return bytes;
}
+
+/*
+ * A function, which can be used as a core part of the test programs,
+ * intended to detect various problems with the help of fuzzing input
+ * to pixman API (according to some templates, aka "smart" fuzzing).
+ * Some general information about such testing can be found here:
+ * http://en.wikipedia.org/wiki/Fuzz_testing
+ *
+ * It may help detecting:
+ * - crashes on bad handling of valid or reasonably invalid input to
+ * pixman API.
+ * - deviations from the behavior of older pixman releases.
+ * - deviations from the behavior of the same pixman release, but
+ * configured in a different way (for example with SIMD optimizations
+ * disabled), or running on a different OS or hardware.
+ *
+ * The test is performed by calling a callback function a huge number
+ * of times. The callback function is expected to run some snippet of
+ * pixman code with pseudorandom variations to the data feeded to
+ * pixman API. A result of running each callback function should be
+ * some deterministic value which depends on test number (test number
+ * can be used as a seed for PRNG). When 'verbose' argument is nonzero,
+ * callback function is expected to print to stdout some information
+ * about what it does.
+ *
+ * Return values from many small tests are accumulated together and
+ * used as final checksum, which can be compared to some expected
+ * value. Running the tests not individually, but in a batch helps
+ * to reduce process start overhead and also allows to parallelize
+ * testing and utilize multiple CPU cores.
+ *
+ * The resulting executable can be run without any arguments. In
+ * this case it runs a batch of tests starting from 1 and up to
+ * 'default_number_of_iterations'. The resulting checksum is
+ * compared with 'expected_checksum' and FAIL or PASS verdict
+ * depends on the result of this comparison.
+ *
+ * If the executable is run with 2 numbers provided as command line
+ * arguments, they specify the starting and ending numbers for a test
+ * batch.
+ *
+ * If the executable is run with only one number provided as a command
+ * line argument, then this number is used to call the callback function
+ * once, and also with verbose flag set.
+ */
+int
+fuzzer_test_main (const char *test_name,
+ int default_number_of_iterations,
+ uint32_t expected_checksum,
+ uint32_t (*test_function)(int testnum, int verbose),
+ int argc,
+ const char *argv[])
+{
+ int i, n1 = 1, n2 = 0;
+ uint32_t checksum = 0;
+ int verbose = getenv ("VERBOSE") != NULL;
+
+ if (argc >= 3)
+ {
+ n1 = atoi (argv[1]);
+ n2 = atoi (argv[2]);
+ if (n2 < n1)
+ {
+ printf ("invalid test range\n");
+ return 1;
+ }
+ }
+ else if (argc >= 2)
+ {
+ n2 = atoi (argv[1]);
+ checksum = test_function (n2, 1);
+ printf ("%d: checksum=%08X\n", n2, checksum);
+ return 0;
+ }
+ else
+ {
+ n1 = 1;
+ n2 = default_number_of_iterations;
+ }
+
+ for (i = n1; i <= n2; i++)
+ {
+ uint32_t crc = test_function (i, 0);
+ if (verbose)
+ printf ("%d: %08X\n", i, crc);
+ checksum += crc;
+ }
+
+ if (n1 == 1 && n2 == default_number_of_iterations)
+ {
+ if (checksum == expected_checksum)
+ {
+ printf ("%s test passed (checksum=%08X)\n",
+ test_name, checksum);
+ }
+ else
+ {
+ printf ("%s test failed! (checksum=%08X, expected %08X)\n",
+ test_name, checksum, expected_checksum);
+ return 1;
+ }
+ }
+ else
+ {
+ printf ("%d-%d: checksum=%08X\n", n1, n2, checksum);
+ }
+
+ return 0;
+}