Dave Jarvis' Repositories

git clone https://repo.autonoma.ca/repo/treetrek.git
treetrek / Commits / f40ac8d

Optimizes streaming

AuthorDave Jarvis <email>
Date2026-02-10 23:42:55 GMT-0800
Commitf40ac8d0e37e55e5b78da65c490bae29078a0c5d
Parent21eb3fa
Git.php
class Git {
private const CHUNK_SIZE = 128;
- private const MAX_READ_SIZE = 1048576;
+ private const MAX_READ_SIZE = 1048576; // 1MB
private string $repoPath;
fclose( $fileHandle );
return;
+ }
+
+ // Try streaming from pack file first (supports large files)
+ if( method_exists( $this->packs, 'stream' ) ) {
+ $streamed = $this->packs->stream( $sha, $callback );
+
+ if( $streamed ) {
+ return;
+ }
}
+ // Fallback to read method (limited size)
$data = $this->packs->read( $sha );
GitPacks.php
class GitPacks {
private const MAX_READ = 16777216;
- private const MAX_OBJECT_SIZE = 10485760;
-
- private string $objectsPath;
- private array $packFiles;
- private ?string $lastPack = null;
-
- private array $fileHandles = [];
- private array $fanoutCache = [];
- private array $shaBucketCache = [];
- private array $offsetBucketCache = [];
-
- public function __construct( string $objectsPath ) {
- $this->objectsPath = $objectsPath;
- $this->packFiles = glob( "{$this->objectsPath}/pack/*.idx" ) ?: [];
- }
-
- public function __destruct() {
- foreach( $this->fileHandles as $handle ) {
- if( is_resource( $handle ) ) {
- fclose( $handle );
- }
- }
- }
-
- public function read( string $sha ): ?string {
- $info = $this->findPackInfo( $sha );
-
- if( $info['offset'] === -1 ) {
- return null;
- }
-
- $size = $this->extractPackedSize( $info['file'], $info['offset'] );
-
- if( $size > self::MAX_OBJECT_SIZE ) {
- error_log( "GitPacks: Object $sha too large ({$size} bytes, limit " .
- self::MAX_OBJECT_SIZE .
- "), skipping to prevent memory exhaustion"
- );
-
- return null;
- }
-
- $handle = $this->getHandle( $info['file'] );
-
- return $handle
- ? $this->readPackEntry( $handle, $info['offset'], $size )
- : null;
- }
-
- public function getSize( string $sha ): ?int {
- $info = $this->findPackInfo( $sha );
-
- if( $info['offset'] === -1 ) {
- return null;
- }
-
- return $this->extractPackedSize( $info['file'], $info['offset'] );
- }
-
- private function findPackInfo( string $sha ): array {
- if( !ctype_xdigit( $sha ) || strlen( $sha ) !== 40 ) {
- return ['offset' => -1];
- }
-
- $binarySha = hex2bin( $sha );
-
- if( $this->lastPack ) {
- $offset = $this->findInIdx( $this->lastPack, $binarySha );
-
- if( $offset !== -1 ) {
- return $this->makeResult( $this->lastPack, $offset );
- }
- }
-
- foreach( $this->packFiles as $indexFile ) {
- if( $indexFile === $this->lastPack ) {
- continue;
- }
-
- $offset = $this->findInIdx( $indexFile, $binarySha );
-
- if( $offset !== -1 ) {
- $this->lastPack = $indexFile;
-
- return $this->makeResult( $indexFile, $offset );
- }
- }
-
- return ['offset' => -1];
- }
-
- private function makeResult( string $indexPath, int $offset ): array {
- return [
- 'file' => str_replace( '.idx', '.pack', $indexPath ),
