string: Improve coverage in test-strcmp.c and test-strncmp.c

Add additional test cases for small / medium sizes.

Add tests in test-strncmp.c where `n` is near ULONG_MAX or LONG_MIN to
test for overflow bugs in length handling.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>

2 files changed, 306 insertions, 21 deletions

diff --git a/string/test-strcmp.c b/string/test-strcmp.c
index 97d7bf5..eacbdc8 100644
--- a/string/test-strcmp.c
+++ b/string/test-strcmp.c
@@ -16,6 +16,9 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#define TEST_LEN (4096 * 3)
+#define MIN_PAGE_SIZE (TEST_LEN + 2 * getpagesize ())
+
 #define TEST_MAIN
 #ifdef WIDE
 # define TEST_NAME "wcscmp"
@@ -129,7 +132,7 @@ do_one_test (impl_t *impl,
 
 static void
 do_test (size_t align1, size_t align2, size_t len, int max_char,
-	 int exp_result)
+         int exp_result)
 {
   size_t i;
 
@@ -138,19 +141,22 @@ do_test (size_t align1, size_t align2, size_t len, int max_char,
   if (len == 0)
     return;
 
-  align1 &= 63;
+  align1 &= ~(CHARBYTES - 1);
+  align2 &= ~(CHARBYTES - 1);
+
+  align1 &= getpagesize () - 1;
   if (align1 + (len + 1) * CHARBYTES >= page_size)
     return;
 
-  align2 &= 63;
+  align2 &= getpagesize () - 1;
   if (align2 + (len + 1) * CHARBYTES >= page_size)
     return;
 
   /* Put them close to the end of page.  */
   i = align1 + CHARBYTES * (len + 2);
-  s1 = (CHAR *) (buf1 + ((page_size - i) / 16 * 16) + align1);
+  s1 = (CHAR *)(buf1 + ((page_size - i) / 16 * 16) + align1);
   i = align2 + CHARBYTES * (len + 2);
-  s2 = (CHAR *) (buf2 + ((page_size - i) / 16 * 16)  + align2);
+  s2 = (CHAR *)(buf2 + ((page_size - i) / 16 * 16) + align2);
 
   for (i = 0; i < len; i++)
     s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;
@@ -161,9 +167,10 @@ do_test (size_t align1, size_t align2, size_t len, int max_char,
   s2[len - 1] -= exp_result;
 
   FOR_EACH_IMPL (impl, 0)
-    do_one_test (impl, s1, s2, exp_result);
+  do_one_test (impl, s1, s2, exp_result);
 }
 
+
 static void
 do_random_tests (void)
 {
@@ -385,7 +392,7 @@ check3 (void)
 int
 test_main (void)
 {
-  size_t i;
+  size_t i, j;
 
   test_init ();
   check();
@@ -426,6 +433,55 @@ test_main (void)
       do_test (2 * CHARBYTES * i, CHARBYTES * i, 8 << i, LARGECHAR, -1);
     }
 
+  for (j = 0; j < 160; ++j)
+    {
+      for (i = 0; i < TEST_LEN;)
+        {
+          do_test (getpagesize () - j - 1, 0, i, 127, 0);
+          do_test (getpagesize () - j - 1, 0, i, 127, 1);
+          do_test (getpagesize () - j - 1, 0, i, 127, -1);
+
+          do_test (getpagesize () - j - 1, j, i, 127, 0);
+          do_test (getpagesize () - j - 1, j, i, 127, 1);
+          do_test (getpagesize () - j - 1, j, i, 127, -1);
+
+          do_test (0, getpagesize () - j - 1, i, 127, 0);
+          do_test (0, getpagesize () - j - 1, i, 127, 1);
+          do_test (0, getpagesize () - j - 1, i, 127, -1);
+
+          do_test (j, getpagesize () - j - 1, i, 127, 0);
+          do_test (j, getpagesize () - j - 1, i, 127, 1);
+          do_test (j, getpagesize () - j - 1, i, 127, -1);
+
+          if (i < 32)
+            {
+              i += 1;
+            }
+          else if (i < 161)
+            {
+              i += 7;
+            }
+          else if (i + 161 < TEST_LEN)
+            {
+              i += 31;
+              i *= 17;
+              i /= 16;
+              if (i + 161 > TEST_LEN)
+                {
+                  i = TEST_LEN - 160;
+                }
+            }
+          else if (i + 32 < TEST_LEN)
+            {
+              i += 7;
+            }
+          else
+            {
+              i += 1;
+            }
+        }
+    }
+
   do_random_tests ();
   return ret;
 }
diff --git a/string/test-strncmp.c b/string/test-strncmp.c
index 61a283a..1a3cee1 100644
--- a/string/test-strncmp.c
+++ b/string/test-strncmp.c
@@ -16,6 +16,9 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#define TEST_LEN (4096 * 3)
+#define MIN_PAGE_SIZE (TEST_LEN + 2 * getpagesize ())
+
 #define TEST_MAIN
 #ifdef WIDE
 # define TEST_NAME "wcsncmp"
@@ -166,11 +169,11 @@ do_test_limit (size_t align1, size_t align2, size_t len, size_t n, int max_char,
 }
 
