[njs] Fixed ToInt32() with values >= 2**(53+30).

[Dmitry Volyntsev]

details:   https://hg.nginx.org/njs/rev/801e2dbc79c9
branches:  
changeset: 1643:801e2dbc79c9
user:      Dmitry Volyntsev <xeioex at nginx.com>
date:      Mon May 24 14:18:15 2021 +0000
description:
Fixed ToInt32() with values >= 2**(53+30).

diffstat:

 src/njs_number.h         |   6 ++--
 src/test/njs_unit_test.c |  65 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+), 3 deletions(-)

diffs (109 lines):

diff -r a33a16ec5aa0 -r 801e2dbc79c9 src/njs_number.h
--- a/src/njs_number.h	Mon May 24 14:17:59 2021 +0000
+++ b/src/njs_number.h	Mon May 24 14:18:15 2021 +0000
@@ -85,12 +85,12 @@ njs_number_to_int32(double num)
 
     exp = (conv.u64 & NJS_DBL_EXPONENT_MASK) >> NJS_DBL_SIGNIFICAND_SIZE;
 
-    if (njs_fast_path(exp < (NJS_DBL_EXPONENT_OFFSET + 30))) {
+    if (njs_fast_path(exp < (NJS_DBL_EXPONENT_OFFSET + 31))) {
         /* |num| < 2**31. */
         return num;
     }
 
-    if (exp < (NJS_DBL_EXPONENT_OFFSET + 30 + 53)) {
+    if (exp < (NJS_DBL_EXPONENT_OFFSET + 31 + 53)) {
         v = (conv.u64 & NJS_DBL_SIGNIFICAND_MASK) | NJS_DBL_HIDDEN_BIT;
         v <<= (exp - NJS_DBL_EXPONENT_BIAS + 32);
         r = v >> 32;
@@ -105,7 +105,7 @@ njs_number_to_int32(double num)
     /*
      * ES5.1: integer must be modulo 2^32.
      * The distance between larger doubles
-     * (exp >= NJS_DBL_EXPONENT_OFFSET + 30 + 53) is a multiple of 2**32 => 0.
+     * (exp >= NJS_DBL_EXPONENT_OFFSET + 31 + 53) is a multiple of 2**32 => 0.
      * This also handles NaN and Inf.
      */
 
diff -r a33a16ec5aa0 -r 801e2dbc79c9 src/test/njs_unit_test.c
--- a/src/test/njs_unit_test.c	Mon May 24 14:17:59 2021 +0000
+++ b/src/test/njs_unit_test.c	Mon May 24 14:18:15 2021 +0000
@@ -22304,6 +22304,69 @@ njs_string_to_index_test(njs_vm_t *vm, n
 
 
 static njs_int_t
+njs_to_int32_test(njs_vm_t *vm, njs_opts_t *opts, njs_stat_t *stat)
+{
+    int32_t     i32, second;
+    njs_uint_t  i;
+
+    static const struct {
+        double       value;
+        int32_t      expected;
+    } tests[] = {
+        { -1.0, -1 },
+        { 0.0, 0 },
+        { 0.001, 0 },
+        { 1.0, 1 },
+        { 2147483647.0, 2147483647 },
+        { 2147483648.0, -2147483648 },
+        { 2147483649.0, -2147483647 },
+        { -1844674406941458432.0, -2147483648 },
+        { 4.835703278458518e+24 /* 2**(53+29) + 2**30 */, 1073741824 },
+        { 9.671406556917036e+24 /* 2**(53+30) + 2**31 */, -2147483648 },
+    };
+
+    for (i = 0; i < njs_nitems(tests); i++) {
+        i32 = njs_number_to_int32(tests[i].value);
+
+        if (i32 != tests[i].expected) {
+            njs_printf("njs_to_int32_test(%f):\n"
+                       "expected: %D\n     got: %D\n",
+                       tests[i].value, tests[i].expected, i32);
+
+            stat->failed++;
+            continue;
+        }
+
+        second = njs_number_to_int32(i32);
+
+        if (i32 != second) {
+            njs_printf("njs_to_int32_test(%f): not idempodent\n"
+                       "expected: %D\n     got: %D\n",
+                       tests[i].value, i32, second);
+
+            stat->failed++;
+            continue;
+        }
+
+        second = njs_number_to_int32(njs_number_to_uint32(tests[i].value));
+
+        if (i32 != second) {
+            njs_printf("ToInt32(%f) != ToInt32(ToUint32(%f))\n"
+                       "left: %D\n     right: %D\n",
+                       tests[i].value, tests[i].value, i32, second);
+
+            stat->failed++;
+            continue;
+        }
+
+        stat->passed++;
+    }
+
+    return NJS_OK;
+}
+
+
+static njs_int_t
 njs_vm_internal_api_test(njs_unit_test_t unused[], size_t num, njs_str_t *name,
     njs_opts_t *opts, njs_stat_t *stat)
 {
@@ -22329,6 +22392,8 @@ njs_vm_internal_api_test(njs_unit_test_t
           njs_str("njs_sort_test") },
         { njs_string_to_index_test,
           njs_str("njs_string_to_index_test") },
+        { njs_to_int32_test,
+          njs_str("njs_to_int32_test") },
     };
 
     vm = NULL;