- 'offset' => $offset
- ];
- }
-
- private function findInIdx( string $indexFile, string $binarySha ): int {
- $fileHandle = $this->getHandle( $indexFile );
-
- if( !$fileHandle ) {
- return -1;
- }
-
- if( !isset( $this->fanoutCache[$indexFile] ) ) {
- fseek( $fileHandle, 0 );
-
- if( fread( $fileHandle, 8 ) === "\377tOc\0\0\0\2" ) {
- $this->fanoutCache[$indexFile] = array_values(
- unpack( 'N*', fread( $fileHandle, 1024 ) )
- );
- } else {
- return -1;
- }
- }
-
- $fanout = $this->fanoutCache[$indexFile];
-
- $firstByte = ord( $binarySha[0] );
- $start = $firstByte === 0 ? 0 : $fanout[$firstByte - 1];
- $end = $fanout[$firstByte];
-
- if( $end <= $start ) {
- return -1;
- }
-
- $cacheKey = "$indexFile:$firstByte";
-
- if( !isset( $this->shaBucketCache[$cacheKey] ) ) {
- $count = $end - $start;
- fseek( $fileHandle, 1032 + ($start * 20) );
- $this->shaBucketCache[$cacheKey] = fread( $fileHandle, $count * 20 );
-
- fseek(
- $fileHandle,
- 1032 + ($fanout[255] * 24) + ($start * 4)
- );
- $this->offsetBucketCache[$cacheKey] = fread( $fileHandle, $count * 4 );
- }
-
- $shaBlock = $this->shaBucketCache[$cacheKey];
- $count = strlen( $shaBlock ) / 20;
- $low = 0;
- $high = $count - 1;
- $foundIdx = -1;
-
- while( $low <= $high ) {
- $mid = ($low + $high) >> 1;
- $compare = substr( $shaBlock, $mid * 20, 20 );
-
- if( $compare < $binarySha ) {
- $low = $mid + 1;
- } elseif( $compare > $binarySha ) {
- $high = $mid - 1;
- } else {
- $foundIdx = $mid;
- break;
- }
- }
-
- if( $foundIdx === -1 ) {
- return -1;
- }
-
- $offsetData = substr(
- $this->offsetBucketCache[$cacheKey],
- $foundIdx * 4,
- 4
- );
- $offset = unpack( 'N', $offsetData )[1];
-
- if( $offset & 0x80000000 ) {
- $packTotal = $fanout[255];
- $pos64 = 1032 + ($packTotal * 28) +
- (($offset & 0x7FFFFFFF) * 8);
- fseek( $fileHandle, $pos64 );
- $offset = unpack( 'J', fread( $fileHandle, 8 ) )[1];
- }
-
- return (int)$offset;
- }
-
- private function readPackEntry( $fileHandle, int $offset, int $expectedSize ): string {
- fseek( $fileHandle, $offset );
-
- $header = $this->readVarInt( $fileHandle );
- $type = ($header['byte'] >> 4) & 7;
-
- if( $type === 6 ) {
- return $this->handleOfsDelta( $fileHandle, $offset, $expectedSize );
- }
-
- if( $type === 7 ) {
- return $this->handleRefDelta( $fileHandle, $expectedSize );
- }
-
- return $this->decompressWithLimit( $fileHandle, $expectedSize );
- }
-
- private function decompressWithLimit( $fileHandle, int $maxSize ): string {
- $inflator = inflate_init( ZLIB_ENCODING_DEFLATE );
- if( $inflator === false ) {
- return '';
- }
-
- $result = '';
- $totalRead = 0;
-
- while( !feof( $fileHandle ) && $totalRead < $maxSize ) {
- $chunk = fread( $fileHandle, min( 8192, $maxSize - $totalRead ) );
-
- if( $chunk === false || $chunk === '' ) {
- break;
- }
-
- $data = @inflate_add( $inflator, $chunk );
-
- if( $data !== false ) {
- $result .= $data;
- $totalRead = strlen( $result );
-
- if( $totalRead > $maxSize ) {
- error_log( "GitPacks: Decompressed size exceeded limit, truncating" );
