Initial Commit

internal/index/pacman.go

@@ -0,0 +1,145 @@
+/*
+ * distrohop - A utility for correlating and identifying equivalent software
+ * packages across different Linux distributions
+ *
+ * Copyright (C) 2025 Elara Ivy <elara@elara.ws>
+ *
+ * This file is part of distrohop.
+ *
+ * distrohop is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * distrohop 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with distrohop.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package index
+
+import (
+	"archive/tar"
+	"bufio"
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"net/url"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/mholt/archives"
+	"go.elara.ws/distrohop/internal/tags"
+)
+
+type Pacman struct{}
+
+func (Pacman) Name() string {
+	return "pacman"
+}
+
+func (Pacman) IndexURL(baseURL, version, repo, arch string) ([]string, error) {
+	baseURL = os.Expand(baseURL, func(s string) string {
+		switch s {
+		case "repo":
+			return repo
+		case "arch":
+			return arch
+		}
+		return "$" + s
+	})
+
+	u, err := url.ParseRequestURI(baseURL)
+	if err != nil {
+		return nil, err
+	}
+	filePath, err := url.JoinPath(u.Path, repo+".files")
+	if err != nil {
+		return nil, err
+	}
+	u.Path = filePath
+	return []string{u.String()}, nil
+}
+
+func (Pacman) ReadPkgData(r io.Reader, out chan Record) {
+	ctx := context.Background()
+	format, r, err := archives.Identify(ctx, "", r)
+	if err != nil {
+		out <- Record{Error: err}
+		return
+	}
+
+	decomp, ok := format.(archives.Decompressor)
+	if !ok {
+		out <- Record{Error: errors.New("downloaded index is not a valid compressed file")}
+		return
+	}
+
+	dr, err := decomp.OpenReader(r)
+	if err != nil {
+		out <- Record{Error: err}
+		return
+	}
+	defer dr.Close()
+
+	tr := tar.NewReader(dr)
+	var currentPkg string
+
+	for {
+		hdr, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			close(out)
+			break
+		} else if err != nil {
+			out <- Record{Error: err}
+			return
+		}
+
+		switch path.Base(hdr.Name) {
+		case "desc":
+			data, err := io.ReadAll(tr)
+			if err != nil {
+				out <- Record{Error: err}
+				return
+			}
+
+			labelIdx := bytes.Index(data, []byte("%NAME%\n"))
+			if labelIdx == -1 {
+				continue
+			}
+
+			start := labelIdx + 7
+			end := start + bytes.IndexByte(data[start:], '\n')
+			currentPkg = string(data[start:end])
+		case "files":
+			br := bufio.NewReader(tr)
+			for {
+				fpath, err := br.ReadString('\n')
+				if errors.Is(err, io.EOF) {
+					break
+				} else if err != nil {
+					out <- Record{Error: err}
+					return
+				}
+
+				fpath = strings.TrimSpace(fpath)
+				if fpath == "%FILES%" || strings.HasSuffix(fpath, "/") {
+					continue
+				}
+
+				fpath = "/" + fpath
+
+				out <- Record{
+					Name: currentPkg,
+					Tags: tags.Generate(fpath),
+				}
+			}
+		}
+	}
+}