Add quarantine unit tests.

Verify that freed regions are quarantined, and that redzone corruption
is detected.

Introduce a testing idiom for intercepting/replacing internal functions.
In this case the replaced function is ordinarily a static function, but
the idiom should work similarly for library-private functions.

test/unit/quarantine.c

@@ -0,0 +1,108 @@
+#include "test/jemalloc_test.h"
+
+#define	QUARANTINE_SIZE		8192
+#define	STRINGIFY_HELPER(x)	#x
+#define	STRINGIFY(x)		STRINGIFY_HELPER(x)
+
+#ifdef JEMALLOC_FILL
+const char *malloc_conf = "abort:false,junk:true,redzone:true,quarantine:"
+    STRINGIFY(QUARANTINE_SIZE);
+#endif
+
+void
+quarantine_clear(void)
+{
+	void *p;
+
+	p = mallocx(QUARANTINE_SIZE*2, 0);
+	assert_ptr_not_null(p, "Unexpected mallocx() failure");
+	dallocx(p, 0);
+}
+
+TEST_BEGIN(test_quarantine)
+{
+#define	SZ		256
+#define	NQUARANTINED	(QUARANTINE_SIZE/SZ)
+	void *quarantined[NQUARANTINED+1];
+	size_t i, j;
+
+	test_skip_if(!config_fill);
+
+	assert_zu_eq(nallocx(SZ, 0), SZ,
+	    "SZ=%zu does not precisely equal a size class", SZ);
+
+	quarantine_clear();
+
+	/*
+	 * Allocate enough regions to completely fill the quarantine, plus one
+	 * more.  The last iteration occurs with a completely full quarantine,
+	 * but no regions should be drained from the quarantine until the last
+	 * deallocation occurs.  Therefore no region recycling should occur
+	 * until after this loop completes.
+	 */
+	for (i = 0; i < NQUARANTINED+1; i++) {
+		void *p = mallocx(SZ, 0);
+		assert_ptr_not_null(p, "Unexpected mallocx() failure");
+		quarantined[i] = p;
+		dallocx(p, 0);
+		for (j = 0; j < i; j++) {
+			assert_ptr_ne(p, quarantined[j],
+			    "Quarantined region recycled too early; "
+			    "i=%zu, j=%zu", i, j);
+		}
+	}
+#undef NQUARANTINED
+#undef SZ
+}
+TEST_END
+
+static bool detected_redzone_corruption;
+
+static void
+arena_redzone_corruption_replacement(void *ptr, size_t usize, bool after,
+    size_t offset, uint8_t byte)
+{
+
+	detected_redzone_corruption = true;
+}
+
+TEST_BEGIN(test_quarantine_redzone)
+{
+	char *s;
+	arena_redzone_corruption_t *arena_redzone_corruption_orig;
+
+	test_skip_if(!config_fill);
+
+	arena_redzone_corruption_orig = arena_redzone_corruption_fptr;
+	arena_redzone_corruption_fptr = arena_redzone_corruption_replacement;
+
+	/* Test underflow. */
+	detected_redzone_corruption = false;
+	s = (char *)mallocx(1, 0);
+	assert_ptr_not_null((void *)s, "Unexpected mallocx() failure");
+	s[-1] = 0xbb;
+	dallocx(s, 0);
+	assert_true(detected_redzone_corruption,
+	    "Did not detect redzone corruption");
+
+	/* Test overflow. */
+	detected_redzone_corruption = false;
+	s = (char *)mallocx(1, 0);
+	assert_ptr_not_null((void *)s, "Unexpected mallocx() failure");
+	s[sallocx(s, 0)] = 0xbb;
+	dallocx(s, 0);
+	assert_true(detected_redzone_corruption,
+	    "Did not detect redzone corruption");
+
+	arena_redzone_corruption_fptr = arena_redzone_corruption_orig;
+}
+TEST_END
+
+int
+main(void)
+{
+
+	return (test(
+	    test_quarantine,
+	    test_quarantine_redzone));
+}