Avoid strtoul for numbered references

src/prism.c

@@ -5852,54 +5852,41 @@ pm_numbered_parameters_node_create(pm_parser_t *parser, const pm_token_t *openin
     );
 }
 
-/**
- * The maximum numbered reference value is defined as the maximum value that an
- * integer can hold minus 1 bit for CRuby instruction sequence operand tagging.
- */
-#define NTH_REF_MAX ((uint32_t) (INT_MAX >> 1))
-
 /**
  * Parse the decimal number represented by the range of bytes. Returns
- * 0 if the number fails to parse or if the number is greater than the maximum
- * value representable by a numbered reference. This function assumes that the
- * range of bytes has already been validated to contain only decimal digits.
+ * 0 if the number is greater than the maximum value representable by a numbered
+ * reference. This function assumes that the range of bytes has already been
+ * validated to contain only decimal digits.
  */
 static uint32_t
 pm_numbered_reference_read_node_number(pm_parser_t *parser, const pm_token_t *token) {
-    const uint8_t *start = token->start + 1;
-    const uint8_t *end = token->end;
+/**
+ * The maximum numbered reference value is defined as the maximum value that an
+ * integer can hold minus 1 bit for CRuby instruction sequence operand tagging.
+ */
+#define NTH_REF_MAX ((uint64_t) (uint32_t) (INT_MAX >> 1))
 
-    ptrdiff_t diff = end - start;
+    const uint8_t *start = token->start + 1;
+    ptrdiff_t diff = token->end - start;
     assert(diff > 0);
-#if PTRDIFF_MAX > SIZE_MAX
-    assert(diff < (ptrdiff_t) SIZE_MAX);
-#endif
-    size_t length = (size_t) diff;
-
-    char *digits = xcalloc(length + 1, sizeof(char));
-    memcpy(digits, start, length);
-    digits[length] = '\0';
 
-    char *endptr;
-    errno = 0;
-    unsigned long value = strtoul(digits, &endptr, 10);
-
-    if ((digits == endptr) || (*endptr != '\0')) {
-        pm_parser_err(parser, U32(start - parser->start), U32(length), PM_ERR_INVALID_NUMBER_DECIMAL);
-        value = 0;
-    }
+    size_t length = (size_t) diff;
+    uint64_t value = 0;
 
-    xfree_sized(digits, sizeof(char) * (length + 1));
+    for (size_t idx = 0; idx < length; ++idx) {
+        value = value * 10 + (uint64_t) (start[idx] - '0');
 
-    if ((errno == ERANGE) || (value > NTH_REF_MAX)) {
-        PM_PARSER_WARN_FORMAT(parser, U32(start - parser->start), U32(length), PM_WARN_INVALID_NUMBERED_REFERENCE, (int) (length + 1), (const char *) token->start);
-        value = 0;
+        if (value > NTH_REF_MAX) {
+            PM_PARSER_WARN_FORMAT(parser, U32(start - parser->start), U32(length), PM_WARN_INVALID_NUMBERED_REFERENCE, (int) (length + 1), (const char *) token->start);
+            value = 0;
+            break;
+        }
     }
 
     return (uint32_t) value;
-}
 
 #undef NTH_REF_MAX
+}
 
 /**
  * Allocate and initialize a new NthReferenceReadNode node.