<?php
$str = file_get_contents('_-357038350_97.wxapkg.unpacked/app-service.js');
$preg = '/(data:image.*?)\"/';
$len = strlen('data:image/png;base64,');
if(preg_match_all($preg, $str, $arr)){
  foreach($arr[1] as $k => $img){
    file_put_contents('./images/'.$k.'.png',base64_decode(substr($img,$len)));
    //echo substr($img,$len);exit;
  }
} else {
  echo 'no';
}

$str = file_get_contents('_-357038350_97.wxapkg.unpacked/app-wxss.js');
$preg = '/\((data:image.*?)\)/';
$len = strlen('data:image/png;base64,');
if(preg_match_all($preg, $str, $arr)){
  foreach($arr[1] as $k => $img){
    file_put_contents('./images/a2_'.$k.'.png',base64_decode(substr($img,$len)));
    //echo substr($img,$len);exit;
  }
} else {
  echo 'no';
}

<?php
/**
源文件目录
  /data/data/com.tencent.mm/MicroMsg/{{一串32位的16进制字符串文件夹}}/appbrand/pkg/
  /data/data/com.eg.android.AlipayGphone, 在files/nebulaInstallApps/目录下存储了所有加载过的小程序
 * [php] /path/to/unpack-wxapkg.php <xxx.wxapkg>
 * php unpak.php _1123949441_351.wxapkg
 */

function unpack_wxapkg($file, $targetDir)
{
  if (!is_dir($targetDir)){
    mkdir($targetDir);
  }

  echo "Reading file.\n";
  $file = file_get_contents($file);
  $ptr = 18;

  $headerStruct = new StructDef([
    'mask1' => 'ushort',
    'info1' => 'ulong',
    'indexInfoLength' => 'ulong',
    'bodyInfoLength' => 'ushort',
    'mask2' => 'ushort',
    'fileCount' => 'ulong',
  ]);

  echo "Parsing file header...\n";

  $header = $headerStruct->unpack($file);
//  print_r(['header' => $header]);

  $unpackULong = function () use (&$file, &$ptr) {
    $ret = unpack_ulong(substr($file, $ptr, 4));
    $ptr += 4;
    return $ret;
  };

  $unpackUShort = function () use (&$file, &$ptr) {
    $ret = unpack_ushort(substr($file, $ptr, 2));
    $ptr += 2;
    return $ret;
  };


  $unpackStr = function ($len) use (&$file, &$ptr) {
    $ret = substr($file, $ptr, $len);
    $ptr += $len;
    return $ret;
  };


  $fileCount = $header['fileCount'];

  echo "Got $fileCount files.\n";

  $unpackedFiles = [];

  for ($i = 0; $i < $fileCount; $i++) {
    $nameLength = $unpackULong();
    $f = [
      'nameLength' => $nameLength,
      'name' => $unpackStr($nameLength),
      'offset' => $unpackULong(),
      'size' => $unpackULong(),
    ];

    echo "Unpacking file {$f['name']} ({$f['size']}bytes)...\n";

    $f['content'] = substr($file, $f['offset'], $f['size']);
    $unpackedFiles[] = $f;

    $destFile = $targetDir . $f['name'];
    $destDir = dirname($destFile);
    if (!is_dir($destDir)){
      mkdir($destDir, 0777, true);
    }

    file_put_contents($targetDir . $f['name'], $f['content']);
  }


//  print_r(['unpackedFiles' => $unpackedFiles]);



  echo "All done.\n";
}

function unpack_ulong($str)
{
  $x = unpack('N', $str);
  return $x[1];
}

function unpack_ushort($str)
{
  $x = unpack('n', $str);
  return $x[1];
}

class StructDef
{
  protected $def;
  protected $unpackFormat;

  public function __construct($def)
  {
    $this->def = $def;
    $this->unpackFormat = self::convertStructDefToUnpackFormat($def);
  }

  public function unpack($data)
  {
    return unpack($this->unpackFormat, $data);
  }

  protected static function convertStructDefToUnpackFormat($def)
  {
    $defTypeToUnpackType = [
      'byte' => 'C',
      'uchar' => 'C',
      'u8' => 'C',
      'ushort' => 'n',
      'u16' => 'n',
      'ulong' => 'N',
      'u32' => 'N',
    ];

    $ret = [];
    foreach ($def as $key => $type) {
      $ret[] = $defTypeToUnpackType[$type] . $key;
    }

    return implode('/', $ret);
  }
}

$packageFile = $argv[1];

//支持目录下文件批量解压
 if (is_dir($packageFile)){
  $handle = opendir($packageFile);
  if($handle){
    while(($fl = readdir($handle)) !== false){
      $temp = $packageFile.DIRECTORY_SEPARATOR.$fl;
      //如果不加 $fl!='.' && $fl != '..' 则会造成把$dir的父级目录也读取出来
      if(is_file($temp)){
        if($fl!='.' && $fl != '..'){
          $targetDir = $temp . '.unpacked';
          unpack_wxapkg($temp, $targetDir);
        }
      }
    }
  } 
}else if (is_file($packageFile)){
  $targetDir = $packageFile . '.unpacked';
  unpack_wxapkg($packageFile, $targetDir);
}else{
  echo <<<HELP
Usage:
  [php] {$argv[0]} <xxx.wxapkg>
  - Unpack the `xxx.wxapkg` to `xxx.wxapkg.unpacked` directory.
HELP;

  exit(1);
}

exit(0);