zfs build warnings

[slavonnet]

last master repo checkout

zpool_influxdb.c: In function ‘print_stats’:
zpool_influxdb.c:280:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  280 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:279:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  279 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  280 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  281 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:280:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  280 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:279:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  279 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  280 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  281 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:280:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  280 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:279:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  279 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  280 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  281 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:280:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  280 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:279:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  279 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  280 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  281 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:280:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  280 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:279:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  279 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  280 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  281 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In file included from ../../include/sys/zfs_context.h:98,
                 from ../../include/sys/lua/lua.h:13,
                 from ../../module/zfs/zcp_get.c:20:
../../module/zfs/zcp_get.c: In function ‘get_special_prop’:
../../lib/libspl/include/assert.h:55:11: warning: ‘ds_type’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   55 |  (void) ((!(cond)) &&      \
      |           ^
../../module/zfs/zcp_get.c:233:13: note: ‘ds_type’ was declared here
  233 |  zfs_type_t ds_type;
      |             ^~~~~~~

[rincebrain]

Can't reproduce.

It would probably be helpful if you hadn't deleted the field for "what OS and version did I do this on", and whether you're using a non-default compiler or CFLAGS.

[nabijaczleweli]

Oddly, current Clang 13 doesn't see this

[nabijaczleweli]

Oh, this is just a really obtuse recursive truncation warning that GCC 8 sees, I'll include this in some patchset soon

[slavonnet]

Last master

  CC       zpool_influxdb.o
zpool_influxdb.c: In function ‘print_stats’:
zpool_influxdb.c:281:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  281 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:280:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  280 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  281 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  282 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:281:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  281 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:280:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  280 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  281 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  282 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:281:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  281 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:280:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  280 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  281 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  282 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:281:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  281 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:280:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  280 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  281 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  282 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zpool_influxdb.c:281:13: warning: ‘-’ directive output may be truncated writing 1 byte into a region of size between 0 and 255 [-Wformat-truncation=]
  281 |       "%s/%s-%llu",
      |             ^
zpool_influxdb.c:280:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  280 |   (void) snprintf(vdev_name, sizeof (vdev_name),
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  281 |       "%s/%s-%llu",
      |       ~~~~~~~~~~~~~
  282 |       parent_name, vdev_type, (u_longlong_t)vdev_id);
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  CCLD     zpool_influxdb


  CC       zcp_get.lo
In file included from ../../include/sys/zfs_context.h:97,
                 from ../../include/sys/lua/lua.h:13,
                 from ../../module/zfs/zcp_get.c:20:
../../module/zfs/zcp_get.c: In function ‘get_special_prop’:
../../lib/libspl/include/assert.h:55:11: warning: ‘ds_type’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   55 |  (void) ((!(cond)) &&      \
      |           ^
../../module/zfs/zcp_get.c:233:13: note: ‘ds_type’ was declared here
  233 |  zfs_type_t ds_type;
      |             ^~~~~~~

[slavonnet]

[root@vm2 zfs]# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/opt/rh/gcc-toolset-10/root/usr/libexec/gcc/x86_64-redhat-linux/10/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,lto --prefix=/opt/rh/gcc-toolset-10/root/usr --mandir=/opt/rh/gcc-toolset-10/root/usr/share/man --infodir=/opt/rh/gcc-toolset-10/root/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl=/builddir/build/BUILD/gcc-10.2.1-20201112/obj-x86_64-redhat-linux/isl-install --disable-libmpx --enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 --build=x86_64-redhat-linux
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.1 20201112 (Red Hat 10.2.1-8) (GCC)

[rincebrain]

I don't see those with the apparently same gcc on CentOS 8 (from gcc-toolset-10) with f3678d7, with or without --enable-debug, and make rpm-utils rpm-kmod.

Could you please include:

• your exact complete commands from ./autogen.sh through the last make?
• your exact git revision?

[slavonnet]

commit 4357552 . Centos Stream. All updates. Sunny Bridge CPU 2960 v1

[root@vm2 ~]# scl enable gcc-toolset-10 bash

[root@vm2 ~]# export | grep FLAGS
declare -x CFLAGS="-Ofast  -march=native -mtune=native"
declare -x CXXFLAGS="-Ofast  -march=native  -mtune=native"


[root@vm2 zfs]# ./autogen.sh
autoreconf: Entering directory `.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal --force -I config
autoreconf: configure.ac: tracing
autoreconf: configure.ac: AM_GNU_GETTEXT is used, but not AM_GNU_GETTEXT_VERSION
autoreconf: running: libtoolize --copy --force
libtoolize: putting auxiliary files in AC_CONFIG_AUX_DIR, 'config'.
libtoolize: copying file 'config/ltmain.sh'
libtoolize: putting macros in AC_CONFIG_MACRO_DIRS, 'config'.
libtoolize: copying file 'config/libtool.m4'
libtoolize: copying file 'config/ltoptions.m4'
libtoolize: copying file 'config/ltsugar.m4'
libtoolize: copying file 'config/ltversion.m4'
libtoolize: copying file 'config/lt~obsolete.m4'
autoreconf: running: /usr/bin/autoconf --force
autoreconf: running: /usr/bin/autoheader --force
autoreconf: running: automake --add-missing --copy --force-missing
configure.ac:48: installing 'config/compile'
configure.ac:42: installing 'config/missing'
cmd/mount_zfs/Makefile.am: installing 'config/depcomp'
autoreconf: Leaving directory `.'


# $ ./configure --prefix=/usr/ --with-linux=/usr/src/kernels/5.13.8-1.el8.elrepo.x86_64/
# make

[szubersk]

This issue can be reproduced using latest master in centos:8 container with gcc-toolset-10 enabled.

@slavonnet Those warnings can be safely ignored. Feel free to apply 6c4ccfb to see if it helped you.

../../lib/libspl/include/assert.h:56:11: warning: ‘ds_type’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   56 |  (void) ((!(cond)) &&      \
      |           ^
../../module/zfs/zcp_get.c:233:13: note: ‘ds_type’ was declared here

zfs/module/zfs/zcp_get.c

Lines 233 to 235 in 10271af

	zfs_type_t ds_type;
	zprop_type_t prop_type = zfs_prop_get_type(zfs_prop);
	(void) get_objset_type(ds, &ds_type);

zpool_influxdb.c:280:10: note: ‘snprintf’ output 4 or more bytes (assuming 259) into a destination of size 256
  280 |   (void) snprintf(vdev_name, sizeof (vdev_name),

zfs/cmd/zpool_influxdb/zpool_influxdb.c

Lines 279 to 283 in 10271af

	} else {
	(void) snprintf(vdev_name, sizeof (vdev_name),
	"%s/%s-%llu",
	parent_name, vdev_type, (u_longlong_t)vdev_id);
	}