Programming Forums > Web Development and Design > PHP

grimpirate · Aug 5th, 2007, 2:43 PM

I haven't had much experience with regular expressions because I tend to avoid them like the plague. However, for this particular application it appeared to fit my needs well. In any case I wanted to create a function that would verify a pathname with the following structure:

(Toggle Plain Text)

whatever/whatever/whatever/........../whatever.php

It should follow the guidelines specified here, and my own stipulations:

The pathname need not end in a filename
If a filename is present it must end in '.php'

This was my solution:[PHP]preg_match('/^([a-z0-9_][a-z0-9\-_]*\/{1,1})*([a-z0-9_][a-z0-9\-_]*)*(\.php){0,1}$/iD', $text);[/PHP]Due to my inexperience I'd appreciate any regular expression gurus here on the forum highlighting where I might have missed something in my regular expression that would cause it to behave beyond the scope of the specified parameters. Thanks in advance for the help.

DaWei · Aug 5th, 2007, 3:09 PM

Have you looked at the pathinfo function?

grimpirate · Aug 5th, 2007, 5:35 PM

I did indeed DaWei, but there are certain things about its behavior which didn't seem correct. Take for instance the basename function, if I use that but the file doesn't have a '.***' extension it returns what I would interpret as a directory name. If the pathname starts with a '/' it also considers it ok. For my purposes those things don't work. I tried using pathinfo at first, but with certain pathnames the behavior is kinda screwy and I have to worry about these exceptions which kind of extends my code needlessly I think. I may not be using it properly I have no clue, but thus far the preg_match is working exactly as I want. Also, pathinfo doesn't check for the non-compliant characters and their positions. I figured with preg_match I could do all of these things in one shot rather than having to code for all the possibilties that transpire using pathinfo. I'm not one for abusing regular expressions especially since I don't really feel comfortable using them, but I do recognize their versatility in certain applications.

titaniumdecoy · Aug 5th, 2007, 6:04 PM

I believe this is what you are looking for:

(Toggle Plain Text)

ereg('^([[:alnum:]_/\-])*/?([[:alnum:]_\-]+\.php)?$', $str);

Both this regular expression and the one you provided will only allow a period before the filename. Your regular expression will match a path with a filename but no extension, such as "whatever/whatever". It will also reject paths that begin with a /. Other than that, it appears okay, although verbose. Also, why not allow file/directory names to begin with a -, as this can occur in URIs?

grimpirate · Aug 6th, 2007, 1:09 AM

I don't want path names to begin with a '/' that's why I provided the example; I should've stated that explicitly. The POSIX standard doesn't allow file/directories to begin with a hyphen. I think the portion of your regular expression '([[:alnum:]_/\-])' allows for things pathnames which could have something like '//////' which is something I'm also not allowing (assuming I'm reading it right, again I'm no regex genius). Let me give some explicit examples of the types of pathnames I'm interested in validating:

(Toggle Plain Text)

VALID EXAMPLES
whatever/*****/whatever
whatever/*****/whatever/
whatever
whatever/
whatever/whatever.php
whatever.php
_whatever
_whatever/
INVALID EXAMPLES
////////whatever////////
./
../
.
..
-whatever
-whatever/
whatever.txt
/whatever

My regular expression actually doesn't fit those needs so I do need to modify it. The 'whatever' portions don't actually mean whatever, they should be comprised only of alphanumerics, hyphens, and/or underscores exclusively and can only be broken up by a single '/' character. The whatever segments must have a length of at least one character. If no filename is present then the pathname can terminate with a '/' or not. If a filename is present it must end in '.php'. I think I've described all the rules here.

titaniumdecoy · Aug 6th, 2007, 1:26 AM

I believe the following regular expression matches your description:

(Toggle Plain Text)

^([[:alnum:]_][[:alnum:]_\-]*/?)*?([[:alnum:]_]+[[:alnum:]_\-]*\.php)?$

grimpirate · Aug 6th, 2007, 1:33 AM

I think I've got it now by splitting it into two cases and then ORing the result

(Toggle Plain Text)

