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Fix overflow check in StringInfo; add missing casts

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A few thinkos I introduced in fa2fa9955280.  Also, amend a similarly
broken comment.

Report by Daniel Vérité.
Authors: Daniel Vérité, Álvaro Herrera
Discussion: https://postgr.es/m/1706e85e-60d2-494e-8a64-9af1e1b2186e@manitou-mail.org
This commit is contained in:
Alvaro Herrera 2017-01-10 11:41:13 -03:00
parent e898437460
commit 42f50cb8fa
1 changed files with 7 additions and 6 deletions
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13
src/backend/lib/stringinfo.c
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@ -313,19 +313,20 @@ enlargeStringInfo(StringInfo str, int needed)
* for efficiency, double the buffer size each time it overflows. * for efficiency, double the buffer size each time it overflows.
* Actually, we might need to more than double it if 'needed' is big... * Actually, we might need to more than double it if 'needed' is big...
*/ */
newlen = 2 * str->maxlen; newlen = 2 * (Size) str->maxlen;
while (needed > newlen) while ((Size) needed > newlen)
newlen = 2 * newlen; newlen = 2 * newlen;
/* /*
* Clamp to the limit in case we went past it. Note we are assuming here * Clamp to the limit in case we went past it. (We used to depend on
* that limit <= INT_MAX/2, else the above loop could overflow. We will * limit <= INT32_MAX/2, to avoid overflow in the loop above; we no longer
* still have newlen >= needed. * depend on that, but if "needed" and str->maxlen ever become wider, we
* will need similar caution here.) We will still have newlen >= needed.
*/ */
if (newlen > limit) if (newlen > limit)
newlen = limit; newlen = limit;
str->data = (char *) repalloc_huge(str->data, (Size) newlen); str->data = (char *) repalloc_huge(str->data, newlen);
str->maxlen = newlen; str->maxlen = newlen;
} }