-"WASI" the WebAssembly System Interface.
+# WASI libc "bottom half".
-WASI libc is conceptually the lower half of a traditional libc implementation.
-It provides C interfaces to the low-level WASI syscalls.
+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 is largely based on [CloudABI], [cloudlibc], and [libpreopen], however we
-use just the low-level syscall wrappers rather than all of cloudlibc and
-libpreopen, and we have several customizations for use in a WebAssembly sysroot.
+This implementation is partially derived from the "bottom half" of [cloudlibc],
+revision 8835639f27fc42d32096d59d294a0bbb857dc368.
-[CloudABI]: https://github.com/NuxiNL/cloudabi
[cloudlibc]: https://github.com/NuxiNL/cloudlibc
-[libpreopen]: https://github.com/musec/libpreopen
-
-The upstream repositories and versions used here are:
-cloudlibc - https://github.com/NuxiNL/cloudlibc 8835639f27fc42d32096d59d294a0bbb857dc368
-libpreopen - https://github.com/musec/libpreopen b29e9287cc75a7db7291ce3eb468a3d2bad8ceb1
+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.
-Whole files which are unused are omitted. Changes to upstream code are wrapped
-in preprocessor directives controlled by the macro `__wasilibc_unmodified_upstream`,
-except that CloudABI names have also been renamed to WASI names without annotations.
+[libpreopen]: https://github.com/musec/libpreopen
-WASI libc currently depends on the basics and dlmalloc components of reference-sysroot.
+The WASI libc lower half currently depends on the dlmalloc component.
projects / wasi-libc.git / blobdiff