Create new files as sparse on NT systems. (2nd try)

[Vaclav Haisman]

This is a little bit improved version of my previous post.
By default creation of sparse files is disabled. It can be enabled by CYGWIN
option sparse_files.

Vaclav Haisman


2003-02-03  Vaclav Haisman  <[EMAIL PROTECTED]>
        * fhandler.h (allow_sparse): Declare new extern variable.
        * fhandler.cc (METHOD_BUFFERED): New macro.
        (FSCTL_SET_SPARSE): Ditto.
        (allow_sparse): Define the new variable.
        (fhandler_base::open): Try to set newly created or trucated files
        as sparse on NT systems.
        * environ.cc (parse_thing): Add new CYGWIN option.

Index: cygwin/environ.cc
===================================================================
RCS file: /cvs/src/src/winsup/cygwin/environ.cc,v
retrieving revision 1.90
diff -p -u -r1.90 environ.cc
--- cygwin/environ.cc   30 Sep 2002 03:05:13 -0000      1.90
+++ cygwin/environ.cc   3 Feb 2003 12:54:40 -0000
@@ -522,6 +522,7 @@ static struct parse_thing
   {"title", {&display_title}, justset, NULL, {{FALSE}, {TRUE}}},
   {"tty", {NULL}, set_process_state, NULL, {{0}, {PID_USETTY}}},
   {"winsymlinks", {&allow_winsymlinks}, justset, NULL, {{FALSE}, {TRUE}}},
+  {"sparse_files", {&allow_sparse}, justset, NULL, {{FALSE}, {TRUE}}},
   {NULL, {0}, justset, 0, {{0}, {0}}}
 };

Index: cygwin/fhandler.cc
===================================================================
RCS file: /cvs/src/src/winsup/cygwin/fhandler.cc,v
retrieving revision 1.143
diff -p -u -r1.143 fhandler.cc
--- cygwin/fhandler.cc  20 Dec 2002 01:48:22 -0000      1.143
+++ cygwin/fhandler.cc  3 Feb 2003 12:54:42 -0000
@@ -27,12 +27,18 @@ details. */
 #include "pinfo.h"
 #include <assert.h>
 #include <limits.h>
+#include <winioctl.h>
+
+#define METHOD_BUFFERED 0
+#define FSCTL_SET_SPARSE CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 49, \
+  METHOD_BUFFERED, FILE_SPECIAL_ACCESS)

 static NO_COPY const int CHUNK_SIZE = 1024; /* Used for crlf conversions */

 struct __cygwin_perfile *perfile_table;

 DWORD binmode;
+BOOL allow_sparse;

 inline fhandler_base&
 fhandler_base::operator =(fhandler_base &x)
@@ -371,6 +377,8 @@ fhandler_base::open (path_conv *pc, int
   int shared;
   int creation_distribution;
   SECURITY_ATTRIBUTES sa = sec_none;
+  DWORD dw;
+  BOOL r;

   syscall_printf ("(%s, %p) query_open %d", get_win32_name (), flags, get_query_open 
());

@@ -486,6 +494,16 @@ fhandler_base::open (path_conv *pc, int
       && !allow_ntsec && allow_ntea)
     set_file_attribute (has_acls (), get_win32_name (), mode);

+  /* Try to set newly created files as sparse files on NT system. */
+  if (allow_sparse && wincap.is_winnt () && get_device () == FH_DISK
+      && (access & GENERIC_WRITE) == GENERIC_WRITE
+      && (flags & (O_CREAT | O_TRUNC)))
+    {
+      r = DeviceIoControl(x, 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, x);
+    }
+
   set_io_handle (x);
   set_flags (flags, pc ? pc->binmode () : 0);

Index: cygwin/fhandler.h
===================================================================
RCS file: /cvs/src/src/winsup/cygwin/fhandler.h,v
retrieving revision 1.154
diff -p -u -r1.154 fhandler.h
--- cygwin/fhandler.h   10 Jan 2003 12:32:46 -0000      1.154
+++ cygwin/fhandler.h   3 Feb 2003 12:54:47 -0000
@@ -110,6 +110,7 @@ extern struct __cygwin_perfile *perfile_
 #define __fmode (*(user_data->fmode_ptr))
 extern const char proc[];
 extern const int proc_len;
+extern BOOL allow_sparse;

 class select_record;
 class path_conv;