lib: Add unit test for random_fill()

diff --git a/src/lib/randgen.c b/src/lib/randgen.c
index f6b2da9c9902d0419783f76cb94584da3820541a..54d6800dac7f0ea96c0d6aca34fdd3fca28d92ee 100644 (file)
--- a/src/lib/randgen.c
+++ b/src/lib/randgen.c
@@ -61,14 +61,6 @@ static int init_refcount = 0;
 static int urandom_fd = -1;
 
 #if defined(USE_GETRANDOM) || defined(USE_RANDOM_DEV)
-/* Use a small buffer when reading randomness. This is mainly to make small
-   random reads more efficient, such as i_rand*(). When reading larger amount
-   of randomness this buffer is bypassed.
-
-   There doesn't seem to be a big difference in Linux system CPU usage when
-   buffer size is above 16 bytes. Double it just to be safe. Avoid it being
-   too large anyway so we don't unnecessarily waste CPU and memory. */
-#define RANDOM_READ_BUFFER_SIZE 32
 static unsigned char random_next[RANDOM_READ_BUFFER_SIZE];
 static size_t random_next_pos = 0;
 static size_t random_next_size = 0;

diff --git a/src/lib/randgen.h b/src/lib/randgen.h
index d532880fb3fe9ec663651912241e202fd0439d69..cab234d9844f3c67cbe248ca6d045c5a8ceb0260 100644 (file)
--- a/src/lib/randgen.h
+++ b/src/lib/randgen.h
@@ -14,4 +14,15 @@ void random_deinit(void);
 int rand_get_last_seed(unsigned int *seed_r);
 #endif
 
+/* Internal for unit test:
+
+   Use a small buffer when reading randomness. This is mainly to make small
+   random reads more efficient, such as i_rand*(). When reading larger amount
+   of randomness this buffer is bypassed.
+
+   There doesn't seem to be a big difference in Linux system CPU usage when
+   buffer size is above 16 bytes. Double it just to be safe. Avoid it being
+   too large anyway so we don't unnecessarily waste CPU and memory. */
+#define RANDOM_READ_BUFFER_SIZE 32
+
 #endif

diff --git a/src/lib/test-random.c b/src/lib/test-random.c
index 6c83ff6b88438455cf56c0e63cf633294e40db9a..cb30de4c04ef39eba68a2dd8cac1a549e3dd902e 100644 (file)
--- a/src/lib/test-random.c
+++ b/src/lib/test-random.c
@@ -1,6 +1,7 @@
 /* Copyright (c) 2018 Dovecot authors, see the included COPYING file */
 
 #include "test-lib.h"
+#include "hash.h"
 #include "stats-dist.h"
 #include "randgen.h"
 #include <math.h>
@@ -43,10 +44,36 @@ static void test_random_limits(void)
        test_end();
 }
 
+static void test_random_fill(void)
+{
+       test_begin("random_fill()");
+       unsigned int hash = 0;
+       for (unsigned int i = 0; i <= (2*RANDOM_READ_BUFFER_SIZE)+1; i++) {
+               /* Rely on valgrind to verify that there are no uninitialized
+                  bytes, so don't use i_malloc(). */
+               unsigned char *buf = malloc(i);
+               random_fill(buf, i);
+               hash ^= mem_hash(buf, i);
+               free(buf);
+       }
+       /* Try also with some random small numbers */
+       for (unsigned int i = 0; i < 100; i++) {
+               /* 32 = RANDOM_READ_BUFFER_SIZE */
+               unsigned int size = i_rand_minmax(1, RANDOM_READ_BUFFER_SIZE);
+               unsigned char *buf = malloc(size);
+               random_fill(buf, size);
+               hash ^= mem_hash(buf, size);
+               free(buf);
+       }
+       test_out_reason("hash", TRUE, dec2str(hash));
+       test_end();
+}
+
 void test_random(void)
 {
        test_random_median();
        test_random_limits();
+       test_random_fill();
 }
 
 enum fatal_test_state fatal_random(unsigned int stage)