Close() Syscall | 32 Bit OS Dev (in C)

Channel:
United States Queso Fuego
Subscribers:
5,840
Published on ● Video Link: https://www.youtube.com/watch?v=L7iP5Okx81o


Duration: 49:03
216 views
9

Adding a close() syscall to clear file table and inode table entries for files opened by open().

Errata:
- close() does not free the memory allocated for a file from open(), causing a memory leak! D'oh. This is fixed at the start of the next video. I also need to think through logic for handing O_RDONLY/O_WRONLY/O_RDWR in read() & write() later on.

Next video:
- Seek() syscall and basic tests

OS Dev playlist:
https://www.youtube.com/playlist?list=PLT7NbkyNWaqajsw8Xh7SP9KJwjfpP8TNX

Git Repos:
Sourcehut: https://git.sr.ht/~queso_fuego/quesos
Github mirror: https://github.com/queso-fuego/amateuros

Repo state at the start of this video:
git clone -n https://github.com/queso-fuego/amateuros
cd amateuros
git checkout 1bf04d9f7df879bb65cf9bf6c0a5de92979b5e3d

Join the Community Discord: https://discord.gg/yKm4T89QFn

Notes/Thoughts:
- While I'm not too picky on the recording & programming time for these videos, a maximum time of 1 or 1.5 hrs should have benefits: faster editing and uploading, especially at 4K file sizes; a more consistent upload schedule; a more focused effort, trying for only 1-3 things or ideas per video; not wasting people's time as much as I have been; and more motivation and energy to make content.

I want to get meaningful progress done on more than 1 project, and not have 100s or 1000s of videos of barely making anything and taking forever to do anything substantial. I'll try to strike a middle-ground and get 1-3 working "deliverables" per video e.g. 1 syscall with a test, a ppm viewer, normal vs insert mode toggle in a text editor, etc. This has the benefit of clearly marking checkpoints/commits in git repos, marking a start/end per feature or video, and easier tracking of progress and output. That's my hope, at least.

Contact:
email: fuegoqueso@gmail.com
twitter: @Queso_Fuego
twitch: https://www.twitch.tv/queso_fuego

- Let me know if there's anything specific you'd like to see!

Outline:
0:00 changes since last video
8:33 close() syscall
25:11 neovim formatoptions/colorcolumn
26:37 close() syscall
31:38 test close()
39:55 add seek() whence values
47:55 wrap up & outro

Questions about setup/software/etc.?
Check the FAQ: https://queso_fuego.srht.site/about.html

Music credits:
City Life by Artificial.Music | https://soundcloud.com/artificial-music/
Music promoted by https://www.chosic.com/free-music/all/
Creative Commons CC BY 3.0
https://creativecommons.org/licenses/by/3.0/

#osdev #close #syscalls



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Tags:
queso fuego
os dev
syscalls
system calls
close
low level
c programming
kernel dev