- break;
- }
- }
-
- if( $data === false ||
- inflate_get_status( $inflator ) === ZLIB_STREAM_END ) {
- break;
- }
- }
-
- return $result;
- }
-
- private function extractPackedSize( string $packPath, int $offset ): int {
- $fileHandle = $this->getHandle( $packPath );
-
- if( !$fileHandle ) {
- return 0;
- }
-
- fseek( $fileHandle, $offset );
-
- $header = $this->readVarInt( $fileHandle );
- $size = $header['value'];
- $type = ($header['byte'] >> 4) & 7;
-
- if( $type === 6 || $type === 7 ) {
- return $this->readDeltaTargetSize( $fileHandle, $type );
- }
-
- return $size;
- }
-
- private function handleOfsDelta( $fileHandle, int $offset, int $expectedSize ): string {
- $byte = ord( fread( $fileHandle, 1 ) );
- $negative = $byte & 127;
-
- while( $byte & 128 ) {
- $byte = ord( fread( $fileHandle, 1 ) );
- $negative = (($negative + 1) << 7) | ($byte & 127);
- }
-
- $currentPos = ftell( $fileHandle );
-
- $baseOffset = $offset - $negative;
- $baseHandle = $fileHandle;
- fseek( $baseHandle, $baseOffset );
- $baseHeader = $this->readVarInt( $baseHandle );
- $baseSize = $baseHeader['value'];
-
- if( $baseSize > self::MAX_OBJECT_SIZE ) {
- error_log( "GitPacks: Base object too large ($baseSize bytes), cannot apply delta" );
- return '';
- }
-
- fseek( $fileHandle, $baseOffset );
- $base = $this->readPackEntry( $fileHandle, $baseOffset, $baseSize );
-
- fseek( $fileHandle, $currentPos );
-
- $remainingBytes = min( self::MAX_READ, $expectedSize * 2 );
- $compressed = fread( $fileHandle, $remainingBytes );
- $delta = @gzuncompress( $compressed ) ?: '';
-
- return $this->applyDelta( $base, $delta );
- }
-
- private function handleRefDelta( $fileHandle, int $expectedSize ): string {
- $baseSha = bin2hex( fread( $fileHandle, 20 ) );
- $baseSize = $this->getSize( $baseSha );
-
- if( $baseSize === null || $baseSize > self::MAX_OBJECT_SIZE ) {
- error_log( "GitPacks: Referenced base object $baseSha too large or not found" );
- return '';
- }
-
- $base = $this->read( $baseSha ) ?? '';
-
- $remainingBytes = min( self::MAX_READ, $expectedSize * 2 );
- $compressed = fread( $fileHandle, $remainingBytes );
- $delta = @gzuncompress( $compressed ) ?: '';
-
- return $this->applyDelta( $base, $delta );
- }
-
- private function applyDelta( string $base, string $delta ): string {
- $position = 0;
- $this->skipSize( $delta, $position );
- $this->skipSize( $delta, $position );
-
- $output = '';
- $deltaLength = strlen( $delta );
-
- while( $position < $deltaLength ) {
- $opcode = ord( $delta[$position++] );
-
- if( $opcode & 128 ) {
- $offset = 0;
- $length = 0;
-
- if( $opcode & 0x01 ) {
- $offset |= ord( $delta[$position++] );
- }
- if( $opcode & 0x02 ) {
- $offset |= ord( $delta[$position++] ) << 8;
- }
- if( $opcode & 0x04 ) {
- $offset |= ord( $delta[$position++] ) << 16;
- }
- if( $opcode & 0x08 ) {
- $offset |= ord( $delta[$position++] ) << 24;
- }
-
- if( $opcode & 0x10 ) {
- $length |= ord( $delta[$position++] );
- }
- if( $opcode & 0x20 ) {
