[njs] Issues found by Coverity Scan in Regex have been fixed.

[Igor Sysoev]

details:   http://hg.nginx.org/njs/rev/027e0e8e7f61
branches:  
changeset: 90:027e0e8e7f61
user:      Igor Sysoev <igor at sysoev.ru>
date:      Thu Mar 24 14:22:08 2016 +0300
description:
Issues found by Coverity Scan in Regex have been fixed.

diffstat:

 njs/njs_regexp.c |  22 +++++++++++++++++++---
 1 files changed, 19 insertions(+), 3 deletions(-)

diffs (60 lines):

diff -r 425cf63a7283 -r 027e0e8e7f61 njs/njs_regexp.c
--- a/njs/njs_regexp.c	Thu Mar 24 13:57:06 2016 +0300
+++ b/njs/njs_regexp.c	Thu Mar 24 14:22:08 2016 +0300
@@ -36,6 +36,8 @@ static int njs_regexp_pattern_compile(pc
     u_char *source, int options);
 static njs_ret_t njs_regexp_exec_result(njs_vm_t *vm, njs_regexp_t *regexp,
     u_char *string, int *captures, nxt_uint_t utf8);
+static njs_ret_t njs_regexp_string_create(njs_vm_t *vm, njs_value_t *value,
+    u_char *start, uint32_t size, int32_t length);
 
 
 njs_ret_t
@@ -436,7 +438,7 @@ njs_regexp_prototype_source(njs_vm_t *vm
     size = strlen((char *) source) - pattern->flags;
     length = nxt_utf8_length(source, size);
 
-    return njs_string_create(vm, &vm->retval, source, size, length);
+    return njs_regexp_string_create(vm, &vm->retval, source, size, length);
 }
 
 
@@ -454,7 +456,7 @@ njs_regexp_prototype_to_string(njs_vm_t 
     size = strlen((char *) source);
     length = nxt_utf8_length(source, size);
 
-    return njs_string_create(vm, &vm->retval, source, size, length);
+    return njs_regexp_string_create(vm, &vm->retval, source, size, length);
 }
 
 
@@ -621,7 +623,8 @@ njs_regexp_exec_result(njs_vm_t *vm, njs
                 break;
             }
 
-            ret = njs_string_create(vm, &array->start[i], start, size, length);
+            ret = njs_regexp_string_create(vm, &array->start[i],
+                                           start, size, length);
             if (nxt_slow_path(ret != NXT_OK)) {
                 return NXT_ERROR;
             }
@@ -684,6 +687,19 @@ njs_regexp_exec_result(njs_vm_t *vm, njs
 }
 
 
+static njs_ret_t
+njs_regexp_string_create(njs_vm_t *vm, njs_value_t *value, u_char *start,
+    uint32_t size, int32_t length)
+{
+    if (nxt_fast_path(length >= 0)) {
+        return njs_string_create(vm, value, start, size, length);
+    }
+
+    vm->exception = &njs_exception_internal_error;
+    return NXT_ERROR;
+}
+
+
 static const njs_object_prop_t  njs_regexp_constructor_properties[] =
 {
     /* RegExp.name == "RegExp". */