From ae5c818674e2c9ca950ca7a9bf93f1283e7411b7 Mon Sep 17 00:00:00 2001
From: Runxi Yu
Date: Sun, 8 Mar 2026 12:03:26 +0800
Subject: receivepack, format/pack/ingest: Two-stage ingestion

---
 format/pack/ingest/header.go | 41 ++++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

(limited to 'format/pack/ingest/header.go')

diff --git a/format/pack/ingest/header.go b/format/pack/ingest/header.go
index fba2b175..76d43bef 100644
--- a/format/pack/ingest/header.go
+++ b/format/pack/ingest/header.go
@@ -3,32 +3,47 @@ package ingest
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
 
 	"codeberg.org/lindenii/furgit/format/pack"
 )
 
-// readAndValidatePackHeader reads and validates PACK header from the stream.
-func readAndValidatePackHeader(state *ingestState) error {
-	var hdr [12]byte
+const packHeaderSize = 12
 
-	err := state.stream.readFull(hdr[:])
+// readAndValidatePackHeader reads one PACK header from src and validates it.
+func readAndValidatePackHeader(src io.Reader) (HeaderInfo, [packHeaderSize]byte, error) {
+	var hdr [packHeaderSize]byte
+
+	_, err := io.ReadFull(src, hdr[:])
+	if err != nil {
+		return HeaderInfo{}, [packHeaderSize]byte{}, &InvalidPackHeaderError{
+			Reason: fmt.Sprintf("read header: %v", err),
+		}
+	}
+
+	header, err := parseAndValidatePackHeader(hdr)
 	if err != nil {
-		return &InvalidPackHeaderError{Reason: fmt.Sprintf("read header: %v", err)}
+		return HeaderInfo{}, [packHeaderSize]byte{}, err
 	}
 
+	return header, hdr, nil
+}
+
+// parseAndValidatePackHeader validates one already-read PACK header.
+func parseAndValidatePackHeader(hdr [packHeaderSize]byte) (HeaderInfo, error) {
 	if binary.BigEndian.Uint32(hdr[:4]) != pack.Signature {
-		return &InvalidPackHeaderError{Reason: "signature mismatch"}
+		return HeaderInfo{}, &InvalidPackHeaderError{Reason: "signature mismatch"}
 	}
 
 	version := binary.BigEndian.Uint32(hdr[4:8])
 	if !pack.VersionSupported(version) {
-		return &InvalidPackHeaderError{Reason: fmt.Sprintf("unsupported version %d", version)}
-	}
-
-	state.objectCountHeader = binary.BigEndian.Uint32(hdr[8:12])
-	if state.objectCountHeader == 0 {
-		return &InvalidPackHeaderError{Reason: "zero objects"}
+		return HeaderInfo{}, &InvalidPackHeaderError{
+			Reason: fmt.Sprintf("unsupported version %d", version),
+		}
 	}
 
-	return nil
+	return HeaderInfo{
+		Version:     version,
+		ObjectCount: binary.BigEndian.Uint32(hdr[8:12]),
+	}, nil
 }
-- 
cgit v1.3.1-10-gc9f91