gcry_mpi_sub_ui: fix subtracting from negative value

* mpi/mpi-add.c (_gcry_mpi_sub_ui): Set output sign bit when 'u'
is negative.
* tests/mpitests.c (test_add): Additional tests for mpi_add_ui; Check
test output and fail if output does not match expected.
(test_sub): Additional tests for mpi_sub_ui; Check test output and fail
if output does not match expected.
(test_mul): Additional tests for mpi_mul_ui; Check test output and fail
if output does not match expected.
--

Reported-by: Guido Vranken <guidovranken@gmail.com>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>

1 files changed, 112 insertions, 7 deletions

diff --git a/tests/mpitests.c b/tests/mpitests.c
index 96e01551..48ea18b2 100644
--- a/tests/mpitests.c
+++ b/tests/mpitests.c
@@ -378,7 +378,8 @@ test_add (void)
   gcry_mpi_t two;
   gcry_mpi_t ff;
   gcry_mpi_t result;
-  unsigned char* pc;
+  gcry_mpi_t minusfive;
+  char *pc;
 
   gcry_mpi_scan(&one, GCRYMPI_FMT_USG, ones, sizeof(ones), NULL);
   gcry_mpi_scan(&two, GCRYMPI_FMT_USG, twos, sizeof(twos), NULL);
@@ -386,21 +387,47 @@ test_add (void)
   result = gcry_mpi_new(0);
 
   gcry_mpi_add(result, one, two);
-  gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
   if (debug)
     gcry_log_debug ("Result of one plus two:\n%s\n", pc);
+  if (strcmp (pc, "030303030303030303030303030303030303030303030303"
+                  "030303030303030303030303030303030303030303030303") != 0)
+    fail ("mpi_add failed at line %d", __LINE__);
   gcry_free(pc);
 
   gcry_mpi_add(result, ff, one);
-  gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
   if (debug)
     gcry_log_debug ("Result of ff plus one:\n%s\n", pc);
+  if (strcmp (pc, "010101010101010101010101010101010101010101010101"
+                  "01010101010101010101010101010101010101010101010100") != 0)
+    fail ("mpi_add failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_scan(&minusfive, GCRYMPI_FMT_HEX, "-5", 0, NULL);
+  gcry_mpi_add_ui (result, minusfive, 2);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of minus five plus two:\n%s\n", pc);
+  if (strcmp (pc, "-03") != 0)
+    fail ("mpi_add_ui failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_add_ui (result, result, 3);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of minus three plus three:\n%s\n", pc);
+  if (strcmp (pc, "00") != 0)
+    fail ("mpi_add_ui failed at line %d", __LINE__);
   gcry_free(pc);
 
   gcry_mpi_release(one);
   gcry_mpi_release(two);
   gcry_mpi_release(ff);
   gcry_mpi_release(result);
+  gcry_mpi_release(minusfive);
   return 1;
 }
 
@@ -408,24 +435,76 @@ test_add (void)
 static int
 test_sub (void)
 {
+  gcry_mpi_t zero;
   gcry_mpi_t one;
   gcry_mpi_t two;
+  gcry_mpi_t five;
   gcry_mpi_t result;
-  unsigned char* pc;
+  gcry_mpi_t minusfive;
+  char *pc;
 
   gcry_mpi_scan(&one, GCRYMPI_FMT_USG, ones, sizeof(ones), NULL);
   gcry_mpi_scan(&two, GCRYMPI_FMT_USG, twos, sizeof(twos), NULL);
   result = gcry_mpi_new(0);
   gcry_mpi_sub(result, two, one);
 
-  gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
   if (debug)
     gcry_log_debug ("Result of two minus one:\n%s\n", pc);
+  if (strcmp (pc, "010101010101010101010101010101010101010101010101"
+                  "010101010101010101010101010101010101010101010101") != 0)
+    fail ("mpi_sub failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  zero = gcry_mpi_new(0);
+  five = gcry_mpi_new(0);
+  minusfive = gcry_mpi_new(0);
+  gcry_mpi_set_ui (zero, 0);
+  gcry_mpi_set_ui (one, 1);
+  gcry_mpi_set_ui (two, 2);
+  gcry_mpi_set_ui (five, 5);
+  gcry_mpi_sub (minusfive, zero, five);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, minusfive);
+  if (debug)
+    gcry_log_debug ("Result of zero minus five:\n%s\n", pc);
+  if (strcmp (pc, "-05") != 0)
+    fail ("mpi_sub failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_sub_ui (result, five, 2);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of five minus two:\n%s\n", pc);
+  if (strcmp (pc, "03") != 0)
+    fail ("mpi_sub_ui failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_sub_ui (result, one, 10);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of one minus ten:\n%s\n", pc);
+  if (strcmp (pc, "-09") != 0)
+    fail ("mpi_sub_ui failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_sub_ui (result, minusfive, 2);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of minus five minus two:\n%s\n", pc);
+  if (strcmp (pc, "-07") != 0)
+    fail ("mpi_sub_ui failed at line %d", __LINE__);
   gcry_free(pc);
 
   gcry_mpi_release(one);
   gcry_mpi_release(two);
   gcry_mpi_release(result);
+  gcry_mpi_release(zero);
+  gcry_mpi_release(five);
+  gcry_mpi_release(minusfive);
   return 1;
 }
 
@@ -436,21 +515,47 @@ test_mul (void)
   gcry_mpi_t two;
   gcry_mpi_t three;
   gcry_mpi_t result;
-  unsigned char* pc;
+  gcry_mpi_t minusfive;
+  char *pc;
 
   gcry_mpi_scan(&two, GCRYMPI_FMT_USG, twos, sizeof(twos), NULL);
   gcry_mpi_scan(&three, GCRYMPI_FMT_USG, threes, sizeof(threes), NULL);
   result = gcry_mpi_new(0);
   gcry_mpi_mul(result, two, three);
 
-  gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
   if (debug)
     gcry_log_debug ("Result of two mul three:\n%s\n", pc);
+  if (strcmp (pc, "060C12181E242A30363C42484E545A60666C72787E848A90"
+                  "969CA2A8AEB4BAC0C6CCD2D8DEE4EAF0F6FD03090F151B21"
+                  "1B150F0902FCF6F0EAE4DED8D2CCC6C0BAB4AEA8A29C9690"
+                  "8A847E78726C66605A544E48423C36302A241E18120C06") != 0)
+    fail ("mpi_mul failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_scan(&minusfive, GCRYMPI_FMT_HEX, "-5", 0, NULL);
+  gcry_mpi_mul_ui (result, minusfive, 3);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of minus five mul three:\n%s\n", pc);
+  if (strcmp (pc, "-0F") != 0)
+    fail ("mpi_mul_ui failed at line %d", __LINE__);
+  gcry_free(pc);
+
+  gcry_mpi_mul_ui (result, result, 0);
+
+  gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+  if (debug)
+    gcry_log_debug ("Result of minus fifteen mul zero:\n%s\n", pc);
+  if (strcmp (pc, "00") != 0)
+    fail ("mpi_mul_ui failed at line %d", __LINE__);
   gcry_free(pc);
 
   gcry_mpi_release(two);
   gcry_mpi_release(three);
   gcry_mpi_release(result);
+  gcry_mpi_release(minusfive);
   return 1;
 }