complier warnings from ecpg tests

Started by Sergei Kornilovover 6 years ago6 messages

Hello

I noticed few warnings from my compiler (gcc version 8.3.0 (Debian 8.3.0-6)) during make check-world:

array.pgc: In function ‘main’:
array.pgc:41:16: warning: ‘%d’ directive writing between 1 and 11 bytes into a region of size 10 [-Wformat-overflow=]
sprintf(str, "2000-1-1 0%d:00:00", j);
^~~~~~~~~~~~~~~~~~~~
array.pgc:41:16: note: directive argument in the range [-2147483648, 9]
array.pgc:41:3: note: ‘sprintf’ output between 18 and 28 bytes into a destination of size 20
sprintf(str, "2000-1-1 0%d:00:00", j);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
array.pgc:43:16: warning: ‘sprintf’ may write a terminating nul past the end of the destination [-Wformat-overflow=]
sprintf(str, "2000-1-1%d\n", j);
^~~~~~~~~~~~~~
array.pgc:43:3: note: ‘sprintf’ output between 11 and 21 bytes into a destination of size 20
sprintf(str, "2000-1-1%d\n", j);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

They coming from src/interfaces/ecpg tests ( ./src/interfaces/ecpg/test/sql/array.pgc ).
Seems this code is 4 year old but I did not found discussion related to such compiler warnings. Is this expected?

regards, Sergei

#2Michael Paquier
michael@paquier.xyz
In reply to: Sergei Kornilov (#1)
Re: complier warnings from ecpg tests

On Thu, Jul 11, 2019 at 03:21:15PM +0300, Sergei Kornilov wrote:

I noticed few warnings from my compiler (gcc version 8.3.0 (Debian
8.3.0-6)) during make check-world:

They coming from src/interfaces/ecpg tests (
./src/interfaces/ecpg/test/sql/array.pgc ).
Seems this code is 4 year old but I did not found discussion related
to such compiler warnings. Is this expected?

Are you using -Wformat-overflow? At which level?
--
Michael

In reply to: Michael Paquier (#2)
Re: complier warnings from ecpg tests

Hi

Are you using -Wformat-overflow? At which level?

I use: ./configure --prefix=somepath --enable-cassert --enable-debug CFLAGS="-ggdb -Og -g3 -fno-omit-frame-pointer" --enable-tap-tests
No other explicit options.

pg_config reports:

CPPFLAGS = -D_GNU_SOURCE
CFLAGS = -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation -g -ggdb -Og -g3 -fno-omit-frame-pointer
CFLAGS_SL = -fPIC

regards, Sergei

#4Michael Paquier
michael@paquier.xyz
In reply to: Sergei Kornilov (#3)
Re: complier warnings from ecpg tests

On Thu, Jul 11, 2019 at 04:57:08PM +0300, Sergei Kornilov wrote:

I use: ./configure --prefix=somepath --enable-cassert --enable-debug
CFLAGS="-ggdb -Og -g3 -fno-omit-frame-pointer" --enable-tap-tests
No other explicit options.

Thanks for the set of flags. So this comes from the use of -Og, and
the rest of the tree does not complain. The issue is that gcc
complains about the buffer not being large enough, but %d only uses up
to 2 characters so there is no overflow. In order to fix the issue it
is fine enough to increase the buffer size to 28 bytes, so I would
recommend to just do that. This is similar to the business done in
3a4b891.
--
Michael

#5Michael Paquier
michael@paquier.xyz
In reply to: Michael Paquier (#4)
Re: complier warnings from ecpg tests

On Thu, Aug 01, 2019 at 03:14:06PM +0900, Michael Paquier wrote:

Thanks for the set of flags. So this comes from the use of -Og, and
the rest of the tree does not complain. The issue is that gcc
complains about the buffer not being large enough, but %d only uses up
to 2 characters so there is no overflow. In order to fix the issue it
is fine enough to increase the buffer size to 28 bytes, so I would
recommend to just do that. This is similar to the business done in
3a4b891.

And fixed with a9f301d.
--
Michael

In reply to: Michael Paquier (#5)
Re: complier warnings from ecpg tests

Hi

 Thanks for the set of flags. So this comes from the use of -Og, and
 the rest of the tree does not complain. The issue is that gcc
 complains about the buffer not being large enough, but %d only uses up
 to 2 characters so there is no overflow. In order to fix the issue it
 is fine enough to increase the buffer size to 28 bytes, so I would
 recommend to just do that. This is similar to the business done in
 3a4b891.

And fixed with a9f301d.

Thank you! My compiler is now quiet

regards, Sergei