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Re: Why would chmod( ... ) fail with "No such file or directory" [message #173161 is a reply to message #173160]

Fri, 25 March 2011 12:37

Simon
Messages: 29
Registered: February 2011

Karma:

Junior Member

On 3/25/2011 12:31 PM, "Álvaro G. Vicario" wrote:
> El 25/03/2011 10:35, Simon escribió/wrote:
>> Hi,
>>
>> I have some code that creates a temp file, writes to it and then calls
>> chmod(...) to make sure that the file has 0644 permissions.
>>
>> // -------------
>> // pseudo code
>> //
>> $tmpfname = 'xyx'; // come from another function.
>>
>> if (!($fd = @fopen($tmpfname, 'wb')))
>> {
>> return false;
>> }
>>
>> fwrite($fd, $data ); // the data comes from another function has well.
>> no warnings given.
>
> fwrite() returns FALSE if there was an error, you don't need to rely on
> getting warnings.
>
>> fclose($fd); // no warnings given.
>
> Same with fclose().
>
>> chmod( $tmpfname, 0644 ); <!-- error here with "No such file or
>> directory"
>> // -------------
>>
>> The issue I have is that it works _sometimes_, in fact, 99% of the time
>> it works.
>> But from time to time the log reports that the file does not exist.
>>
>> But how it is possible, if the file opened successfully with fopen( ... )
>
> Perhaps that $tmpfname string that comes from another function is not
> always unique. If the file was created by another process, you may not
> be its owner thus you don't have permission to change permissions, or
> the other process may have removed it while you were writing it. There
> are a number of tools that can prevent access to a file for security
> reasons (from PHP's safe mode to SELInux) and you don't always get an
> accurate error message.
>

It make a lot of sense, and yes, it is very possible that the name is
not unique, but I wonder how I could prevent the error/warning message
in the first place.

I cannot add a file_exists(...) just before chmod(...) because between
the call to file_exists(...) and chmod(...) I could loose ownership of
the file.

Maybe I could/should use a temp name, open that temp file, write to it,
close it, chmod(...) it and then just rename it.

That might be a little better, maybe.

Simon

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[Message index]

		Why would chmod( ... ) fail with "No such file or directory" By: Simon on Fri, 25 March 2011 09:35
		Re: Why would chmod( ... ) fail with "No such file or directory" By: alvaro.NOSPAMTHANX on Fri, 25 March 2011 10:31
		Re: Why would chmod( ... ) fail with "No such file or directory" By: Simon on Fri, 25 March 2011 12:37
		Re: Why would chmod( ... ) fail with "No such file or directory" By: alvaro.NOSPAMTHANX on Fri, 25 March 2011 12:52
		Re: Why would chmod( ... ) fail with "No such file or directory" By: Jerry Stuckle on Fri, 25 March 2011 13:29
		Re: Why would chmod( ... ) fail with "No such file or directory" By: Leonardo Azpurua on Fri, 25 March 2011 14:14
		Re: Why would chmod( ... ) fail with "No such file or directory" By: The Natural Philosoph on Fri, 25 March 2011 14:00
		Re: Why would chmod( ... ) fail with "No such file or directory" By: crankypuss on Fri, 25 March 2011 17:52
		Re: Why would chmod( ... ) fail with "No such file or directory" By: Twayne on Fri, 25 March 2011 23:20

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