From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 25 Apr 2011 20:22:28 +0000 (-0400)
Subject: Fix pg_size_pretty() to avoid overflow for inputs close to INT64_MAX.
X-Git-Tag: REL8_2_22~51
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d3964cdb9c3e14e97c226b8143b5471d7b98c597;p=thirdparty%2Fpostgresql.git

Fix pg_size_pretty() to avoid overflow for inputs close to INT64_MAX.

The expression that tried to round the value to the nearest TB could
overflow, leading to bogus output as reported in bug #5993 from Nicola
Cossu.  This isn't likely to ever happen in the intended usage of the
function (if it could, we'd be needing to use a wider datatype instead);
but it's not hard to give the expected output, so let's do so.
---

diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 343817116c5..66221766f24 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -405,9 +405,15 @@ pg_size_pretty(PG_FUNCTION_ARGS)
 							 (size + mult / 2) / mult);
 				else
 				{
+					/* Here we have to worry about avoiding overflow */
+					int64	val;
+
 					mult *= 1024;
+					val = size / mult;
+					if ((size % mult) >= (mult / 2))
+						val++;
 					snprintf(VARDATA(result), 50, INT64_FORMAT " TB",
-							 (size + mult / 2) / mult);
+							 val);
 				}
 			}
 		}