From 6bffe0e09738fc47eacf66f9d138dd434f5aebdf Mon Sep 17 00:00:00 2001
From: Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>
Date: Fri, 12 Oct 2018 21:08:48 +0200
Subject: [PATCH] Add basic wasm32: C types and malloc/realloc/free.

---
 src/lib.rs    |  8 ++++---
 src/wasm32.rs | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 3 deletions(-)
 create mode 100644 src/wasm32.rs

diff --git a/src/lib.rs b/src/lib.rs
index c997960a4b29c..95604fe60d222 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -102,9 +102,8 @@ extern crate std as core;
 mod dox;
 
 /*
- * `c_void` should be defined for all targets except wasm.
+ * `c_void` should be defined for all targets
  */
-#[cfg(not(all(target_arch = "wasm32", not(target_os = "emscripten"))))]
 cfg_if! {
     if #[cfg(core_cvoid)] {
         pub use core::ffi::c_void;
@@ -125,7 +124,10 @@ cfg_if! {
 
 cfg_if! {
     if #[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))] {
-        // empty ...
+        // wasm32-unknown-unknown does not have a real C library.
+        // Some useful definitions are in the wasm32.rs file.
+        mod wasm32;
+        pub use wasm32::*;
     } else if #[cfg(target_os = "switch")] {
         // On the Switch, we only define some useful universal types for
         // convenience. Those can be found in the switch.rs file.
diff --git a/src/wasm32.rs b/src/wasm32.rs
new file mode 100644
index 0000000000000..340c550bf57ac
--- /dev/null
+++ b/src/wasm32.rs
@@ -0,0 +1,66 @@
+pub type int8_t = i8;
+pub type int16_t = i16;
+pub type int32_t = i32;
+pub type int64_t = i64;
+pub type uint8_t = u8;
+pub type uint16_t = u16;
+pub type uint32_t = u32;
+pub type uint64_t = u64;
+
+pub type c_char = u8;
+pub type c_schar = i8;
+pub type c_uchar = u8;
+pub type c_short = i16;
+pub type c_ushort = u16;
+pub type c_int = i32;
+pub type c_uint = u32;
+pub type c_long = i64;
+pub type c_ulong = u64;
+pub type c_float = f32;
+pub type c_double = f64;
+pub type c_longlong = i64;
+pub type c_ulonglong = u64;
+pub type intmax_t = i64;
+pub type uintmax_t = u64;
+
+pub type size_t = usize;
+pub type ptrdiff_t = isize;
+pub type intptr_t = isize;
+pub type uintptr_t = usize;
+pub type ssize_t = isize;
+pub type off_t = u64;
+
+const MALLOC_HEADER : isize = 8;
+const MALLOC_ALIGN : usize = 8;
+
+use super::c_void;
+use std::alloc::{self, Layout};
+use std::ptr;
+
+pub unsafe fn malloc(size: size_t) -> *mut c_void {
+    let lay = Layout::from_size_align_unchecked(MALLOC_HEADER as usize + size, MALLOC_ALIGN);
+    let p = alloc::alloc(lay);
+    if p.is_null() {
+        return ptr::null_mut();
+    }
+    *(p as *mut size_t) = size;
+    p.offset(MALLOC_HEADER) as *mut c_void
+}
+pub unsafe fn free(p: *mut c_void) {
+    let p = p.offset(-MALLOC_HEADER) as *mut u8;
+    let size = *(p as *mut size_t);
+    let lay = Layout::from_size_align_unchecked(MALLOC_HEADER as usize + size, MALLOC_ALIGN);
+    alloc::dealloc(p, lay);
+}
+pub unsafe fn realloc(p: *mut c_void, _size: size_t) -> *mut c_void {
+    let p = p.offset(-MALLOC_HEADER) as *mut u8;
+    let size = *(p as *mut size_t);
+    let lay = Layout::from_size_align_unchecked(MALLOC_HEADER as usize + size, MALLOC_ALIGN);
+    let p = alloc::realloc(p, lay, size);
+    if p.is_null() {
+        return ptr::null_mut();
+    }
+    *(p as *mut size_t) = size;
+    p.offset(MALLOC_HEADER) as *mut c_void
+}
+