add apt gestion

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

internal/clone/apt/packages.go

@@ -0,0 +1,128 @@
+package apt
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+)
+
+// DebPackage represents a single stanza from a Debian Packages file.
+type DebPackage struct {
+	Package      string
+	Version      string
+	Architecture string
+	Filename     string // relative path, e.g. pool/main/c/curl/curl_7.88_amd64.deb
+	SHA256       string
+	Size         int64
+	Raw          []byte // original stanza bytes for faithful re-emission
+}
+
+// ParsePackages parses all stanzas from a Debian Packages control file.
+// Stanzas are separated by blank lines.
+func ParsePackages(data []byte) ([]DebPackage, error) {
+	// Normalise line endings.
+	data = bytes.ReplaceAll(data, []byte("\r\n"), []byte("\n"))
+
+	var pkgs []DebPackage
+	stanzas := bytes.Split(data, []byte("\n\n"))
+
+	for _, stanza := range stanzas {
+		stanza = bytes.TrimSpace(stanza)
+		if len(stanza) == 0 {
+			continue
+		}
+		pkg, err := parseStanza(stanza)
+		if err != nil {
+			return nil, fmt.Errorf("parse stanza: %w", err)
+		}
+		pkgs = append(pkgs, pkg)
+	}
+	return pkgs, nil
+}
+
+func parseStanza(stanza []byte) (DebPackage, error) {
+	var pkg DebPackage
+	pkg.Raw = stanza
+
+	lines := bytes.Split(stanza, []byte("\n"))
+	for _, rawLine := range lines {
+		line := bytes.TrimRight(rawLine, " \t")
+		// Continuation lines (description body etc.) start with a space — skip.
+		if len(line) == 0 || line[0] == ' ' || line[0] == '\t' {
+			continue
+		}
+
+		colonIdx := bytes.IndexByte(line, ':')
+		if colonIdx < 0 {
+			continue
+		}
+		key := string(bytes.TrimSpace(line[:colonIdx]))
+		value := string(bytes.TrimSpace(line[colonIdx+1:]))
+
+		switch key {
+		case "Package":
+			pkg.Package = value
+		case "Version":
+			pkg.Version = value
+		case "Architecture":
+			pkg.Architecture = value
+		case "Filename":
+			pkg.Filename = value
+		case "SHA256":
+			pkg.SHA256 = value
+		case "Size":
+			n, err := strconv.ParseInt(value, 10, 64)
+			if err != nil {
+				return DebPackage{}, fmt.Errorf("bad Size value %q: %w", value, err)
+			}
+			pkg.Size = n
+		}
+	}
+
+	if pkg.Package == "" {
+		return DebPackage{}, fmt.Errorf("stanza missing Package field")
+	}
+	return pkg, nil
+}
+
+// FilterPackages returns only the packages for which presentOnDisk returns true.
+func FilterPackages(pkgs []DebPackage, presentOnDisk func(filename string) bool) []DebPackage {
+	var out []DebPackage
+	for _, p := range pkgs {
+		if presentOnDisk(p.Filename) {
+			out = append(out, p)
+		}
+	}
+	return out
+}
+
+// emitPackages serialises a slice of DebPackage back to Packages-file format,
+// using the original Raw bytes for each stanza.
+func emitPackages(pkgs []DebPackage) []byte {
+	var buf bytes.Buffer
+	for i, pkg := range pkgs {
+		// Strip trailing whitespace from each line within the stanza.
+		lines := bytes.Split(pkg.Raw, []byte("\n"))
+		for j, l := range lines {
+			lines[j] = bytes.TrimRight(l, " \t")
+		}
+		buf.Write(bytes.Join(lines, []byte("\n")))
+		if i < len(pkgs)-1 {
+			buf.WriteString("\n\n")
+		} else {
+			buf.WriteString("\n")
+		}
+	}
+	return buf.Bytes()
+}
+
+// diskPresenceChecker returns a presentOnDisk func rooted at localDir.
+func diskPresenceChecker(localDir string) func(string) bool {
+	return func(filename string) bool {
+		p := filepath.Join(localDir, filepath.FromSlash(filename))
+		_, err := os.Stat(p)
+		return err == nil
+	}
+}