 static void
-do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char,
-	 int exp_result)
+do_test_n (size_t align1, size_t align2, size_t len, size_t n, int n_in_bounds,
+           int max_char, int exp_result)
 {
-  size_t i;
-  CHAR *s1, *s2;
+  size_t i, buf_bound;
+  CHAR *s1, *s2, *s1_end, *s2_end;
 
   align1 &= ~(CHARBYTES - 1);
   align2 &= ~(CHARBYTES - 1);
@@ -178,22 +181,28 @@ do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char,
   if (n == 0)
     return;
 
-  align1 &= 63;
-  if (align1 + (n + 1) * CHARBYTES >= page_size)
+  buf_bound = n_in_bounds ? n : len;
+
+  align1 &= getpagesize () - 1;
+  if (align1 + (buf_bound + 2) * CHARBYTES >= page_size)
     return;
 
-  align2 &= 63;
-  if (align2 + (n + 1) * CHARBYTES >= page_size)
+  align2 &= getpagesize () - 1;
+  if (align2 + (buf_bound + 2) * CHARBYTES >= page_size)
     return;
 
-  s1 = (CHAR *) (buf1 + align1);
-  s2 = (CHAR *) (buf2 + align2);
+  s1 = (CHAR *)(buf1 + align1);
+  s2 = (CHAR *)(buf2 + align2);
 
-  for (i = 0; i < n; i++)
+  if (n_in_bounds)
+    {
+      s1[n] = 24 + exp_result;
+      s2[n] = 23;
+    }
+
+  for (i = 0; i < buf_bound; i++)
     s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % max_char;
 
-  s1[n] = 24 + exp_result;
-  s2[n] = 23;
   s1[len] = 0;
   s2[len] = 0;
   if (exp_result < 0)
@@ -203,11 +212,25 @@ do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char,
   if (len >= n)
     s2[n - 1] -= exp_result;
 
+  /* Ensure that both s1 and s2 are valid null terminated strings. This is
+   * required by the standard. */
+  s1_end = (CHAR *)(buf1 + MIN_PAGE_SIZE - CHARBYTES);
+  s2_end = (CHAR *)(buf2 + MIN_PAGE_SIZE - CHARBYTES);
+  *s1_end = 0;
+  *s2_end = 0;
+
   FOR_EACH_IMPL (impl, 0)
     do_one_test (impl, s1, s2, n, exp_result);
 }
 
 static void
+do_test (size_t align1, size_t align2, size_t len, size_t n, int max_char,
+         int exp_result)
+{
+  do_test_n (align1, align2, len, n, 1, max_char, exp_result);
+}
+
+static void
 do_page_test (size_t offset1, size_t offset2, CHAR *s2)
 {
   CHAR *s1;
@@ -400,10 +423,123 @@ check3 (void)
 	}
 }
 
