Re: Checking whether a file is a genuine PDF file
Re: Checking whether a file is a genuine PDF file
- Subject: Re: Checking whether a file is a genuine PDF file
- From: James Walker <email@hidden>
- Date: Mon, 05 Oct 2009 19:02:54 -0700
Graham Cox wrote:
On 04/10/2009, at 11:07 PM, Squ Aire wrote:
But that isn't good enough really, because a file can have the pdf
extension without being a true PDF file.
This is true, but how far are you prepared to go? Others have suggested
checking a few bytes into the file's header which should be reasonable
enough, but I could create a file having a valid PDF header and garbage
thereafter... you cannot protect yourself against that sort of thing, so
the question is where your code would draw the line. Most people would
draw it with a simple check of the extension and maybe for files that
traditionally have been subject to extension abuse (I don't think pdf is
one of them), a few header bytes.
What is it you're afraid of?
FWIW, in the classic Mac OS, it was not uncommon to see a PDF with NO
extension, but with the file type set to 'PDF '.
--
James W. Walker, Innoventive Software LLC
<http://www.frameforge3d.com/>
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