bug in stdio (setbuf) ?

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2 total messages Started by crl Fri, 09 Sep 1983 16:18

#129

Author: crl
Date: Fri, 09 Sep 1983 16:18

17 lines
1326 bytes

I think I have discovered a bug in the way stdio handles its buffers
when you've used setbuf().  We run 2.8 BSD, but I bet it's present
elsewhere.  It seems that iop->_base is not set to NULL by fclose
if you've used a setbuf() to assign your own buffer.  The specific
code is:
	if (iop->_flag & _IOMYBUF)
		free(iop->_base);
	if (iop->_flag & (_IOMYBUF|_IONBF))
		iop->_base = NULL;
in fclose().  Thus, if _base was pointing to your stack, you'll in for
problems the next time you fopen() since this does not zero it either.
I can't think of a good reason why _base should not be zeroed on an
fclose().  Comments?

Charles LaBrec
UUCP:		pur-ee!Physics:crl, purdue!Physics:crl
INTERNET:	crl @ pur-phy.UUCP

Re: bug in stdio (setbuf) ?

#130

Author: Guy Harris
Date: Mon, 12 Sep 1983 04:43

7 lines
814 bytes

This bug also causes problems if the buffer is static (it gets reused
improperly).  See my article 1127@rlgvax.UUCP.  Article 30@ism780.UUCP
stated that the simple fix won't fix it, and that it has been fixed in
System V.

	Guy Harris
	{seismo,mcnc,we13,brl-bmd,allegra}!rlgvax!guy

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