- $length |= ord( $delta[$position++] ) << 8;
- }
- if( $opcode & 0x40 ) {
- $length |= ord( $delta[$position++] ) << 16;
- }
-
- if( $length === 0 ) {
- $length = 0x10000;
- }
-
- $output .= substr( $base, $offset, $length );
- } else {
- $length = $opcode & 127;
- $output .= substr( $delta, $position, $length );
- $position += $length;
- }
- }
-
- return $output;
- }
-
- private function readVarInt( $fileHandle ): array {
- $byte = ord( fread( $fileHandle, 1 ) );
- $value = $byte & 15;
- $shift = 4;
- $first = $byte;
-
- while( $byte & 128 ) {
- $byte = ord( fread( $fileHandle, 1 ) );
- $value |= (($byte & 127) << $shift);
- $shift += 7;
- }
-
- return ['value' => $value, 'byte' => $first];
- }
-
- private function readDeltaTargetSize( $fileHandle, int $type ): int {
- if( $type === 6 ) {
- $byte = ord( fread( $fileHandle, 1 ) );
-
- while( $byte & 128 ) {
- $byte = ord( fread( $fileHandle, 1 ) );
- }
- } else {
- fseek( $fileHandle, 20, SEEK_CUR );
- }
-
- $inflator = inflate_init( ZLIB_ENCODING_DEFLATE );
- if( $inflator === false ) {
- return 0;
- }
-
- $header = '';
- $attempts = 0;
- $maxAttempts = 64;
-
- while( !feof( $fileHandle ) && strlen( $header ) < 32 && $attempts < $maxAttempts ) {
- $chunk = fread( $fileHandle, 512 );
-
- if( $chunk === false || $chunk === '' ) {
- break;
- }
-
- $output = @inflate_add( $inflator, $chunk, ZLIB_NO_FLUSH );
-
- if( $output !== false ) {
- $header .= $output;
- }
-
- if( inflate_get_status( $inflator ) === ZLIB_STREAM_END ) {
- break;
- }
-
- $attempts++;
- }
-
- $position = 0;
-
- if( strlen( $header ) > 0 ) {
- $this->skipSize( $header, $position );
-
- return $this->readSize( $header, $position );
- }
-
- return 0;
- }
-
- private function skipSize( string $data, int &$position ): void {
- $length = strlen( $data );
-
- while( $position < $length && (ord( $data[$position++] ) & 128) ) {
- // Loop continues while MSB is 1
- }
- }
-
- private function readSize( string $data, int &$position ): int {
- $byte = ord( $data[$position++] );
- $value = $byte & 127;
- $shift = 7;
-
- while( $byte & 128 ) {
- $byte = ord( $data[$position++] );
- $value |= (($byte & 127) << $shift);
- $shift += 7;
- }
-
- return $value;
- }
-
- private function getHandle( string $path ) {
- if( !isset( $this->fileHandles[$path] ) ) {
- $this->fileHandles[$path] = @fopen( $path, 'rb' );
- }
-
- return $this->fileHandles[$path];
- }
-}
-
+ private const MAX_RAM = 1048576;
+
+ private string $objectsPath;
+ private array $packFiles;
+ private ?string $lastPack = null;
+
+ private array $fileHandles = [];
+ private array $fanoutCache = [];
+ private array $shaBucketCache = [];
+ private array $offsetBucketCache = [];
+
+ public function __construct( string $objectsPath ) {
+ $this->objectsPath = $objectsPath;
+ $this->packFiles = glob( "{$this->objectsPath}/pack/*.idx" ) ?: [];
+ }
+
+ public function __destruct() {
+ foreach( $this->fileHandles as $handle ) {
+ if( is_resource( $handle ) ) {
+ fclose( $handle );
+ }
+ }
+ }
+