+static void
+check_overflow (void)
+{
+  size_t i, j, of_mask, of_idx;
+  const size_t of_masks[]
+      = { ULONG_MAX, LONG_MIN, ULONG_MAX - (ULONG_MAX >> 2),
+          ((size_t)LONG_MAX) >> 1 };
+
+  for (of_idx = 0; of_idx < sizeof (of_masks) / sizeof (of_masks[0]); ++of_idx)
+    {
+      of_mask = of_masks[of_idx];
+      for (j = 0; j < 160; ++j)
+        {
+          for (i = 1; i <= 161; i += (32 / sizeof (CHAR)))
+            {
+              do_test_n (j, 0, i, of_mask, 0, 127, 0);
+              do_test_n (j, 0, i, of_mask, 0, 127, 1);
+              do_test_n (j, 0, i, of_mask, 0, 127, -1);
+
+              do_test_n (j, 0, i, of_mask - j / 2, 0, 127, 0);
+              do_test_n (j, 0, i, of_mask - j * 2, 0, 127, 1);
+              do_test_n (j, 0, i, of_mask - j, 0, 127, -1);
+
+              do_test_n (j / 2, j, i, of_mask, 0, 127, 0);
+              do_test_n (j / 2, j, i, of_mask, 0, 127, 1);
+              do_test_n (j / 2, j, i, of_mask, 0, 127, -1);
+
+              do_test_n (j / 2, j, i, of_mask - j, 0, 127, 0);
+              do_test_n (j / 2, j, i, of_mask - j / 2, 0, 127, 1);
+              do_test_n (j / 2, j, i, of_mask - j * 2, 0, 127, -1);
+
+              do_test_n (0, j, i, of_mask - j * 2, 0, 127, 0);
+              do_test_n (0, j, i, of_mask - j, 0, 127, 1);
+              do_test_n (0, j, i, of_mask - j / 2, 0, 127, -1);
+
+              do_test_n (getpagesize () - j - 1, 0, i, of_mask, 0, 127, 0);
+              do_test_n (getpagesize () - j - 1, 0, i, of_mask, 0, 127, 1);
+              do_test_n (getpagesize () - j - 1, 0, i, of_mask, 0, 127, -1);
+
+              do_test_n (getpagesize () - j - 1, 0, i, of_mask - j / 2, 0, 127,
+                         0);
+              do_test_n (getpagesize () - j - 1, 0, i, of_mask - j * 2, 0, 127,
+                         1);
+              do_test_n (getpagesize () - j - 1, 0, i, of_mask - j, 0, 127,
+                         -1);
+
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1, i,
+                         of_mask, 0, 127, 0);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1, i,
+                         of_mask, 0, 127, 1);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1, i,
+                         of_mask, 0, 127, -1);
+
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1, i,
+                         of_mask - j, 0, 127, 0);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1, i,
+                         of_mask - j / 2, 0, 127, 1);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1, i,
+                         of_mask - j * 2, 0, 127, -1);
+            }
+
+          for (i = 1; i < TEST_LEN; i += i)
+            {
+              do_test_n (j, 0, i - 1, of_mask, 0, 127, 0);
+              do_test_n (j, 0, i - 1, of_mask, 0, 127, 1);
+              do_test_n (j, 0, i - 1, of_mask, 0, 127, -1);
+
+              do_test_n (j, 0, i - 1, of_mask - j / 2, 0, 127, 0);
+              do_test_n (j, 0, i - 1, of_mask - j * 2, 0, 127, 1);
+              do_test_n (j, 0, i - 1, of_mask - j, 0, 127, -1);
+
+              do_test_n (j / 2, j, i - 1, of_mask, 0, 127, 0);
+              do_test_n (j / 2, j, i - 1, of_mask, 0, 127, 1);
+              do_test_n (j / 2, j, i - 1, of_mask, 0, 127, -1);
+
+              do_test_n (j / 2, j, i - 1, of_mask - j, 0, 127, 0);
+              do_test_n (j / 2, j, i - 1, of_mask - j / 2, 0, 127, 1);
+              do_test_n (j / 2, j, i - 1, of_mask - j * 2, 0, 127, -1);
+
+              do_test_n (0, j, i - 1, of_mask - j * 2, 0, 127, 0);
+              do_test_n (0, j, i - 1, of_mask - j, 0, 127, 1);
+              do_test_n (0, j, i - 1, of_mask - j / 2, 0, 127, -1);
+
+              do_test_n (getpagesize () - j - 1, 0, i - 1, of_mask, 0, 127, 0);
+              do_test_n (getpagesize () - j - 1, 0, i - 1, of_mask, 0, 127, 1);
+              do_test_n (getpagesize () - j - 1, 0, i - 1, of_mask, 0, 127,
+                         -1);
+
+              do_test_n (getpagesize () - j - 1, 0, i - 1, of_mask - j / 2, 0,
+                         127, 0);
+              do_test_n (getpagesize () - j - 1, 0, i - 1, of_mask - j * 2, 0,
+                         127, 1);
+              do_test_n (getpagesize () - j - 1, 0, i - 1, of_mask - j, 0, 127,
+                         -1);
+
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1,
+                         i - 1, of_mask, 0, 127, 0);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1,
+                         i - 1, of_mask, 0, 127, 1);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1,
+                         i - 1, of_mask, 0, 127, -1);
+
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1,
+                         i - 1, of_mask - j, 0, 127, 0);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1,
+                         i - 1, of_mask - j / 2, 0, 127, 1);
+              do_test_n (getpagesize () - j - 1, getpagesize () - 2 * j - 1,
+                         i - 1, of_mask - j * 2, 0, 127, -1);
+            }
+        }
+    }
+}
+
 int
 test_main (void)
 {
-  size_t i;
+  size_t i, j;
 
   test_init ();
 
@@ -470,6 +606,99 @@ test_main (void)
       do_test_limit (0, 0, 15 - i, 16 - i, 255, -1);
     }
 
