SunshinePHP Developer Conference 2015

gzopen

(PHP 4, PHP 5)

gzopengz ファイルを開く

説明

resource gzopen ( string $filename , string $mode [, int $use_include_path = 0 ] )

読み込みもしくは書き込みのために gzip (.gz) ファイルをオープンします。

gzopen() は、gzip フォーマットでないファイルの読み込みについても使用することができます。 この場合、gzread()は、ファイルを解凍せずに直接読み 込まれます。

パラメータ

filename

ファイル名を指定します

mode

fopen() と同じ (rb または wb) ですが、 圧縮レベル (wb9) または圧縮の方策、 つまり、wb6f のようにフィルターを通したデータを f で指定したり、h でハフマン圧縮のみを行うことを指定したりすることができます (方策に関するパラメータの詳細については、zlib.h の中の deflateInit2 の説明を参照ください)。

use_include_path

このオプションパラメータを 1 にすることにより、 include_pathにあるファイルも 検索することができます。

返り値

オープンしたファイルへのファイルポインタを返します。その後、 このファイルディスクプリタから読み込んだ全ては透過的に解凍され、 書き込んだものは圧縮されます。

オープンに失敗した場合、この関数は FALSE を返します。

例1 gzopen() の例

<?php
$fp 
gzopen("/tmp/file.gz""r");
?>

参考

  • gzclose() - 開かれたgzファイルへのポインタを閉じる

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User Contributed Notes 7 notes

up
1
David Gero dave at havidave dot com
3 years ago
gzopen("php://output","wb") doesn't work on a web server, nor does fopen("compress.zlib://php://output","wb").

Here is a snippet to gzip a file and output it on the fly, without using a temporary file, without reading the file into memory, and without reading the file more than once:

<?php
$fin
= fopen($file, "rb");
if (
$fin !== FALSE) {
   
$fout = fopen("php://output", "wb");
    if (
$fout !== FALSE) {
   
// write gzip header
   
fwrite($fout, "\x1F\x8B\x08\x08".pack("V", filemtime($file))."\0\xFF", 10);
   
// write the original file name
   
$oname = str_replace("\0", "", basename($file));
   
fwrite($fout, $oname."\0", 1+strlen($oname));
   
// add the deflate filter using default compression level
   
$fltr = stream_filter_append($fout, "zlib.deflate", STREAM_FILTER_WRITE, -1);
   
// set up the CRC32 hashing context
   
$hctx = hash_init("crc32b");
   
// turn off the time limit
   
if (!ini_get("safe_mode")) set_time_limit(0);
   
$con = TRUE;
   
$fsize = 0;
    while ((
$con !== FALSE) && !feof($fin)) {
       
// deflate works best with buffers >32K
       
$con = fread($fin, 64 * 1024);
        if (
$con !== FALSE) {
       
hash_update($hctx, $con);
       
$clen = strlen($con);
       
$fsize += $clen;
       
fwrite($fout, $con, $clen);
        }
    }
   
// remove the deflate filter
   
stream_filter_remove($fltr);
   
// write the CRC32 value
    // hash_final is a string, not an integer
   
$crc = hash_final($hctx, TRUE);
   
// need to reverse the hash_final string so it's little endian
   
fwrite($fout, $crc[3].$crc[2].$crc[1].$crc[0], 4);
   
// write the original uncompressed file size
   
fwrite($fout, pack("V", $fsize), 4);
   
fclose($fout);
    }
   
fclose($fin);
}
?>
up
1
dtorop932 at hotmail dot com
10 years ago
RE dubious's comment: "Being able to read gzip streams from ftp and http is near the top of my personal wishlist at the moment..."

One way to read a gzip stream over http is to daisychain stream wrappers, e.g.:

<?
$fp = fopen("compress.zlib://http://some.website.org/example.gz", "r");
?>
up
0
plasma
6 years ago
This worked unstable for me under high load (50+ files per second):

<?php
    $gz
= gzopen ( $file, 'w9' );
   
gzwrite ( $gz, $content );
   
gzclose ( $gz );
?>

The following works fine:

<?php
    $f
= fopen ( $file, 'w' );
   
fwrite ( $f, gzcompress ( $content, 9 ) );
   
fclose ( $f );
?>
up
0
katzlbtjunk at hotmail dot com
6 years ago
WARNING gzopen and gzread have a major disadvantage. They makes NO checksum and NO length verification of the gzipped data and discard this valuable information. This should be documented here.
up
0
rob at digital-crocus dot com
9 years ago
dtorop932 at hotmail dot com's comments, according to my tests, is incorrect. That code wishes to download the entire file before parsing, which is inconvinient. The wget method works though.
up
0
pentek_imre at mailbox dot hu
9 years ago
Be aware that when opening a remote file on a http server the gzopen will return by default false after 120 seconds waiting to any answer.
up
-1
-delete-this-part-dubious at 2xtreme dot net
12 years ago
"On the fly" gunzipping actually DOES seem to work - it just appears that only LOCAL streams/files (including php://stdin) can be accessed for some reason.  I THINK (but have not yet tested) that you could similarly gzopen "php://stdout" and pass a stream of gzipped data to the browser (when run from a web page) or console (when run standalone) through there.

I HAVE tested scripts from the command line like:

wget -q -O- ftp://some.host.net/pub/some_gzip_file.gz | php gunzip_stuff.php

where gunzip_stuff.php would be a script that gzopened "php://stdin" and did gzgets from that stream, and it seems to work fine, but that obviously doesn't help someone wanting to grab gzipped streams from remote sites from a web-based script.

Being able to read gzip streams from ftp and http is near the top of my personal wishlist at the moment...
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