Be careful when reading data in a loop. gzread() behaves a little differently than bzread() or fread(), it does NOT return false when reading past the end of stream. It instead returns an empty string.
So a loop like:
$handle = gzopen($file);
while (false !== $chunk = gzread($handle, $bytes)) {
//...
}
will loop indefinitely.
PHP - Manual: gzread
2024-12-22
gzread
(PHP 4, PHP 5, PHP 7, PHP 8)
gzread — Binary-safe gz-file read
说明
gzread(resource
$stream, int $length): string|false
gzread() reads up to length bytes
from the given gz-file pointer. Reading stops when
length (uncompressed) bytes have been read
or EOF is reached, whichever comes first.
参数
-
stream -
The gz-file pointer. It must be valid, and must point to a file successfully opened by gzopen().
-
length -
The number of bytes to read.
返回值
The data that have been read, 或者在失败时返回 false.
更新日志
| 版本 | 说明 |
|---|---|
| 7.4.0 |
This functions returns false on failure now; previously 0 was returned.
|
范例
示例 #1 gzread() example
<?php
// get contents of a gz-file into a string
$filename = "/usr/local/something.txt.gz";
$zd = gzopen($filename, "r");
$contents = gzread($zd, 10000);
gzclose($zd);
?>
add a note
User Contributed Notes 8 notes
waldermort at gmail dot com ¶
4 years ago
Nitrogen ¶
9 years ago
Here is a function for returning the uncompressed filesize of a gzip file. The filesize is stored as a 32-bit integer in the end of the compressed file, that's how this function works. Additionally, this function checks to see if it's a real gzip compressed file before doing the work; if it isn't, then just like other gz- functions, it'll treat it just like a regular file and perform a normal filesize operation. Enjoy!
<?php
function gzfilesize($filename) {
$gzfs = FALSE;
if(($zp = fopen($filename, 'r'))!==FALSE) {
if(@fread($zp, 2) == "\x1F\x8B") { // this is a gzip'd file
fseek($zp, -4, SEEK_END);
if(strlen($datum = @fread($zp, 4))==4)
extract(unpack('Vgzfs', $datum));
}
else // not a gzip'd file, revert to regular filesize function
$gzfs = filesize($filename);
fclose($zp);
}
return($gzfs);
}
?>
utku ¶
14 years ago
I don't think it would be wise to open a whole gzip file (it _is_ compressed for a reason, and likely to be a very big file) into a single string. You would most likely hit the php memory limits. Instead, if you need to process the file, put your gzread calls in a loop, and read incrementally by a setting $length to a constant value.
denis at bitrix dot ru ¶
11 years ago
Note that this functions' behavior differs from fread in case of EOF.
When you read the last chunk (mean the last bytes from file), it is EOF just after gzread, but in case of fread you need to read once more to get EOF.
Hope, I am clear :)
robinv12001 at yahoo dot co dot in ¶
13 years ago
<?php
//Extracting the content of a gzip file in php and creating a new csv file using the content
//Create a folder uploads inside current folder
$local_file = 'test.gz';
//To Get the size of the uncompressed file
$FileRead = $local_file;
$FileOpen = fopen($FileRead, "rb");
fseek($FileOpen, -4, SEEK_END);
$buf = fread($FileOpen, 4);
$GZFileSize = end(unpack("V", $buf));
fclose($FileOpen);
//To Get the size of the zip file
$fzip_size = $GZFileSize;
$filename = $local_file;
$ext = pathinfo($filename,PATHINFO_EXTENSION);
$file_name = pathinfo($filename,PATHINFO_FILENAME);
$file_name = $file_name.".csv";
$zd = gzopen($filename, "rb");
$contents = gzread($zd, $fzip_size);
gzclose($zd);
$file_name = "uploads/".$file_name;
$fp = fopen($file_name, "wb");
fwrite($fp, $contents); //write contents of feed to cache file
fclose($fp);
if(file_exists($file_name))
{
chmod($file_name,0755);
unlink($local_file);
}
?>
robinv12001 at yahoo dot co dot in ¶
