Revert "plumbing: format/packfile, prevent large objects from being read into memory completely (#303)" (#329)v5.4.2

This reverts commit 720c192831a890d0a36b4c6720b60411fa4a0159.

4 files changed, 0 insertions, 313 deletions

diff --git a/plumbing/format/packfile/fsobject.go b/plumbing/format/packfile/fsobject.go
index 4aa3c8e..c5edaf5 100644
--- a/plumbing/format/packfile/fsobject.go
+++ b/plumbing/format/packfile/fsobject.go
@@ -7,7 +7,6 @@ import (
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/format/idxfile"
-	"github.com/go-git/go-git/v5/utils/ioutil"
 )
 
 // FSObject is an object from the packfile on the filesystem.
@@ -64,20 +63,6 @@ func (o *FSObject) Reader() (io.ReadCloser, error) {
 	}
 
 	p := NewPackfileWithCache(o.index, nil, f, o.cache)
-	if o.size > LargeObjectThreshold {
-		// We have a big object
-		h, err := p.objectHeaderAtOffset(o.offset)
-		if err != nil {
-			return nil, err
-		}
-
-		r, err := p.getReaderDirect(h)
-		if err != nil {
-			_ = f.Close()
-			return nil, err
-		}
-		return ioutil.NewReadCloserWithCloser(r, f.Close), nil
-	}
 	r, err := p.getObjectContent(o.offset)
 	if err != nil {
 		_ = f.Close()
diff --git a/plumbing/format/packfile/packfile.go b/plumbing/format/packfile/packfile.go
index 77861d2..ddd7f62 100644
--- a/plumbing/format/packfile/packfile.go
+++ b/plumbing/format/packfile/packfile.go
@@ -32,12 +32,6 @@ var (
 // wrapped in FSObject.
 const smallObjectThreshold = 16 * 1024
 
-// Conversely there are large objects that should not be cached and kept
-// in memory as they're too large to be reasonably cached. Objects larger
-// than this threshold are now always never read into memory to be stored
-// in the cache
-const LargeObjectThreshold = 1024 * 1024
-
 // Packfile allows retrieving information from inside a packfile.
 type Packfile struct {
 	idxfile.Index
@@ -288,37 +282,6 @@ func (p *Packfile) getObjectContent(offset int64) (io.ReadCloser, error) {
 	return obj.Reader()
 }
 
-func (p *Packfile) getReaderDirect(h *ObjectHeader) (io.ReadCloser, error) {
-	switch h.Type {
-	case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject:
-		return p.s.ReadObject()
-	case plumbing.REFDeltaObject:
-		deltaRC, err := p.s.ReadObject()
-		if err != nil {
-			return nil, err
-		}
-		r, err := p.readREFDeltaObjectContent(h, deltaRC)
-		if err != nil {
-			_ = deltaRC.Close()
-			return nil, err
-		}
-		return r, nil
-	case plumbing.OFSDeltaObject:
-		deltaRC, err := p.s.ReadObject()
-		if err != nil {
-			return nil, err
-		}
-		r, err := p.readOFSDeltaObjectContent(h, deltaRC)
-		if err != nil {
-			_ = deltaRC.Close()
-			return nil, err
-		}
-		return r, nil
-	default:
-		return nil, ErrInvalidObject.AddDetails("type %q", h.Type)
-	}
-}
-
 func (p *Packfile) getNextMemoryObject(h *ObjectHeader) (plumbing.EncodedObject, error) {
 	var obj = new(plumbing.MemoryObject)
 	obj.SetSize(h.Length)
@@ -371,20 +334,6 @@ func (p *Packfile) fillREFDeltaObjectContent(obj plumbing.EncodedObject, ref plu
 	return p.fillREFDeltaObjectContentWithBuffer(obj, ref, buf)
 }
 
-func (p *Packfile) readREFDeltaObjectContent(h *ObjectHeader, deltaRC io.ReadCloser) (io.ReadCloser, error) {
-	var err error
-
-	base, ok := p.cacheGet(h.Reference)
-	if !ok {
-		base, err = p.Get(h.Reference)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return ReaderFromDelta(h, base, deltaRC)
-}
-
 func (p *Packfile) fillREFDeltaObjectContentWithBuffer(obj plumbing.EncodedObject, ref plumbing.Hash, buf *bytes.Buffer) error {
 	var err error
 
@@ -415,28 +364,6 @@ func (p *Packfile) fillOFSDeltaObjectContent(obj plumbing.EncodedObject, offset
 	return p.fillOFSDeltaObjectContentWithBuffer(obj, offset, buf)
 }
 
