(PHP 4, PHP 5, PHP 7)
fopen — Opens file or URL
$filename
, string $mode
[, bool $use_include_path = false
[, resource $context
]] )
fopen() binds a named resource, specified by
filename, to a stream.
filename
If filename is of the form "scheme://...", it
is assumed to be a URL and PHP will search for a protocol handler
(also known as a wrapper) for that scheme. If no wrappers for that
protocol are registered, PHP will emit a notice to help you track
potential problems in your script and then continue as though
filename specifies a regular file.
If PHP has decided that filename specifies
a local file, then it will try to open a stream on that file.
The file must be accessible to PHP, so you need to ensure that
the file access permissions allow this access.
If you have enabled safe mode
or open_basedir further
restrictions may apply.
If PHP has decided that filename specifies
a registered protocol, and that protocol is registered as a
network URL, PHP will check to make sure that
allow_url_fopen is
enabled. If it is switched off, PHP will emit a warning and
the fopen call will fail.
Note:
The list of supported protocols can be found in Supported Protocols and Wrappers. Some protocols (also referred to as wrappers) support context and/or php.ini options. Refer to the specific page for the protocol in use for a list of options which can be set. (e.g. php.ini value user_agent used by the http wrapper).
On the Windows platform, be careful to escape any backslashes used in the path to the file, or use forward slashes.
<?php
$handle = fopen("c:\\folder\\resource.txt", "r");
?>
mode
The mode parameter specifies the type of access
you require to the stream. It may be any of the following:
mode |
Description |
|---|---|
| 'r' | Open for reading only; place the file pointer at the beginning of the file. |
| 'r+' | Open for reading and writing; place the file pointer at the beginning of the file. |
| 'w' | Open for writing only; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it. |
| 'w+' | Open for reading and writing; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it. |
| 'a' | Open for writing only; place the file pointer at the end of the file. If the file does not exist, attempt to create it. In this mode, fseek() has no effect, writes are always appended. |
| 'a+' | Open for reading and writing; place the file pointer at the end of the file. If the file does not exist, attempt to create it. In this mode, fseek() only affects the reading position, writes are always appended. |
| 'x' |
Create and open for writing only; place the file pointer at the
beginning of the file. If the file already exists, the
fopen() call will fail by returning FALSE and
generating an error of level E_WARNING. If
the file does not exist, attempt to create it. This is equivalent
to specifying O_EXCL|O_CREAT flags for the
underlying open(2) system call.
|
| 'x+' | Create and open for reading and writing; otherwise it has the same behavior as 'x'. |
| 'c' | Open the file for writing only. If the file does not exist, it is created. If it exists, it is neither truncated (as opposed to 'w'), nor the call to this function fails (as is the case with 'x'). The file pointer is positioned on the beginning of the file. This may be useful if it's desired to get an advisory lock (see flock()) before attempting to modify the file, as using 'w' could truncate the file before the lock was obtained (if truncation is desired, ftruncate() can be used after the lock is requested). |
| 'c+' | Open the file for reading and writing; otherwise it has the same behavior as 'c'. |
Note:
Different operating system families have different line-ending conventions. When you write a text file and want to insert a line break, you need to use the correct line-ending character(s) for your operating system. Unix based systems use \n as the line ending character, Windows based systems use \r\n as the line ending characters and Macintosh based systems use \r as the line ending character.
If you use the wrong line ending characters when writing your files, you might find that other applications that open those files will "look funny".
Windows offers a text-mode translation flag ('t') which will transparently translate \n to \r\n when working with the file. In contrast, you can also use 'b' to force binary mode, which will not translate your data. To use these flags, specify either 'b' or 't' as the last character of the
modeparameter.The default translation mode depends on the SAPI and version of PHP that you are using, so you are encouraged to always specify the appropriate flag for portability reasons. You should use the 't' mode if you are working with plain-text files and you use \n to delimit your line endings in your script, but expect your files to be readable with applications such as notepad. You should use the 'b' in all other cases.
If you do not specify the 'b' flag when working with binary files, you may experience strange problems with your data, including broken image files and strange problems with \r\n characters.
Note:
For portability, it is strongly recommended that you always use the 'b' flag when opening files with fopen().
Note:
Again, for portability, it is also strongly recommended that you re-write code that uses or relies upon the 't' mode so that it uses the correct line endings and 'b' mode instead.
use_include_path
The optional third use_include_path parameter
can be set to '1' or TRUE if you want to search for the file in the
include_path, too.
contextNote: Context support was added with PHP 5.0.0. For a description of contexts, refer to Streams.
Returns a file pointer resource on success, or FALSE on error.