13 years ago
<?php
//Using FTP Download a gzip file on current date from a remote server
//The gzip files are extracted
function parse_rawlist( $array )
{
$i=0;
foreach($array as $curraw)
{
$struc = array();
$current = preg_split("/[\s]+/",$curraw,9);
$struc['perms'] = $current[0];
$struc['number'] = $current[1];
$struc['owner'] = $current[2];
$struc['group'] = $current[3];
$struc['size'] = $current[4];
$struc['month'] = $current[5];
$struc['day'] = $current[6];
$struc['time'] = $current[7];
$struc['zfile_name'] = $current[8];
$structure[$i] = $struc;
$i++;
}
return $structure;
}
ini_set('memory_limit', '100M');
//Give FTP Information Here
//------------------------------------------------------------
$ftp_server = "example.com";
$ftp_user_name = "example";
$ftp_user_pass = "test";
//------------------------------------------------------------
//------------------------------------------------------------
$local_path = '/opt/lampp/htdocs/sample/test.gz';//Local Path
$server_path = 'outgoing/folder/';//Remote Sever Path
//------------------------------------------------------------
$conn_id = ftp_connect($ftp_server,21);
if($conn_id)
{
echo "Successfully connected";
}
$login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);
ftp_chdir($conn_id, $server_path);//Change Current Working Directory
$file_list = ftp_rawlist($conn_id,".");
$zip_details = parse_rawlist($file_list);
set_time_limit(1000);
$curr_date = strtotime(date("F d Y"));
for($i=0;$i<count($zip_details);$i++)
{
$fname = $zip_details[$i]['zfile_name'];
$mod_date1 = $zip_details[$i]['month']." ".$zip_details[$i]['day']." ".date("Y");
$mod_date = strtotime($mod_date1);//File Modified Date
if($mod_date == $curr_date)//If modified date equals current date
{
$local_file = $fname;
$server_file = $fname;
if (ftp_get($conn_id, $local_file, $server_file, FTP_BINARY))
{
echo "<br/>Successfully written to $local_file\n";
}
else
{
echo "<br/>There was a problem\n";
}
if(file_exists($local_file))
{
$fzip_size = $zip_details[$i]['size'];
$filename = $local_file;
$ext = pathinfo($filename,PATHINFO_EXTENSION);
$file_name = pathinfo($filename,PATHINFO_FILENAME);
$file_name = $file_name.".csv";
$zd = gzopen($filename, "r");
$contents = gzread($zd, $fzip_size);
$file_name = "uploads/".$file_name;
file_put_contents($file_name,addslashes($contents));
if(file_exists($file_name))
{
chmod($file_name,0755);
unlink($local_file);
}
gzclose($zd);
}
}
}
ftp_close($conn_id);
?>
zaotong at yahoo dot com ¶
15 years ago
As was shown to me in another forum there is a way to get the uncompressed size of the gz file by viewing the last 4 bytes of the gz file.
Here is a piece of code that will do this
<?php
$FileRead = 'SomeText.txt';
$FileOpen = fopen($FileRead, "rb");
fseek($FileOpen, -4, SEEK_END);
$buf = fread($FileOpen, 4);
$GZFileSize = end(unpack("V", $buf));
fclose($FileOpen);
$HandleRead = gzopen($FileRead, "rb");
$ContentRead = gzread($HandleRead, $GZFileSize);
?>
This will read the last 4 bytes of the gz file and use it as the file int for the gzread.
Thanks to stereofrog for helping me with this code.
calin_ip at yahoo dot com ¶
11 years ago
Regarding finding out the lenght of the gz file.
For some reason the seek() function didn't worked, so, I've tried finding out the last 4 bytes using string functions.
That worked pretty well. Here is the code.
<?php
$stringu='my_beautiful_file.txt.gz';
$gzip=file_get_contents($stringu);
$rest = substr($gzip, -4);
$GZFileSize = end(unpack("V", $rest));
$FileRead = $stringu;
$HandleRead = gzopen($FileRead, "rb");
$ContentRead = gzread($HandleRead, $GZFileSize);
gzclose($HandleRead);
?>
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