Revert "Compute checksum when reading packfiles"

This reverts commit 1dcb92427c23d0a8b23c0154b892243c749afa5a.

Yeah this should be part of the network protocol rather than being done
on *every read*.

4 files changed, 3 insertions, 58 deletions

diff --git a/pack_idx.go b/pack_idx.go
index a9cb9056..68170ad3 100644
--- a/pack_idx.go
+++ b/pack_idx.go
@@ -196,23 +196,6 @@ func (pi *packIndex) parse(buf []byte) error {
 	pi.numObjects = nobj
 	pi.names = buf[namesStart:namesEnd]
 	pi.crcs = buf[crcStart:crcEnd]
-
-	if len(buf) < 2*pi.repo.hashSize {
-		return ErrInvalidObject
-	}
-	idxChecksumStart := len(buf) - pi.repo.hashSize
-	idxChecksumInFile := buf[idxChecksumStart:]
-
-	hashFn, ok := hashFuncs[pi.repo.hashSize]
-	if !ok {
-		return fmt.Errorf("furgit: unsupported hash size %d", pi.repo.hashSize)
-	}
-
-	computedHash := hashFn(buf[:idxChecksumStart])
-	if !bytes.Equal(computedHash.data[:pi.repo.hashSize], idxChecksumInFile) {
-		return fmt.Errorf("furgit: index checksum mismatch in %s", pi.idxRel)
-	}
-
 	return nil
 }
 
diff --git a/pack_midx.go b/pack_midx.go
index 04151dfe..748bdaf6 100644
--- a/pack_midx.go
+++ b/pack_midx.go
@@ -1,7 +1,6 @@
 package furgit
 
 import (
-	"bytes"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -236,23 +235,6 @@ func (midx *multiPackIndex) parse(buf []byte) error {
 	midx.oids = oids
 	midx.offsets = offsets
 	midx.largeOffs = largeOffs
-
-	if len(buf) < midx.repo.hashSize {
-		return ErrInvalidObject
-	}
-	midxChecksumStart := len(buf) - midx.repo.hashSize
-	midxChecksumInFile := buf[midxChecksumStart:]
-
-	hashFn, ok := hashFuncs[midx.repo.hashSize]
-	if !ok {
-		return fmt.Errorf("furgit: unsupported hash size %d", midx.repo.hashSize)
-	}
-
-	computedHash := hashFn(buf[:midxChecksumStart])
-	if !bytes.Equal(computedHash.data[:midx.repo.hashSize], midxChecksumInFile) {
-		return fmt.Errorf("furgit: multi-pack-index checksum mismatch")
-	}
-
 	return nil
 }
 
diff --git a/pack_pack.go b/pack_pack.go
index 6d740b73..5c2c8628 100644
--- a/pack_pack.go
+++ b/pack_pack.go
@@ -487,7 +487,7 @@ type packFile struct {
 	closeMu sync.Once
 }
 
-func openPackFile(absPath, rel string, hashSize int) (*packFile, error) {
+func openPackFile(absPath, rel string) (*packFile, error) {
 	f, err := os.Open(absPath)
 	if err != nil {
 		return nil, err
@@ -498,7 +498,7 @@ func openPackFile(absPath, rel string, hashSize int) (*packFile, error) {
 		_ = f.Close()
 		return nil, err
 	}
-	if stat.Size() < 12+int64(hashSize) {
+	if stat.Size() < 12 {
 		_ = f.Close()
 		return nil, ErrInvalidObject
 	}
@@ -532,26 +532,6 @@ func openPackFile(absPath, rel string, hashSize int) (*packFile, error) {
 		_ = syscall.Munmap(region)
 		return nil, err
 	}
-
-	if len(region) < hashSize {
-		_ = syscall.Munmap(region)
-		return nil, ErrInvalidObject
-	}
-	dataEnd := len(region) - hashSize
-	checksumInFile := region[dataEnd:]
-
-	hashFn, ok := hashFuncs[hashSize]
-	if !ok {
-		_ = syscall.Munmap(region)
-		return nil, fmt.Errorf("furgit: unsupported hash size %d", hashSize)
-	}
-
-	computedHash := hashFn(region[:dataEnd])
-	if !bytes.Equal(computedHash.data[:hashSize], checksumInFile) {
-		_ = syscall.Munmap(region)
-		return nil, fmt.Errorf("furgit: pack checksum mismatch in %s", rel)
-	}
-
 	return &packFile{
 		relPath: rel,
 		size:    stat.Size(),
diff --git a/repo.go b/repo.go
index 50849c0d..0fdfa5dd 100644
--- a/repo.go
+++ b/repo.go
@@ -132,7 +132,7 @@ func (repo *Repository) packFile(rel string) (*packFile, error) {
 	if pf, ok := repo.packFiles.Load(rel); ok {
 		return pf.(*packFile), nil
 	}
-	pf, err := openPackFile(repo.repoPath(rel), rel, repo.hashSize)
+	pf, err := openPackFile(repo.repoPath(rel), rel)
 	if err != nil {
 		return nil, err
 	}