A fork of Gitea (see branch `mj`) adding Majority Judgment Polls 𐄷 over Issues and Merge Requests. https://git.mieuxvoter.fr
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// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package git
import (
"bufio"
"bytes"
"io"
"math"
"strconv"
"strings"
)
// CatFileBatch opens git cat-file --batch in the provided repo and returns a stdin pipe, a stdout reader and cancel function
func CatFileBatch(repoPath string) (*io.PipeWriter, *bufio.Reader, func()) {
// Next feed the commits in order into cat-file --batch, followed by their trees and sub trees as necessary.
// so let's create a batch stdin and stdout
batchStdinReader, batchStdinWriter := io.Pipe()
batchStdoutReader, batchStdoutWriter := io.Pipe()
cancel := func() {
_ = batchStdinReader.Close()
_ = batchStdinWriter.Close()
_ = batchStdoutReader.Close()
_ = batchStdoutWriter.Close()
}
go func() {
stderr := strings.Builder{}
err := NewCommand("cat-file", "--batch").RunInDirFullPipeline(repoPath, batchStdoutWriter, &stderr, batchStdinReader)
if err != nil {
_ = batchStdoutWriter.CloseWithError(ConcatenateError(err, (&stderr).String()))
_ = batchStdinReader.CloseWithError(ConcatenateError(err, (&stderr).String()))
} else {
_ = batchStdoutWriter.Close()
_ = batchStdinReader.Close()
}
}()
// For simplicities sake we'll us a buffered reader to read from the cat-file --batch
batchReader := bufio.NewReader(batchStdoutReader)
return batchStdinWriter, batchReader, cancel
}
// ReadBatchLine reads the header line from cat-file --batch
// We expect:
// <sha> SP <type> SP <size> LF
func ReadBatchLine(rd *bufio.Reader) (sha []byte, typ string, size int64, err error) {
sha, err = rd.ReadBytes(' ')
if err != nil {
return
}
sha = sha[:len(sha)-1]
typ, err = rd.ReadString(' ')
if err != nil {
return
}
typ = typ[:len(typ)-1]
var sizeStr string
sizeStr, err = rd.ReadString('\n')
if err != nil {
return
}
size, err = strconv.ParseInt(sizeStr[:len(sizeStr)-1], 10, 64)
return
}
// ReadTagObjectID reads a tag object ID hash from a cat-file --batch stream, throwing away the rest of the stream.
func ReadTagObjectID(rd *bufio.Reader, size int64) (string, error) {
id := ""
var n int64
headerLoop:
for {
line, err := rd.ReadBytes('\n')
if err != nil {
return "", err
}
n += int64(len(line))
idx := bytes.Index(line, []byte{' '})
if idx < 0 {
continue
}
if string(line[:idx]) == "object" {
id = string(line[idx+1 : len(line)-1])
break headerLoop
}
}
// Discard the rest of the tag
discard := size - n
for discard > math.MaxInt32 {
_, err := rd.Discard(math.MaxInt32)
if err != nil {
return id, err
}
discard -= math.MaxInt32
}
_, err := rd.Discard(int(discard))
return id, err
}
// ReadTreeID reads a tree ID from a cat-file --batch stream, throwing away the rest of the stream.
func ReadTreeID(rd *bufio.Reader, size int64) (string, error) {
id := ""
var n int64
headerLoop:
for {
line, err := rd.ReadBytes('\n')
if err != nil {
return "", err
}
n += int64(len(line))
idx := bytes.Index(line, []byte{' '})
if idx < 0 {
continue
}
if string(line[:idx]) == "tree" {
id = string(line[idx+1 : len(line)-1])
break headerLoop
}
}
// Discard the rest of the commit
discard := size - n
for discard > math.MaxInt32 {
_, err := rd.Discard(math.MaxInt32)
if err != nil {
return id, err
}
discard -= math.MaxInt32
}
_, err := rd.Discard(int(discard))
return id, err
}
// git tree files are a list:
// <mode-in-ascii> SP <fname> NUL <20-byte SHA>
//
// Unfortunately this 20-byte notation is somewhat in conflict to all other git tools
// Therefore we need some method to convert these 20-byte SHAs to a 40-byte SHA
// constant hextable to help quickly convert between 20byte and 40byte hashes
const hextable = "0123456789abcdef"
// To40ByteSHA converts a 20-byte SHA in a 40-byte slice into a 40-byte sha in place
// without allocations. This is at least 100x quicker that hex.EncodeToString
// NB This requires that sha is a 40-byte slice
func To40ByteSHA(sha []byte) []byte {
for i := 19; i >= 0; i-- {
v := sha[i]
vhi, vlo := v>>4, v&0x0f
shi, slo := hextable[vhi], hextable[vlo]
sha[i*2], sha[i*2+1] = shi, slo
}
return sha
}
// ParseTreeLineSkipMode reads an entry from a tree in a cat-file --batch stream
// This simply skips the mode - saving a substantial amount of time and carefully avoids allocations - except where fnameBuf is too small.