+ public function read( string $sha ): ?string {
+ $info = $this->findPackInfo( $sha );
+
+ if( $info['offset'] === -1 ) {
+ return null;
+ }
+
+ $size = $this->extractPackedSize( $info['file'], $info['offset'] );
+
+ if( $size > self::MAX_RAM ) {
+ return null;
+ }
+
+ $handle = $this->getHandle( $info['file'] );
+
+ return $handle
+ ? $this->readPackEntry( $handle, $info['offset'], $size )
+ : null;
+ }
+
+ public function stream( string $sha, callable $callback ): bool {
+ $info = $this->findPackInfo( $sha );
+
+ if( $info['offset'] === -1 ) {
+ return false;
+ }
+
+ $size = $this->extractPackedSize( $info['file'], $info['offset'] );
+ $handle = $this->getHandle( $info['file'] );
+
+ if( !$handle ) {
+ return false;
+ }
+
+ return $this->streamPackEntry( $handle, $info['offset'], $size, $callback );
+ }
+
+ public function getSize( string $sha ): ?int {
+ $info = $this->findPackInfo( $sha );
+
+ if( $info['offset'] === -1 ) {
+ return null;
+ }
+
+ return $this->extractPackedSize( $info['file'], $info['offset'] );
+ }
+
+ private function findPackInfo( string $sha ): array {
+ if( !ctype_xdigit( $sha ) || strlen( $sha ) !== 40 ) {
+ return ['offset' => -1];
+ }
+
+ $binarySha = hex2bin( $sha );
+
+ if( $this->lastPack ) {
+ $offset = $this->findInIdx( $this->lastPack, $binarySha );
+
+ if( $offset !== -1 ) {
+ return $this->makeResult( $this->lastPack, $offset );
+ }
+ }
+
+ foreach( $this->packFiles as $indexFile ) {
+ if( $indexFile === $this->lastPack ) {
+ continue;
+ }
+
+ $offset = $this->findInIdx( $indexFile, $binarySha );
+
+ if( $offset !== -1 ) {
+ $this->lastPack = $indexFile;
+
+ return $this->makeResult( $indexFile, $offset );
+ }
+ }
+
+ return ['offset' => -1];
+ }
+
+ private function makeResult( string $indexPath, int $offset ): array {
+ return [
+ 'file' => str_replace( '.idx', '.pack', $indexPath ),
+ 'offset' => $offset
+ ];
+ }
+
+ private function findInIdx( string $indexFile, string $binarySha ): int {
+ $fileHandle = $this->getHandle( $indexFile );
+
+ if( !$fileHandle ) {
+ return -1;
+ }
+
+ if( !isset( $this->fanoutCache[$indexFile] ) ) {
+ fseek( $fileHandle, 0 );
+
+ if( fread( $fileHandle, 8 ) === "\377tOc\0\0\0\2" ) {
+ $this->fanoutCache[$indexFile] = array_values(
+ unpack( 'N*', fread( $fileHandle, 1024 ) )
+ );
+ } else {
+ return -1;
+ }
+ }
+
+ $fanout = $this->fanoutCache[$indexFile];
+
+ $firstByte = ord( $binarySha[0] );
+ $start = $firstByte === 0 ? 0 : $fanout[$firstByte - 1];
+ $end = $fanout[$firstByte];
+
+ if( $end <= $start ) {
+ return -1;
+ }
+
+ $cacheKey = "$indexFile:$firstByte";
+
+ if( !isset( $this->shaBucketCache[$cacheKey] ) ) {
+ $count = $end - $start;
+ fseek( $fileHandle, 1032 + ($start * 20) );
+ $this->shaBucketCache[$cacheKey] = fread( $fileHandle, $count * 20 );
+
+ fseek(
+ $fileHandle,
+ 1032 + ($fanout[255] * 24) + ($start * 4)
+ );
+ $this->offsetBucketCache[$cacheKey] = fread( $fileHandle, $count * 4 );
+ }
+
+ $shaBlock = $this->shaBucketCache[$cacheKey];
+ $count = strlen( $shaBlock ) / 20;
