require - PHP - Failed to open stream : No such file or directory

Question

In PHP scripts, whether calling include(), require(), fopen(), or their derivatives such as include_once, require_once, or even, move_uploaded_file(), one often runs into an error or warning:

Failed to open stream : No such file or directory.

What is a good process to quickly find the root cause of the problem?

Answer 1

There are many reasons why one might run into this error and thus a good checklist of what to check first helps considerably.

Let's consider that we are troubleshooting the following line:

require "/path/to/file"

Checklist

1. Check the file path for typos

• either check manually (by visually checking the path)

• or move whatever is called by require* or include* to its own variable, echo it, copy it, and try accessing it from a terminal:

  $path = "/path/to/file";
  
  echo "Path : $path";
  
  require "$path";
  

  Then, in a terminal:

  cat <file path pasted>
  

2. Check that the file path is correct regarding relative vs absolute path considerations

• if it is starting by a forward slash "/" then it is not referring to the root of your website's folder (the document root), but to the root of your server.
  • for example, your website's directory might be /users/tony/htdocs
• if it is not starting by a forward slash then it is either relying on the include path (see below) or the path is relative. If it is relative, then PHP will calculate relatively to the path of the current working directory.
  • thus, not relative to the path of your web site's root, or to the file where you are typing
  • for that reason, always use absolute file paths

Best practices :

In order to make your script robust in case you move things around, while still generating an absolute path at runtime, you have 2 options :

1. use require __DIR__ . "/relative/path/from/current/file". The __DIR__ magic constant returns the directory of the current file.

2. define a SITE_ROOT constant yourself :

   • at the root of your web site's directory, create a file, e.g. config.php

   • in config.php, write

     define('SITE_ROOT', __DIR__);
     

   • in every file where you want to reference the site root folder, include config.php, and then use the SITE_ROOT constant wherever you like :

     require_once __DIR__."/../config.php";
     ...
     require_once SITE_ROOT."/other/file.php";
     

These 2 practices also make your application more portable because it does not rely on ini settings like the include path.

3. Check your include path

Another way to include files, neither relatively nor purely absolutely, is to rely on the include path. This is often the case for libraries or frameworks such as the Zend framework.

Such an inclusion will look like this :

include "Zend/Mail/Protocol/Imap.php"

In that case, you will want to make sure that the folder where "Zend" is, is part of the include path.

You can check the include path with :

echo get_include_path();

You can add a folder to it with :

set_include_path(get_include_path().":"."/path/to/new/folder");

4. Check that your server has access to that file

It might be that all together, the user running the server process (Apache or PHP) simply doesn't have permission to read from or write to that file.

To check under what user the server is running you can use posix_getpwuid :

$user = posix_getpwuid(posix_geteuid());

var_dump($user);

To find out the permissions on the file, type the following command in the terminal:

ls -l <path/to/file>

and look at permission symbolic notation

5. Check PHP settings

If none of the above worked, then the issue is probably that some PHP settings forbid it to access that file.

Three settings could be relevant :

1. open_basedir
   • If this is set PHP won't be able to access any file outside of the specified directory (not even through a symbolic link).
   • However, the default behavior is for it not to be set in which case there is no restriction
   • This can be checked by either calling phpinfo() or by using ini_get("open_basedir")
   • You can change the setting either by editing your php.ini file or your httpd.conf file
2. safe mode
   • if this is turned on restrictions might apply. However, this has been removed in PHP 5.4. If you are still on a version that supports safe mode upgrade to a PHP version that is still being supported.
3. allow_url_fopen and allow_url_include
   • this applies only to including or opening files through a network process such as http:// not when trying to include files on the local file system
   • this can be checked with ini_get("allow_url_include") and set with ini_set("allow_url_include", "1")

Corner cases

If none of the above enabled to diagnose the problem, here are some special situations that could happen :

1. The inclusion of library relying on the include path

It can happen that you include a library, for example, the Zend framework, using a relative or absolute path. For example :

require "/usr/share/php/libzend-framework-php/Zend/Mail/Protocol/Imap.php"

But then you still get the same kind of error.

This could happen because the file that you have (successfully) included, has itself an include statement for another file, and that second include statement assumes that you have added the path of that library to the include path.

For example, the Zend framework file mentioned before could have the following include :

include "Zend/Mail/Protocol/Exception.php" 

which is neither an inclusion by relative path, nor by absolute path. It is assuming that the Zend framework directory has been added to the include path.

In such a case, the only practical solution is to add the directory to your include path.

2. SELinux

If you are running Security-Enhanced Linux, then it might be the reason for the problem, by denying access to the file from the server.

To check whether SELinux is enabled on your system, run the sestatus command in a terminal. If the command does not exist, then SELinux is not on your system. If it does exist, then it should tell you whether it is enforced or not.

To check whether SELinux policies are the reason for the problem, you can try turning it off temporarily. However be CAREFUL, since this will disable protection entirely. Do not do this on your production server.

setenforce 0

If you no longer have the problem with SELinux turned off, then this is the root cause.

To solve it, you will have to configure SELinux accordingly.

The following context types will be necessary :

• httpd_sys_content_t for files that you want your server to be able to read
• httpd_sys_rw_content_t for files on which you want read and write access
• httpd_log_t for log files
• httpd_cache_t for the cache directory

For example, to assign the httpd_sys_content_t context type to your website root directory, run :

semanage fcontext -a -t httpd_sys_content_t "/path/to/root(/.*)?"
restorecon -Rv /path/to/root

If your file is in a home directory, you will also need to turn on the httpd_enable_homedirs boolean :

setsebool -P httpd_enable_homedirs 1

In any case, there could be a variety of reasons why SELinux would deny access to a file, depending on your policies. So you will need to enquire into that. Here is a tutorial specifically on configuring SELinux for a web server.

3. Symfony

If you are using Symfony, and experiencing this error when uploading to a server, then it can be that the app's cache hasn't been reset, either because app/cache has been uploaded, or that cache hasn't been cleared.

You can test and fix this by running the following console command:

cache:clear

4. Non ACSII characters inside Zip file

Apparently, this error can happen also upon calling zip->close() when some files inside the zip have non-ASCII characters in their filename, such as "é".

A potential solution is to wrap the file name in utf8_decode() before creating the target file.

Credits to Fran Cano for identifying and suggesting a solution to this issue