If the open fails, an error of level
E_WARNING is generated. You may use @ to suppress this
warning.
| Version | Description |
|---|---|
| 5.2.6 | The 'c' and 'c+' options were added |
| 4.3.2 | As of PHP 4.3.2, the default mode is set to binary for all platforms that distinguish between binary and text mode. If you are having problems with your scripts after upgrading, try using the 't' flag as a workaround until you have made your script more portable as mentioned before |
Example #1 fopen() examples
<?php
$handle = fopen("/home/rasmus/file.txt", "r");
$handle = fopen("/home/rasmus/file.gif", "wb");
$handle = fopen("http://www.example.com/", "r");
$handle = fopen("ftp://user:password@example.com/somefile.txt", "w");
?>
When using SSL, Microsoft IIS will violate the protocol by closing the connection without sending a close_notify indicator. PHP will report this as "SSL: Fatal Protocol Error" when you reach the end of the data. To work around this, the value of error_reporting should be lowered to a level that does not include warnings. PHP can detect buggy IIS server software when you open the stream using the https:// wrapper and will suppress the warning. When using fsockopen() to create an ssl:// socket, the developer is responsible for detecting and suppressing this warning.
Note: When safe mode is enabled, PHP checks whether the directory in which the script is operating has the same UID (owner) as the script that is being executed.
Note:
If you are experiencing problems with reading and writing to files and you're using the server module version of PHP, remember to make sure that the files and directories you're using are accessible to the server process.
Note:
This function may also succeed when
filenameis a directory. If you are unsure whetherfilenameis a file or a directory, you may need to use the is_dir() function before calling fopen().
Note - using fopen in 'w' mode will NOT update the modification time (filemtime) of a file like you may expect. You may want to issue a touch() after writing and closing the file which update its modification time. This may become critical in a caching situation, if you intend to keep your hair.
With php 5.2.5 on Apache 2.2.4, accessing files on an ftp server with fopen() or readfile() requires an extra forwardslash if an absolute path is needed.
i.e., if a file called bullbes.txt is stored under /var/school/ on ftp server example.com and you're trying to access it with user blossom and password buttercup, the url would be:
ftp://blossom:buttercup@example.com//var/school/bubbles.txt
Note the two forwardslashes. It looks like the second one is needed so the server won't interpret the path as relative to blossom's home on townsville.
On a Windows webserver, when using fopen with a file path stored in a variable, PHP will return an error if the variable isn't encoded in ASCII, which may be the case if the file file path is retrieved from a database.
Possible workaround :
<?
$encoding = mb_detect_encoding($filePath);
$filePath = mb_convert_encoding($filePath, "ASCII", $encoding);
$filePath = str_replace("?", "", $filePath);
$filePath = addslashes($filePath);
if(file_exists($filePath)) {
echo "File Found.";
$handle = fopen($filePath, "r");
$fileContents = fread($handle, filesize($filePath));
fclose($handle);
if(!empty($fileContents)) {
echo "<pre>".$fileContents."</pre>";
}
}
else {
echo "File Not Found.";
}
?>
Simple class to fetch a HTTP URL. Supports "Location:"-redirections. Useful for servers with allow_url_fopen=false. Works with SSL-secured hosts.
<?php
#usage:
$r = new HTTPRequest('http://www.example.com');
echo $r->DownloadToString();
class HTTPRequest
{
var $_fp; // HTTP socket
var $_url; // full URL
var $_host; // HTTP host
var $_protocol; // protocol (HTTP/HTTPS)
var $_uri; // request URI
var $_port; // port
// scan url
function _scan_url()
{
$req = $this->_url;
$pos = strpos($req, '://');
$this->_protocol = strtolower(substr($req, 0, $pos));
$req = substr($req, $pos+3);
$pos = strpos($req, '/');
if($pos === false)
$pos = strlen($req);
$host = substr($req, 0, $pos);
if(strpos($host, ':') !== false)
{
list($this->_host, $this->_port) = explode(':', $host);
}
else
{
$this->_host = $host;
$this->_port = ($this->_protocol == 'https') ? 443 : 80;
}
$this->_uri = substr($req, $pos);
if($this->_uri == '')
$this->_uri = '/';
}
// constructor
function HTTPRequest($url)
{
$this->_url = $url;
$this->_scan_url();
}
// download URL to string
function DownloadToString()
{
$crlf = "\r\n";
// generate request
$req = 'GET ' . $this->_uri . ' HTTP/1.0' . $crlf
. 'Host: ' . $this->_host . $crlf
. $crlf;
// fetch
$this->_fp = fsockopen(($this->_protocol == 'https' ? 'ssl://' : '') . $this->_host, $this->_port);
fwrite($this->_fp, $req);
while(is_resource($this->_fp) && $this->_fp && !feof($this->_fp))
$response .= fread($this->_fp, 1024);
fclose($this->_fp);
// split header and body
$pos = strpos($response, $crlf . $crlf);
if($pos === false)
return($response);
$header = substr($response, 0, $pos);
$body = substr($response, $pos + 2 * strlen($crlf));
// parse headers
$headers = array();
$lines = explode($crlf, $header);
foreach($lines as $line)
if(($pos = strpos($line, ':')) !== false)
$headers[strtolower(trim(substr($line, 0, $pos)))] = trim(substr($line, $pos+1));
// redirection?
if(isset($headers['location']))
{
$http = new HTTPRequest($headers['location']);
return($http->DownloadToString($http));
}
else
{
return($body);
}
}
}
?>
a variable $http_response_header is available when doing the fopen(). Which contains an array of the response header.