-func (p *Packfile) readOFSDeltaObjectContent(h *ObjectHeader, deltaRC io.ReadCloser) (io.ReadCloser, error) {
-	hash, err := p.FindHash(h.OffsetReference)
-	if err != nil {
-		return nil, err
-	}
-
-	base, err := p.objectAtOffset(h.OffsetReference, hash)
-	if err != nil {
-		return nil, err
-	}
-
-	base, ok := p.cacheGet(h.Reference)
-	if !ok {
-		base, err = p.Get(h.Reference)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return ReaderFromDelta(h, base, deltaRC)
-}
-
 func (p *Packfile) fillOFSDeltaObjectContentWithBuffer(obj plumbing.EncodedObject, offset int64, buf *bytes.Buffer) error {
 	hash, err := p.FindHash(offset)
 	if err != nil {
diff --git a/plumbing/format/packfile/patch_delta.go b/plumbing/format/packfile/patch_delta.go
index 76fef4a..9e90f30 100644
--- a/plumbing/format/packfile/patch_delta.go
+++ b/plumbing/format/packfile/patch_delta.go
@@ -1,11 +1,9 @@
 package packfile
 
 import (
-	"bufio"
 	"bytes"
 	"errors"
 	"io"
-	"math"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/utils/ioutil"
@@ -75,131 +73,6 @@ func PatchDelta(src, delta []byte) ([]byte, error) {
 	return b.Bytes(), nil
 }
 
-func ReaderFromDelta(h *ObjectHeader, base plumbing.EncodedObject, deltaRC io.ReadCloser) (io.ReadCloser, error) {
-	deltaBuf := bufio.NewReaderSize(deltaRC, 1024)
-	srcSz, err := decodeLEB128ByteReader(deltaBuf)
-	if err != nil {
-		if err == io.EOF {
-			return nil, ErrInvalidDelta
-		}
-		return nil, err
-	}
-	if srcSz != uint(base.Size()) {
-		return nil, ErrInvalidDelta
-	}
-
-	targetSz, err := decodeLEB128ByteReader(deltaBuf)
-	if err != nil {
-		if err == io.EOF {
-			return nil, ErrInvalidDelta
-		}
-		return nil, err
-	}
-	remainingTargetSz := targetSz
-
-	dstRd, dstWr := io.Pipe()
-
-	go func() {
-		baseRd, err := base.Reader()
-		if err != nil {
-			_ = dstWr.CloseWithError(ErrInvalidDelta)
-			return
-		}
-		defer baseRd.Close()
-
-		baseBuf := bufio.NewReader(baseRd)
-		basePos := uint(0)
-
-		for {
-			cmd, err := deltaBuf.ReadByte()
-			if err == io.EOF {
-				_ = dstWr.CloseWithError(ErrInvalidDelta)
-				return
-			}
-			if err != nil {
-				_ = dstWr.CloseWithError(err)
-				return
-			}
-
-			if isCopyFromSrc(cmd) {
-				offset, err := decodeOffsetByteReader(cmd, deltaBuf)
-				if err != nil {
-					_ = dstWr.CloseWithError(err)
-					return
-				}
-				sz, err := decodeSizeByteReader(cmd, deltaBuf)
-				if err != nil {
-					_ = dstWr.CloseWithError(err)
-					return
-				}
-
-				if invalidSize(sz, targetSz) ||
-					invalidOffsetSize(offset, sz, srcSz) {
-					_ = dstWr.Close()
-					return
-				}
-
-				discard := offset - basePos
-				if discard < 0 {
-					_ = baseRd.Close()
-					baseRd, err = base.Reader()
-					if err != nil {
-						_ = dstWr.CloseWithError(ErrInvalidDelta)
-						return
-					}
-					baseBuf.Reset(baseRd)
-					discard = offset
-				}
-				for discard > math.MaxInt32 {
-					n, err := baseBuf.Discard(math.MaxInt32)
-					if err != nil {
-						_ = dstWr.CloseWithError(err)
-						return
-					}
-					basePos += uint(n)
-					discard -= uint(n)
-				}
-				for discard > 0 {
-					n, err := baseBuf.Discard(int(discard))
-					if err != nil {
-						_ = dstWr.CloseWithError(err)
-						return
-					}
-					basePos += uint(n)
-					discard -= uint(n)
-				}
-				if _, err := io.Copy(dstWr, io.LimitReader(baseBuf, int64(sz))); err != nil {
-					_ = dstWr.CloseWithError(err)
-					return
-				}
-				remainingTargetSz -= sz
-				basePos += sz
-			} else if isCopyFromDelta(cmd) {
-				sz := uint(cmd) // cmd is the size itself
-				if invalidSize(sz, targetSz) {
-					_ = dstWr.CloseWithError(ErrInvalidDelta)
-					return
-				}
-				if _, err := io.Copy(dstWr, io.LimitReader(deltaBuf, int64(sz))); err != nil {
-					_ = dstWr.CloseWithError(err)
-					return
-				}
-
-				remainingTargetSz -= sz
-			} else {
-				_ = dstWr.CloseWithError(ErrDeltaCmd)
-				return
-			}
-			if remainingTargetSz <= 0 {
-				_ = dstWr.Close()
-				return
-			}
-		}
-	}()
-
-	return dstRd, nil
-}
-
 func patchDelta(dst *bytes.Buffer, src, delta []byte) error {
 	if len(delta) < deltaSizeMin {
 		return ErrInvalidDelta
@@ -288,25 +161,6 @@ func decodeLEB128(input []byte) (uint, []byte) {
 	return num, input[sz:]
 }
 