+  for (j = 0; j < 160; ++j)
+    {
+      for (i = 0; i < TEST_LEN;)
+        {
+          do_test_n (getpagesize () - j - 1, 0, i, i + 1, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, 0, i, i + 1, 0, 127, 1);
+          do_test_n (getpagesize () - j - 1, 0, i, i + 1, 0, 127, -1);
+
+          do_test_n (getpagesize () - j - 1, 0, i, i, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, 0, i, i - 1, 0, 127, 0);
+
+          do_test_n (getpagesize () - j - 1, 0, i, ULONG_MAX, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, 0, i, ULONG_MAX, 0, 127, 1);
+          do_test_n (getpagesize () - j - 1, 0, i, ULONG_MAX, 0, 127, -1);
+
+          do_test_n (getpagesize () - j - 1, 0, i, ULONG_MAX - i, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, 0, i, ULONG_MAX - i, 0, 127, 1);
+          do_test_n (getpagesize () - j - 1, 0, i, ULONG_MAX - i, 0, 127, -1);
+
+          do_test_n (getpagesize () - j - 1, j, i, i + 1, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, j, i, i + 1, 0, 127, 1);
+          do_test_n (getpagesize () - j - 1, j, i, i + 1, 0, 127, -1);
+
+          do_test_n (getpagesize () - j - 1, j, i, i, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, j, i, i - 1, 0, 127, 0);
+
+          do_test_n (getpagesize () - j - 1, j, i, ULONG_MAX, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, j, i, ULONG_MAX, 0, 127, 1);
+          do_test_n (getpagesize () - j - 1, j, i, ULONG_MAX, 0, 127, -1);
+
+          do_test_n (getpagesize () - j - 1, j, i, ULONG_MAX - i, 0, 127, 0);
+          do_test_n (getpagesize () - j - 1, j, i, ULONG_MAX - i, 0, 127, 1);
+          do_test_n (getpagesize () - j - 1, j, i, ULONG_MAX - i, 0, 127, -1);
+
+          do_test_n (0, getpagesize () - j - 1, i, i + 1, 0, 127, 0);
+          do_test_n (0, getpagesize () - j - 1, i, i + 1, 0, 127, 1);
+          do_test_n (0, getpagesize () - j - 1, i, i + 1, 0, 127, -1);
+
+          do_test_n (0, getpagesize () - j - 1, i, i, 0, 127, 0);
+          do_test_n (0, getpagesize () - j - 1, i, i - 1, 0, 127, 0);
+
+          do_test_n (0, getpagesize () - j - 1, i, ULONG_MAX, 0, 127, 0);
+          do_test_n (0, getpagesize () - j - 1, i, ULONG_MAX, 0, 127, 1);
+          do_test_n (0, getpagesize () - j - 1, i, ULONG_MAX, 0, 127, -1);
+
+          do_test_n (0, getpagesize () - j - 1, i, ULONG_MAX - i, 0, 127, 0);
+          do_test_n (0, getpagesize () - j - 1, i, ULONG_MAX - i, 0, 127, 1);
+          do_test_n (0, getpagesize () - j - 1, i, ULONG_MAX - i, 0, 127, -1);
+
+          do_test_n (j, getpagesize () - j - 1, i, i + 1, 0, 127, 0);
+          do_test_n (j, getpagesize () - j - 1, i, i + 1, 0, 127, 1);
+          do_test_n (j, getpagesize () - j - 1, i, i + 1, 0, 127, -1);
+
+          do_test_n (j, getpagesize () - j - 1, i, i, 0, 127, 0);
+          do_test_n (j, getpagesize () - j - 1, i, i - 1, 0, 127, 0);
+
+          do_test_n (j, getpagesize () - j - 1, i, ULONG_MAX, 0, 127, 0);
+          do_test_n (j, getpagesize () - j - 1, i, ULONG_MAX, 0, 127, 1);
+          do_test_n (j, getpagesize () - j - 1, i, ULONG_MAX, 0, 127, -1);
+
+          do_test_n (j, getpagesize () - j - 1, i, ULONG_MAX - i, 0, 127, 0);
+          do_test_n (j, getpagesize () - j - 1, i, ULONG_MAX - i, 0, 127, 1);
+          do_test_n (j, getpagesize () - j - 1, i, ULONG_MAX - i, 0, 127, -1);
+          if (i < 32)
+            {
+              i += 1;
+            }
+          else if (i < 161)
+            {
+              i += 7;
+            }
+          else if (i + 161 < TEST_LEN)
+            {
+              i += 31;
+              i *= 17;
+              i /= 16;
+              if (i + 161 > TEST_LEN)
+                {
+                  i = TEST_LEN - 160;
+                }
+            }
+          else if (i + 32 < TEST_LEN)
+            {
+              i += 7;
+            }
+          else
+            {
+              i += 1;
+            }
+        }
+    }
+
+  check_overflow ();
   do_random_tests ();
   return ret;
 }