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I'm calling the following:

while ( (!file_exists('./download/ah141090676723_100.jpg')) || (filesize('./download/ah141090676723_100.jpg') == '1359') ) { code that retrieves a remote file and writes it to '/ah141090676723_100.jpg'  }
... and getting a "filesize(): stat failed for ./download/ah141090676723_100.jpg" error.
The problem I'm trying to solve is that the remote server is flaky, and sometimes returns a garbage response (which is always 1359 bytes long).  So, I want to check to see if either A) the file doesn't exist (first run through), or B) the file equals garbage (1359); if either is true, attempt to grab and write the file.  Rinse and repeat until we get something that's not garbage.
The code actually seems to be working -- the file is retrieved and written, and I haven't had any garbage responses get through this loop -- but the error mystifies me.  I thought it might be that on the first run-through, the file doesn't exist, so filesize is throwing this error.  But the "||" operator should be preventing that second evaluation on the first run-through... right?
I should mention that I'm calling "clearstatcache();" inside the loop, after the retrieval/write.
Any help appreciated!
Scott
                that does appear to be the root of the problem; I noticed that when the file already exists, the error isn't thrown.  So when the file doesn't exist, it's "not writeable".  But the question still remains: shouldn't "||" prevent it from getting to that part of the code?
– FoulFoot
                Oct 15, 2013 at 1:24
                All these years later, I think I understand what's going on.  Sorry for thread necro. I always thought that PHP would step through the script in logical fashion, and only stop if it hit an error -- which it wouldn't, under this theory, because the double-OR operator ("||") prevents it from getting to filesize() if file_exists() fails.  But that's not how PHP works.  At runtime, it parses the entire script first, and then executes it.  That's why a misplaced comma in a section of your script that is otherwise unreachable will terminate the script in an error.  :)
– FoulFoot
                Aug 18, 2020 at 15:47
Change to 
while ( file_exists('./download/ah141090676723_100.jpg') && filesize('./download/ah141090676723_100.jpg') == 1359) 
as file_exists is always required. filesize() returns "stat failed" when a file does not exist or is not readable.
        
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