make-sparse: Write a zero-byte at the end of the image

This is necessary to preserve the i_size of the output file; otherwise
programs like e2fsck will complain that the filesystem has been
truncated.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 8 insertions, 0 deletions

diff --git a/contrib/make-sparse.c b/contrib/make-sparse.c
index 4a7a3155..1b3d5506 100644
--- a/contrib/make-sparse.c
+++ b/contrib/make-sparse.c
@@ -48,6 +48,7 @@ int full_read(int fd, char *buf, size_t count)
 int main(int argc, char **argv)
 {
 	int fd, got, i;
+	int zflag = 0;
 	char buf[1024];
 
 	if (argc != 2) {
@@ -69,11 +70,18 @@ int main(int argc, char **argv)
 					break;
 			if (i == sizeof(buf)) {
 				lseek(fd, sizeof(buf), SEEK_CUR);
+				zflag = 1;
 				continue;
 			}
 		}
+		zflag = 0;
 		write(fd, buf, got);
 	}
+	if (zflag) {
+		lseek(fd, -1, SEEK_CUR);
+		buf[0] = 0;
+		write(fd, buf, 1);
+	}
 	return 0;
 }