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Path: utzoo!linus!decvax!ucbvax!ucdavis!lll-crg!well!fnf
From: fnf@well.UUCP (Fred Fish)
Newsgroups: net.micro.amiga
Subject: bug in Lattice fopen()
Message-ID: <430@well.UUCP>
Date: Mon, 6-Jan-86 00:26:09 EST
Article-I.D.: well.430
Posted: Mon Jan  6 00:26:09 1986
Date-Received: Tue, 7-Jan-86 06:24:01 EST
Organization: Whole Earth Lectronic Link, Sausalito, CA
Lines: 31
Keywords: append mode

I just got bit by a bug in the Lattice C runtime environment function
"fopen".  When the second argument to fopen is either "a" or "a+",
the specified file is always truncated, regardless of whether or not
it already exists.  A simple workaround for cases where only one
process will be writing to the file is to replace:

	if ((fp = fopen (filename, "a+")) == NULL)
		perror ("can't open file!");

with

	if ((fp = fopen (filename, "r+")) == NULL)
		if ((fp = fopen (filename "w+")) == NULL)
			perror ("can't open file!");
	fseek (fp, 0L, 2);

And occurances of

	fwrite (ptr, size, nitems, fp);

with

	fseek (fp, 0L, 2);
	fwrite (ptr, size, nitems, fp);

-Fred
-- 

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Fred Fish  (415) 644-1230 ext 242  ucbvax!unisoft!fnf  well!fnf
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