Function code in PHP to determine whether an empty file directory has read and write permissions

Function code in PHP to determine whether an empty file directory has read and write permissions_PHP Tutorial

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Release： 2016-07-21 15:17:13

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is_writable is used to handle this, remember that PHP may only be able to access the file as the username running the webserver (usually 'nobody'). Does not count towards Safe Mode limits.
Example #1 is_writable() Example

Copy code The code is as follows:

 
$ filename = 'test.txt'; 
if (is_writable($filename)) { 
echo 'The file is writable'; 
} else { 
echo 'The file is not writable'; 
} 
?> 

One problem with the above function is that filename is required. It is stipulated that the file to be checked must be a file, and the directory cannot be judged. Next, we will judge the empty directory.
Example 1
This function is very commonly used, especially in some projects that need to generate static files. Whether a directory can be used depends on whether the directory has permission to create files and delete files

Copy code The code is as follows:

 
/* 
The problem arises: how to check whether a directory is writable, and how there are directories and files in the directory, then All should be checked 
 Ideas: 
 (1) First write out the algorithm to check whether the empty directory is writable: 
 Generate a file in the directory. If it cannot be generated, it means that the directory does not have write permission
(2) Use recursive method to check
Code implementation: 
*/ 
set_time_limit(1000); 
function check_dir_iswritable($dir_path){ 
$dir_path=str_replace(' ','/',$dir_path); 
$is_writale=1; 
if(!is_dir($dir_path)){ 
$is_writale=0; 
return $is_writale; 
} else{ 
$file_hd=@fopen($dir_path.'/test.txt','w'); 
if(!$file_hd){ 
@fclose($file_hd); 
@ unlink($dir_path.'/test.txt'); 
$is_writale=0; 
return $is_writale; 
} 
$dir_hd=opendir($dir_path); 
while(false !==($file=readdir($dir_hd))){ 
if ($file != "." && $file != "..") { 
if(is_file($dir_path.'/ '.$file)){ 
//The file is not writable, return directly 
if(!is_writable($dir_path.'/'.$file)){ 
return 0; 
} 
}else{ 
$file_hd2=@fopen($dir_path.'/'.$file.'/test.txt','w'); 
if(!$file_hd2){ 
@fclose ($file_hd2); 
@unlink($dir_path.'/'.$file.'/test.txt'); 
$is_writale=0; 
return $is_writale; 
} 
//Recursion
$is_writale=check_dir_iswritable($dir_path.'/'.$file); 
} 
} 
} 
} 
return $is_writale; 
} 

The above example mainly uses fopen to create files in the directory or write content in the file, so that the read and write permissions of the directory can be determined.