Reading the code, I was surprised to see that cd was implemented by calling out to the os library. I assumed that was something the shell or at least userspace handled. At what level does the concept of a “current directory” exist?
It's at the kernel level. Each process has its own current working directory. On Linux, these CWD values are exposed at `/proc/[...]/cwd`. This value affects the resolution of relative paths in filesystem operations at a syscall level.
Very cool. Good use of quickjs, although it would have been cool if it somehow didn’t need a libc and just used the syscall interface. Makes me want to give that a try.
Check out this:
https://bellard.org/jslinux/vm.html?url=alpine-x86.cfg&mem=1...
and
https://bellard.org/jslinux/
By the famous Fabrice Bellard who is the creator of QuickJS, QEMU, FFMPEG and many other brilliant and fascinating tools!
https://bellard.org/
Reading the code, I was surprised to see that cd was implemented by calling out to the os library. I assumed that was something the shell or at least userspace handled. At what level does the concept of a “current directory” exist?
It's at the kernel level. Each process has its own current working directory. On Linux, these CWD values are exposed at `/proc/[...]/cwd`. This value affects the resolution of relative paths in filesystem operations at a syscall level.
Unix defines a Working Directory that every process has, changed with chdir(2): https://man7.org/linux/man-pages/man2/chdir.2.html
In the kernel’s process structure. See NOTES - https://man7.org/linux/man-pages/man2/chdir.2.html
Very cool. Good use of quickjs, although it would have been cool if it somehow didn’t need a libc and just used the syscall interface. Makes me want to give that a try.
It’s never early to prepare for JavaScript complete takeover.