Verify the return value for warn_unused_result functions

Under Linux the following functions are flagged with the
attribute warn_unused_result, this triggers a warning when
ever they are used without checking the return value.

To handle this case we check the result VERIFY().  It's
better to detect this immediately on failure rather than
segfault farther down in the function.

  ../../cmd/ztest/ztest.c:6033:2: warning:
  ignoring return value of 'asprintf', declared with
  attribute warn_unused_result [-Wunused-result]
  ../../cmd/ztest/ztest.c:739:3: warning:
  ignoring return value of 'realpath', declared with
  attribute warn_unused_result [-Wunused-result]

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index bc2f56fb878b27e233158521e94c12194fdb652e..09f3d5678a251afcc8b7c497de9a3d5c8d17e60e 100644 (file)
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -736,7 +736,7 @@ process_options(int argc, char **argv)
                char *isa;
                int isalen;
 
-               (void) realpath(getexecname(), cmd);
+               VERIFY(NULL != realpath(getexecname(), cmd));
                if (0 != access(altdir, F_OK)) {
                        ztest_dump_core = B_FALSE;
                        fatal(B_TRUE, "invalid alternate ztest path: %s",
@@ -6030,8 +6030,8 @@ main(int argc, char **argv)
        ASSERT3U(ztest_opts.zo_datasets, ==, ztest_shared_hdr->zh_ds_count);
 
        /* Override location of zpool.cache */
-       (void) asprintf((char **)&spa_config_path, "%s/zpool.cache",
-           ztest_opts.zo_dir);
+       VERIFY(asprintf((char **)&spa_config_path, "%s/zpool.cache",
+           ztest_opts.zo_dir) != -1);
 
        ztest_ds = umem_alloc(ztest_opts.zo_datasets * sizeof (ztest_ds_t),
            UMEM_NOFAIL);