<?php
// AudioExif.class.php
// 用PHP进行音频文件头部信息的读取与写入
// 目前只支持 WMA 和 MP3 两种格式, 只支持常用的几个头部信息
//
// 写入信息支持: Title(名称), Artist(艺术家), Copyright(版权), Description (描述)
// Year(年代), Genre (流派), AlbumTitle (专辑标题)
// 其中 mp3 和 wma 略有不同, 具体返回的信息还可能更多, 但只有以上信息可以被写入
// mp3 还支持 Track (曲目编号写入)
// 对于 MP3 文件支持 ID3v1也支持ID3v2, 读取时优先 v2, 写入时总是会写入v1, 必要时写入v2
//
// 用法说明: (由于 wma 使用 Unicode 存取, 故还需要 mb_convert_encoding() 扩展
// 返回数据及写入数据均为 ANSI 编码, 即存什么就显示什么 (中文_GB2312)
//
// require (\'AudioExif.class.php\');
// $AE = new AudioExif;
// $file = \'/path/to/test.mp3\';
//
// 1. 检查文件是否完整 (only for wma, mp3始终返回 true)
//
// $AE->CheckSize($file);
//
// 2. 读取信息, 返回值由信息组成的数组, 键名解释参见上方
//
// print_r($AE->GetInfo($file));
//
// 3. 写入信息, 第二参数是一个哈希数组, 键->值, 支持的参见上方的, mp3也支持 Track
// 要求第一参数的文件路径可由本程序写入
// $pa = array(\'Title\' => \'新标题\', \'AlbumTitle\' => \'新的专辑名称\');
// $AE->SetInfo($file, $pa);
//
// 其它: 该插件花了不少时间搜集查找 wma及mp3 的文件格式说明文档与网页, 希望对大家有用.
// 其实网上已经有不少类似的程序, 但对 wma 实在太少了, 只能在 win 平台下通过 M$ 的
// API 来操作, 而 MP3 也很少有可以在 unix/linux 命令行操作的, 所以特意写了这个模块
//
// 如果发现 bug 或提交 patch, 或加以改进使它更加健壮, 请告诉我.
// (关于 ID3和Wma的文件格式及结构 在网上应该都可以找到参考资料)
//
if (!extension_loaded(\'mbstring\')){
trigger_error(\'PHP Extension module `mbstring` is required for AudioExif\', E_USER_WARNING);
return true;
}
// the Main Class
class AudioExif{
// public vars
var $_wma = false;
var $_mp3 = false;
// Construct
function AudioExif() {
// nothing to do
}
// check the filesize
function CheckSize($file) {
$handler = &$this->_get_handler($file);
if (!$handler) return false;
return $handler->check_size($file);
}
// get the infomations
function GetInfo($file) {
$handler = &$this->_get_handler($file);
if (!$handler) return false;
return $handler->get_info($file);
}
// write the infomations
function SetInfo($file, $pa) {
if (!is_writable($file)) {
trigger_error(\'AudioExif: file `\' . $file . \'` can not been overwritten\', E_USER_WARNING);
return false;
}
$handler = &$this->_get_handler($file);
if (!$handler) return false;
return $handler->set_info($file, $pa);
}
// private methods
function &_get_handler($file) {
$ext = strtolower(strrchr($file, \'.\'));
$ret = false;
if ($ext == \'.mp3\') {
// MP3
$ret = &$this->_mp3;
if (!$ret) $ret = new _Mp3Exif();

}
else if ($ext == \'.wma\')
{ // wma
$ret = &$this->_wma;
if (!$ret) $ret = new _WmaExif();
}
else
{ // unknown
trigger_error(\'AudioExif not supported `\' . $ext . \'` file.\', E_USER_WARNING);
}
return $ret;
}
}

// DBCS => gb2312
function dbcs_gbk($str)
{
// strip the last \"\\0\\0\"
$str = substr($str, 0, -2);
return mb_convert_encoding($str, \'GBK\', \'UCS-2LE\');
}