If you're using fopen to open a URL that requires authorization, you might need to force a HTTP/1.0 request for it since fopen won't support HTTP/1.1 requests. You can do that by setting your user_agent to one that is known only to support HTTP/1.0 (most webservers will be configured to force HTTP/1.0 for some browsers). Here's what worked for me:
<?php
$returned=URLopen("http://$username:$password@example.com");
function URLopen($url)
{
// Fake the browser type
ini_set('user_agent','MSIE 4\.0b2;');
$dh = fopen("$url",'r');
$result = fread($dh,8192);
return $result;
}
?>
download: i need a function to simulate a "wget url" and do not buffer the data in the memory to avoid thouse problems on large files:
<?php
function download($file_source, $file_target) {
$rh = fopen($file_source, 'rb');
$wh = fopen($file_target, 'wb');
if ($rh===false || $wh===false) {
// error reading or opening file
return true;
}
while (!feof($rh)) {
if (fwrite($wh, fread($rh, 1024)) === FALSE) {
// 'Download error: Cannot write to file ('.$file_target.')';
return true;
}
}
fclose($rh);
fclose($wh);
// No error
return false;
}
?>
While opening a file with multibyte data (Ex: données multi-octets), faced some issues with the encoding. Got to know that it uses windows-1250. Used iconv to convert it to UTF-8 and it resolved the issue.
<?php
function utf8_fopen_read($fileName) {
$fc = iconv('windows-1250', 'utf-8', file_get_contents($fileName));
$handle=fopen("php://memory", "rw");
fwrite($handle, $fc);
fseek($handle, 0);
return $handle;
}
?>
Example usage:
<?php
$fh = utf8_fopen_read("./tpKpiBundle.csv");
while (($data = fgetcsv($fh, 1000, ",")) !== false) {
foreach ($data as $value) {
echo $value . "<br />\n";
}
}
?>
Hope it helps.
"Do not use the following reserved device names for the name of a file:
CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1,
LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9. Also avoid these names
followed immediately by an extension; for example, NUL.txt is not recommended.
For more information, see Namespaces"
it is a windows limitation.
see:
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
<?php
#going to update last users counter script since
#aborting a write because a file is locked is not correct.
$counter_file = '/tmp/counter.txt';
clearstatcache();
ignore_user_abort(true); ## prevent refresh from aborting file operations and hosing file
if (file_exists($counter_file)) {
$fh = fopen($counter_file, 'r+');
while(1) {
if (flock($fh, LOCK_EX)) {
#$buffer = chop(fgets($fh, 2));
$buffer = chop(fread($fh, filesize($counter_file)));
$buffer++;
rewind($fh);
fwrite($fh, $buffer);
fflush($fh);
ftruncate($fh, ftell($fh));
flock($fh, LOCK_UN);
break;
}
}
}
else {
$fh = fopen($counter_file, 'w+');
fwrite($fh, "1");
$buffer="1";
}
fclose($fh);
print "Count is $buffer";
?>
I was wondering why was added the "x" mode, it works only if the file do not exists, will create it and open it in read only, it's useless !!
But I found something I could do with that.
Here is a little mk_file function.
<?php
function mk_file($filename) {
if(!is_file($filename)) {
fclose(fopen($filename,"x")); //create the file and close it
return true;
} else return false; //file already exists
}
?>
You can improve it, add chmod support etc...
Writing and reading on a serial port.
If you are unable or unwilling to install the serial device library for PHP, its still possible to communicate through a serial port or USB device.
There are two issues to note:
- you must use a system call to set the port control options
- you must use NON blocking stream mode for reading (not for writing unless you use flow control)
<?php
// Set timeout to 500 ms
$timeout=microtime(true)+0.5;
// Set device controle options (See man page for stty)
exec("/bin/stty -F /dev/ttyS0 19200 sane raw cs8 hupcl cread clocal -echo -onlcr ");
// Open serial port
$fp=fopen("/dev/ttyS0","c+");
if(!$fp) die("Can't open device");
// Set blocking mode for writing
stream_set_blocking($fp,1);
fwrite($fp,"foo\n");
// Set non blocking mode for reading
stream_set_blocking($fp,0);
do{
// Try to read one character from the device
$c=fgetc($fp);
// Wait for data to arive
if($c === false){
usleep(50000);
continue;
}
$line.=$c;
}while($c!="\n" && microtime(true)<$timeout);
echo "Responce: $line";
?>
PHP will open a directory if a path with no file name is supplied. This just bit me. I was not checking the filename part of a concatenated string.
