How to set image file upload size in PHP_PHP tutorial

The default upload limit of PHP is a maximum of 2M. If you want to upload files exceeding this setting, you need to adjust some parameters of PHP, apache, etc. Below, we briefly introduce some parameters involved in PHP file upload:

• file_uploads: Switch whether to allow file upload via HTTP, the default is ON.
• upload_tmp_dir: upload_tmp_dir is used to describe the temporary directory where files uploaded by PHP are placed. If you want to upload files, you must ensure that the server has not closed the temporary files and has write permissions on the folder. If not specified, PHP uses the system default value.
• upload_max_filesize: The maximum allowed upload file size, the default is 2M.
• post_max_size: Controls the maximum amount of data that PHP can receive during a form submission using the POST method. If you want to use the PHP file upload function, you need to change this value to be larger than upload_max_filesize.
• max_input_time: Limit the time in seconds for receiving data through POST, GET and PUT methods. If your application is running on a slow link, you may need to increase this value to accommodate the additional time required to receive data.
• memory_limit: In order to avoid running scripts from using a large amount of system available memory, PHP allows defining memory usage limits. Use the memory_limit variable to specify the maximum memory capacity that a single script can use. The value of the variable memory_limit should be appropriately larger than the value of post_max_size.
• max_execution_time: max_execution_time sets the time that PHP waits for the script to complete before forcibly terminating the script. This time is calculated in seconds. This variable is useful when the script enters an infinite loop. However, this feature can also cause the operation to fail when there is a legitimate activity that takes a long time to complete (such as uploading a large file). In such cases, you must consider increasing the value of this variable to prevent PHP from shutting down the script while it is performing some important process.

For Linux hosts, there may be a php.conf file under /etc/httpd/conf.d/access.conf/. This file may solve the file size limit problem of some systems.

Add the following code to PHP upload to temporarily enable PHP to upload large files, as follows:

<?php  
//HTTP上传文件的开关，默认为ON即是开  
ini_set('file_uploads','ON');
//通过POST、GET以及PUT方式接收数据时间进行限制为90秒 默认值：60  
ini_set('max_input_time','90');
//脚本执行时间就由默认的30秒变为180秒  
ini_set('max_execution_time', '180');
//Post变量由2M修改为8M，此值改为比upload_max_filesize要大  
ini_set('post_max_size', '12M');
//上传文件修改也为8M，和上面这个有点关系，大小不等的关系。
ini_set('upload_max_filesize','10M');  
//正在运行的脚本大量使用系统可用内存,上传图片给多点，最好比post_max_size大1.5倍  
ini_set('memory_limit','20M');
?>  

Check whether the above variables are modified successfully:

<?php  
echo ini_get('file_uploads')."\n";   
echo ini_get('max_input_time')."\n";   
echo ini_get('max_execution_time')."\n";   
echo ini_get('post_max_size')."\n";   
echo ini_get('upload_max_filesize')."\n";   
echo ini_get('memory_limit')."\n";   
?> 

Modified in php.ini, involving the size constraint relationship of three values. So it is a temporary solution. Why this cannot be modified has a lot to do with the operating mode of PHP, such as safe mode.

The ini_set instructions cannot be used in safe mode: max_execution_time, memory_limit, child_terminate.

Therefore, things like post_max_size and upload_max_filesize cannot be modified using the following methods:

ini_set('post_max_size','10M');  
ini_set('upload_max_filesize','8M');  

The correct way is to use .htaccess file:

php_value upload_max_filesize 8M  
php_value post_max_size 10M  

The premise is that the site is configured in httpd.conf: AllowOverride All.

It is stated in the PHP documentation that the modifiable range of upload_max_filesize is PHP_INI_PERDIR. PHP_INI_PERDIR means that the domain directive can be modified in the php.ini, httpd.conf or .htaccess file. The PHP_INI_SYSTEM domain directive can be modified in the php.ini and httpd.conf files. Therefore, upload_max_filesize cannot be modified using int_set. Only the modifiable range is PHP_INI_ALL can be modified with int_set.

Method to obtain value:

if(@ini_get("file_uploads")) {
	$arrInfo['fileupload'] = "允许 - 文件 ".ini_get("upload_max_filesize")." - 表单：".ini_get("post_max_size");
} 
else {
	$arrInfo['fileupload'] = "<font color='red'>禁止</font>";
}
if (get_cfg_var('register_globals')){
	$arrInfo['onoff'] ="打开";
}else{
	$arrInfo['onoff'] = "关闭";
}