2b853ff079
This change represents a rather large re-design in how `wasi-libc` builds and runs its tests. Initially, #346 retrieved the `libc-test` repository and built a subset of those tests to give us some amount of test coverage. Later, because there was no way to add custom C tests, #522 added a `smoke` directory which allowed this. But (a) each of these test suites was built and run separately and (b) it was unclear how to add more tests flexibly--some tests should only run on `*p2` targets or `*-threads` targets, e.g. This change reworks all of this so that all tests are built the same way, in the same place. For downloaded tests like those from `libc-test`, I chose to add "stub tests" that `#include` the original version. This not only keeps all enabled tests in one place, it also allows us to add "directives," C comments that the `Makefile` uses to filter out tests for certain targets or add special compile, link or run flags. These rudimentary scripts, along with other Bash logic I moved out of the Makefile now live in the `scripts` directory. Finally, all of this is explained more clearly in an updated `README.md`. The hope with documenting this a bit better is that it would be easier for drive-by contributors to be able to either dump in new C tests for regressions they may find or enable more libc-tests. As of my current count, we only enable 40/75 of libc-test's functional tests, 0/228 math tests, 0/69 regression tests, and 0/79 API tests. Though many of these may not apply to WASI programs, it would be nice to explore how many more of these tests can be enabled to increase wasi-libc's test coverage. This change should explain how to do that and, with directives, make it possible to condition how the tests compile and run. |
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| .github/workflows | ||
| dlmalloc | ||
| emmalloc | ||
| expected | ||
| fts | ||
| libc-bottom-half | ||
| libc-top-half | ||
| scripts | ||
| stub-pthreads | ||
| test | ||
| tools/wasi-headers | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| CODE_OF_CONDUCT.md | ||
| LICENSE | ||
| LICENSE-APACHE | ||
| LICENSE-APACHE-LLVM | ||
| LICENSE-MIT | ||
| linker-provided-symbols.txt | ||
| Makefile | ||
| README.md | ||
wasi-libc
wasi-libc is a libc for WebAssembly programs built on top of WASI system
calls. It provides a wide array of POSIX-compatible C APIs, including support
for standard I/O, file I/O, filesystem manipulation, memory management, time,
string, environment variables, program startup, and many other APIs.
wasi-libc is sufficiently stable and usable for many purposes, as most of the
POSIX-compatible APIs are stable, though it is continuing to evolve to better
align with wasm and WASI. For example, pthread support is experimentally
provided via the wasi-threads proposal.
Usage
The easiest way to get started with this is to use wasi-sdk, which includes a
build of wasi-libc in its sysroot.
Building from source
To build a WASI sysroot from source, obtain a WebAssembly-supporting C compiler (currently this is only clang 10+, though we'd like to support other compilers as well), and then run:
make CC=/path/to/clang/with/wasm/support \
AR=/path/to/llvm-ar \
NM=/path/to/llvm-nm
This makes a directory called "sysroot" by default. See the top of the Makefile for customization options.
To use the sysroot, use the --sysroot= option:
/path/to/wasm/supporting/c/compiler --sysroot=/path/to/the/newly/built/sysroot ...
to run the compiler using the newly built sysroot.
Note that Clang packages typically don't include cross-compiled builds of
compiler-rt, libcxx, or libcxxabi, for libclang_rt.builtins-wasm32.a,
libc++.a, or libc++abi.a, respectively, so they may not be usable without
extra setup. This is one of the things wasi-sdk simplifies, as it includes
cross-compiled builds of compiler-rt, libc++.a, and libc++abi.a.
Building in pthread support
To enable pthreads support via the wasi-threads proposal, follow the above
build directions with one addition: make ... THREAD_MODEL=posix. This creates
additional artifacts in sysroot/lib/wasm32-wasi-threads to support --target wasm32-wasi-threads.
Arch Linux AUR package
For Arch Linux users, there's an official wasi-libc package tracking this Git repository. You might want to install other WASI related packages as well.