Fix gcc 9 build errors for make xcheck. [BZ #24556]

This patch fixes the following gcc 9 warnings for "make xcheck" / "make bench":
-string/tst-strcasestr.c:
../include/bits/../../misc/bits/error.h:42:5: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

-argp/argp-test.c:
argp-test.c:130:20: error: ‘%d’ directive writing between 1 and 11 bytes into a region of size 10 [-Werror=format-overflow=]
argp-test.c:130:19: note: directive argument in the range [-2147483648, 122]
argp-test.c:130:5: note: ‘sprintf’ output between 2 and 12 bytes into a destination of size 10

-nss/tst-field.c:
tst-field.c:52:7: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

-benchtests/bench-strstr.c:
../include/bits/../../misc/bits/error.h:42:5: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

-benchtests/bench-malloc-simple.c:
bench-malloc-simple.c:93:16: error: iteration 3 invokes undefined behavior [-Werror=aggressive-loop-optimizations]

ChangeLog:

	[BZ #24556]
	* string/test-strcasestr.c (check_result): Add NULL check.
	* nss/tst-field.c (check_rewrite): Likewise.
	* benchtests/bench-strstr.c (do_one_test): Likewise.
	* string/test-strstr.c (check_result): Likewise.
	* argp/argp-test.c (popt): Increase size of buf to 12.
	* benchtests/bench-malloc-simple.c (bench):
	Do not initialize tests array out of bounds.

7 files changed, 21 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index f32b734166..48d59d37ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2019-06-19  Stefan Liebler  <stli@linux.ibm.com>
+
+	[BZ #24556]
+	* string/test-strcasestr.c (check_result): Add NULL check.
+	* nss/tst-field.c (check_rewrite): Likewise.
+	* benchtests/bench-strstr.c (do_one_test): Likewise.
+	* string/test-strstr.c (check_result): Likewise.
+	* argp/argp-test.c (popt): Increase size of buf to 12.
+	* benchtests/bench-malloc-simple.c (bench):
+	Do not initialize tests array out of bounds.
+
 2019-06-19  Florian Weimer  <fweimer@redhat.com>
 
 	[BZ #24166]
diff --git a/argp/argp-test.c b/argp/argp-test.c
index cb2976ddad..13e0c6df14 100644
--- a/argp/argp-test.c
+++ b/argp/argp-test.c
@@ -123,7 +123,7 @@ static const char doc[] = "Test program for argp."
 static void
 popt (int key, char *arg)
 {
-  char buf[10];
+  char buf[12];
   if (isprint (key))
     sprintf (buf, "%c", key);
   else
diff --git a/benchtests/bench-malloc-simple.c b/benchtests/bench-malloc-simple.c
index b8bb2cc116..c4f06f6999 100644
--- a/benchtests/bench-malloc-simple.c
+++ b/benchtests/bench-malloc-simple.c
@@ -87,7 +87,7 @@ bench (unsigned long size)
   size_t iters = NUM_ITERS;
   int **arr = (int**) malloc (MAX_ALLOCS * sizeof (void*));
 
-  for (int t = 0; t <= 3; t++)
+  for (int t = 0; t < 3; t++)
     for (int i = 0; i < NUM_ALLOCS; i++)
       {
 	tests[t][i].n = allocs[i];
diff --git a/benchtests/bench-strstr.c b/benchtests/bench-strstr.c
index 2cbe13e9ac..89d1755813 100644
--- a/benchtests/bench-strstr.c
+++ b/benchtests/bench-strstr.c
@@ -147,7 +147,8 @@ do_one_test (impl_t *impl, const char *s1, const char *s2, char *exp_result)
   if (res != exp_result)
     {
       error (0, 0, "Wrong result in function %s %s %s", impl->name,
-	     res, exp_result);
+	     (res == NULL) ? "(null)" : res,
+	     (exp_result == NULL) ? "(null)" : exp_result);
       ret = 1;
     }
 }
diff --git a/nss/tst-field.c b/nss/tst-field.c
index 23d2f2abf6..d98d3eead0 100644
--- a/nss/tst-field.c
+++ b/nss/tst-field.c
@@ -50,7 +50,8 @@ check_rewrite (const char *input, const char *expected)
   if (result != NULL && strcmp (result, expected) != 0)
     {
       printf ("FAIL: rewrite \"%s\" -> \"%s\", expected \"%s\"\n",
-	      input, result, expected);
+	      (input == NULL) ? "(null)" : input, result,
+	      (expected == NULL) ? "(null)" : expected);
       errors = true;
     }
   free (to_free);
diff --git a/string/test-strcasestr.c b/string/test-strcasestr.c
index 0a16f85dcd..7649cc6e1d 100644
--- a/string/test-strcasestr.c
+++ b/string/test-strcasestr.c
@@ -67,7 +67,8 @@ check_result (impl_t *impl, const char *s1, const char *s2,
   if (result != exp_result)
     {
       error (0, 0, "Wrong result in function %s %s %s", impl->name,
-	     result, exp_result);
+	     (result == NULL) ? "(null)" : result,
+	     (exp_result == NULL) ? "(null)" : exp_result);
       ret = 1;
       return -1;
     }
diff --git a/string/test-strstr.c b/string/test-strstr.c
index 031aff5534..df6dbc251e 100644
--- a/string/test-strstr.c
+++ b/string/test-strstr.c
@@ -66,7 +66,8 @@ check_result (impl_t *impl, const char *s1, const char *s2,
   if (result != exp_result)
     {
       error (0, 0, "Wrong result in function %s %s %s", impl->name,
-	     result, exp_result);
+	     (result == NULL) ? "(null)" : result,
+	     (exp_result == NULL) ? "(null)" : exp_result);
       ret = 1;
       return -1;
     }