linux-ext4 - [PATCH 2/2 -v2] e2image: attempt to use ftruncate64 to set i

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Date:	Fri, 17 Feb 2012 09:35:50 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>
Subject: [PATCH 2/2 -v2] e2image: attempt to use ftruncate64 to set i_size for raw images

If ftruncate64() exists, try to use it to set i_size.  This isn't
guaranteed to work, per SuSv3, but if it doesn't work, it's guaranteed
to return an error.  So for file systems and/or operating systems that
don't support extending i_size via ftruncate64(), fall back to writing
the trailing null.

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

Oops, sent the wrong version of the patch.  My bad.

 misc/e2image.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/misc/e2image.c b/misc/e2image.c
index 3cb92fe..93359cf 100644
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -510,8 +510,19 @@ static void output_meta_data_blocks(ext2_filsys fs, int fd)
 			}
 		}
 	}
+#ifdef HAVE_FTRUNCATE64
+	if (sparse) {
+		ext2_loff_t offset = ext2fs_llseek(fd, sparse, SEEK_CUR);
+
+		if (offset < 0)
+			lseek_error_and_exit(errno);
+		if (ftruncate64(fd, offset) < 0)
+			write_block(fd, zero_buf, -1, 1, -1);
+	}
+#else
 	if (sparse)
 		write_block(fd, zero_buf, sparse-1, 1, -1);
+#endif
 	ext2fs_free_mem(&zero_buf);
 	ext2fs_free_mem(&buf);
 }
-- 
1.7.9.107.g97f9a

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