For example:
<?php
$fd = fopen('/home/mydir/' . $somefile, 'r');
?>
Will open the directory if $somefile = ''
If you attempt to read using the file handle you will get the binary directory contents. I tried append mode and it errors out so does not seem to be dangerous.
This is with FreeBSD 4.5 and PHP 4.3.1. Behaves the same on 4.1.1 and PHP 4.1.2. I have not tested other version/os combinations.
If you are getting message "Warning: fopen(): URL file-access is disabled in the server configuration", you can use function below to get the content from a local or remote file.
Function uses CURL lib, follow the link to get help: http://www.php.net/curl
<?php
/*
* @return string
* @param string $url
* @desc Return string content from a remote file
* @author Luiz Miguel Axcar (lmaxcar@yahoo.com.br)
*/
function get_content($url)
{
$ch = curl_init();
curl_setopt ($ch, CURLOPT_URL, $url);
curl_setopt ($ch, CURLOPT_HEADER, 0);
ob_start();
curl_exec ($ch);
curl_close ($ch);
$string = ob_get_contents();
ob_end_clean();
return $string;
}
#usage:
$content = get_content ("http://www.php.net");
var_dump ($content);
?>
If you are getting a "HTTP request failed!" without further details, the socket timeout could be expired. This default to 60 seconds. See stream_set_timeout().
For the directory separators use the PHP constant DIRECTORY_SEPARATOR.
fopen() will block if the file to be opened is a fifo. This is true whether it's opened in "r" or "w" mode. (See man 7 fifo: this is the correct, default behaviour; although Linux supports non-blocking fopen() of a fifo, PHP doesn't).
The consequence of this is that you can't discover whether an initial fifo read/write would block because to do that you need stream_select(), which in turn requires that fopen() has happened!
There IS an option to use fopen with a proxy, it's in $context.
No need to recode everything.
Note that whether you may open directories is operating system dependent. The following lines:
<?php
// Windows ($fh === false)
$fh = fopen('c:\\Temp', 'r');
// UNIX (is_resource($fh) === true)
$fh = fopen('/tmp', 'r');
?>
demonstrate that on Windows (2000, probably XP) you may not open a directory (the error is "Permission Denied"), regardless of the security permissions on that directory.
On UNIX, you may happily read the directory format for the native filesystem.
Quick tip. If using fopen to make http requests that contain a querystring, it is advised that you urlencode() your values, else characters like @ can make fopen (or whatever wrapper it is using) throw an error.
Note that if specifying the optional 'b' (binary) mode, it appears that it cannot be the first letter for some unaccountable reason. In other words, "br" doesn't work, while "rb" is ok!
I have found that I can do fopen("COM1:", "r+"); to open the comport in windows. You have to make sure the comport isn't already open or you will get a permission denied.
I am still playing around with this but you have to somehow flush what you send to the comport if you are trying to communicate realtime with a device.
I was working on a consol script for win32 and noticed a few things about it. On win32 it appears that you can't re-open the input stream for reading, but rather you have to open it once, and read from there on. Also, i don't know if this is a bug or what but it appears that fgets() reads until the new line anyway. The number of characters returned is ok, but it will not halt reading and return to the script. I don't know of a work around for this right now, but i'll keep working on it.
This is some code to work around the close and re-open of stdin.
<?php
function read($length='255'){
if (!isset($GLOBALS['StdinPointer'])){
$GLOBALS['StdinPointer']=fopen("php://stdin","r");
}
$line=fgets($GLOBALS['StdinPointer'],$length);
return trim($line);
}
echo "Enter your name: ";
$name=read();
echo "Enter your age: ";
$age=read();
echo "Hi $name, Isn't it Great to be $age years old?";
@fclose($StdinPointer);
?>
If you're running PHP as apache module, it will always write files as "nobody", "www", "httpd", (or whatever user your webserver runs as) unless you specify a different user/group in httpd.conf, or compile apache with suexec support.
However, if you run PHP as a CGI wrapper, you may setuid the PHP executable to whatever user you wish (*severe* security issues apply). If you really want to be able to su to other user, I recommend compiling with suexec support.
AFAIK, PHP can't NOT use SuEXEC if apache does. If PHP is configured as an apache module it will act as whatever user the apache is. If apache SuEXEC's to otheruser:othergroup (e.g. root:root), that's what PHP will write files as, because it acts as a part of apache code. I suggest you double-check your SuEXEC configuration and settings. Note: you can't su to another user within the PHP code -- it has to be an apache directive, either through <VirtualHost>, or through .htaccess. Also note: I'm not sure how it all works (if it works at all) on Win32 platforms.
Check www.apache.org to see how it's done.
