From: Nicolás Bértolo <nicolasbertolo@gmail.com>
Date: Thu, 13 May 2021 11:30:29 +0000 (+0200)
Subject: Make searching for files faster under Windows
X-Git-Tag: emacs-28.0.90~2486
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=0e69c85d7d6d46ab9c0d10051066a365e76a901f;p=emacs.git

Make searching for files faster under Windows

* src/lread.c (openp): Use faccessat to check that a file exists
before opening it on Windows (bug#41646).  This speeds up
searching for files.
---

diff --git a/src/lread.c b/src/lread.c
index d2e6323cb14..bca53a9a37a 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -1945,7 +1945,17 @@ openp (Lisp_Object path, Lisp_Object str, Lisp_Object suffixes,
 	      }
 	    else
 	      {
-		fd = emacs_open (pfn, O_RDONLY, 0);
+                /*  In some systems (like Windows) finding out if a
+                    file exists is cheaper to do than actually opening
+                    it.  Only open the file when we are sure that it
+                    exists.  */
+#ifdef WINDOWSNT
+                if (faccessat (AT_FDCWD, pfn, R_OK, AT_EACCESS))
+                  fd = -1;
+                else
+#endif
+                  fd = emacs_open (pfn, O_RDONLY, 0);
+
 		if (fd < 0)
 		  {
 		    if (! (errno == ENOENT || errno == ENOTDIR))