// It is recommended therefore to pass in an fnameBuf large enough to avoid almost all allocations
//
// Each line is composed of:
// <mode-in-ascii-dropping-initial-zeros> SP <fname> NUL <20-byte SHA>
//
// We don't attempt to convert the 20-byte SHA to 40-byte SHA to save a lot of time
func ParseTreeLineSkipMode(rd *bufio.Reader, fnameBuf, shaBuf []byte) (fname, sha []byte, n int, err error) {
var readBytes []byte
// Skip the Mode
readBytes, err = rd.ReadSlice(' ') // NB: DOES NOT ALLOCATE SIMPLY RETURNS SLICE WITHIN READER BUFFER
if err != nil {
return
}
n += len(readBytes)
// Deal with the fname
readBytes, err = rd.ReadSlice('\x00')
copy(fnameBuf, readBytes)
if len(fnameBuf) > len(readBytes) {
fnameBuf = fnameBuf[:len(readBytes)] // cut the buf the correct size
} else {
fnameBuf = append(fnameBuf, readBytes[len(fnameBuf):]...) // extend the buf and copy in the missing bits
}
for err == bufio.ErrBufferFull { // Then we need to read more
readBytes, err = rd.ReadSlice('\x00')
fnameBuf = append(fnameBuf, readBytes...) // there is little point attempting to avoid allocations here so just extend
}
n += len(fnameBuf)
if err != nil {
return
}
fnameBuf = fnameBuf[:len(fnameBuf)-1] // Drop the terminal NUL
fname = fnameBuf // set the returnable fname to the slice
// Now deal with the 20-byte SHA
idx := 0
for idx < 20 {
read := 0
read, err = rd.Read(shaBuf[idx:20])
n += read
if err != nil {
return
}
idx += read
}
sha = shaBuf
return
}
// ParseTreeLine reads an entry from a tree in a cat-file --batch stream
// This carefully avoids allocations - except where fnameBuf is too small.
// It is recommended therefore to pass in an fnameBuf large enough to avoid almost all allocations
//
// Each line is composed of:
// <mode-in-ascii-dropping-initial-zeros> SP <fname> NUL <20-byte SHA>
//
// We don't attempt to convert the 20-byte SHA to 40-byte SHA to save a lot of time
func ParseTreeLine(rd *bufio.Reader, modeBuf, fnameBuf, shaBuf []byte) (mode, fname, sha []byte, n int, err error) {
var readBytes []byte
// Read the Mode
readBytes, err = rd.ReadSlice(' ')
if err != nil {
return
}
n += len(readBytes)
copy(modeBuf, readBytes)
if len(modeBuf) > len(readBytes) {
modeBuf = modeBuf[:len(readBytes)]
} else {
modeBuf = append(modeBuf, readBytes[len(modeBuf):]...)
}
mode = modeBuf[:len(modeBuf)-1] // Drop the SP
// Deal with the fname
readBytes, err = rd.ReadSlice('\x00')
copy(fnameBuf, readBytes)
if len(fnameBuf) > len(readBytes) {
fnameBuf = fnameBuf[:len(readBytes)]
} else {
fnameBuf = append(fnameBuf, readBytes[len(fnameBuf):]...)
}
for err == bufio.ErrBufferFull {
readBytes, err = rd.ReadSlice('\x00')
fnameBuf = append(fnameBuf, readBytes...)
}
n += len(fnameBuf)
if err != nil {
return
}
fnameBuf = fnameBuf[:len(fnameBuf)-1]
fname = fnameBuf
// Deal with the 20-byte SHA
idx := 0
for idx < 20 {
read := 0
read, err = rd.Read(shaBuf[idx:20])
n += read
if err != nil {
return
}
idx += read
}
sha = shaBuf
return
}