// gb2312 => DBCS
function gbk_dbcs($str)
{
$str = mb_convert_encoding($str, \'UCS-2LE\', \'GBK\');
$str .= \"\\0\\0\";
return $str;
}

// file exif
class _AudioExif
{
var $fd;
var $head;
var $head_off;
var $head_buf;

// init the file handler
function _file_init($fpath, $write = false)
{
$mode = ($write ? \'rb+\' : \'rb\');
$this->fd = @fopen($fpath, $mode);
if (!$this->fd)
{
trigger_error(\'AudioExif: `\' . $fpath . \'` can not be opened with mode `\' . $mode . \'`\', E_USER_WARNING);
return false;
}
$this->head = false;
$this->head_off = 0;
$this->head_buf = \'\';
return true;
}

// read buffer from the head_buf & move the off pointer
function _read_head_buf($len)
{
if ($len <= 0) return NULL;
$buf = substr($this->head_buf, $this->head_off, $len);
$this->head_off += strlen($buf);
return $buf;
}

// read one short value
function _read_head_short()
{
$ord1 = ord(substr($this->head_buf, $this->head_off, 1));
$ord2 = ord(substr($this->head_buf, $this->head_off+1, 1));
$this->head_off += 2;
return ($ord1 + ($ord2<<8));
}

// save the file head
function _file_save($head, $olen, $nlen = 0)
{
if ($nlen == 0) $nlen = strlen($head);
if ($nlen == $olen)
{
// shorter
flock($this->fd, LOCK_EX);
fseek($this->fd, 0, SEEK_SET);
fwrite($this->fd, $head, $nlen);
flock($this->fd, LOCK_UN);
}
else
{
// longer, buffer required
$stat = fstat($this->fd);
$fsize = $stat[\'size\'];

// buf required (4096?) 应该不会 nlen - olen > 4096 吧
$woff = 0;
$roff = $olen;

// read first buffer
flock($this->fd, LOCK_EX);
fseek($this->fd, $roff, SEEK_SET);
$buf = fread($this->fd, 4096);

// seek to start
fseek($this->fd, $woff, SEEK_SET);
fwrite($this->fd, $head, $nlen);
$woff += $nlen;

// seek to woff & write the data
do
{
$buf2 = $buf;
$roff += 4096;
if ($roff < $fsize)
{
fseek($this->fd, $roff, SEEK_SET);
$buf = fread($this->fd, 4096);
}

// save last buffer
$len2 = strlen($buf2);
fseek($this->fd, $woff, SEEK_SET);
fwrite($this->fd, $buf2, $len2);
$woff += $len2;
}
while ($roff < $fsize);
ftruncate($this->fd, $woff);
flock($this->fd, LOCK_UN);
}
}

// close the file
function _file_deinit()
{
if ($this->fd)
{
fclose($this->fd);
$this->fd = false;
}
}
}

// wma class
class _WmaExif extends _AudioExif
{
var $items1 = array(\'Title\', \'Artist\', \'Copyright\', \'Description\', \'Reserved\');
var $items2 = array(\'Year\', \'Genre\', \'AlbumTitle\');

// check file size (length) maybe invalid file
function check_size($file)
{
$ret = false;
if (!$this->_file_init($file)) return true;
if ($this->_init_header())
{
$buf = fread($this->fd, 24);
$tmp = unpack(\'H32id/Vlen/H8unused\', $buf);
if ($tmp[\'id\'] == \'3626b2758e66cf11a6d900aa0062ce6c\')
{
$stat = fstat($this->fd);
$ret = ($stat[\'size\'] == ($this->head[\'len\'] + $tmp[\'len\']));
}
}
$this->_file_deinit();
return $ret;
}

// set info (save the infos)
function set_info($file, $pa)
{
// check the pa
settype($pa, \'array\');
if (!$this->_file_init($file, true)) return false;
if (!$this->_init_header())
{
$this->_file_deinit();
return false;
}

