On 06/07/2018 01:28 PM, Ari Sundholm wrote:
On 06/07/2018 07:13 PM, no-re...@patchew.org wrote:
Hi,
This series failed build test on s390x host. Please find the details
below.
/var/tmp/patchew-tester-tmp-8bz4jnox/src/block/blklogwrites.c: In
function ‘blk_log_writes_refresh_filename’:
/var/tmp/patchew-tester-tmp-8bz4jnox/src/block/blklogwrites.c:136:32:
error: ‘%s’ directive output may be truncated writing up to 4095 bytes
into a region of size 4083 [-Werror=format-truncation=]
"blklogwrites:%s:%s",
^~
In file included from /usr/include/stdio.h:939:0,
from
/var/tmp/patchew-tester-tmp-8bz4jnox/src/include/qemu/osdep.h:68,
from
/var/tmp/patchew-tester-tmp-8bz4jnox/src/block/blklogwrites.c:12:
/usr/include/bits/stdio2.h:64:10: note: ‘__builtin___snprintf_chk’
output between 15 and 8205 bytes into a destination of size 4096
return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
__bos (__s), __fmt, __va_arg_pack ());
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/var/tmp/patchew-tester-tmp-8bz4jnox/src/rules.mak:69:
block/blklogwrites.o] Error 1
make: *** Waiting for unfinished jobs....
CC block/qapi.o
=== OUTPUT END ===
Test command exited with code: 2
Given that blkverify.c has a similar snprintf() call, with the exception
that it checks the return value in case the string was truncated, am I
safe in assuming that adding a check for the return value of snprintf()
fixes this one? I don't really see anything else I could do about the
error.
Well, ideally we'd g_strdup_printf() the string (and g_free() it later)
rather than use a fixed-size array, if we HAVE to produce a
legacy-format name in the first place. But if we stick with a
fixed-width buffer, perhaps checking for snprintf() truncation, and
returning NULL in that case, is enough to force a fallback to a
pseudo-JSON string so that the end user doesn't lose information and the
compiler doesn't complain about failure to check for truncation.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
