mingw32: Make NTFS sparse file on --file-allocation=trunc

1 files changed, 13 insertions, 1 deletions

diff --git a/src/AbstractDiskWriter.cc b/src/AbstractDiskWriter.cc
index dea6f0ee..578f64e9 100644
--- a/src/AbstractDiskWriter.cc
+++ b/src/AbstractDiskWriter.cc
@@ -463,11 +463,23 @@ void AbstractDiskWriter::truncate(int64_t length)
     }
 }
 
-void AbstractDiskWriter::allocate(int64_t offset, int64_t length)
+void AbstractDiskWriter::allocate(int64_t offset, int64_t length, bool sparse)
 {
   if(fd_ == A2_BAD_FD) {
     throw DL_ABORT_EX("File not yet opened.");
   }
+  if(sparse) {
+#ifdef __MINGW32__
+    DWORD bytesReturned;
+    if(!DeviceIoControl(fd_, FSCTL_SET_SPARSE, 0, 0, 0, 0,
+                        &bytesReturned, 0)) {
+      A2_LOG_WARN(fmt("Making file sparse failed or pending: %s",
+                      fileStrerror(GetLastError()).c_str()));
+    }
+#endif // __MINGW32__
+    truncate(offset+length);
+    return;
+  }
 #ifdef  HAVE_SOME_FALLOCATE
 # ifdef __MINGW32__
   truncate(offset+length);