err
+	}
+
+	err = d.verifyHash(opts)
+	if err != nil {
+		return false, err
+	}
+
+	if manifestOK {
+		err = writeManifest(opts.Destination, m)
+	}
+
+	return true, err
+}