FDN-01: repository & projektgerüst

Git-Repository für bestehenden archivdms-Code initialisiert, Branch-/Commit-Konvention (feature/<ticket>-<slug>-Branches, Ticket-Prefix in Commit-Nachricht) etabliert.

internal/barcode/barcode.go

@@ -0,0 +1,64 @@
+// Package barcode wraps the system zbarimg binary (Debian package
+// zbar-tools) as a best-effort barcode decoding sidecar, consistent with
+// archivdms's general philosophy of shelling out to small CLI tools via
+// os/exec instead of adding CGO/native Go dependencies (see
+// internal/ocr/ocr.go package comment for the same rationale applied to
+// tesseract/poppler-utils).
+//
+// Barcode decoding failures (binary missing, non-zero exit because no
+// barcode was found, timeout) are never fatal to an upload: DecodeBarcodes
+// returns an empty slice and a nil error in the "nothing found / binary
+// missing" cases, matching how OCR failures are tolerated by callers.
+package barcode
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+const defaultTimeout = 20 * time.Second
+
+// DecodeBarcodes runs `zbarimg --raw -q <imagePath>` and returns the
+// decoded raw values, one per line of output. If zbarimg is not installed,
+// this returns an empty slice and a nil error (tolerant, no hard-fail) —
+// callers that want to warn about a missing binary should check
+// exec.LookPath("zbarimg") themselves if they need to distinguish
+// "not installed" from "installed, nothing found".
+func DecodeBarcodes(ctx context.Context, imagePath string) ([]string, error) {
+	if _, err := exec.LookPath("zbarimg"); err != nil {
+		// Binary not present: tolerated, same as a missing tesseract binary.
+		return nil, nil
+	}
+
+	cctx, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+
+	cmd := exec.CommandContext(cctx, "zbarimg", "--raw", "-q", imagePath)
+	var out, stderr bytes.Buffer
+	cmd.Stdout = &out
+	cmd.Stderr = &stderr
+	err := cmd.Run()
+	if err != nil {
+		// zbarimg exits non-zero (typically exit code 4) when no barcode is
+		// found in the image at all — that is a normal, expected outcome for
+		// the vast majority of scanned documents, not an error condition.
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			_ = exitErr
+			return nil, nil
+		}
+		return nil, fmt.Errorf("barcode: zbarimg failed: %w (%s)", err, strings.TrimSpace(stderr.String()))
+	}
+
+	var values []string
+	for _, line := range strings.Split(out.String(), "\n") {
+		line = strings.TrimSpace(line)
+		if line != "" {
+			values = append(values, line)
+		}
+	}
+	return values, nil
+}