[PATCH 3/3] Fix overflow checking in repeat()

icc optimizes away `check + VARHDRSZ <= check' since signed integer
overflow is undefined behavior. Simplify the overflow check for
`VARHDRSZ + count * slen' as `count > (INT_MAX - VARHDRSZ) / slen'.
---
src/backend/utils/adt/oracle_compat.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/src/backend/utils/adt/oracle_compat.c b/src/backend/utils/adt/oracle_compat.c
index d448088..a85a672 100644
--- a/src/backend/utils/adt/oracle_compat.c
+++ b/src/backend/utils/adt/oracle_compat.c
@@ -15,6 +15,8 @@
*/
#include "postgres.h"

+#include <limits.h>
+
#include "utils/builtins.h"
#include "utils/formatting.h"
#include "mb/pg_wchar.h"
@@ -1034,20 +1036,14 @@ repeat(PG_FUNCTION_ARGS)
count = 0;

slen = VARSIZE_ANY_EXHDR(string);
- tlen = VARHDRSZ + (count * slen);

/* Check for integer overflow */
- if (slen != 0 && count != 0)
- {
- int check = count * slen;
- int check2 = check + VARHDRSZ;
-
- if ((check / slen) != count || check2 <= check)
- ereport(ERROR,
- (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("requested length too large")));
- }
+ if (slen != 0 && count > (INT_MAX - VARHDRSZ) / slen)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("requested length too large")));

+ tlen = VARHDRSZ + (count * slen);
result = (text *) palloc(tlen);

SET_VARSIZE(result, tlen);
--
1.7.10.4