w32api:

        * include/winioctl.h (FSCTL_SET_SPARSE): Define.

cygwin:

        * wincap.h (wincaps::supports_sparse_files): New flag.
        (wincapc::supports_sparse_files): New method.
        * wincap.cc (wincap_unknown): Define value for the new flag.
        (wincap_95): Ditto.
        (wincap_95osr2): Ditto.
        (wincap_98): Ditto.
        (wincap_98se): Ditto.
        (wincap_me): Ditto.
        (wincap_nt3): Ditto.
        (wincap_nt4): Ditto.
        (wincap_nt4sp4): Ditto.
        (wincap_2000): Ditto.
        (wincap_xp): Ditto.
        * path.h (path_conv::fs_flags): New method.
        * fhandler_disk_file.cc: Include winioctl.h for DeviceIoControl.
        (fhandler_disk_file::open): Set newly created and truncated files as
        sparse on platforms that support it.

1 files changed, 14 insertions, 0 deletions

diff --git a/winsup/cygwin/fhandler_disk_file.cc b/winsup/cygwin/fhandler_disk_file.cc
index 8deb7fb16..27e621708 100644
--- a/winsup/cygwin/fhandler_disk_file.cc
+++ b/winsup/cygwin/fhandler_disk_file.cc
@@ -26,6 +26,7 @@ details. */
 #include "pinfo.h"
 #include <assert.h>
 #include <ctype.h>
+#include <winioctl.h>
 
 #define _COMPILING_NEWLIB
 #include <dirent.h>
@@ -386,6 +387,19 @@ fhandler_disk_file::open (path_conv *real_path, int flags, mode_t mode)
       return 0;
     }
 
+  /* Set newly created and truncated files as sparse files. */
+  if ((real_path->fs_flags () & FILE_SUPPORTS_SPARSE_FILES)
+      && (get_access () & GENERIC_WRITE) == GENERIC_WRITE
+      && (get_flags () & (O_CREAT | O_TRUNC)))
+    {
+      DWORD dw;
+      HANDLE h = get_handle ();
+      BOOL r = DeviceIoControl (h , FSCTL_SET_SPARSE, NULL, 0, 	NULL, 0, &dw,
+				NULL);
+      syscall_printf ("%d = DeviceIoControl(0x%x, FSCTL_SET_SPARSE, NULL, 0, "
+		      "NULL, 0, &dw, NULL)", r, h);
+    }
+
   set_symlink_p (real_path->issymlink ());
   set_execable_p (real_path->exec_state ());
   set_socket_p (real_path->issocket ());