+ $low = 0;
+ $high = $count - 1;
+ $foundIdx = -1;
+
+ while( $low <= $high ) {
+ $mid = ($low + $high) >> 1;
+ $compare = substr( $shaBlock, $mid * 20, 20 );
+
+ if( $compare < $binarySha ) {
+ $low = $mid + 1;
+ } elseif( $compare > $binarySha ) {
+ $high = $mid - 1;
+ } else {
+ $foundIdx = $mid;
+ break;
+ }
+ }
+
+ if( $foundIdx === -1 ) {
+ return -1;
+ }
+
+ $offsetData = substr(
+ $this->offsetBucketCache[$cacheKey],
+ $foundIdx * 4,
+ 4
+ );
+ $offset = unpack( 'N', $offsetData )[1];
+
+ if( $offset & 0x80000000 ) {
+ $packTotal = $fanout[255];
+ $pos64 = 1032 + ($packTotal * 28) +
+ (($offset & 0x7FFFFFFF) * 8);
+ fseek( $fileHandle, $pos64 );
+ $offset = unpack( 'J', fread( $fileHandle, 8 ) )[1];
+ }
+
+ return (int)$offset;
+ }
+
+ private function readPackEntry( $fileHandle, int $offset, int $expectedSize ): string {
+ fseek( $fileHandle, $offset );
+
+ $header = $this->readVarInt( $fileHandle );
+ $type = ($header['byte'] >> 4) & 7;
+
+ if( $type === 6 ) {
+ return $this->handleOfsDelta( $fileHandle, $offset, $expectedSize );
+ }
+
+ if( $type === 7 ) {
+ return $this->handleRefDelta( $fileHandle, $expectedSize );
+ }
+
+ return $this->decompressToString( $fileHandle, $expectedSize );
+ }
+
+ private function streamPackEntry( $fileHandle, int $offset, int $expectedSize, callable $callback ): bool {
+ fseek( $fileHandle, $offset );
+
+ $header = $this->readVarInt( $fileHandle );
+ $type = ($header['byte'] >> 4) & 7;
+
+ if( $type === 6 || $type === 7 ) {
+ return $this->streamDeltaObject( $fileHandle, $offset, $type, $expectedSize, $callback );
+ }
+
+ return $this->streamDecompression( $fileHandle, $callback );
+ }
+
+ private function streamDeltaObject( $fileHandle, int $offset, int $type, int $expectedSize, callable $callback ): bool {
+ fseek( $fileHandle, $offset );
+ $this->readVarInt( $fileHandle );
+
+ if( $type === 6 ) {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ $negative = $byte & 127;
+
+ while( $byte & 128 ) {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ $negative = (($negative + 1) << 7) | ($byte & 127);
+ }
+
+ $deltaPos = ftell( $fileHandle );
+ $baseOffset = $offset - $negative;
+
+ $base = '';
+ $this->streamPackEntry( $fileHandle, $baseOffset, 0, function( $chunk ) use ( &$base ) {
+ $base .= $chunk;
+ } );
+
+ fseek( $fileHandle, $deltaPos );
+ } else {
+ $baseSha = bin2hex( fread( $fileHandle, 20 ) );
+
+ $base = '';
+ $streamed = $this->stream( $baseSha, function( $chunk ) use ( &$base ) {
+ $base .= $chunk;
+ } );
+
+ if( !$streamed ) {
+ return false;
+ }
+ }
+
+ $compressed = fread( $fileHandle, self::MAX_READ );
+ $delta = @gzuncompress( $compressed ) ?: '';
+
+ $result = $this->applyDelta( $base, $delta );
+
+ $chunkSize = 8192;
+ $length = strlen( $result );
+ for( $i = 0; $i < $length; $i += $chunkSize ) {
+ $callback( substr( $result, $i, $chunkSize ) );
+ }
+
+ return true;
+ }
+
+ private function streamDecompression( $fileHandle, callable $callback ): bool {
+ $inflator = inflate_init( ZLIB_ENCODING_DEFLATE );
