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Re: Filters: 6 vs 7 Arguments

Tobias Peciva wrote:
Hey List...

CUPS filters and backends take either six or seven arguments, with the optional one being the filename of the file to print. If no file is provided, print data is read from standard in.

Now, it seems that printing from native Mac OS X GUI applications will always cause the print data to be sent on standard in. The only situation where a filename is actually specified as an argument is when you print using lpr on the command line. Is this universally true? If we don't care about command line printing, is print data guaranteed to arrive on the input stream? Are there any scenarios where this will not hold true (managed printing, specific applications, certain input formats, whatever)?

You can't depend on the your filter always reading from stdin or
always reading from a file; if you make an assumption about where
your print data comes from, you'll almost certainly run into an
issue with one or more of your users.

If you want to structure your code to always read from stdin,
use the following code:

if (argc == 7)
if (!freopen(argv[6], "r", stdin))
{
fprintf(stderr, "ERROR: Unable to open print file \"%s\": %s\n"
argv[6], strerror(errno));
exit(1);
}

--
______________________________________________________________________
Michael Sweet, Easy Software Products email@hidden
Printing Software for UNIX http://www.easysw.com
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References: 
 >Filters: 6 vs 7 Arguments (From: Tobias Peciva <email@hidden>)



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