[fopen note]
I have been trying unsuccessfully to upload and read a Mac OS file on a Linux server. Lots of records show up a just one big using only the following:
<?php $fhandle = fopen($file, 'r'); ?>
or
<?php $fhandle = fopen($file, 'rb'); ?>
It does work, however, this way:
<?php
ini_set('auto_detect_line_endings', TRUE);
$fhandle = fopen($file, 'r');
?>
TIP: If you are using fopen and fread to read HTTP or FTP or Remote Files, and experiencing some performance issues such as stalling, slowing down and otherwise, then it's time you learned a thing called cURL.
Performance Comparison:
10 per minute for fopen/fread for 100 HTTP files
2000 per minute for cURL for 2000 HTTP files
cURL should be used for opening HTTP and FTP files, it is EXTREMELY reliable, even when it comes to performance.
I noticed when using too many scripts at the same time to download the data from the site I was harvesting from, fopen and fread would go into deadlock. When using cURL i can open 50 windows, running 10 URL's from each window, and getting the best performance possible.
Just a Tip :)
With this it isn't possible to get data from another port than 80 (and 443) - at least for me. Because of that I've made this function who gets data from every port you want using HTTP:
<?php;
function getcontent($server, $port, $file)
{
$cont = "";
$ip = gethostbyname($server);
$fp = fsockopen($ip, $port);
if (!$fp)
{
return "Unknown";
}
else
{
$com = "GET $file HTTP/1.1\r\nAccept: */*\r\nAccept-Language: de-ch\r\nAccept-Encoding: gzip, deflate\r\nUser-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)\r\nHost: $server:$port\r\nConnection: Keep-Alive\r\n\r\n";
fputs($fp, $com);
while (!feof($fp))
{
$cont .= fread($fp, 500);
}
fclose($fp);
$cont = substr($cont, strpos($cont, "\r\n\r\n") + 4);
return $cont;
}
}
echo getcontent("www.myhost.com", "81", "/"));
?>
Works fine for me. Had to do this especially for a shoutcast server, which only delivered the HTML-file if the user-agent was given.
This is an addendum to ibetyouare at home dot com's note about Apache directory permissions. If you are on a shared host and cannot tweak Apache's permissions directives then you might try setting the same thing in a .htaccess file. Failing that, if you are having trouble just creating files then set the directory permissions to allow writing (for whatever directory the file is supposed to be in) and include the following before fopen():
`touch /path/to/myfile/myfile.txt`;
That will usually create a new empty file that you can write to even when fopen fails. - PHP 4.3.0
If you need fopen() on a URL to timeout, you can do like:
<?php
$timeout = 3;
$old = ini_set('default_socket_timeout', $timeout);
$file = fopen('http://example.com', 'r');
ini_set('default_socket_timeout', $old);
stream_set_timeout($file, $timeout);
stream_set_blocking($file, 0);
//the rest is standard
?>
I couldn't for the life of me get a certain php script working when i moved my server to a new Fedora 4 installation. The problem was that fopen() was failing when trying to access a file as a URL through apache -- even though it worked fine when run from the shell and even though the file was readily readable from any browser. After trying to place blame on Apache, RedHat, and even my cat and dog, I finally ran across this bug report on Redhat's website:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=164700
Basically the problem was SELinux (which I knew nothing about) -- you have to run the following command in order for SELinux to allow php to open a web file:
/usr/sbin/setsebool httpd_can_network_connect=1
To make the change permanent, run it with the -P option:
/usr/sbin/setsebool -P httpd_can_network_connect=1
Hope this helps others out -- it sure took me a long time to track down the problem.
If fopen() has been disabled for security reasons, is possible a porting FROM:
<?php
$f=fopen($file,'rb');
$data='';
while(!feof($f))
$data.=fread($f,$size);
fclose($f);
?>
TO:
<?php
$data = file_get_contents($file); // (PHP 4 >= 4.3.0, PHP 5)
?>
and also a porting FROM:
<?php
$f = fopen($file,'wb');
fwrite($f,$content,strlen($content));
fclose($f);
?>
TO:
<?php
$f=file_put_contents($file, $content); // (PHP 5)
?>
For detail read the php manual.
Here you have a function found on the website http://softontherocks.blogspot.com/2014/11/funcion-para-escribir-en-un-fichero-log.html with an example of how to make a log file.
The function is this:
function writeLog($data) {
list($usec, $sec) = explode(' ', microtime());
$datetime = strftime("%Y%m%d %H:%M:%S",time());
$msg = "$datetime'". sprintf("%06s",intval($usec*1000000)).": $data";
$save_path = 'foo.txt';
$fp = @fopen($save_path, 'a'); // open or create the file for writing and append info
fputs($fp, "$msg\n"); // write the data in the opened file
fclose($fp); // close the file
}
if fopen() throws a E_WARNING "failed to open stream: HTTP request failed!" at you when opening a valid URL that you know returns data, i advise you to do the following before calling fopen($url,'r'):
<?php
ini_set ('user_agent', $_SERVER['HTTP_USER_AGENT']);
?>
or anyways, set that 'user_agent' with ini_set() to something valid.
thanks, pollita|at|php.net @ http://bugs.php.net/bug.php?id=22937#c64196 , for the clue to this
Important note:
You have always to use the real path name for a file with the command fopen [for example: fopen($filename, 'w')], never use a symbolic link, it will not work (unable to open $filename).