+ if( $inflator === false ) {
+ return false;
+ }
+
+ while( !feof( $fileHandle ) ) {
+ $chunk = fread( $fileHandle, 8192 );
+
+ if( $chunk === false || $chunk === '' ) {
+ break;
+ }
+
+ $data = @inflate_add( $inflator, $chunk );
+
+ if( $data !== false && $data !== '' ) {
+ $callback( $data );
+ }
+
+ if( $data === false ||
+ inflate_get_status( $inflator ) === ZLIB_STREAM_END ) {
+ break;
+ }
+ }
+
+ return true;
+ }
+
+ /**
+ * Decompress to string (for small objects < 1MB)
+ */
+ private function decompressToString( $fileHandle, int $maxSize ): string {
+ $inflator = inflate_init( ZLIB_ENCODING_DEFLATE );
+ if( $inflator === false ) {
+ return '';
+ }
+
+ $result = '';
+
+ while( !feof( $fileHandle ) ) {
+ $chunk = fread( $fileHandle, 8192 );
+
+ if( $chunk === false || $chunk === '' ) {
+ break;
+ }
+
+ $data = @inflate_add( $inflator, $chunk );
+
+ if( $data !== false ) {
+ $result .= $data;
+ }
+
+ if( $data === false ||
+ inflate_get_status( $inflator ) === ZLIB_STREAM_END ) {
+ break;
+ }
+ }
+
+ return $result;
+ }
+
+ private function extractPackedSize( string $packPath, int $offset ): int {
+ $fileHandle = $this->getHandle( $packPath );
+
+ if( !$fileHandle ) {
+ return 0;
+ }
+
+ fseek( $fileHandle, $offset );
+
+ $header = $this->readVarInt( $fileHandle );
+ $size = $header['value'];
+ $type = ($header['byte'] >> 4) & 7;
+
+ if( $type === 6 || $type === 7 ) {
+ return $this->readDeltaTargetSize( $fileHandle, $type );
+ }
+
+ return $size;
+ }
+
+ private function handleOfsDelta( $fileHandle, int $offset, int $expectedSize ): string {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ $negative = $byte & 127;
+
+ while( $byte & 128 ) {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ $negative = (($negative + 1) << 7) | ($byte & 127);
+ }
+
+ $currentPos = ftell( $fileHandle );
+ $baseOffset = $offset - $negative;
+
+ fseek( $fileHandle, $baseOffset );
+ $baseHeader = $this->readVarInt( $fileHandle );
+ $baseSize = $baseHeader['value'];
+
+ fseek( $fileHandle, $baseOffset );
+ $base = $this->readPackEntry( $fileHandle, $baseOffset, $baseSize );
+
+ fseek( $fileHandle, $currentPos );
+
+ $remainingBytes = min( self::MAX_READ, max( $expectedSize * 2, 1048576 ) );
+ $compressed = fread( $fileHandle, $remainingBytes );
+ $delta = @gzuncompress( $compressed ) ?: '';
+
+ return $this->applyDelta( $base, $delta );
+ }
+
+ private function handleRefDelta( $fileHandle, int $expectedSize ): string {
+ $baseSha = bin2hex( fread( $fileHandle, 20 ) );
+ $base = $this->read( $baseSha ) ?? '';
+
+ $remainingBytes = min( self::MAX_READ, max( $expectedSize * 2, 1048576 ) );
+ $compressed = fread( $fileHandle, $remainingBytes );
+ $delta = @gzuncompress( $compressed ) ?: '';
+
+ return $this->applyDelta( $base, $delta );
+ }
+
+ private function applyDelta( string $base, string $delta ): string {
+ $position = 0;
+ $this->skipSize( $delta, $position );
+ $this->skipSize( $delta, $position );
+
+ $output = '';
+ $deltaLength = strlen( $delta );
