Previously in a post I made for uploading a file from URL we wanted to include a file size check to make sure the file wasn’t too big before we upload it. Here I’ll show you how to get the remote file’s size and other information before doing other functions with it.
We’ll do this through a simple form. By default a form will encode all characters and convert spaces to “+” so we will leave the enctype undefined.
Then we just need the text input named “url” which I gave a default value “Enter URL Here…” and the Javascript-related attribute – onfocus. So when you focus on the text input it will change from the default value to blank.
Finally of course, we include the submit input named “submit” with the value “Submit.” We will use this value to check that the form was submitted.
[codesyntax lang=”html4strict” title=”HTML Form”]
<form action=”getinfo.php” method=”post”>
<input type=”text” name=”url” size=”40″ value=”Enter URL Here…” onfocus=”if(this.value == ‘Enter URL Here…’) this.value = ”;” /> <input type=”submit” name=”submit” value=”Submit” />
</form>
[/codesyntax]
This HTML form will submit the entered url to getinfo.php.
We are going to the function fopen() to get the information we need from the remote file. There is one thing to be aware of using fopen() to retrieve this data. You need to be sure the fopen wrappers is enabled in your php.ini. This can not be changed using ini_set().
We are going to create a variable “contents” and add each line of the file to it as we read it. Then we will use the function mb_strlen() to get the file size of the variable. Normally we would use strlen(), however that will only read one character as one byte. That doesn’t really give you the most accurate reading if you have special characters in the file which are more than one byte.
By default the function fgets() reads each line of a file 1024 bytes at a time. The function runs until either the specified length is reached (1024 bytes) or to the end of the file. It is more resource efficient to specify a read length:
“Until PHP 4.3.0, omitting it would assume 1024 as the line length. If the majority of the lines in the file are all larger than 8KB, it is more resource efficient for your script to specify the maximum line length.” – php.net
getinfo.php
[codesyntax lang=”php” title=”getinfo.php Source Code”]
<?php
// getinfo.php
if($_POST[“submit”]){
// Form is submitted.
// Check the fopen wrapper settings in php.ini
if (ini_get(“allow_url_fopen”) == 1) {
// Open the file.
$file = fopen(trim($_POST[“url”]), “r”);
if($file){
// We got the file.
$contents = “”;
while($line = fgets($file,1024)){
// Write each line to the string contents a kilobyte at a time.
$contents .= $line;
}
$filesize = mb_strlen($contents,”8bit”);
$kb = $filesize / 1024; // Returns the file size in kilobytes
echo “<strong>File Size</strong>: “.$filesize.” bytes or “.$kb.” kilobytes.”;
} else {
echo “Remote file not found.”;
}
} else {
echo “Fopen wrappers not enabled.”;
}
}
?>
[/codesyntax]
The page will display the file size in bytes and kilobytes, as so:
File Size: 1024 bytes or 1 kilobytes.
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Great little tidbit of code. This could be very useful. Is there any particular reason why you are downloading only 1024 bits each time thru the loop?
I updated the post to show why, but it is more resource efficient to specify a reading length with PHP 4.3 and further, due to increased file size.
So this value is dependent upon what type of file you are reading. Preferably a file with many line breaks.