// parse the old header & generate the new header
$head_body = \'\';
$st_found = $ex_found = false;
$head_num = $this->head[\'num\'];
while (($tmp = $this->_get_head_frame()) && ($head_num > 0))
{
$head_num--;
if ($tmp[\'id\'] == \'3326b2758e66cf11a6d900aa0062ce6c\')
{ // Standard Info
// 1-4
$st_found = true;
$st_body1 = $st_body2 = \'\';
$lenx = unpack(\'v5\', $this->_read_head_buf(10));
$tmp[\'len\'] -= 34; // 10 + 24
for ($i = 0; $i < count($this->items1); $i++)
{
$l = $lenx[$i+1];
$k = $this->items1[$i];
$tmp[\'len\'] -= $l;

$data = $this->_read_head_buf($l);
if (isset($pa[$k])) $data = gbk_dbcs($pa[$k]);

$st_body2 .= $data;
$st_body1 .= pack(\'v\', strlen($data));
}
// left length
if ($tmp[\'len\'] > 0) $st_body2 .= $this->_read_head_buf($tmp[\'len\']);

// save to head_body
$head_body .= pack(\'H32VH8\', $tmp[\'id\'], strlen($st_body1 . $st_body2)+24, $tmp[\'unused\']);
$head_body .= $st_body1 . $st_body2;

$st_body2 .= $data;
}

// save to head_body
$head_body .= pack(\'H32Va4\', \'3326b2758e66cf11a6d900aa0062ce6c\', strlen($st_body1 . $st_body2)+24, \'\');
$head_body .= $st_body1 . $st_body2;
$this->head[\'num\']++;
}
// ex not found?
if (!$ex_found)
{
$inum = 0;
$et_body = \'\';
foreach ($this->items2 as $k)
{
$nbuf = gbk_dbcs(\'WM/\' . $k);
$vbuf = (isset($pa[$k]) ? gbk_dbcs($pa[$k]) : \"\");
$et_body .= pack(\'v\', strlen($nbuf)) . $nbuf . pack(\'vv\', 0, strlen($vbuf)) . $vbuf;
$inum++;
}
$head_body .= pack(\'H32Va4v\', \'40a4d0d207e3d21197f000a0c95ea850\', strlen($et_body)+26, \'\', $inum);
$head_body .= $et_body;
$this->head[\'num\']++;
}

// after save
$new_len = strlen($head_body) + 30;
$old_len = $this->head[\'len\'];
if ($new_len < $old_len)
{
$head_body .= str_repeat(\"\\0\", $old_len - $new_len);
$new_len = $old_len;
}
$tmp = $this->head;
$head_buf = pack(\'H32VVVH4\', $tmp[\'id\'], $new_len, $tmp[\'len2\'], $tmp[\'num\'], $tmp[\'unused\']);
$head_buf .= $head_body;
$this->_file_save($head_buf, $old_len, $new_len);

// close the file & return
$this->_file_deinit();
return true;
}

// get info
function get_info($file)
{
$ret = array();
if (!$this->_file_init($file)) return false;
if (!$this->_init_header())
{
$this->_file_deinit();
return false;
}

// get the data from head_buf
$head_num = $this->head[\'num\']; // num of head_frame
while (($tmp = $this->_get_head_frame()) && $head_num > 0)
{
$head_num--;
if ($tmp[\'id\'] == \'3326b2758e66cf11a6d900aa0062ce6c\')
{ // Standard Info
$lenx = unpack(\'v*\', $this->_read_head_buf(10));
for ($i = 1; $i <= count($this->items1); $i++)
{
$k = $this->items1[$i-1];
$ret[$k] = dbcs_gbk($this->_read_head_buf($lenx[$i]));
}
}
else if ($tmp[\'id\'] == \'40a4d0d207e3d21197f000a0c95ea850\')
{ // Extended Info
$inum = $this->_read_head_short();
$tmp[\'len\'] -= 26;
while ($inum > 0 && $tmp[\'len\'] > 0)
{
// attribute name
$nlen = $this->_read_head_short();
$nbuf = $this->_read_head_buf($nlen);