+
+ while( $position < $deltaLength ) {
+ $opcode = ord( $delta[$position++] );
+
+ if( $opcode & 128 ) {
+ $offset = 0;
+ $length = 0;
+
+ if( $opcode & 0x01 ) {
+ $offset |= ord( $delta[$position++] );
+ }
+ if( $opcode & 0x02 ) {
+ $offset |= ord( $delta[$position++] ) << 8;
+ }
+ if( $opcode & 0x04 ) {
+ $offset |= ord( $delta[$position++] ) << 16;
+ }
+ if( $opcode & 0x08 ) {
+ $offset |= ord( $delta[$position++] ) << 24;
+ }
+
+ if( $opcode & 0x10 ) {
+ $length |= ord( $delta[$position++] );
+ }
+ if( $opcode & 0x20 ) {
+ $length |= ord( $delta[$position++] ) << 8;
+ }
+ if( $opcode & 0x40 ) {
+ $length |= ord( $delta[$position++] ) << 16;
+ }
+
+ if( $length === 0 ) {
+ $length = 0x10000;
+ }
+
+ $output .= substr( $base, $offset, $length );
+ } else {
+ $length = $opcode & 127;
+ $output .= substr( $delta, $position, $length );
+ $position += $length;
+ }
+ }
+
+ return $output;
+ }
+
+ private function readVarInt( $fileHandle ): array {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ $value = $byte & 15;
+ $shift = 4;
+ $first = $byte;
+
+ while( $byte & 128 ) {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ $value |= (($byte & 127) << $shift);
+ $shift += 7;
+ }
+
+ return ['value' => $value, 'byte' => $first];
+ }
+
+ private function readDeltaTargetSize( $fileHandle, int $type ): int {
+ if( $type === 6 ) {
+ $byte = ord( fread( $fileHandle, 1 ) );
+
+ while( $byte & 128 ) {
+ $byte = ord( fread( $fileHandle, 1 ) );
+ }
+ } else {
+ fseek( $fileHandle, 20, SEEK_CUR );
+ }
+
+ $inflator = inflate_init( ZLIB_ENCODING_DEFLATE );
+ if( $inflator === false ) {
+ return 0;
+ }
+
+ $header = '';
+ $attempts = 0;
+ $maxAttempts = 64;
+
+ while( !feof( $fileHandle ) && strlen( $header ) < 32 && $attempts < $maxAttempts ) {
+ $chunk = fread( $fileHandle, 512 );
+
+ if( $chunk === false || $chunk === '' ) {
+ break;
+ }
+
+ $output = @inflate_add( $inflator, $chunk, ZLIB_NO_FLUSH );
+
+ if( $output !== false ) {
+ $header .= $output;
+ }
+
+ if( inflate_get_status( $inflator ) === ZLIB_STREAM_END ) {
+ break;
+ }
+
+ $attempts++;
+ }
+
+ $position = 0;
+
+ if( strlen( $header ) > 0 ) {
+ $this->skipSize( $header, $position );
+
+ return $this->readSize( $header, $position );
+ }
+
+ return 0;
+ }
+
+ private function skipSize( string $data, int &$position ): void {
+ $length = strlen( $data );
+
+ while( $position < $length && (ord( $data[$position++] ) & 128) ) {
+ // Loop continues while MSB is 1
+ }
+ }
+
+ private function readSize( string $data, int &$position ): int {
+ $byte = ord( $data[$position++] );
+ $value = $byte & 127;
+ $shift = 7;
+
+ while( $byte & 128 ) {
+ $byte = ord( $data[$position++] );
+ $value |= (($byte & 127) << $shift);
+ $shift += 7;
+ }
+
+ return $value;
+ }
+
+ private function getHandle( string $path ) {
+ if( !isset( $this->fileHandles[$path] ) ) {
+ $this->fileHandles[$path] = @fopen( $path, 'rb' );
+ }
+
+ return $this->fileHandles[$path];
+ }
+}
Delta554 lines added, 460 lines removed, 94-line increase