$regExpDir = '/^([a-z0-9_][a-z0-9\-_]*\/)*([a-z0-9_][a-z0-9\-_]*\/{0,1})+$/iD';
$regExpFil = '/^([a-z0-9_][a-z0-9\-_]*\/)*([a-z0-9_][a-z0-9\-_]*\.php)+$/iD';
return preg_match($regExpDir, $fileName) || preg_match($regExpFil, $fileName);

grimpirate · Aug 6th, 2007, 1:36 AM

What exactly is it the '?' character does? The PHP documentation's description of it doesn't make sense to me.

grimpirate · Aug 6th, 2007, 1:46 AM

Actually I tried your expression out and received the following error message:
Warning: preg_match() [function.preg-match]: Unknown modifier '?' in C:\Program Files\Apache Software Foundation\Apache2.2\htdocs\test.php on line 9
Did I implement it incorrectly?

(Toggle Plain Text)

$regExp = '/^([[:alnum:]_][[:alnum:]_\-]*/?)*(\.php)?$/';
echo preg_match($regExp, $fileName);

grimpirate · Aug 6th, 2007, 1:56 AM

oh I see you're using the POSIX expressions rather than the PERL expressions, yeah that's just totally lost on me *_*

Aug 5th, 2007, 2:43 PM	#1
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	POSIX compliant portable pathname I haven't had much experience with regular expressions because I tend to avoid them like the plague. However, for this particular application it appeared to fit my needs well. In any case I wanted to create a function that would verify a pathname with the following structure: (Toggle Plain Text) whatever/whatever/whatever/........../whatever.php whatever/whatever/whatever/........../whatever.php It should follow the guidelines specified here, and my own stipulations: The pathname need not end in a filename If a filename is present it must end in '.php' This was my solution:[PHP]preg_match('/^([a-z0-9_][a-z0-9\-_]\/{1,1})([a-z0-9_][a-z0-9\-_])(\.php){0,1}$/iD', $text);[/PHP]Due to my inexperience I'd appreciate any regular expression gurus here on the forum highlighting where I might have missed something in my regular expression that would cause it to behave beyond the scope of the specified parameters. Thanks in advance for the help. __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

Aug 5th, 2007, 3:09 PM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Have you looked at the pathinfo function? __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Aug 5th, 2007, 5:35 PM	#3
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	I did indeed DaWei, but there are certain things about its behavior which didn't seem correct. Take for instance the basename function, if I use that but the file doesn't have a '.***' extension it returns what I would interpret as a directory name. If the pathname starts with a '/' it also considers it ok. For my purposes those things don't work. I tried using pathinfo at first, but with certain pathnames the behavior is kinda screwy and I have to worry about these exceptions which kind of extends my code needlessly I think. I may not be using it properly I have no clue, but thus far the preg_match is working exactly as I want. Also, pathinfo doesn't check for the non-compliant characters and their positions. I figured with preg_match I could do all of these things in one shot rather than having to code for all the possibilties that transpire using pathinfo. I'm not one for abusing regular expressions especially since I don't really feel comfortable using them, but I do recognize their versatility in certain applications. __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

Aug 5th, 2007, 6:04 PM	#4
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 837 Rep Power: 3	I believe this is what you are looking for: (Toggle Plain Text) ereg('^([[:alnum:]_/\-])/?([[:alnum:]_\-]+\.php)?$', $str); ereg('^([[:alnum:]_/\-])/?([[:alnum:]_\-]+\.php)?$', $str); Both this regular expression and the one you provided will only allow a period before the filename. Your regular expression will match a path with a filename but no extension, such as "whatever/whatever". It will also reject paths that begin with a /. Other than that, it appears okay, although verbose. Also, why not allow file/directory names to begin with a -, as this can occur in URIs? Last edited by titaniumdecoy; Aug 5th, 2007 at 6:23 PM.

