On Sat, Sep 21, 2024 at 01:23:09AM +0000, Dexuan Cui wrote: > > From: Saurabh Singh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx> > > Sent: Friday, September 13, 2024 12:31 AM > > To: Dexuan Cui <decui@xxxxxxxxxxxxx> > > Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang > > <haiyangz@xxxxxxxxxxxxx>; Wei Liu <wei.liu@xxxxxxxxxx>; Long Li > > <longli@xxxxxxxxxxxxx>; Greg Kroah-Hartman > > <gregkh@xxxxxxxxxxxxxxxxxxx>; open list:Hyper-V/Azure CORE AND DRIVERS > > <linux-hyperv@xxxxxxxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx>; > > stable@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH] tools: hv: Fix a complier warning in the fcopy uio > > daemon > > > > On Tue, Sep 10, 2024 at 12:44:32AM +0000, Dexuan Cui wrote: > > > hv_fcopy_uio_daemon.c:436:53: warning: '%s' directive output may be > > truncated > > > writing up to 14 bytes into a region of size 10 [-Wformat-truncation=] > > > 436 | snprintf(uio_dev_path, sizeof(uio_dev_path), "/dev/%s", > > uio_name); > > > > Makefile today doesn't have -Wformat-truncation flag enabled, I tried to add > > -Wformat-truncation=2 but I don't see any error in this file. > > > > Do you mind sharing more details how you get this error ? > > > > - Saurabh > > This repros in a Ubuntu 20.04 VM: > > root@decui-u2004-2024-0920:~/linux/tools/hv# cat /etc/os-release > NAME="Ubuntu" > VERSION="20.04.6 LTS (Focal Fossa)" > ... > > root@decui-u2004-2024-0920:~/linux/tools/hv# gcc --version > gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0 > Copyright (C) 2019 Free Software Foundation, Inc. > This is free software; see the source for copying conditions. There is NO > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. > > root@decui-u2004-2024-0920:~/linux/tools/hv# make clean; make > ... > make -f /root/linux/tools/build/Makefile.build dir=. obj=hv_fcopy_uio_daemon > make[1]: Entering directory '/root/linux/tools/hv' > CC hv_fcopy_uio_daemon.o > hv_fcopy_uio_daemon.c: In function 'main': > hv_fcopy_uio_daemon.c:443:53: warning: '%s' directive output may be truncated writing up to 14 bytes into a region of size 10 [-Wformat-truncation=] > 443 | snprintf(uio_dev_path, sizeof(uio_dev_path), "/dev/%s", uio_name); > | ^~ ~~~~~~~~ > In file included from /usr/include/stdio.h:867, > from hv_fcopy_uio_daemon.c:20: > /usr/include/x86_64-linux-gnu/bits/stdio2.h:67:10: note: '__builtin___snprintf_chk' output between 6 and 20 bytes into a destination of size 15 > 67 | return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1, > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 68 | __bos (__s), __fmt, __va_arg_pack ()); > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > CC vmbus_bufring.o > LD hv_fcopy_uio_daemon-in.o > make[1]: Leaving directory '/root/linux/tools/hv' > LINK hv_fcopy_uio_daemon Thanks for the details. Looks this is the behaviour of old gcc versions. How about fixing it like this : --- a/tools/hv/hv_fcopy_uio_daemon.c +++ b/tools/hv/hv_fcopy_uio_daemon.c @@ -35,7 +35,7 @@ #define WIN8_SRV_MINOR 1 #define WIN8_SRV_VERSION (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR) -#define MAX_FOLDER_NAME 15 +#define MAX_FOLDER_NAME 10 #define MAX_PATH_LEN 15 - Saurabh
