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A couple of small cleanup commits #5

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7903b5a
bspatch: Migrate away from usages of io/ioutil
Jille Jun 18, 2025
3ac85ed
bspatch: Replace zreadall() with io.ReadFull()
Jille Jun 19, 2025
8b01a75
bspatch: Remove noop nil assignments
Jille Jun 19, 2025
406e741
bspatch: Also Close the bzip2 readers when returning an error
Jille Jun 19, 2025
da1d10c
bspatch: Speed up converting little endian integers a little
Jille Jun 19, 2025
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109 changes: 21 additions & 88 deletions pkg/bspatch/bspatch.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,9 +27,10 @@ package bspatch

import (
"bytes"
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"os"

"github.com/dsnet/compress/bzip2"
"github.com/gabstv/go-bsdiff/pkg/util"
Expand All @@ -42,11 +43,11 @@ func Bytes(oldfile, patch []byte) (newfile []byte, err error) {

// Reader applies a BSDIFF4 patch (using oldbin and patchf) to create the newbin
func Reader(oldbin io.Reader, newbin io.Writer, patchf io.Reader) error {
oldbs, err := ioutil.ReadAll(oldbin)
oldbs, err := io.ReadAll(oldbin)
if err != nil {
return err
}
diffbytes, err := ioutil.ReadAll(patchf)
diffbytes, err := io.ReadAll(patchf)
if err != nil {
return err
}
Expand All @@ -59,19 +60,19 @@ func Reader(oldbin io.Reader, newbin io.Writer, patchf io.Reader) error {

// File applies a BSDIFF4 patch (using oldfile and patchfile) to create the newfile
func File(oldfile, newfile, patchfile string) error {
oldbs, err := ioutil.ReadFile(oldfile)
oldbs, err := os.ReadFile(oldfile)
if err != nil {
return fmt.Errorf("could not read oldfile '%v': %v", oldfile, err.Error())
}
patchbs, err := ioutil.ReadFile(patchfile)
patchbs, err := os.ReadFile(patchfile)
if err != nil {
return fmt.Errorf("could not read patchfile '%v': %v", patchfile, err.Error())
}
newbytes, err := patchb(oldbs, patchbs)
if err != nil {
return fmt.Errorf("bspatch: %v", err.Error())
}
if err := ioutil.WriteFile(newfile, newbytes, 0644); err != nil {
if err := os.WriteFile(newfile, newbytes, 0644); err != nil {
return fmt.Errorf("could not create newfile '%v': %v", newfile, err.Error())
}
return nil
Expand All @@ -82,7 +83,6 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
var newsize int
header := make([]byte, 32)
buf := make([]byte, 8)
var lenread int
var i int
ctrl := make([]int, 3)

Expand Down Expand Up @@ -131,6 +131,7 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
if err != nil {
return nil, err
}
defer cpfbz2.Close()
dpf := bytes.NewReader(patch)
if _, err := dpf.Seek(int64(32+bzctrllen), io.SeekStart); err != nil {
return nil, err
Expand All @@ -139,6 +140,7 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
if err != nil {
return nil, err
}
defer dpfbz2.Close()
epf := bytes.NewReader(patch)
if _, err := epf.Seek(int64(32+bzctrllen+bzdatalen), io.SeekStart); err != nil {
return nil, err
Expand All @@ -147,6 +149,7 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
if err != nil {
return nil, err
}
defer epfbz2.Close()

pnew := make([]byte, newsize)

Expand All @@ -156,13 +159,8 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
for newpos < newsize {
// Read control data
for i = 0; i <= 2; i++ {
lenread, err = zreadall(cpfbz2, buf, 8)
if lenread != 8 || (err != nil && err != io.EOF) {
e0 := ""
if err != nil {
e0 = err.Error()
}
return nil, fmt.Errorf("corrupt patch or bzstream ended: %s (read: %v/8)", e0, lenread)
if _, err = io.ReadFull(cpfbz2, buf); err != nil {
return nil, fmt.Errorf("corrupt patch or bzstream ended: %s", err)
}
ctrl[i] = offtin(buf)
}
Expand All @@ -172,14 +170,8 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
}

// Read diff string
// lenread, err = dpfbz2.Read(pnew[newpos : newpos+ctrl[0]])
lenread, err = zreadall(dpfbz2, pnew[newpos:newpos+ctrl[0]], ctrl[0])
if lenread < ctrl[0] || (err != nil && err != io.EOF) {
e0 := ""
if err != nil {
e0 = err.Error()
}
return nil, fmt.Errorf("corrupt patch or bzstream ended (2): %s", e0)
if _, err := io.ReadFull(dpfbz2, pnew[newpos:newpos+ctrl[0]]); err != nil {
return nil, fmt.Errorf("corrupt patch or bzstream ended (2): %s", err)
}
// Add pold data to diff string
for i = 0; i < ctrl[0]; i++ {
Expand All @@ -198,81 +190,22 @@ func patchb(oldfile, patch []byte) ([]byte, error) {
}

// Read extra string
// epfbz2.Read was not reading all the requested bytes, probably an internal buffer limitation ?
// it was encapsulated by zreadall to work around the issue
lenread, err = zreadall(epfbz2, pnew[newpos:newpos+ctrl[1]], ctrl[1])
if lenread < ctrl[1] || (err != nil && err != io.EOF) {
e0 := ""
if err != nil {
e0 = err.Error()
}
return nil, fmt.Errorf("corrupt patch or bzstream ended (3): %s", e0)
if _, err := io.ReadFull(epfbz2, pnew[newpos:newpos+ctrl[1]]); err != nil {
return nil, fmt.Errorf("corrupt patch or bzstream ended (3): %s", err)
}
// Adjust pointers
newpos += ctrl[1]
oldpos += ctrl[2]
}

// Clean up the bzip2 reads
if err = cpfbz2.Close(); err != nil {
return nil, err
}
if err = dpfbz2.Close(); err != nil {
return nil, err
}
if err = epfbz2.Close(); err != nil {
return nil, err
}
cpfbz2 = nil
dpfbz2 = nil
epfbz2 = nil
cpf = nil
dpf = nil
epf = nil

return pnew, nil
}

// offtin reads an int64 (little endian)
// offtin reads an int64 (little endian using a sign-bit, not two's complement)
func offtin(buf []byte) int {

y := int(buf[7] & 0x7f)
y = y * 256
y += int(buf[6])
y = y * 256
y += int(buf[5])
y = y * 256
y += int(buf[4])
y = y * 256
y += int(buf[3])
y = y * 256
y += int(buf[2])
y = y * 256
y += int(buf[1])
y = y * 256
y += int(buf[0])

if (buf[7] & 0x80) != 0 {
y = -y
}
return y
}

func zreadall(r io.Reader, b []byte, expected int) (int, error) {
var allread int
var offset int
for {
nread, err := r.Read(b[offset:])
if nread == expected {
return nread, err
}
if err != nil {
return allread + nread, err
}
allread += nread
if allread >= expected {
return allread, nil
}
offset += nread
v := binary.LittleEndian.Uint64(buf)
if v&(1<<63) != 0 {
return -int(v &^ (1 << 63))
}
return int(v)
}
3 changes: 2 additions & 1 deletion pkg/bspatch/bspatch_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import (
"bytes"
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"os"
"testing"
Expand Down Expand Up @@ -280,7 +281,7 @@ func TestZReadAll(t *testing.T) {
rr := &lowcaprdr{
read: make([]byte, 1024),
}
nr, err := zreadall(rr, buf, len(buf))
nr, err := io.ReadFull(rr, buf)
if err != nil {
t.Fail()
}
Expand Down