nobu	2016-09-13 21:11:57 +0900 (Tue, 13 Sep 2016)

  New Revision: 56151

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=56151

  Log:
    string.c: STR_EMBEDABLE_P
    
    * string.c (STR_EMBEDABLE_P): extract the predicate macro to tell
      if the given length is capable in an embedded string, and fix
      possible integer overflow.

  Modified files:
    trunk/ChangeLog
    trunk/string.c
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 56150)
+++ ChangeLog	(revision 56151)
@@ -1,3 +1,9 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Tue Sep 13 21:11:56 2016  Nobuyoshi Nakada  <nobu@r...>
+
+	* string.c (STR_EMBEDABLE_P): extract the predicate macro to tell
+	  if the given length is capable in an embedded string, and fix
+	  possible integer overflow.
+
 Tue Sep 13 18:37:08 2016  Koichi Sasada  <ko1@a...>
 
 	* test/ruby/test_exception.rb: fix thread issues.
Index: string.c
===================================================================
--- string.c	(revision 56150)
+++ string.c	(revision 56151)
@@ -165,6 +165,9 @@ VALUE rb_cSymbol; https://github.com/ruby/ruby/blob/trunk/string.c#L165
 #define SHARABLE_SUBSTRING_P(beg, len, end) 1
 #endif
 
+#define STR_EMBEDABLE_P(len, termlen) \
+    ((len) <= RSTRING_EMBED_LEN_MAX + 1 - (termlen))
+
 static VALUE str_replace_shared_without_enc(VALUE str2, VALUE str);
 static VALUE str_new_shared(VALUE klass, VALUE str);
 static VALUE str_new_frozen(VALUE klass, VALUE orig);
@@ -1068,7 +1071,7 @@ str_replace_shared_without_enc(VALUE str https://github.com/ruby/ruby/blob/trunk/string.c#L1071
     long len;
 
     RSTRING_GETMEM(str, ptr, len);
-    if (len+termlen <= RSTRING_EMBED_LEN_MAX+1) {
+    if (STR_EMBEDABLE_P(len, termlen)) {
 	char *ptr2 = RSTRING(str2)->as.ary;
 	STR_SET_EMBED(str2);
 	memcpy(ptr2, RSTRING_PTR(str), len);
@@ -2524,14 +2527,14 @@ rb_str_resize(VALUE str, long len) https://github.com/ruby/ruby/blob/trunk/string.c#L2527
 	const int termlen = TERM_LEN(str);
 	if (STR_EMBED_P(str)) {
 	    if (len == slen) return str;
-	    if (len + termlen <= RSTRING_EMBED_LEN_MAX + 1) {
+	    if (STR_EMBEDABLE_P(len, termlen)) {
 		STR_SET_EMBED_LEN(str, len);
 		TERM_FILL(RSTRING(str)->as.ary + len, termlen);
 		return str;
 	    }
 	    str_make_independent_expand(str, slen, len - slen, termlen);
 	}
-	else if (len + termlen <= RSTRING_EMBED_LEN_MAX + 1) {
+	else if (STR_EMBEDABLE_P(len, termlen)) {
 	    char *ptr = STR_HEAP_PTR(str);
 	    STR_SET_EMBED(str);
 	    if (slen > len) slen = len;

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