From f5cc0f7d09a1e6a89c9a5754d42884065d53aca0 Mon Sep 17 00:00:00 2001
From: Robert Shearman <rob@codeweavers.com>
Date: Thu, 3 Aug 2006 20:25:28 +0100
Subject: [PATCH] ntdll: Add an optimisation for NtQueryDirectoryFile to not
 read the whole directory if the mask doesn't contain any wildcards and the
 file exists on in the directory with the same case as the mask.

---
 dlls/ntdll/directory.c | 81 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 78 insertions(+), 3 deletions(-)

diff --git a/dlls/ntdll/directory.c b/dlls/ntdll/directory.c
index faeca6c1ab1..47d018a4be4 100644
--- a/dlls/ntdll/directory.c
+++ b/dlls/ntdll/directory.c
@@ -1126,6 +1126,74 @@ static void read_directory_readdir( int fd, IO_STATUS_BLOCK *io, void *buffer, U
     else io->u.Status = restart_scan ? STATUS_NO_SUCH_FILE : STATUS_NO_MORE_FILES;
 }
 
+/***********************************************************************
+ *           read_directory_stat
+ *
+ * Read a single file from a directory by determining whether the file
+ * identified by mask exists using stat.
+ */
+static int read_directory_stat( int fd, IO_STATUS_BLOCK *io, void *buffer, ULONG length,
+                                BOOLEAN single_entry, const UNICODE_STRING *mask,
+                                BOOLEAN restart_scan )
+{
+    int unix_len, ret, used_default;
+    char *unix_name;
+    struct stat st;
+
+    TRACE("trying optimisation for file %s\n", debugstr_us( mask ));
+
+    unix_len = ntdll_wcstoumbs( 0, mask->Buffer, mask->Length / sizeof(WCHAR), NULL, 0, NULL, NULL );
+    if (!(unix_name = RtlAllocateHeap( GetProcessHeap(), 0, unix_len )))
+    {
+        io->u.Status = STATUS_NO_MEMORY;
+        return 0;
+    }
+    ret = ntdll_wcstoumbs( 0, mask->Buffer, mask->Length / sizeof(WCHAR), unix_name, unix_len,
+                           NULL, &used_default );
+    if (ret > 0 && !used_default)
+    {
+        if (restart_scan)
+        {
+            lseek( fd, 0, SEEK_SET );
+        }
+        else if (lseek( fd, 0, SEEK_CUR ) != 0)
+        {
+            io->u.Status = STATUS_NO_MORE_FILES;
+            ret = 0;
+            goto done;
+        }
+
+        ret = stat( unix_name, &st );
+        if (!ret)
+        {
+            FILE_BOTH_DIR_INFORMATION *info = append_entry( buffer, &io->Information, length, unix_name, NULL, mask );
+            if (info)
+            {
+                info->NextEntryOffset = 0;
+                if ((char *)info->FileName + info->FileNameLength > (char *)buffer + length)
+                    io->u.Status = STATUS_BUFFER_OVERFLOW;
+                else
+                    lseek( fd, 1, SEEK_CUR );
+            }
+        }
+    }
+    else ret = -1;
+
+done:
+    RtlFreeHeap( GetProcessHeap(), 0, unix_name );
+
+    TRACE("returning %d\n", ret);
+
+    return ret;
+}
+
+
+static inline WCHAR *mempbrkW( const WCHAR *ptr, const WCHAR *accept, size_t n )
+{
+    const WCHAR *end;
+    for (end = ptr + n; ptr < end; ptr++) if (strchrW( accept, *ptr )) return (WCHAR *)ptr;
+    return NULL;
+}
 
 /******************************************************************************
  *  NtQueryDirectoryFile	[NTDLL.@]
@@ -1141,6 +1209,7 @@ NTSTATUS WINAPI NtQueryDirectoryFile( HANDLE handle, HANDLE event,
                                       BOOLEAN restart_scan )
 {
     int cwd, fd;
+    static const WCHAR wszWildcards[] = { '*','?',0 };
 
     TRACE("(%p %p %p %p %p %p 0x%08lx 0x%08x 0x%08x %s 0x%08x\n",
           handle, event, apc_routine, apc_context, io, buffer,
@@ -1171,14 +1240,20 @@ NTSTATUS WINAPI NtQueryDirectoryFile( HANDLE handle, HANDLE event,
 
     if ((cwd = open(".", O_RDONLY)) != -1 && fchdir( fd ) != -1)
     {
+        if (mask && !mempbrkW( mask->Buffer, wszWildcards, mask->Length / sizeof(WCHAR) ) &&
+            read_directory_stat( fd, io, buffer, length, single_entry, mask, restart_scan ) != -1)
+            goto done;
 #ifdef VFAT_IOCTL_READDIR_BOTH
-        if ((read_directory_vfat( fd, io, buffer, length, single_entry, mask, restart_scan )) == -1)
+        if ((read_directory_vfat( fd, io, buffer, length, single_entry, mask, restart_scan )) != -1)
+            goto done;
 #endif
 #ifdef USE_GETDENTS
-            if ((read_directory_getdents( fd, io, buffer, length, single_entry, mask, restart_scan )) == -1)
+        if ((read_directory_getdents( fd, io, buffer, length, single_entry, mask, restart_scan )) != -1)
+            goto done;
 #endif
-                read_directory_readdir( fd, io, buffer, length, single_entry, mask, restart_scan );
+        read_directory_readdir( fd, io, buffer, length, single_entry, mask, restart_scan );
 
+    done:
         if (fchdir( cwd ) == -1) chdir( "/" );
     }
     else io->u.Status = FILE_GetNtStatus();