// the flag & value length
$flag = $this->_read_head_short();
$vlen = $this->_read_head_short();
$vbuf = $this->_read_head_buf($vlen);

// update the XX

$tmp[\'len\'] -= (6 + $nlen + $vlen);
$inum--;

$name = dbcs_gbk($nbuf);
$k = substr($name, 3);
if (in_array($k, $this->items2))
{ // all is string value (refer to falg for other tags)
$ret[$k] = dbcs_gbk($vbuf);
}
}
}

else
{ // skip only
if ($tmp[\'len\'] > 24) $this->head_off += ($tmp[\'len\'] - 24);
}
}
$this->_file_deinit();
return $ret;
}

// get the header?
function _init_header()
{
fseek($this->fd, 0, SEEK_SET);
$buf = fread($this->fd, 30);
if (strlen($buf) != 30) return false;
$tmp = unpack(\'H32id/Vlen/Vlen2/Vnum/H4unused\', $buf);
if ($tmp[\'id\'] != \'3026b2758e66cf11a6d900aa0062ce6c\')
return false;

$this->head_buf = fread($this->fd, $tmp[\'len\'] - 30);
$this->head = $tmp;
return true;
}

// _get_head_frame()
function _get_head_frame()
{
$buf = $this->_read_head_buf(24);
if (strlen($buf) != 24) return false;
$tmp = unpack(\'H32id/Vlen/H8unused\', $buf);
return $tmp;
}
}

// mp3 class (if not IDv2 then select IDv1)
class _Mp3Exif extends _AudioExif
{
var $head1;
var $genres = array(\'Blues\',\'Classic Rock\',\'Country\',\'Dance\',\'Disco\',\'Funk\',\'Grunge\',\'Hip-Hop\',\'Jazz\',\'Metal\',\'New Age\',\'Oldies\',\'Other\',\'Pop\',\'R&B\',\'Rap\',\'Reggae\',\'Rock\',\'Techno\',\'Industrial\',\'Alternative\',\'Ska\',\'Death Metal\',\'Pranks\',\'Soundtrack\',\'Euro-Techno\',\'Ambient\',\'Trip-Hop\',\'Vocal\',\'Jazz+Funk\',\'Fusion\',\'Trance\',\'Classical\',\'Instrumental\',\'Acid\',\'House\',\'Game\',\'Sound Clip\',\'Gospel\',\'Noise\',\'AlternRock\',\'Bass\',\'Soul\',\'Punk\',\'Space\',\'Meditative\',\'Instrumental Pop\',\'Instrumental Rock\',\'Ethnic\',\'Gothic\',\'Darkwave\',\'Techno-Industrial\',\'Electronic\',\'Pop-Folk\',\'Eurodance\',\'Dream\',\'Southern Rock\',\'Comedy\',\'Cult\',\'Gangsta\',\'Top 40\',\'Christian Rap\',\'Pop/Funk\',\'Jungle\',\'Native American\',\'Cabaret\',\'New Wave\',\'Psychadelic\',\'Rave\',\'Showtunes\',\'Trailer\',\'Lo-Fi\',\'Tribal\',\'Acid Punk\',\'Acid Jazz\',\'Polka\',\'Retro\',\'Musical\',\'Rock & Roll\',\'Hard Rock\',\'Unknown\');

// MP3 always return true
function check_size($file)
{
return true;
}

// get info
function get_info($file)
{
if (!$this->_file_init($file)) return false;
$ret = false;
if ($this->_init_header())
{
$ret = ($this->head ? $this->_get_v2_info() : $this->_get_v1_info());
$ret[\'meta\'] = $this->_get_meta_info();
}
$this->_file_deinit();
return $ret;
}

