Replace lstat to GetFileAttributes

bench_result.txt

ruby 2.0.0dev (2011-12-09 trunk 33995) [i386-mingw32]
Windows 7 on VirtualBox
2.4GHz Core 2 Duo

Rails 3.1.3
command: ruby script/rails r "p 1"

Average and standard deviation of 10 times trials

+----------+--------+----------+---------+
|                realpath                |
+----------+--------+----------+---------+
| ruby     | time   | average  | stddev  |
+----------+--------+----------+---------+
| trunk    | real   | 11.03240 | 0.09976 |
| trunk    | system |  5.64950 | 0.29720 |
| trunk    | user   |  2.56050 | 0.25395 |
| patched  | real   | 10.52460 | 0.09762 |
| patched  | system |  5.02600 | 0.13435 |
| patched  | user   |  2.61360 | 0.10037 |
+----------+--------+----------+---------+

realpath_rec.patch

diff --git a/file.c b/file.c
index fb62c51..c260a63 100644
--- a/file.c
+++ b/file.c
@@ -3306,6 +3306,45 @@ realpath_rec(long *prefixlenp, VALUE *resolvedp, char *unresolved, VALUE loopche
                 struct stat sbuf;
                 int ret;
                 VALUE testpath2 = rb_str_encode_ospath(testpath);
+#ifdef _WIN32
+		static int use_attribute = -1;
+		if (use_attribute == -1) {
+		    if (getenv("RUBY_REALPATH_REPLACE") == NULL) {
+			use_attribute = 0;
+		    }
+		    else {
+			use_attribute = 1;
+		    }
+		}
+		if (use_attribute) {
+		    ret = rb_w32_GetFileAttributes(RSTRING_PTR(testpath2));
+		    if (ret == -1) {
+			if (GetLastError() == ERROR_FILE_NOT_FOUND) {
+			    if (strict || !last || *unresolved_firstsep)
+				rb_sys_fail(RSTRING_PTR(testpath));
+			    *resolvedp = testpath;
+			    break;
+			}
+			else {
+			    rb_sys_fail(RSTRING_PTR(testpath));
+			}
+		    }
+		}
+		else {
+		    ret = lstat(RSTRING_PTR(testpath2), &sbuf);
+		    if (ret == -1) {
+			if (errno == ENOENT) {
+			    if (strict || !last || *unresolved_firstsep)
+				rb_sys_fail(RSTRING_PTR(testpath));
+			    *resolvedp = testpath;
+			    break;
+			}
+			else {
+			    rb_sys_fail(RSTRING_PTR(testpath));
+			}
+		    }
+		}
+#else
                 ret = lstat(RSTRING_PTR(testpath2), &sbuf);
                 if (ret == -1) {
                     if (errno == ENOENT) {
@@ -3318,6 +3357,7 @@ realpath_rec(long *prefixlenp, VALUE *resolvedp, char *unresolved, VALUE loopche
                         rb_sys_fail(RSTRING_PTR(testpath));
                     }
                 }
+#endif
 #ifdef HAVE_READLINK
                 if (S_ISLNK(sbuf.st_mode)) {
                     volatile VALUE link;
diff --git a/include/ruby/win32.h b/include/ruby/win32.h
index 83da87a..c9ac6e5 100644
--- a/include/ruby/win32.h
+++ b/include/ruby/win32.h
@@ -304,6 +304,7 @@ extern int rb_w32_stati64(const char *, struct stati64 *);
 extern int rb_w32_ustati64(const char *, struct stati64 *);
 extern int rb_w32_access(const char *, int);
 extern int rb_w32_uaccess(const char *, int);
+extern int rb_w32_GetFileAttributes(const char *);
 
 #ifdef __BORLANDC__
 extern int rb_w32_fstati64(int, struct stati64 *);
diff --git a/win32/win32.c b/win32/win32.c
index 67a392e..7726607 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -4612,6 +4612,20 @@ rb_w32_ustati64(const char *path, struct stati64 *st)
     return ret;
 }
 
+int
+rb_w32_GetFileAttributes(const char *path)
+{
+    WCHAR *wpath;
+    int ret;
+
+    if (!(wpath = utf8_to_wstr(path, NULL)))
+	return -1;
+    ret = GetFileAttributesW(wpath);
+    free(wpath);
+    return ret;
+}
+
+
 /* License: Ruby's */
 int
 rb_w32_stati64(const char *path, struct stati64 *st)