Hack together enough emscripten stack stuff to make it happy

Cargo.lock

@@ -58,6 +58,11 @@ name = "bitflags"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "byteorder"
+version = "1.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "cc"
 version = "1.0.25"
@@ -672,6 +677,7 @@ dependencies = [
 name = "wasmer"
 version = "0.1.0"
 dependencies = [
+ "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "cranelift-codegen 0.23.0",
  "cranelift-entity 0.23.0",
  "cranelift-native 0.23.0",
@@ -730,6 +736,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "89a47830402e9981c5c41223151efcced65a0510c13097c769cede7efb34782a"
 "checksum backtrace-sys 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)" = "c66d56ac8dabd07f6aacdaf633f4b8262f5b3601a810a0dcddffd5c22c69daa0"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
+"checksum byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)" = "94f88df23a25417badc922ab0f5716cc1330e87f71ddd9203b3a3ccd9cedf75d"
 "checksum cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)" = "f159dfd43363c4d08055a07703eb7a3406b0dac4d0584d96965a3262db3c9d16"
 "checksum cfg-if 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "0c4e7bb64a8ebb0d856483e1e682ea3422f883c5f5615a90d51a2c82fe87fdd3"
 "checksum clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b957d88f4b6a63b9d70d5f454ac8011819c6efa7727858f458ab71c756ce2d3e"

Cargo.toml

@@ -45,6 +45,7 @@ target-lexicon = "0.2.0"
 libc = { git = "https://github.com/rust-lang/libc" }
 nix = "0.11"
 rayon = "1.0.3"
+byteorder = "1"
 
 [build-dependencies]
 wabt = "0.7.1"

src/apis/emscripten/mod.rs

@@ -1,5 +1,7 @@
 /// NOTE: TODO: These emscripten api implementation only support wasm32 for now because they assume offsets are u32
-use crate::webassembly::{ImportObject, ImportValue};
+use crate::webassembly::{ImportObject, ImportValue, LinearMemory};
+use byteorder::{ByteOrder, LittleEndian};
+use std::mem;
 
 // EMSCRIPTEN APIS
 mod env;
@@ -17,6 +19,41 @@ mod nullfunc;
 pub use self::utils::is_emscripten_module;
 pub use self::storage::{align_memory, static_alloc};
 
+// TODO: Magic number - how is this calculated?
+const TOTAL_STACK: u32 = 5242880;
+// TODO: Magic number stolen from the generated JS - how is this calculated?
+const DYNAMICTOP_PTR_DIFF: u32 = 1088;
+
+const STATIC_BUMP: u32 = 215536; // TODO: make this variable
+
+fn stacktop(static_bump: u32) -> u32 {
+    align_memory(dynamictop_ptr(static_bump) + 4)
+}
+
+fn stack_max(static_bump: u32) -> u32 {
+    stacktop(static_bump) + TOTAL_STACK
+}
+
+fn dynamic_base(static_bump: u32) -> u32 {
+    align_memory(stack_max(static_bump))
+}
+
+fn dynamictop_ptr(static_bump: u32) -> u32 {
+    static_bump + DYNAMICTOP_PTR_DIFF
+}
+
+// fn static_alloc(size: usize, static_top: &mut size) -> usize {
+//     let ret = *static_top;
+//     *static_top = (*static_top + size + 15) & (-16 as usize);
+//     ret
+// }
+
+pub fn emscripten_set_up_memory(memory: &mut LinearMemory) {
+    let dynamictop_ptr = dynamictop_ptr(STATIC_BUMP) as usize;
+    let mem = &mut memory[dynamictop_ptr..dynamictop_ptr+mem::size_of::<u32>()];
+    LittleEndian::write_u32(mem, dynamic_base(STATIC_BUMP));
+}
+
 pub fn generate_emscripten_env<'a, 'b>() -> ImportObject<&'a str, &'b str> {
     let mut import_object = ImportObject::new();
     // Global
@@ -35,6 +72,28 @@ pub fn generate_emscripten_env<'a, 'b>() -> ImportObject<&'a str, &'b str> {
         "global3",
         ImportValue::Global(67), // TODO
     );
+
+    import_object.set(
+        "env",
+        "STACKTOP",
+        ImportValue::Global(stacktop(STATIC_BUMP) as _),
+    );
+    import_object.set(
+        "env",
+        "STACK_MAX",
+        ImportValue::Global(stack_max(STATIC_BUMP) as _),
+    );
+    import_object.set(
+        "env",
+        "DYNAMICTOP_PTR",
+        ImportValue::Global(dynamictop_ptr(STATIC_BUMP) as _),
+    );
+    import_object.set(
+        "env",
+        "tableBase",
+        ImportValue::Global(0),
+    );
+
     // Print functions
     import_object.set("env", "printf", ImportValue::Func(io::printf as *const u8));
     import_object.set(

src/apis/emscripten/storage.rs

@@ -1,13 +1,8 @@
 
 use crate::webassembly::{LinearMemory, Instance};
 
-pub fn align_memory(size: u32, factor: u32) -> u32 {
+pub fn align_memory(ptr: u32) -> u32 {
-    assert!(factor != 0, "memory cannot be aligned by 0 offset!");
+    (ptr + 15) & !15
-    if size % factor == 1 {
-        (size) - (size % factor) + (factor)
-    } else {
-        size
-    }
 }
 
 // pub fn static_alloc(size: u32, instance: &mut Instance) -> u32 {

src/main.rs

@@ -14,6 +14,7 @@ extern crate wasmparser;
 extern crate target_lexicon;
 extern crate nix;
 extern crate rayon;
+extern crate byteorder;
 
 use std::fs::File;
 use std::io;

src/webassembly/instance.rs

@@ -454,6 +454,7 @@ impl Instance {
                 let to_init = &mut mem_mut[offset..offset + init.data.len()];
                 to_init.copy_from_slice(&init.data);
             }
+            crate::apis::emscripten::emscripten_set_up_memory(&mut memories[0]);
         }
 
         let start_func: Option<FuncIndex> =

src/webassembly/memory.rs

@@ -110,11 +110,11 @@ impl LinearMemory {
         let end = start + size as usize;
         let slice: &[u8] = &*self;
 
-        // if end <= self.mapped_size() {
+        if end <= self.current_size() as usize {
-        Some(&slice[start..end])
+            Some(&slice[start..end])
-        // } else {
+        } else {
-        //     None
+            None
-        // }
+        }
     }
 }