// set info
function set_info($file, $pa)
{
if (!$this->_file_init($file, true)) return false;
if ($this->_init_header())
{
// always save v1 info
$this->_set_v1_info($pa);
// set v2 first if need
$this->_set_v2_info($pa);
}
$this->_file_deinit();
return true;
}

// get the header information[v1+v2], call after file_init
function _init_header()
{
$this->head1 = false;
$this->head = false;

// try to get ID3v1 first
fseek($this->fd, -128, SEEK_END);
$buf = fread($this->fd, 128);

if (strlen($buf) == 128 && substr($buf, 0, 3) == \'TAG\')
{
$tmp = unpack(\'a3id/a30Title/a30Artist/a30AlbumTitle/a4Year/a28Description/CReserved/CTrack/CGenre\', $buf);
$this->head1 = $tmp;
}

// try to get ID3v2
fseek($this->fd, 0, SEEK_SET);
$buf = fread($this->fd, 10);
if (strlen($buf) == 10 && substr($buf, 0, 3) == \'ID3\')
{
$tmp = unpack(\'a3id/Cver/Crev/Cflag/C4size\', $buf);
$tmp[\'size\'] = ($tmp[\'size1\']<<21)|($tmp[\'size2\']<<14)|($tmp[\'size3\']<<7)|$tmp[\'size4\'];
unset($tmp[\'size1\'], $tmp[\'size2\'], $tmp[\'size3\'], $tmp[\'size4\']);

$this->head = $tmp;
$this->head_buf = fread($this->fd, $tmp[\'size\']);
}
return ($this->head1 || $this->head);
}

// get v1 info
function _get_v1_info()
{
$ret = array();
$tmpa = array(\'Title\', \'Artist\', \'Copyright\', \'Description\', \'Year\', \'AlbumTitle\');
foreach ($tmpa as $tmp)
{
$ret[$tmp] = $this->head1[$tmp];
if ($pos = strpos($ret[$tmp], \"\\0\"))
$ret[$tmp] = substr($ret[$tmp], 0, $pos);
}

// count the Genre, [Track]
if ($this->head1[\'Reserved\'] == 0) $ret[\'Track\'] = $this->head1[\'Track\'];
else $ret[\'Description\'] .= chr($ret[\'Reserved\']) . chr($ret[\'Track\']);

// Genre_idx
$g = $this->head1[\'Genre\'];
if (!isset($this->genres[$g])) $ret[\'Genre\'] = \'Unknown\';
else $ret[\'Genre\'] = $this->genres[$g];

// return the value
$ret[\'ID3v1\'] = \'yes\';
return $ret;
}

// get v2 info
function _get_v2_info()
{
$ret = array();
$items = array( \'TCOP\'=>\'Copyright\', \'TPE1\'=>\'Artist\', \'TIT2\'=>\'Title\', \'TRCK\'=> \'Track\',
\'TCON\'=>\'Genre\', \'COMM\'=>\'Description\', \'TYER\'=>\'Year\', \'TALB\'=>\'AlbumTitle\');
while (true)
{
$buf = $this->_read_head_buf(10);
if (strlen($buf) != 10) break;
$tmp = unpack(\'a4fid/Nsize/nflag\', $buf);
if ($tmp[\'size\'] == 0) break;
$tmp[\'dat\'] = $this->_read_head_buf($tmp[\'size\']);

// 0x6000 (11000000 00000000)
if ($tmp[\'flag\'] & 0x6000) continue;

// mapping the data
if ($k = $items[$tmp[\'fid\']])
{ // If first char is \"\\0\", just skip
if (substr($tmp[\'dat\'], 0, 1) == \"\\0\") $tmp[\'dat\'] = substr($tmp[\'dat\'], 1);
$ret[$k] = $tmp[\'dat\'];
}
}

