Writing binary is no longer executable

[daephx]

Writing binary is no longer executable

[AlexZoe]

Hey, Raafat, I ran into the same issue and investigate a bit to see what's wrong.

It seems the conversion with HexDump inserts random bytes into the dump file, which obviously breaks the binary file when writing the buffer back to disk with HexAssemble.
This happens for both manual conversion and automatic one (i.e. ReadBuf and WriteBuf).

Using the same xxd commands manually in a terminal works without problems.
Converting a binary file to a hexdump in nvim also works directly in ExecMode (%! xxd -g 1 -u <file>).

NVim version used with LinuxMint 20.1.

NVIM v0.10.0-dev-289+gfa1baa9a4
Build type: Release
LuaJIT 2.1.0-beta3

I attached two screenshots below to show the output side by side (left: regular dump, right: HexDump).
The first image shows the differing sizes (hex offset at the bottom).
The second highlights the first line where random bytes got inserted.

I hope this helps.

[RaafatTurki]

Writing the buffer triggers a binary "rebuild" from the hex dump using xxd.

• Are you sure your xxd is properly working? (try using it to dump and revert a binary file)?
• Does this occur with other file types such as a png file?

[daephx]

I did some tests to find if there was any discrepancies.
The issue persists on WSL and on bare metal pop_OS, both with minimal config.
However, so far I can only reproduce the issue when my CWD is ~/.config/nvim.
If I do the same exact steps somewhere else like a /tmp folder, the issue doesn't occur.

When writing the dump buffer the "Hello, World!" string get shifted ~20 lines downward, resulting in the exec format error.

[daephx]

Are you sure your xxd is properly working? (try using it to dump and revert a binary file)?

I can't be sure, I'm not too familiar with the program.

Does this occur with other file types such as a png file?

I did test a image file located at ~/Downloads/image.jpg without issue.
I'm not sure if you or someone else could reproduce but it seems like some obscure behaviour that the rebuilding would not work in neovim config directory.

cd ~/.config/nvim
nvim -u minimal_config.lua
# Write hello.c
$ gcc hello.c
$ ./a.out
Hello, World!

# Modify "Hello, World!" and write hex
$ ./a.out
exec format error: ./a.out