Re: [PATCH SLOF v2 4/5] disk-label: introduce helper to check fat filesystem
From: Thomas Huth <hidden>
Date: 2015-06-29 08:47:23
On Thu, 25 Jun 2015 12:15:28 +0530 Nikunj A Dadhania [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Signed-off-by: Nikunj A Dadhania <redacted> --- slof/fs/packages/disk-label.fs | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)diff --git a/slof/fs/packages/disk-label.fs b/slof/fs/packages/disk-label.fs index 0995808..7ed5526 100644 --- a/slof/fs/packages/disk-label.fs +++ b/slof/fs/packages/disk-label.fs@@ -321,6 +321,14 @@ CONSTANT /gpt-part-entry \ Load from first active DOS boot partition. +: fat-bootblock? ( addr -- flag ) + \ byte 0-2 of the bootblock is a jump instruction in + \ all FAT filesystems. + \ e9 and eb are jump instructions in x86 assembler. + dup c@ e9 = IF drop true EXIT THEN + dup c@ eb = swap 2+ c@ 90 = and +; + \ NOTE: block-size is always 512 bytes for DOS partition tables. : load-from-dos-boot-partition ( addr -- size )@@ -549,14 +557,7 @@ AA268B49521E5A8B CONSTANT GPT-PREP-PARTITION-4 : try-dos-files ( -- found? ) no-mbr? IF false EXIT THEN - \ disk-buf 0 byte 0-2 is a jump instruction in all FAT - \ filesystems. - \ e9 and eb are jump instructions in x86 assembler. - disk-buf c@ e9 <> IF - disk-buf c@ eb <> - disk-buf 2+ c@ 90 <> or - IF false EXIT THEN - THEN + disk-buf fat-bootblock? 0= IF false EXIT THEN s" fat-files" (interpose-filesystem) true ;
Reviewed-by: Thomas Huth <redacted>