// reset the genre
if ($g = $ret[\'Genre\'])
{
if (substr($g,0,1) == \'(\' && substr($g,-1,1) == \')\') $g = substr($g, 1, -1);
if (is_numeric($g))
{
$g = intval($g);
$ret[\'Genre\'] = (isset($this->genres[$g]) ? $this->genres[$g] : \'Unknown\');
}
}

$ret[\'ID3v1\'] = \'no\';
return $ret;
}
// get meta info of MP3
function _get_meta_info()
{
// seek to the lead buf: 0xff
$off = 0;
if ($this->head) $off = $this->head[\'size\'] + 10;
fseek($this->fd, $off, SEEK_SET);
while (!feof($this->fd))
{
$skip = ord(fread($this->fd, 1));
if ($skip == 0xff) break;
}
if ($skip != 0xff) return false;
$buf = fread($this->fd, 3);
if (strlen($buf) != 3) return false;
$tmp = unpack(\'C3\', $buf);
if (($tmp[1] & 0xf0) != 0xf0) return false;
// get the meta info
$meta = array();
// get mpeg version
$meta[\'mpeg\'] = ($tmp[1] & 0x08 ? 1 : 2);
$meta[\'layer\'] = ($tmp[1] & 0x04) ? (($tmp[1] & 0x02) ? 1 : 2) : (($tmp[1] & 0x02) ? 3 : 0);
$meta[\'epro\'] = ($tmp[1] & 0x01) ? \'no\' : \'yes\';
// bit rates
$bit_rates = array(
1 => array(
1 => array(0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0),
2 => array(0,32,48,56,64,80,96,112,128,160,192,224,256,320,384,0),
3 => array(0,32,40,48,56,64,80,96,112,128,160,192,224,256,320,0)
),
2 => array(
1 => array(0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0),
2 => array(0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0),
3 => array(0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0)
)
);
$i = $meta[\'mpeg\'];
$j = $meta[\'layer\'];
$k = ($tmp[2]>>4);
$meta[\'bitrate\'] = $bit_rates[$i][$j][$k];
// sample rates <采样率>
$sam_rates = array(1=>array(44100,48000,32000,0), 2=>array(22050,24000,16000,0));
$meta[\'samrate\'] = $sam_rates[$i][$k];
$meta[\"padding\"] = ($tmp[2] & 0x02) ? \'on\' : \'off\';
$meta[\"private\"] = ($tmp[2] & 0x01) ? \'on\' : \'off\';
// mode & mode_ext
$k = ($tmp[3]>>6);
$channel_modes = array(\'stereo\', \'joint stereo\', \'dual channel\', \'single channel\');
$meta[\'mode\'] = $channel_modes[$k];
$k = (($tmp[3]>>4) & 0x03);
$extend_modes = array(\'MPG_MD_LR_LR\', \'MPG_MD_LR_I\', \'MPG_MD_MS_LR\', \'MPG_MD_MS_I\');
$meta[\'ext_mode\'] = $extend_modes[$k];
$meta[\'copyright\'] = ($tmp[3] & 0x08) ? \'yes\' : \'no\';
$meta[\'original\'] = ($tmp[3] & 0x04) ? \'yes\' : \'no\';
$emphasis = array(\'none\', \'50/15 microsecs\', \'rreserved\', \'CCITT J 17\');
$k = ($tmp[3] & 0x03);
$meta[\'emphasis\'] = $emphasis[$k];
return $meta;
}
// set v1 info
function _set_v1_info($pa)
{
// ID3v1 (simpled)
$off = -128;
if (!($tmp = $this->head1))
{
$off = 0;
$tmp[\'id\'] = \'TAG\';
$tmp[\'Title\'] = $tmp[\'Artist\'] = $tmp[\'AlbumTitle\'] = $tmp[\'Year\'] = $tmp[\'Description\'] = \'\';
$tmp[\'Reserved\'] = $tmp[\'Track\'] = $tmp[\'Genre\'] = 0;
}

