invalid format string conversion in src/common.c

[jeffhammond]

I dislike compiler warnings...

$ icc -std=gnu99 -DHAVE_CONFIG_H -I. -I.. -I../include -D_GNU_SOURCE -D__USE_XOPEN2K8 -DSYSCONFDIR=\"/home/jrhammon/NWCHEM/deps/etc\" -DRDMADIR=\"@rdmadir@\" -DPROVDLDIR=\"/home/jrhammon/NWCHEM/deps/lib/libfabric\" -I../prov/sockets/include -I../prov/sockets -Wall -fvisibility=hidden -O2 -DNDEBUG -Wall -Wundef -Wpointer-arith -MT src/src_libfabric_la-common.lo -MD -MP -MF src/.deps/src_libfabric_la-common.Tpo -c ../src/common.c  -fPIC -DPIC -o src/.libs/src_libfabric_la-common.o
../src/common.c(305): warning #269: invalid format string conversion
  	ret = sscanf(str, "%m[^:]://", &fmt);
  	                               ^

../src/common.c(354): warning #269: invalid format string conversion
  	ret = sscanf(str, "%*[^:]://%m[^:]:%" SCNu16, &ip, &sin->sin_port);
  	                                              ^

../src/common.c(358): warning #269: invalid format string conversion
  	ret = sscanf(str, "%*[^:]://%m[^:/]", &ip);
  	                                      ^

../src/common.c(394): warning #269: invalid format string conversion
  	ret = sscanf(str, "%*[^:]://[%m[^]]]:%" SCNu16, &ip, &sin6->sin6_port);
  	                                                ^

../src/common.c(398): warning #269: invalid format string conversion
  	ret = sscanf(str, "%*[^:]://[%m[^]]", &ip);
  	                                      ^

Compiler Version

$ icc -v
icc version 17.0.4 (gcc version 4.8.5 compatibility)

[shefty]

Does icc not like the %m format?

[jeffhammond]

It's not ISO C: https://stackoverflow.com/a/20577576/2189128.

The fix is easy enough. Just apply the definition found on http://www.gnu.org/software/libc/manual/html_node/Other-Output-Conversions.html:

Thus:

fprintf (stderr, "can't open %s': %m\n", filename);`

is equivalent to:

fprintf (stderr, "can't open %s': %s\n", filename, strerror (errno));`

[jeffhammond]

And indeed, ICC will not compile this with -Werror when I used std=gnu11. I will file a compiler bug report w.r.t. ICC not providing full GCC compatibility here.

[shefty]

With sscanf, the %m allocates a buffer of an appropriate size. I can switch to using a fixed-size buffer, with checks to see that it doesn't get overrun (I think).