-func decodeLEB128ByteReader(input io.ByteReader) (uint, error) {
-	var num, sz uint
-	for {
-		b, err := input.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-
-		num |= (uint(b) & payload) << (sz * 7) // concats 7 bits chunks
-		sz++
-
-		if uint(b)&continuation == 0 {
-			break
-		}
-	}
-
-	return num, nil
-}
-
 const (
 	payload      = 0x7f // 0111 1111
 	continuation = 0x80 // 1000 0000
@@ -320,40 +174,6 @@ func isCopyFromDelta(cmd byte) bool {
 	return (cmd&0x80) == 0 && cmd != 0
 }
 
-func decodeOffsetByteReader(cmd byte, delta io.ByteReader) (uint, error) {
-	var offset uint
-	if (cmd & 0x01) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		offset = uint(next)
-	}
-	if (cmd & 0x02) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		offset |= uint(next) << 8
-	}
-	if (cmd & 0x04) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		offset |= uint(next) << 16
-	}
-	if (cmd & 0x08) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		offset |= uint(next) << 24
-	}
-
-	return offset, nil
-}
-
 func decodeOffset(cmd byte, delta []byte) (uint, []byte, error) {
 	var offset uint
 	if (cmd & 0x01) != 0 {
@@ -388,36 +208,6 @@ func decodeOffset(cmd byte, delta []byte) (uint, []byte, error) {
 	return offset, delta, nil
 }
 
-func decodeSizeByteReader(cmd byte, delta io.ByteReader) (uint, error) {
-	var sz uint
-	if (cmd & 0x10) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		sz = uint(next)
-	}
-	if (cmd & 0x20) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		sz |= uint(next) << 8
-	}
-	if (cmd & 0x40) != 0 {
-		next, err := delta.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		sz |= uint(next) << 16
-	}
-	if sz == 0 {
-		sz = 0x10000
-	}
-
-	return sz, nil
-}
-
 func decodeSize(cmd byte, delta []byte) (uint, []byte, error) {
 	var sz uint
 	if (cmd & 0x10) != 0 {
diff --git a/plumbing/format/packfile/scanner.go b/plumbing/format/packfile/scanner.go
index 5d9e8fb..6e6a687 100644
--- a/plumbing/format/packfile/scanner.go
+++ b/plumbing/format/packfile/scanner.go
@@ -320,21 +320,6 @@ func (s *Scanner) NextObject(w io.Writer) (written int64, crc32 uint32, err erro
 	return
 }
 
-// ReadObject returns a reader for the object content and an error
-func (s *Scanner) ReadObject() (io.ReadCloser, error) {
-	s.pendingObject = nil
-	zr := zlibReaderPool.Get().(io.ReadCloser)
-
-	if err := zr.(zlib.Resetter).Reset(s.r, nil); err != nil {
-		return nil, fmt.Errorf("zlib reset error: %s", err)
-	}
-
-	return ioutil.NewReadCloserWithCloser(zr, func() error {
-		zlibReaderPool.Put(zr)
-		return nil
-	}), nil
-}
-
 // ReadRegularObject reads and write a non-deltified object
 // from it zlib stream in an object entry in the packfile.
 func (s *Scanner) copyObject(w io.Writer) (n int64, err error) {