Path: utzoo!utgpu!watmath!clyde!att!rutgers!bellcore!texbell!sugar!ficc!peter
From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.sources.d
Subject: Re: Comments on INSERT.c
Summary: a small but significant detail of programming style.
Message-ID: <2692@ficc.uu.net>
Date: 11 Jan 89 16:25:14 GMT
References: <308@twwells.uucp> <Jan.8.18.48.59.1989.10861@athos.rutgers.edu> <313@twwells.uucp>
Organization: Xenix Support
Lines: 35

In article <313@twwells.uucp>, bill@twwells.uucp (T. William Wells) writes:
>       perror("Error 1 : ((fdin = open(argv[1],O_RDONLY)) == -1):");

>        into (after setting up ProgramName)

>       fprintf(stderr, "%s: error while opening %s for read: ",
> 	  ProgramName, argv[1]);
>       perror("");

On many, if not all, systems this will eventually produce the error message:

	insert: error while opening foobar.c for read: : Not a typewriter

Or:

	insert: error ...: : Inappropriate ioctl for device.

Because that fprintf() will stomp on errno. Please, people, if you're
going to do stuff before you call perror save and restore errno, or do
this:

	{ char buffer[BUFSIZ];
	  sprintf(buffer, "%s: error while opening %s for read",
		ProgramName, argv[1]);
	  perror(buffer);
	}

Don't you just love getting bounced mail with the error message indicating
that "Fred Bloggs" is not a typewriter, or even worse that someone attempted
to perform an inappropriate ioctl on him? I'm glad I'm not Fred.
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.
Work: uunet.uu.net!ficc!peter, peter@ficc.uu.net, +1 713 274 5180.   `-_-'
Home: bigtex!texbell!sugar!peter, peter@sugar.uu.net.                 'U`
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