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From: gary@sun.mcs.clarkson.edu (Gary Levin)
Newsgroups: comp.sys.mac.programmer
Subject: New scanf bug
Message-ID: <GARY.89Oct31132216@sun.clarkson.edu>
Date: 31 Oct 89 18:20:32 GMT
Sender: news@sun.soe.clarkson.edu
Distribution: comp
Organization: Clarkson University, Potsdam NY
Lines: 42

A new scanf bug has appeared.  If you read a string using %*s, the
unassigned string is stored in a random memory location (pointer 0).

This accounted for my earlier problem of an alert message being
changed.  Apparently, using separate strings put the text in memory
location 0.  Under the debugger, something else must be there.

Correction to ``scanf.c'' in ANSI shown below; just add the line above
the ***.  Please report any other errors found.  It would be
appreciated if the Symantec folks would periodically post bug reports
from other sources to this list.


 string:
    if (!F.haveWidth)
        F.fieldWidth = INT_MAX;
    if (!F.suppress)
	s = va_arg(arg, char *);
    for (; c != EOF; c = getc(fp), ++nread) {
	--F.fieldWidth;
	if (!testbit(c))
	    break;
	F.valid = TRUE;
	if (!F.suppress) *s++ = c;
	****************  only assign if not suppressed.
	if (F.fieldWidth == 0)
	    goto endstring;
    }
    ungetc(c, fp), --nread;
 endstring:
    if (!F.valid)
	goto done;
    if (!F.suppress) {
	*s = 0;
	++nassigned;
    }
    ++nconverted;
    continue;
--
Gary Levin/Dept of Math & CS/Clarkson Univ/Potsdam, NY 13676/(315) 268-2384
BitNet: gary@clutx   Internet: gary@clutx.clarkson.edu