truncate: make new region of file sparse

On Linux when 'truncate' is used to create or extend a file the
new region is sparse.  Do the same on Windows.

If the file is really being truncated, do not change its sparseness.

Adds 144 bytes.

(GitHub issue #501)

1 files changed, 6 insertions, 0 deletions

diff --git a/coreutils/truncate.c b/coreutils/truncate.c
index 8826e6b4c..87a47bb09 100644
--- a/coreutils/truncate.c
+++ b/coreutils/truncate.c
@@ -73,6 +73,12 @@ int truncate_main(int argc UNUSED_PARAM, char **argv)
                          * do not report error, exitcode is also 0.
                          */
                 } else {
+#if ENABLE_PLATFORM_MINGW32
+                        struct stat st;
+
+                        if (fstat(fd, &st) == 0 && size > st.st_size)
+                                make_sparse(fd, st.st_size, size);
+#endif
                         if (ftruncate(fd, size) == -1) {
                                 bb_perror_msg("%s: truncate", *argv);
                                 ret = EXIT_FAILURE;