Merge pull request #18 from github/2.1-expandpath

Backport file_expand memory usage fix

Author: tmm1

file.c

@@ -3397,6 +3397,16 @@ rb_file_expand_path_internal(VALUE fname, VALUE dname, int abs_mode, int long_na
 
 #define EXPAND_PATH_BUFFER() rb_usascii_str_new(0, MAXPATHLEN + 2)
 
+static VALUE
+str_shrink(VALUE str)
+{
+    rb_str_resize(str, RSTRING_LEN(str));
+    return str;
+}
+
+#define expand_path(fname, dname, abs_mode, long_name, result) \
+    str_shrink(rb_file_expand_path_internal(fname, dname, abs_mode, long_name, result))
+
 #define check_expand_path_args(fname, dname) \
     (((fname) = rb_get_path(fname)), \
      (void)(NIL_P(dname) ? (dname) : ((dname) = rb_get_path(dname))))
@@ -3411,13 +3421,13 @@ VALUE
 rb_file_expand_path(VALUE fname, VALUE dname)
 {
     check_expand_path_args(fname, dname);
-    return rb_file_expand_path_internal(fname, dname, 0, 1, EXPAND_PATH_BUFFER());
+    return expand_path(fname, dname, 0, 1, EXPAND_PATH_BUFFER());
 }
 
 VALUE
 rb_file_expand_path_fast(VALUE fname, VALUE dname)
 {
-    return rb_file_expand_path_internal(fname, dname, 0, 0, EXPAND_PATH_BUFFER());
+    return expand_path(fname, dname, 0, 0, EXPAND_PATH_BUFFER());
 }
 
 /*
@@ -3465,7 +3475,7 @@ VALUE
 rb_file_absolute_path(VALUE fname, VALUE dname)
 {
     check_expand_path_args(fname, dname);
-    return rb_file_expand_path_internal(fname, dname, 1, 1, EXPAND_PATH_BUFFER());
+    return expand_path(fname, dname, 1, 1, EXPAND_PATH_BUFFER());
 }
 
 /*
@@ -5408,6 +5418,7 @@ is_explicit_relative(const char *path)
 static VALUE
 copy_path_class(VALUE path, VALUE orig)
 {
+    str_shrink(path);
     RBASIC_SET_CLASS(path, rb_obj_class(orig));
     OBJ_FREEZE(path);
     return path;

string.c

@@ -2034,9 +2034,11 @@ rb_str_resize(VALUE str, long len)
     independent = str_independent(str);
     ENC_CODERANGE_CLEAR(str);
     slen = RSTRING_LEN(str);
-    if (len != slen) {
+
+    {
 	const int termlen = TERM_LEN(str);
 	if (STR_EMBED_P(str)) {
+	    if (len == slen) return str;
 	    if (len + termlen <= RSTRING_EMBED_LEN_MAX + 1) {
 		STR_SET_EMBED_LEN(str, len);
 		TERM_FILL(RSTRING(str)->as.ary + len, termlen);
@@ -2056,11 +2058,13 @@ rb_str_resize(VALUE str, long len)
 	    return str;
 	}
 	else if (!independent) {
+	    if (len == slen) return str;
 	    str_make_independent_expand(str, len - slen);
 	}
-	else if (slen < len || slen - len > 1024) {
+	else if (slen < len || (RSTRING(str)->as.heap.aux.capa - len) > (len < 1024 ? len : 1024)) {
 	    REALLOC_N(RSTRING(str)->as.heap.ptr, char, len + termlen);
 	}
+	else if (len == slen) return str;
 	if (!STR_NOCAPA_P(str)) {
 	    RSTRING(str)->as.heap.aux.capa = len;
 	}

test/ruby/test_file_exhaustive.rb

@@ -458,6 +458,15 @@ def test_expand_path
     end
   end
 
+  def test_expand_path_memsize
+    bug9934 = '[ruby-core:63114] [Bug #9934]'
+    require "objspace"
+    path = File.expand_path("/foo")
+    assert_operator(ObjectSpace.memsize_of(path), :<=, path.bytesize, bug9934)
+    path = File.expand_path("/a"*25)
+    assert_equal(51, ObjectSpace.memsize_of(path), bug9934)
+  end
+
   def test_expand_path_encoding
     drive = (DRIVE ? 'C:' : '')
     if Encoding.find("filesystem") == Encoding::CP1251