[wasi-libc.git] / libc-bottom-half / README.md

# WASI libc "bottom half".

The WASI libc "bottom half" is conceptually the lower half of a traditional libc
implementation, consisting of C interfaces to the low-level WASI syscalls.

This implementation is partially derived from the "bottom half" of [cloudlibc],
revision 8835639f27fc42d32096d59d294a0bbb857dc368.

[cloudlibc]: https://github.com/NuxiNL/cloudlibc

This implementation includes preopen functionality, which emulates POSIX APIs
accepting absolute paths by translating them into pre-opened directory handles
and relative paths that can be opened with `openat`. This technique is inspired
by [libpreopen], however the implementation here is designed to be built into
libc rather than to be a layer on top of libc.

[libpreopen]: https://github.com/musec/libpreopen

The WASI libc lower half currently depends on the dlmalloc component.
Commit	Line	Data
84c0778b	1	# WASI libc "bottom half".
320054e8	2
84c0778b DG	3	The WASI libc "bottom half" is conceptually the lower half of a traditional libc
84c0778b DG	4	implementation, consisting of C interfaces to the low-level WASI syscalls.
320054e8	5
84c0778b DG	6	This implementation is partially derived from the "bottom half" of [cloudlibc],
84c0778b DG	7	revision 8835639f27fc42d32096d59d294a0bbb857dc368.
320054e8	8
320054e8	9	[cloudlibc]: https://github.com/NuxiNL/cloudlibc
320054e8	10
84c0778b DG	11	This implementation includes preopen functionality, which emulates POSIX APIs
	12	accepting absolute paths by translating them into pre-opened directory handles
	13	and relative paths that can be opened with `openat`. This technique is inspired
	14	by [libpreopen], however the implementation here is designed to be built into
	15	libc rather than to be a layer on top of libc.
320054e8	16
84c0778b	17	[libpreopen]: https://github.com/musec/libpreopen
320054e8	18
753cc434	19	The WASI libc lower half currently depends on the dlmalloc component.