From 25ae3bba79221ceacf8a6ec0313a039ecd18e528 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Thu, 16 Mar 2023 14:08:44 -0700 Subject: [PATCH] Work around spurious compiler warning in inet operators gcc 12+ has complaints like the following: ../../../../../pgsql/src/backend/utils/adt/network.c: In function 'inetnot': ../../../../../pgsql/src/backend/utils/adt/network.c:1893:34: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 1893 | pdst[nb] = ~pip[nb]; | ~~~~~~~~~^~~~~~~~~~ ../../../../../pgsql/src/include/utils/inet.h:27:23: note: at offset -1 into destination object 'ipaddr' of size 16 27 | unsigned char ipaddr[16]; /* up to 128 bits of address */ | ^~~~~~ ../../../../../pgsql/src/include/utils/inet.h:27:23: note: at offset -1 into destination object 'ipaddr' of size 16 This is due to a compiler bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104986 It has been a year since the bug has been reported without getting fixed. As the warnings are verbose and use of gcc 12 is becoming more common, it seems worth working around the bug. Particularly because a simple reformulation of the loop condition fixes the issue and isn't any less readable. Author: Tom Lane Author: Andres Freund Discussion: https://postgr.es/m/144536.1648326206@sss.pgh.pa.us Backpatch: 11- --- src/backend/utils/adt/network.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/src/backend/utils/adt/network.c b/src/backend/utils/adt/network.c index 5af7f4e046..270a26a533 100644 --- a/src/backend/utils/adt/network.c +++ b/src/backend/utils/adt/network.c @@ -1282,7 +1282,7 @@ inetnot(PG_FUNCTION_ARGS) unsigned char *pip = ip_addr(ip); unsigned char *pdst = ip_addr(dst); - while (nb-- > 0) + while (--nb >= 0) pdst[nb] = ~pip[nb]; } ip_bits(dst) = ip_bits(ip); @@ -1314,7 +1314,7 @@ inetand(PG_FUNCTION_ARGS) unsigned char *pip2 = ip_addr(ip2); unsigned char *pdst = ip_addr(dst); - while (nb-- > 0) + while (--nb >= 0) pdst[nb] = pip[nb] & pip2[nb]; } ip_bits(dst) = Max(ip_bits(ip), ip_bits(ip2)); @@ -1346,7 +1346,7 @@ inetor(PG_FUNCTION_ARGS) unsigned char *pip2 = ip_addr(ip2); unsigned char *pdst = ip_addr(dst); - while (nb-- > 0) + while (--nb >= 0) pdst[nb] = pip[nb] | pip2[nb]; } ip_bits(dst) = Max(ip_bits(ip), ip_bits(ip2)); @@ -1371,7 +1371,7 @@ internal_inetpl(inet *ip, int64 addend) unsigned char *pdst = ip_addr(dst); int carry = 0; - while (nb-- > 0) + while (--nb >= 0) { carry = pip[nb] + (int) (addend & 0xFF) + carry; pdst[nb] = (unsigned char) (carry & 0xFF); @@ -1455,7 +1455,7 @@ inetmi(PG_FUNCTION_ARGS) unsigned char *pip2 = ip_addr(ip2); int carry = 1; - while (nb-- > 0) + while (--nb >= 0) { int lobyte;