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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 <tgl@sss.pgh.pa.us>
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/144536.1648326206@sss.pgh.pa.us
Backpatch: 11-
This commit is contained in:
Andres Freund 2023-03-16 14:08:44 -07:00
parent 6a9229da65
commit 0dc40196f2
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/backend/utils/adt/network.c
View File

@ -1866,7 +1866,7 @@ 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);
@ -1898,7 +1898,7 @@ 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));
@ -1930,7 +1930,7 @@ 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));
@ -1955,7 +1955,7 @@ 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);
@ -2039,7 +2039,7 @@ inetmi(PG_FUNCTION_ARGS)
unsigned char *pip2 = ip_addr(ip2);
int carry = 1;
while (nb-- > 0)
while (--nb >= 0)
{
int lobyte;