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fanglingsu / vimb

Vimb - the vim like browser is a webkit based web browser that behaves like the vimperator plugin for the firefox and usage paradigms from the great editor vim. The goal of vimb is to build a completely keyboard-driven, efficient and pleasurable browsing-experience.
https://fanglingsu.github.io/vimb/
GNU General Public License v3.0
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Fix scroll percentage on ppc64le, ppc64, ppc & armv7l (possibly others) #680

Closed Sadoon-AlBader closed 2 years ago

Sadoon-AlBader commented 2 years ago

Version: 3.6.0-39-ged7d365 WebKit compile: 2.32.3 WebKit run: 2.32.3 GTK compile: 3.24.24 GTK run: 3.24.24 libsoup compile: 2.72.0 libsoup run: 2.72.0 Extension dir: /home/$USER/.local/lib/vimb

(x86, x86_64, ppc64le)

Version: 3.6.0-34-g652f411 WebKit compile: 2.32.3 WebKit run: 2.32.3 GTK compile: 3.24.30 GTK run: 3.24.30 libsoup compile: 2.74.0 libsoup run: 2.74.0 Extension dir: /home/$USER/.local/lib/vimb

(ppc64, ppc)

Version: 3.6.0-37-g837ff36 WebKit compile: 2.32.3 WebKit run: 2.32.3 GTK compile: 3.24.5 GTK run: 3.24.5 libsoup compile: 2.64.2 libsoup run: 2.64.2 Extension dir: /home/pi/.local//lib/vimb

(rpi4)

Steps to reproduce

Use the browser

Expected behaviour

Correct scroll percentage shown

Actual behaviour

Different behavior accross architectures: (x86, x86_64, and ppc64le using Devuan Linux Chimaera; ppc64 and ppc using Debian Sid; Rpi4 using Raspbian (Debian 10) )

On x86 and x86_64, the values show as expected.

on ppc64le, ppc64, ppc and armv7l, different outcomes are observed, I chose to display the value in hexadecimal, making it easier to find the specific bug.

ppc, ppc64: Lower 2 bytes are always set to 0x0000, upper 2 bytes contain the percentage of scrolling.

ppc64le: Upper two bytes are set to random numbers on each page, lower two bytes contain the percentage of scrolling.

armv7l: Upper two bytes are set to 0xABC0 always, lower bytes are the percentage.

The fix: Using a guint16 instead of guint seems to completely fix the issue without introducing bugs on any architecture.

I can't figure out for the life of me why this is happening, but I'm going to investigate libwegkit2gtk later because I am very sure it's an issue with the library itself.

Sadoon-AlBader commented 2 years ago

It seemed that the fix was only working on the rpi4, ppc, and ppc64le, and ppc64 was still having an issue. I decided to clean up the patch so that it treats the scroll percentage as a 16-bit uint only on affected architectures. Overall I think it's much cleaner. I know "pointer manipulation" and whatnot but it makes it work both on big endian and little endian systems this way. A simple typecast will not work for BE systems.

fanglingsu commented 2 years ago

@Sadoon-AlBader Thank you for you investigation an for the patch!