WASI libc prototype implementation.

This incoporates pieces from musl-libc, cloudlibc, cloudabi, libpreopen,
and dlmalloc, as well as a significant amount of new code.

Author: sunfishcode

LICENSE

@@ -2,5 +2,13 @@ Please see the LICENSE file in each top-level directory for the terms applicable
 
 The relevant directories and licenses are:
 
-basics/      - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
-dlmalloc/    - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+basics/                       - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+dlmalloc/                     - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+libc-bottom-half/cloudlibc/   - BSD-2-Clause; see libc-bottom-half/cloudlibc/LICENSE for details
+libc-bottom-half/libpreopen/  - BSD-2-Clause; see the individual files for details
+libc-bottom-half/headers/     - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+libc-bottom-half/sources/     - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+libc-bottom-half/mman/        - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+libc-top-half/musl            - MIT; see libc-top-half/musl/COPYRIGHT for details
+libc-top-half/headers         - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
+libc-top-half/sources         - CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

Makefile

@@ -1,19 +1,36 @@
-# WebAssembly Reference Sysroot
+# WASI Sysroot
 
-Caution: This is currently quite experimental and not generally usable yet!
+This is a work in progress. It's usable for many purposes, though the APIs
+aren't stable yet.
 
 ## What is this?
 
-This is a "reference sysroot", which is meant to be part of a common C ABI
-that can be shared across C libraries and compilers. While it's intended to
-(eventually) be usable in its own right, we fully expect other
-implementations to be used in practice by many different systems, though
-we do hope that in those cases, this library defines a useful ABI that can
-be followed.
+It's several things.
+
+First, it's a usable libc. It builds a "sysroot" which can be pointed to by
+compilers, such as Clang 8.0, using the wasm32-unknown-wasi target triple.
+It's a work in progress, but it is already sufficient to run basic programs.
+
+Second, it's a "reference" implementation, which means the interfaces defined
+here can be used by other tools and libraries, even if they don't use all the
+actual implementations here. For example, we don't expect everyone will want
+to use the exact `malloc` implementation provided here, but tools and
+libraries using an ABI-compatible `malloc` interface will be able to
+interoperate regardless of which actual implementation is used.
+
+Third, it's an example showing the use of the WASI API. The libc functionality
+is implemented using calls to WASI functions.
 
 ## Usage
 
-Obtain a WebAssembly-supporting C compiler, and then run:
+The easiest way to get started with this is to use one of the
+[prepackaged releases](https://github.com/CraneStation/wasmtime-wasi/blob/wasi/docs/WASI-intro.md#how-can-i-write-programs-that-use-wasi).
+
+## Building from source
+
+To build a WASI sysroot from source, obtain a WebAssembly-supporting C compiler
+(currently this is only clang, though we'd like to support other compilers as well),
+and then run:
 
 ```
 make WASM_CC=/path/to/wasm/supporting/c/compiler
@@ -29,20 +46,3 @@ To use the sysroot, use the `--sysroot=` option:
 ```
 
 to run the compiler using the newly built sysroot.
-
-## Why doesn't this contain a full libc implementation?
-
-In the short term, one of the main goals is just to provide a reference
-point for people already maintaining their own libc codebases, to help
-reduce interface incompatibilities between the several different
-environments out there.
-
-In the long term, there may some day be some form of standardized
-syscall/import layer for wasm which would could support a full
-"reference libc", at which point this repository might make sense as
-a place to host such a thing.
-
-In between, if there are specific pieces of libc functionality which
-people would find useful to have here, and which don't depend on any
-syscalls, we could add them, using code from existing third-party
-codebases as appropriate.

README.md

@@ -0,0 +1,20 @@
+#ifndef __wasm_basics___errno_h
+#define __wasm_basics___errno_h
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+extern thread_local int errno;
+#else
+extern _Thread_local int errno;
+#endif
+
+#define errno errno
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

basics/include/__errno.h

@@ -0,0 +1,22 @@
+#ifndef __wasm___functions_malloc_h
+#define __wasm___functions_malloc_h
+
+#define __need_size_t
+#define __need_wchar_t
+#define __need_NULL
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void *malloc(size_t size) __attribute__((__malloc__, __warn_unused_result__));
+void free(void *ptr);
+void *calloc(size_t nmemb, size_t size) __attribute__((__malloc__, __warn_unused_result__));
+void *realloc(void *ptr, size_t size) __attribute__((__warn_unused_result__));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

basics/include/__functions_malloc.h

@@ -0,0 +1,20 @@
+#ifndef __wasm___functions_memcpy_h
+#define __wasm___functions_memcpy_h
+
+#define __need_size_t
+#define __need_NULL
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void *memcpy(void *__restrict__ dst, const void *__restrict__ src, size_t n) __attribute__((__nothrow__, __leaf__, __nonnull__(1, 2)));
+void *memmove(void *dst, const void *src, size_t n) __attribute__((__nothrow__, __leaf__, __nonnull__(1, 2)));
+void *memset(void *dst, int c, size_t n) __attribute__((__nothrow__, __leaf__, __nonnull__(1)));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

basics/include/__functions_memcpy.h

@@ -0,0 +1,11 @@
+#ifndef __wasm_basics___macro_PAGESIZE_h
+#define __wasm_basics___macro_PAGESIZE_h
+
+/*
+ * The page size in WebAssembly is fixed at 64 KiB. If this ever changes,
+ * it's expected that applications will need to opt in, so we can change
+ * this.
+ */
+#define PAGESIZE (0x10000)
+
+#endif

basics/include/__macro_PAGESIZE.h

@@ -1,5 +1,5 @@
-#ifndef __wasm_sysroot___struct_stat_h
-#define __wasm_sysroot___struct_stat_h
+#ifndef __wasm_basics___struct_stat_h
+#define __wasm_basics___struct_stat_h
 
 #include <__typedef_dev_t.h>
 #include <__typedef_ino_t.h>
@@ -29,7 +29,7 @@ struct stat {
     struct timespec st_atim;
     struct timespec st_mtim;
     struct timespec st_ctim;
-    long long __unused[3];
+    long long __reserved[3];
 };
 
 #endif

basics/include/__struct_stat.h

@@ -1,7 +1,7 @@
-#ifndef __wasm_sysroot___struct_timespec_h
-#define __wasm_sysroot___struct_timespec_h
+#ifndef __wasm_basics___struct_timespec_h
+#define __wasm_basics___struct_timespec_h
 
-#include "__typedef_time_t.h"
+#include <__typedef_time_t.h>
 
 /* As specified in POSIX. */
 struct timespec {

basics/include/__struct_timespec.h

@@ -1,5 +1,5 @@
-#ifndef __wasm_sysroot___typedef_blkcnt_t_h
-#define __wasm_sysroot___typedef_blkcnt_t_h
+#ifndef __wasm_basics___typedef_blkcnt_t_h
+#define __wasm_basics___typedef_blkcnt_t_h
 
 /* Define these as 64-bit signed integers to support files larger than 2 GiB. */
 typedef long long blkcnt_t;