diff mbox series

[v6,1/6] initramfs: refactor do_header() cpio magic checks

Message ID 20220107133814.32655-2-ddiss@suse.de (mailing list archive)
State New, archived
Headers show
Series initramfs: "crc" cpio format and INITRAMFS_PRESERVE_MTIME | expand

Commit Message

David Disseldorp Jan. 7, 2022, 1:38 p.m. UTC 
do_header() is called for each cpio entry and fails if the first six
bytes don't match "newc" magic. The magic check includes a special case
error message if POSIX.1 ASCII (cpio -H odc) magic is detected. This
special case POSIX.1 check can be nested under the "newc" mismatch code
path to avoid calling memcmp() twice in a non-error case.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Martin Wilck <mwilck@suse.com>
---
 init/initramfs.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Comments

Christian Brauner Jan. 7, 2022, 1:52 p.m. UTC | #1 
On Fri, Jan 07, 2022 at 02:38:09PM +0100, David Disseldorp wrote:
> do_header() is called for each cpio entry and fails if the first six
> bytes don't match "newc" magic. The magic check includes a special case
> error message if POSIX.1 ASCII (cpio -H odc) magic is detected. This
> special case POSIX.1 check can be nested under the "newc" mismatch code
> path to avoid calling memcmp() twice in a non-error case.
> 
> Signed-off-by: David Disseldorp <ddiss@suse.de>
> Reviewed-by: Martin Wilck <mwilck@suse.com>
> ---

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
diff mbox series

Patch

diff --git a/init/initramfs.c b/init/initramfs.c
index 2f3d96dc3db6..2f79b3ec0b40 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -257,12 +257,11 @@  static int __init do_collect(void)
 
 static int __init do_header(void)
 {
-	if (memcmp(collected, "070707", 6)==0) {
-		error("incorrect cpio method used: use -H newc option");
-		return 1;
-	}
 	if (memcmp(collected, "070701", 6)) {
-		error("no cpio magic");
+		if (memcmp(collected, "070707", 6) == 0)
+			error("incorrect cpio method used: use -H newc option");
+		else
+			error("no cpio magic");
 		return 1;
 	}
 	parse_header(collected);