Since the http-wrapper doesn't support stat() and so you can't use file_exists() for url's, you can simply use a function like this:
<?php
function http_file_exists($url)
{
$f=@fopen($url,"r");
if($f)
{
fclose($f);
return true;
}
return false;
}
?>
Be aware that fopen($url) also respects HTTP status headers. If the URL responds with a 1xx, 4xx, or 5xx status code, you will get a "failed to open stream: HTTP request failed!", followed by the HTTP status response. Same goes for file_get_contents($url)...
using fopen to upload a file through ftp cannot overwrite that file - use curl instead
If you want to open large files (more than 2GB) that's what I did and it works: you should recompile your php with the CFLAGS="-D_FILE_OFFSET_BITS=64" ./configure etc... This tells to your compiler (I tested only gcc on PHP-4.3.4 binary on Linux and Solaris) to make the PHP parser binary large file aware. This way fopen() will not give you the "Value too large for defined data type" error message.
God bless PHP
ciao
Sergio Paternoster
While adding CFLAGS="-D_FILE_OFFSET_BITS=64" immediately before calling "./configure" on the PHP source will enable support for using fopen() on large files (greater than 2 GB), note that -- if such an installation of PHP is used in conjunction with Apache HTTPD [2.x], Apache will become completely unresponsive even when not serving output from a PHP application.
In order to gain large file support for non-web applications while maintaining the operability of Apache, consider making two distinct PHP installations: one with the above CFLAGS specified during configuration (for non-web uses), and the other without this flag (for use with Apache).
Hello all. I have had trouble getting files through proxy, and the solution posted above only works if the requested file is also hosted on the proxy server (which is quite unlikely). so I've put together the following functions pfopen & preadfile. they quite work like the replaced fopen & readfile, and will resort to them if no proxy is provided :)
<?php
function preadfile($_url, $_proxy_name = null, $_proxy_port = 4480){
if(is_null($_proxy_name) || LOCAL_TEST){
return readfile($_url);
}else{
$proxy_cont = '';
$proxy_fp = pfopen($_url, $_proxy_name, $_proxy_port);
while(!feof($proxy_fp)) {$proxy_cont .= fread($proxy_fp,4096);}
fclose($proxy_fp);
$proxy_cont = substr($proxy_cont, strpos($proxy_cont,"\r\n\r\n")+4);
echo $proxy_cont;
return count($proxy_cont);
}
}
function pfopen($_url, $_proxy_name = null, $_proxy_port = 4480) {
if(is_null($_proxy_name) || LOCAL_TEST){
return fopen($_url);
}else{
$proxy_fp = fsockopen($_proxy_name, $_proxy_port);
if (!$proxy_fp) return false;
$host= substr($_url, 7);
$host = substr($bucket, 0, strpos($host, "/"));
$request = "GET $_url HTTP/1.0\r\nHost:$host\r\n\r\n";
fputs($proxy_fp, $request);
return $proxy_fp;
}
}
?>
Also a small function useful for backup for example. It's a mixed between the fopen() and the mkdir() functions.
This function opens a file but also make the path recursively where the file is contained. This is helpful for ending to finish with "No such file or directory in" errors
<?php
function fopen_recursive($path, $mode, $chmod=0755){
preg_match('`^(.+)/([a-zA-Z0-9]+\.[a-z]+)$`i', $path, $matches);
$directory = $matches[1];
$file = $matches[2];
if (!is_dir($directory)){
if (!mkdir($directory, $chmod, 1)){
return FALSE;
}
}
return fopen ($path, $mode);
}
?>
The issue involving some sites requiring a valid user-agent string when using fopen can easily be resolved by setting the user_agent string in the PHP.INI file.
If you do not have access to the PHP.INI file, then the use of
ini_set('user_agent','Mozilla: (compatible; Windows XP)');
should also work.
The actual agent string is up to you. If you want to identify to the sites that you are using PHP ...
ini_set('user_agent','PHP');
would do.
Regards,
Richard Quadling.
To overwrite a file with a new content without deleting it, and without changing the owner or access rights, it's best to not use:
<?php
$file = fopen($filename, 'r+b'); // binary update mode
//...
ftruncate($file, 0);
fwrite($file, $my_stuff);
//...
fclose($file);
?>
but instead the faster one:
<?php
$file = fopen($filename, 'r+b); // binary update mode
//...
rewind($file);
fwrite($file, $my_stuff);
fflush($file);
ftruncate($file, ftell($file));
//...
fclose($file);
?>
The reason is that truncating a file at size 0 forces the OS to deallocate all storage clusters used by the file, before you write your content which will be reallocated on disk.
