Date: Thu, 20 Aug 1998 21:23:57 -0500 (CDT) From: Joel Ray Holveck <joelh@gnu.org> To: nate@mt.sri.com Cc: dag-erli@ifi.uio.no, imp@village.org, hackers@FreeBSD.ORG Subject: Re: Realloc fix for review Message-ID: <199808210223.VAA10208@detlev.UUCP> In-Reply-To: <199808201943.NAA07889@mt.sri.com> (message from Nate Williams on Thu, 20 Aug 1998 13:43:13 -0600) References: <199808201619.KAA20970@harmony.village.org> <xzplnoj8uq9.fsf@skejdbrimir.ifi.uio.no> <199808201943.NAA07889@mt.sri.com>
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>>> Recently, OpenBSD went through their source tree and fixed all >>> instances of >>> a = realloc(a, size); >>> with >>> na = realloc(a, size); >>> if (!na) >>> free(a); >>> a = na; >> Is that really a good idea? If you free the old block when realloc() >> fails, you lose whatever data was in it (and therefore potentially >> lose the ability to generate a sensible error message or recover >> gracefully). > Umm, reread the code again. His realloc frees the old block when > realloc *succeeds*, not fails. Okay, I must be very confused. First off, I thought that realloc already did free the old block. Second, wouldn't this mean that the block gets freed if SIZE is less that a's old size? > However, is there any case when you want to copy the data from the old > pointer into the new pointer, which would also be a lose with the > suggested change. (I don't know if this is legal or not...) I must be *really* *really* confused. Doesn't realloc copy the data? Best, joelh -- Joel Ray Holveck - joelh@gnu.org - http://www.wp.com/piquan Fourth law of programming: Anything that can go wrong wi sendmail: segmentation violation - core dumped To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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