3 files changed, 21 insertions, 0 deletions

diff --git a/coreutils/dd.c b/coreutils/dd.c
index 3054ec6ea..fc8b1dbb2 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -502,6 +502,9 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
         }
         if (seek) {
                 size_t blocksz = (G.flags & FLAG_SEEK_BYTES) ? 1 : obs;
+#if ENABLE_PLATFORM_MINGW32
+                seek_sparse(ofd, seek * blocksz);
+#endif
                 if (lseek(ofd, seek * blocksz, SEEK_CUR) < 0)
                         goto die_outfile;
         }
diff --git a/include/mingw.h b/include/mingw.h
index 3ab49a920..a5a84cff2 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -533,3 +533,4 @@ int chdir_system_drive(void);
 char *xabsolute_path(char *path);
 char *get_drive_cwd(const char *path, char *buffer, int size);
 void fix_path_case(char *path);
+void seek_sparse(int fd, size_t size);
diff --git a/win32/mingw.c b/win32/mingw.c
index 894388b64..7f8fecdc3 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -1750,3 +1750,20 @@ void fix_path_case(char *path)
                 }
         }
 }
+
+void seek_sparse(int fd, size_t size)
+{
+        DWORD dwTemp;
+        HANDLE fh;
+        FILE_ZERO_DATA_INFORMATION fzdi;
+
+        if ((fh=(HANDLE)_get_osfhandle(fd)) == INVALID_HANDLE_VALUE)
+                return;
+
+        DeviceIoControl(fh, FSCTL_SET_SPARSE, NULL, 0, NULL, 0, &dwTemp, NULL);
+
+        fzdi.FileOffset.QuadPart = 0;
+        fzdi.BeyondFinalZero.QuadPart = size;
+        DeviceIoControl(fh, FSCTL_SET_ZERO_DATA, &fzdi, sizeof(fzdi),
+                                         NULL, 0, &dwTemp, NULL);
+}