The second code simply overwrites the existing content where it is already located on disk, and truncates any remaining bytes that may exist (if the new content is shorter than the old content). The "r+b" mode allows access for both read and write: the file can be kept opened after reading it and before rewriting the modified content.
It's particularly useful for files that are accessed often or have a size larger than a few kilobytes, as it saves lots of system I/O, and also limits the filesystem fragmentation if the updated file is quite large.
And this method also works if the file is locked exclusively once opened (but I would rather recommend using another empty file for locking purpose, opened with "a+" access mode, in "/var/lock/yourapp/*" or other fast filesystems where filelocks are easily monitored and where the webserver running PHP is allowed to create and update lock files, and not forgetting to close the lock file after closing the content file).
If there is a file that´s excessively being rewritten by many different users, you´ll note that two almost-simultaneously accesses on that file could interfere with each other. For example if there´s a chat history containing only the last 25 chat lines. Now adding a line also means deleting the very first one. So while that whole writing is happening, another user might also add a line, reading the file, which, at this point, is incomplete, because it´s just being rewritten. The second user would then rewrite an incomplete file and add its line to it, meaning: you just got yourself some data loss!
If flock() was working at all, that might be the key to not let those interferences happen - but flock() mostly won´t work as expected (at least that´s my experience on any linux webserver I´ve tried), and writing own file-locking-functions comes with a lot of possible issues that would finally result in corrupted files. Even though it´s very unlikely, it´s not impossible and has happened to me already.
So I came up with another solution for the file-interference-problem:
1. A file that´s to be accessed will first be copied to a temp-file directory and its last filemtime() is being stored in a PHP-variable. The temp-file gets a random filename, ensuring no other process is able to interfere with this particular temp-file.
2. When the temp-file has been changed/rewritten/whatever, there´ll be a check whether the filemtime() of the original file has been changed since we copied it into our temp-directory.
2.1. If filemtime() is still the same, the temp-file will just be renamed/moved to the original filename, ensuring the original file is never in a temporary state - only the complete previous state or the complete new state.
2.2. But if filemtime() has been changed while our PHP-process wanted to change its file, the temp-file will just be deleted and our new PHP-fileclose-function will return a FALSE, enabling whatever called that function to do it again (ie. upto 5 times, until it returns TRUE).
These are the functions I´ve written for that purpose:
<?php
$dir_fileopen = "../AN/INTERNAL/DIRECTORY/fileopen";
function randomid() {
return time().substr(md5(microtime()), 0, rand(5, 12));
}
function cfopen($filename, $mode, $overwriteanyway = false) {
global $dir_fileopen;
clearstatcache();
do {
$id = md5(randomid(rand(), TRUE));
$tempfilename = $dir_fileopen."/".$id.md5($filename);
} while(file_exists($tempfilename));
if (file_exists($filename)) {
$newfile = false;
copy($filename, $tempfilename);
}else{
$newfile = true;
}
$fp = fopen($tempfilename, $mode);
return $fp ? array($fp, $filename, $id, @filemtime($filename), $newfile, $overwriteanyway) : false;
}
function cfwrite($fp,$string) { return fwrite($fp[0], $string); }
function cfclose($fp, $debug = "off") {
global $dir_fileopen;
$success = fclose($fp[0]);
clearstatcache();
$tempfilename = $dir_fileopen."/".$fp[2].md5($fp[1]);
if ((@filemtime($fp[1]) == $fp[3]) or ($fp[4]==true and !file_exists($fp[1])) or $fp[5]==true) {
rename($tempfilename, $fp[1]);
}else{
unlink($tempfilename);
if ($debug != "off") echo "While writing, another process accessed $fp[1]. To ensure file-integrity, your changes were rejected.";
$success = false;
}
return $success;
}
?>
$overwriteanyway, one of the parameters for cfopen(), means: If cfclose() is used and the original file has changed, this script won´t care and still overwrite the original file with the new temp file. Anyway there won´t be any writing-interference between two PHP processes, assuming there can be no absolute simultaneousness between two (or more) processes.
Check for UTF-8 content in fread after fopen:
For checking the UTF-8 content I use the function 'htmlentities();'
Example:
<?php
$filename = "CONTENT.htm";
$handle = fopen($filename, "r");
$contents = fread($handle, filesize($filename));
// Check for UTF-8 content
if(htmlentities(utf8_decode($contents))){
$contents = htmlentities(utf8_decode($contents));
}else{
$contents = htmlentities($contents);
}
?>
fopen() and PROXY
I wondered why there is no possibility to use fopen() through a proxy in php. The solution posted above did not work for me.
