From 1adebdc7676e44c91daeee24745a63c2019e2ec3 Mon Sep 17 00:00:00 2001
From: def <dennis@felsin9.de>
Date: Tue, 24 Feb 2015 16:37:54 +0100
Subject: [PATCH] Speed up walkDir significantly

We only know that this works on Linux and Mac OS X, so other systems use
the POSIX conforming version still. This removed the lstat call, which
is especially expensive on NFS filesystems for me.
---
 lib/posix/posix.nim | 13 +++++++++++++
 lib/pure/os.nim     | 10 +++++++---
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/lib/posix/posix.nim b/lib/posix/posix.nim
index 8454967562..895e4b1d58 100644
--- a/lib/posix/posix.nim
+++ b/lib/posix/posix.nim
@@ -70,6 +70,16 @@ const
   STDIN_FILENO* = 0  ## File number of stdin;
   STDOUT_FILENO* = 1 ## File number of stdout;
 
+  DT_UNKNOWN* = 0
+  DT_FIFO* = 1
+  DT_CHR* = 2
+  DT_DIR* = 4
+  DT_BLK* = 6
+  DT_REG* = 8
+  DT_LNK* = 10
+  DT_SOCK* = 12
+  DT_WHT* = 14
+
 type
   TDIR* {.importc: "DIR", header: "<dirent.h>",
           incompleteStruct.} = object
@@ -84,6 +94,9 @@ type
   Tdirent* {.importc: "struct dirent",
              header: "<dirent.h>", final, pure.} = object ## dirent_t struct
     d_ino*: Tino  ## File serial number.
+    d_off*: TOff
+    d_reclen*: cshort
+    d_type*: int8
     d_name*: array [0..255, char] ## Name of entry.
 
   Tflock* {.importc: "struct flock", final, pure,
diff --git a/lib/pure/os.nim b/lib/pure/os.nim
index ceeba182fe..23e01a7d4d 100644
--- a/lib/pure/os.nim
+++ b/lib/pure/os.nim
@@ -1299,10 +1299,14 @@ iterator walkDir*(dir: string): tuple[kind: PathComponent, path: string] {.
         if y != "." and y != "..":
           var s: TStat
           y = dir / y
-          if lstat(y, s) < 0'i32: break
           var k = pcFile
-          if S_ISDIR(s.st_mode): k = pcDir
-          if S_ISLNK(s.st_mode): k = succ(k)
+          when defined(linux) or defined(macosx):
+            if x.d_type == DT_DIR: k = pcDir
+            if x.d_type == DT_LNK: k = succ(k)
+          else:
+            if lstat(y, s) < 0'i32: break
+            if S_ISDIR(s.st_mode): k = pcDir
+            if S_ISLNK(s.st_mode): k = succ(k)
           yield (k, y)
       discard closedir(d)