wasmer/lib/emscripten/src/memory.rs

use super::process::abort_with_message;
use libc::{c_int, c_void, memcpy, size_t};
use wasmer_runtime_core::{
    units::{Pages, WASM_MAX_PAGES, WASM_PAGE_SIZE},
    vm::Ctx,
};

/// emscripten: _emscripten_memcpy_big
pub fn _emscripten_memcpy_big(ctx: &mut Ctx, dest: u32, src: u32, len: u32) -> u32 {
    debug!(
        "emscripten::_emscripten_memcpy_big {}, {}, {}",
        dest, src, len
    );
    let dest_addr = emscripten_memory_pointer!(ctx.memory(0), dest) as *mut c_void;
    let src_addr = emscripten_memory_pointer!(ctx.memory(0), src) as *mut c_void;
    unsafe {
        memcpy(dest_addr, src_addr, len as size_t);
    }
    dest
}

/// emscripten: _emscripten_get_heap_size
pub fn _emscripten_get_heap_size(ctx: &mut Ctx) -> u32 {
    debug!("emscripten::_emscripten_get_heap_size",);
    ctx.memory(0).size().bytes().0 as u32
}

/// emscripten: _emscripten_resize_heap
/// Note: this function only allows growing the size of heap
pub fn _emscripten_resize_heap(ctx: &mut Ctx, requested_size: u32) -> u32 {
    debug!("emscripten::_emscripten_resize_heap {}", requested_size);
    let current_memory_pages = ctx.memory(0).size();
    let current_memory = current_memory_pages.bytes().0 as u32;

    if requested_size > current_memory {
        let remainder = (requested_size - current_memory) as usize % WASM_PAGE_SIZE;
        let delta = {
            let delta = (requested_size - current_memory) as usize / WASM_PAGE_SIZE;

            if remainder != 0 {
                delta + 1
            } else {
                delta
            }
        };

        if current_memory_pages.0 as usize + delta > WASM_MAX_PAGES {
            // TODO: handle this?
            debug!("Can't exceed max pages");
            return 0;
        }

        if let Ok(v) = ctx.memory(0).grow(Pages(delta as u32)) {
            return v.0;
        }
    }
    0
}

/// emscripten: getTotalMemory
pub fn get_total_memory(_ctx: &mut Ctx) -> u32 {
    debug!("emscripten::get_total_memory");
    // instance.memories[0].current_pages()
    // TODO: Fix implementation
    _ctx.memory(0).size().bytes().0 as u32
}

/// emscripten: enlargeMemory
pub fn enlarge_memory(_ctx: &mut Ctx) -> u32 {
    debug!("emscripten::enlarge_memory");
    // instance.memories[0].grow(100);
    // TODO: Fix implementation
    0
}

/// emscripten: abortOnCannotGrowMemory
pub fn abort_on_cannot_grow_memory(ctx: &mut Ctx, _requested_size: u32) -> u32 {
    debug!(
        "emscripten::abort_on_cannot_grow_memory {}",
        _requested_size
    );
    abort_with_message(ctx, "Cannot enlarge memory arrays!");
    0
}

/// emscripten: abortOnCannotGrowMemory
pub fn abort_on_cannot_grow_memory_old(ctx: &mut Ctx) -> u32 {
    debug!("emscripten::abort_on_cannot_grow_memory");
    abort_with_message(ctx, "Cannot enlarge memory arrays!");
    0
}

/// emscripten: ___map_file
pub fn ___map_file(_ctx: &mut Ctx, _one: u32, _two: u32) -> c_int {
    debug!("emscripten::___map_file");
    // NOTE: TODO: Em returns -1 here as well. May need to implement properly
    -1
}