This little function gets http through a given proxy:
<?php
function proxy_url($proxy_url)
{
$proxy_name = '127.0.0.1';
$proxy_port = 4001;
$proxy_cont = '';
$proxy_fp = fsockopen($proxy_name, $proxy_port);
if (!$proxy_fp) {return false;}
fputs($proxy_fp, "GET $proxy_url HTTP/1.0\r\nHost: $proxy_name\r\n\r\n");
while(!feof($proxy_fp)) {$proxy_cont .= fread($proxy_fp,4096);}
fclose($proxy_fp);
$proxy_cont = substr($proxy_cont, strpos($proxy_cont,"\r\n\r\n")+4);
return $proxy_cont;
}
?>
I had to switch from relative paths to full paths when my web host recently migrated the server onto their hosting cloud. This used to work for me:
<?php
$fplog = fopen('ipn.log','a');
?>
After the migration, however, I received the following error message:
Warning: fopen(ipn.log) [function.fopen]: failed to open stream: Permission denied in D:\home\server_name\log_test.php on line 21
I had to change the code to the following to get it to work:
<?php
$logfile = $_SERVER['DOCUMENT_ROOT'].'\\ipn.log';
$fplog = fopen($logfile,'a');
?>
when using ssl / https on windows i would get the error:
"Warning: fopen(https://example.com): failed to open stream: Invalid argument in someSpecialFile.php on line 4344534"
This was because I did not have the extension "php_openssl.dll" enabled.
So if you have the same problem, goto your php.ini file and enable it :)
The following is an example of file locking used in a function to share an array between processes.
In this example the function reads the array, possibly remove stuff like spend semaphores and insert new stuff to share.
The file gets locked for writing thus making sure that two processes doesn't inadvertently delete each others data.
The function can be called multiple times during a script, which becomes increasingly important if you write HTML5 Server Sent Events and websockets apps, since the script dose not end when the page are loaded. (there are other issues with that like garbage collection and memory leaks)
Using the “c” mode of fopen, removes the (remote) change of a race condition to the file lock.
Be aware that the function filesize() is not working correctly when files are in cash memory. You could flush the cash or in this case, since the file size of IPC are neglectable, just give a very large number as length parameter to fread.
<?php
function ipc($new_record=""){
$update=false;
// Open file with locking
$handle=fopen("example.dat","c+");
// Lock the file for writing
flock($handle,LOCK_EX);
// Get file size.
// you can either fluch the file cash to get an acurate number
// clearstatcache();
// Or use a large number
// Load event file into array
$contents=fread($handle,10000000);
$ipc_array=json_decode($contents,true);
// Clean out old stuff
if(is_array($ipc_array)){
$timeout=time()-60;
foreach($ipc_array as $key=>$record){
// eg remove spend semaphores or timed out messages
if( $record['time'] < $timeout ){
unset($ipc_array[$key]);
$update=true;
}
}
}
// Add new message
if(is_array($new_record)){
$new_record['time']=time();
$ipc_array[]=$new_record;
$update=true;
}
// Write file and end
if($update){
// Overwrite the old data
ftruncate($handle,0);
rewind($handle);
// Write the new array to file
fwrite($handle,json_encode($ipc_array,JSON_NUMERIC_CHECK));
}
// Unlock the file - you have to do it! it doesn't happen on fclose
flock($handle,LOCK_UN);
// Close the file
fclose($handle);
return $ipc_array;
}
// Read messages
$ipc=ipc();
// Show messages
foreach( $ipc as $record)
echo $record['message'] ."<br>\n";
// Send a message
$message["message"]="hello world.";
$message["foo"]="bar";
$ipc=ipc($message);
?>
Here is how you could modify file's contents by only opening it once in "r+" mode:
<?php
$filePath = '/path/to/file';
if( !@$fh = fopen($filePath, 'r+') ) {
die("Could not open $filePath in READ+WRITE mode");
}
// Extract contents
$contents = fread($fh, filesize($filePath));
// ..modify $contents in any way you need..
// Truncate file (important to move the pointer first)
fseek($fh, 0);
ftruncate($fh, 0);
// Write
fwrite($fh, $contents);
fclose($fh);
?>
If you open a file with r+ and execute an fwrite(), writing less to the file than what it originally was, it will result in the difference being padded with the end of the file from the previous end of the file. Example:
<?php
// Open file for read and string modification
$file = "/test";
$fh = fopen($file, 'r+');
$contents = fread($fh, filesize($file));
$new_contents = str_replace("hello world", "hello", $contents);
fclose($fh);
// Open file to write
$fh = fopen($file, 'r+');
fwrite($fh, $new_contents);
fclose($fh);
?>
If the end of the file was "abcdefghij", you will notice that the difference in "hello world" and "hello", 6 characters, will be appended to the file, resulting in the new ending: "efghij". To obviate this, fopen() with +w instead, which truncates the file to zero length.
