jump-to-offset negative value doesn't work about binwalk HOT 5 CLOSED

I think what you're looking for is offset-adjust, not jump-to-offset.

from binwalk.

Not really. What i want to do is jump back in file and continue parsing.

from binwalk.

The jump-to-offset keyword is used to instruct binwalk where it should resume the scan (e.g., if binwalk finds a file system that is 2MB in size, there's no point in scanning the next 2MB of data). Keywords are interpreted by binwalk after libmagic has already processed the entire signature, so it can't be used to do what you're attempting.

Due to binwalk's requirement that signatures start at an offset of 0, if you want to process data that comes before your magic string then you'll need to write a plugin to handle that.

With that said, the zero-offset requirement can be quite limiting and is a hold over from older code. With the current code base it should be possible to allow for arbitrary signature offsets without affecting scan speed. I'll leave this issue open while I look into it.

from binwalk.

Ok, understood. I am looking at the source code now to write my own plugin, because there are a lot of limitations in magic file syntax.
And I want to write decoders for firmwares I am reversing.

As an example of magic syntax: to avoid false positive reaction I want to check that lelong value is less then file-size.

Another example: I want to search for magicB blob only if I found magicA before current offset.

from binwalk.

True, sometimes the magic file format just doesn't cut it, which is why binwalk has added some pseudo-extensions to the magic file format.

Speaking of which, the latest check in to the master branch validates the file-size keyword (i.e.., if file-size value plus the signature offset is bigger than the size of the file, it is considered invalid). You'll still need a plugin for only matching magicB if magicA was previously found though.

Additionally, the latest master code supports specifying non-negative offsets for your magic signatures which should alleviate your original issue.

from binwalk.