Check if "the URL" returns an image file?

makeshyft · Post by **makeshyft** » Mon May 20, 2013 5:23 am

How would I go about doing a check whether HTTP link is returning an image file or a 404 page?

I'm worried that not all servers report 404 the same way, so a faulty image link would return a whole 404 page with HTML and etc.

THe HTTP links are intended to point only to an image files recognizable by Livecode.

Any help would be appriciated.....Thank you livecoders.

Simon · Post by **Simon** » Mon May 20, 2013 5:58 am

404 pages contain <html></html> an image wouldn't.
But more: .png have PNG in the first line of the data, jpg have JFIF and bmp's have BM. Not sure if those are constants.

Simon

BvG · Post by **BvG** » Mon May 20, 2013 10:35 am

It'd be worthwhile to check the libURLLastRHHeaders() function. A 404 is required to have a not found response at the start of the headers if I remember the specification correctly.

For example, my server returns the following on the first line, first 404 then "regular":

Code: Select all

HTTP/1.1 404 Not Found

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HTTP/1.1 200 OK

makeshyft · Post by **makeshyft** » Mon May 20, 2013 4:40 pm

Between the both suggestions, I'll be able to make it work. Thank you! Will return to tag subject as solved.

makeshyft · Post by **makeshyft** » Thu May 23, 2013 10:49 pm

Works like a charm:

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 read from file ImageURL for 1 line
   put it into myfilechunk // check file headers
   if it contains "jfif" then answer "JPEG"
   else if it contains "exif" then answer "JPEG with exif"
   else if it contains "BM" then answer "BMP"
   else if it contains "PNG" then answer "PNG"
   else if it contains "GIF" then answer "GIF"
   else 
   end if

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