1 files changed, 98 insertions, 0 deletions
diff --git a/tests/test-memrchr.c b/tests/test-memrchr.c
new file mode 100644
index 00000000..836ed6f2
--- /dev/null
+++ b/tests/test-memrchr.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2008-2024 Free Software Foundation, Inc.
+ * Written by Eric Blake and Bruno Haible
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <string.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (memrchr, void *, (void const *, int, size_t));
+
+#include <stdlib.h>
+
+#include "zerosize-ptr.h"
+#include "macros.h"
+
+/* Work around GCC bug 101494.  */
+#if _GL_GNUC_PREREQ (4, 7) && __GNUC__ < 12
+# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
+/* Calculating void * + int is not portable, so this wrapper converts
+   to char * to make the tests easier to write.  */
+#define MEMRCHR (char *) memrchr
+
+int
+main (void)
+{
+  size_t n = 0x100000;
+  char *input = malloc (n);
+  ASSERT (input);
+
+  input[n - 1] = 'a';
+  input[n - 2] = 'b';
+  memset (input + n - 1026, 'c', 1024);
+  memset (input + 2, 'd', n - 1028);
+  input[1] = 'e';
+  input[0] = 'a';
+
+  /* Basic behavior tests.  */
+  ASSERT (MEMRCHR (input, 'a', n) == input + n - 1);
+
+  ASSERT (MEMRCHR (input, 'a', 0) == NULL);
+  void *page_boundary = zerosize_ptr ();
+  if (page_boundary)
+    ASSERT (MEMRCHR (page_boundary, 'a', 0) == NULL);
+
+  ASSERT (MEMRCHR (input, 'b', n) == input + n - 2);
+  ASSERT (MEMRCHR (input, 'c', n) == input + n - 3);
+  ASSERT (MEMRCHR (input, 'd', n) == input + n - 1027);
+
+  ASSERT (MEMRCHR (input, 'a', n - 1) == input);
+  ASSERT (MEMRCHR (input, 'e', n - 1) == input + 1);
+
+  ASSERT (MEMRCHR (input, 'f', n) == NULL);
+  ASSERT (MEMRCHR (input, '\0', n) == NULL);
+
+  /* Check that a very long haystack is handled quickly if the byte is
+     found near the end.  */
+  {
+    size_t repeat = 10000;
+    for (; repeat > 0; repeat--)
+      {
+        ASSERT (MEMRCHR (input, 'c', n) == input + n - 3);
+      }
+  }
+
+  /* Alignment tests.  */
+  {
+    int i, j;
+    for (i = 0; i < 32; i++)
+      {
+        for (j = 0; j < 256; j++)
+          input[i + j] = j;
+        for (j = 0; j < 256; j++)
+          {
+            ASSERT (MEMRCHR (input + i, j, 256) == input + i + j);
+          }
+      }
+  }
+
+  free (input);
+
+  return test_exit_status;
+}