PHP获取音频文件的相关信息

5年以前  |  阅读数:1088 次  |  编程语言:PHP 

项目需求:现在有一个音频文件上传的功能,在上传后PHP需要获取这个音频文件的相关信息,例如:时长等,由于这个文件是放在买的空间上的,没有像ffmpeg这样的扩展来处理,那么PHP能不能获取到这些信息?

下面是之前在项目中用到的一个用PHP进行音频文件头部信息的读取与写入操作的实现,主要针对 WMA 和 MP3 两种格式,供参考。


    <?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);
    }

以上所述就是本文的全部内容了,希望大家能够喜欢。

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