// basic items
$items = array(\'Title\', \'Artist\', \'Copyright\', \'Description\', \'Year\', \'AlbumTitle\');
foreach ($items as $k)
{
if (isset($pa[$k])) $tmp[$k] = $pa[$k];
}
// genre index
if (isset($pa[\'Genre\']))
{
$g = 0;
foreach ($this->genres as $gtmp)
{
if (!strcasecmp($gtmp, $pa[\'Genre\']))
break;
$g++;
}
$tmp[\'Genre\'] = $g;
}
if (isset($pa[\'Track\'])) $tmp[\'Track\'] = intval($pa[\'Track\']);
// pack the data
$buf = pack(\'a3a30a30a30a4a28CCC\', $tmp[\'id\'], $tmp[\'Title\'], $tmp[\'Artist\'], $tmp[\'AlbumTitle\'],
$tmp[\'Year\'], $tmp[\'Description\'], 0, $tmp[\'Track\'], $tmp[\'Genre\']);
flock($this->fd, LOCK_EX);
fseek($this->fd, $off, SEEK_END);
fwrite($this->fd, $buf, 128);
flock($this->fd, LOCK_UN);
}
// set v2 info
function _set_v2_info($pa)
{
if (!$this->head)
{ // insert ID3
return; // 没有就算了
/**
$tmp = array(\'id\'=>\'ID3\',\'ver\'=>3,\'rev\'=>0,\'flag\'=>0);
$tmp[\'size\'] = -10; // +10 => 0
$this->head = $tmp;
$this->head_buf = \'\';
$this->head_off = 0;
**/
}
$items = array( \'TCOP\'=>\'Copyright\', \'TPE1\'=>\'Artist\', \'TIT2\'=>\'Title\', \'TRAC\'=>\'Track\',
\'TCON\'=>\'Genre\', \'COMM\'=>\'Description\', \'TYER\'=>\'Year\', \'TALB\'=>\'AlbumTitle\');
$head_body = \'\';
while (true)
{
$buf = $this->_read_head_buf(10);
if (strlen($buf) != 10) break;
$tmp = unpack(\'a4fid/Nsize/nflag\', $buf);
if ($tmp[\'size\'] == 0) break;
$data = $this->_read_head_buf($tmp[\'size\']);
if (($k = $items[$tmp[\'fid\']]) && isset($pa[$k]))
{
// the data should prefix by \"\\0\" [replace]
$data = \"\\0\" . $pa[$k];
unset($pa[$k]);
}
$head_body .= pack(\'a4Nn\', $tmp[\'fid\'], strlen($data), $tmp[\'flag\']) . $data;
}
// reverse the items & set the new tags
$items = array_flip($items);
foreach ($pa as $k => $v)
{
if ($fid = $items[$k])
{
$head_body .= pack(\'a4Nn\', $fid, strlen($v) + 1, 0) . \"\\0\" . $v;
}
}
// new length
$new_len = strlen($head_body) + 10;
$old_len = $this->head[\'size\'] + 10;
if ($new_len < $old_len)
{
$head_body .= str_repeat(\"\\0\", $old_len - $new_len);
$new_len = $old_len;
}
// count the size1,2,3,4, no include the header
// 较为变态的算法... :p (28bytes integer)
$size = array();
$nlen = $new_len - 10;
for ($i = 4; $i > 0; $i--)
{
$size[$i] = ($nlen & 0x7f);
$nlen >>= 7;
}
$tmp = $this->head;
//echo \"old_len : $old_len new_len: $new_len\\n\";
$head_buf = pack(\'a3CCCCCCC\', $tmp[\'id\'], $tmp[\'ver\'], $tmp[\'rev\'], $tmp[\'flag\'],
$size[1], $size[2], $size[3], $size[4]);
$head_buf .= $head_body;
$this->_file_save($head_buf, $old_len, $new_len);
}