Aug 6th, 2007, 1:09 AM	#5
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	I don't want path names to begin with a '/' that's why I provided the example; I should've stated that explicitly. The POSIX standard doesn't allow file/directories to begin with a hyphen. I think the portion of your regular expression '([[:alnum:]_/\-])' allows for things pathnames which could have something like '//////' which is something I'm also not allowing (assuming I'm reading it right, again I'm no regex genius). Let me give some explicit examples of the types of pathnames I'm interested in validating: (Toggle Plain Text) VALID EXAMPLES whatever/***/whatever whatever/*/whatever/ whatever whatever/ whatever/whatever.php whatever.php _whatever _whatever/ INVALID EXAMPLES ////////whatever//////// ./ ../ . .. -whatever -whatever/ whatever.txt /whatever VALID EXAMPLES whatever/*/whatever whatever/***/whatever/ whatever whatever/ whatever/whatever.php whatever.php _whatever _whatever/ INVALID EXAMPLES ////////whatever//////// ./ ../ . .. -whatever -whatever/ whatever.txt /whatever My regular expression actually doesn't fit those needs so I do need to modify it. The 'whatever' portions don't actually mean whatever, they should be comprised only of alphanumerics, hyphens, and/or underscores exclusively and can only be broken up by a single '/' character. The whatever segments must have a length of at least one character. If no filename is present then the pathname can terminate with a '/' or not. If a filename is present it must end in '.php'. I think I've described all the rules here. __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

Aug 6th, 2007, 1:26 AM	#6
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 837 Rep Power: 3	I believe the following regular expression matches your description: (Toggle Plain Text) ^([[:alnum:]_][[:alnum:]_\-]/?)?([[:alnum:]_]+[[:alnum:]_\-]\.php)?$ ^([[:alnum:]_][[:alnum:]_\-]/?)?([[:alnum:]_]+[[:alnum:]_\-]\.php)?$ Last edited by titaniumdecoy; Aug 6th, 2007 at 1:50 AM.

Aug 6th, 2007, 1:33 AM	#7
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	I think I've got it now by splitting it into two cases and then ORing the result (Toggle Plain Text) $regExpDir = '/^([a-z0-9_][a-z0-9\-_]\/)([a-z0-9_][a-z0-9\-_]\/{0,1})+$/iD'; $regExpFil = '/^([a-z0-9_][a-z0-9\-_]\/)([a-z0-9_][a-z0-9\-_]\.php)+$/iD'; return preg_match($regExpDir, $fileName) \|\| preg_match($regExpFil, $fileName); $regExpDir = '/^([a-z0-9_][a-z0-9\-_]\/)([a-z0-9_][a-z0-9\-_]\/{0,1})+$/iD'; $regExpFil = '/^([a-z0-9_][a-z0-9\-_]\/)([a-z0-9_][a-z0-9\-_]\.php)+$/iD'; return preg_match($regExpDir, $fileName) \|\| preg_match($regExpFil, $fileName); __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

Aug 6th, 2007, 1:36 AM	#8
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	What exactly is it the '?' character does? The PHP documentation's description of it doesn't make sense to me. __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

Aug 6th, 2007, 1:46 AM	#9
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	Actually I tried your expression out and received the following error message: Warning: preg_match() [function.preg-match]: Unknown modifier '?' in C:\Program Files\Apache Software Foundation\Apache2.2\htdocs\test.php on line 9 Did I implement it incorrectly? (Toggle Plain Text) $regExp = '/^([[:alnum:]_][[:alnum:]_\-]/?)(\.php)?$/'; echo preg_match($regExp, $fileName); $regExp = '/^([[:alnum:]_][[:alnum:]_\-]/?)(\.php)?$/'; echo preg_match($regExp, $fileName); __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

Aug 6th, 2007, 1:56 AM	#10
grimpirate King of Portal Join Date: Sep 2005 Posts: 403 Rep Power: 3	oh I see you're using the POSIX expressions rather than the PERL expressions, yeah that's just totally lost on me _ __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

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Programming Forums > Web Development and Design > PHP

POSIX compliant portable pathname