Thanks Will, I have just seen that it has also been fixed in our master branch. :-)
Frank > On 18. Oct 2018, at 17:40, William Cohen <wco...@redhat.com> wrote: > > On 10/18/18 10:43 AM, Frank Winkler wrote: >> Hi all, >> >> As I did not get a reply from Stephane I would like to turn this to the >> perfmon2-devel mailing list. >> Please see the text below: >> >> Hi Stephane, >> >> I would like to ask for your help. >> There is a build problem of PAPI when using gcc/8. >> >> See open issue here: >> https://bitbucket.org/icl/papi/issues/51/build-failed-using-gcc-810 >> >> >> This issue can be fixed very easily by just increasing the buffer size. >> As this is part of libpfm4 I would like to address this to you. >> >> The main reason for the build failure is that PAPI converts warnings to >> errors, see: >> >> -Werror (Make the specified warning into an error) >> -Wformat-truncation (Warn about calls to formatted input/output functions >> such as |snprintf| and |vsnprintf| that might result in output truncation) >> >> And the latest gcc versions message warnings for snprintf if the buffer is >> too small and output might be truncated. >> >> >> Here a small example: >> >> cat test.c: >> >> int main() >> { >> char dirname[256]; >> char filename[256]; >> >> strcpy(dirname,"/ccs/home/winklerf/sources"); >> strcpy(filename,"frank.txt"); >> char pathname[256]; >> >> snprintf(pathname, sizeof(pathname), "%s/%s", dirname, filename); >> >> puts(pathname); >> return 0; >> } >> >> gcc -Werror -Wformat-truncation test.c -o test >> [winklerf@login3.summit <mailto:winklerf@login3.summit> sources]$ gcc >> -Werror -Wformat-truncation test.c -o test >> test.c: In function 'main': >> test.c:17:43: error: '%s' directive output may be truncated writing up to >> 255 bytes into a region of size between 0 and 255 >> [-Werror=format-truncation=] >> snprintf(pathname, sizeof pathname, "%s/%s", dirname, filename); >> ^~ ~~~~~~~~ >> test.c:17:3: note: 'snprintf' output between 2 and 512 bytes into a >> destination of size 256 >> snprintf(pathname, sizeof pathname, "%s/%s", dirname, filename); >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> cc1: all warnings being treated as errors >> >> >> The same happens with PAPI when building with gcc/8: >> >> make[2]: Entering directory >> `/autofs/nccs-svm1_home2/winklerf/sources/papi-5.6.0/src/libpfm4/lib' >> gcc -Wno-override-init -g -Wall -Werror -Wextra -Wno-unused-parameter -I. >> -I/autofs/nccs-svm1_home2/winklerf/sources/papi-5.6.0/src/libpfm4/lib/../include >> -DCONFIG_PFMLIB_DEBUG -DCONFIG_PFMLIB_OS_LINUX -D_REENTRANT -I. >> -fvisibility=hidden -DCONFIG_PFMLIB_ARCH_POWERPC -I. -c pfmlib_common.c >> gcc -Wno-override-init -g -Wall -Werror -Wextra -Wno-unused-parameter -I. >> -I/autofs/nccs-svm1_home2/winklerf/sources/papi-5.6.0/src/libpfm4/lib/../include >> -DCONFIG_PFMLIB_DEBUG -DCONFIG_PFMLIB_OS_LINUX -D_REENTRANT -I. >> -fvisibility=hidden -DCONFIG_PFMLIB_ARCH_POWERPC -I. -c >> pfmlib_perf_event_pmu.c >> pfmlib_perf_event_pmu.c: In function 'gen_tracepoint_table': >> pfmlib_perf_event_pmu.c:349:36: error: '%s' directive output may be >> truncated writing up to 255 bytes into a region of size between 0 and 4095 >> [-Werror=format-truncation=] >> snprintf(d2path, MAXPATHLEN, "%s/%s", debugfs_mnt, d1->d_name); >> ^~ >> pfmlib_perf_event_pmu.c:349:3: note: 'snprintf' output between 2 and 4352 >> bytes into a destination of size 4096 >> snprintf(d2path, MAXPATHLEN, "%s/%s", debugfs_mnt, d1->d_name); >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> pfmlib_perf_event_pmu.c:399:58: error: '%s' directive output may be >> truncated writing up to 255 bytes into a region of size between 0 and 4095 >> [-Werror=format-truncation=] >> snprintf(idpath, MAXPATHLEN, "%s/%s/id", d2path, >> d2->d_name); >> ^~ >> pfmlib_perf_event_pmu.c:399:25: note: 'snprintf' output between 5 and 4355 >> bytes into a destination of size 4096 >> snprintf(idpath, MAXPATHLEN, "%s/%s/id", d2path, >> d2->d_name); >> >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> cc1: all warnings being treated as errors >> >> >> The 2 lines of the following file have to be fixed: >> >> vi src/libpfm4/lib/pfmlib_perf_event_pmu.c >> >> 349 snprintf(d2path, MAXPATHLEN + 256, "%s/%s", debugfs_mnt, >> d1->d_name); >> >> >> 399 snprintf(idpath, MAXPATHLEN + 3 + 256, >> "%s/%s/id", d2path, d2->d_name); >> >> There should be a more general fix, of course. But this is up to you, maybe >> just increase MAXPATHLEN... >> >> Thanks >> Frank > > > Hi, > > This kind of problem has been encountered before on the Fedora builds. There > are two ways to address it: > > -Ensure that the buffer that result is being stored in is large enough to > never overflow as you mentioned. However, it would be better to avoid using > arithmetic expression with constants in there as that might not match up with > the buffer things are being written into when someone changes the size of the > buffer. Maybe something like the following avoids that problem, but need to > make sure that the last element in buf is '\0'. > > snprintf(buf, sizeof(buf)-1, "%s::%s", pinfo.name, info->name); > buf[sizeof(buf)-1] = '\0'; > > -Check the return value of the snprintf function and take appropriate action > if there is an overflow > an example fix on libpfm, > https://sourceforge.net/p/perfmon2/libpfm4/ci/29f626744df184913a200532408e205e2b0ec2ec/ > > > -Will _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
