Get env printf basic example working

src/integrations/mod.rs

@@ -1,14 +1,21 @@
 use crate::webassembly::{ImportObject, VmCtx};
-use libc::putchar;
+use libc::{printf, putchar};
+use std::io;
+use std::io::Write;
 
-fn printf(format: i32, values: i32, context: &VmCtx) -> i32 {
-    println!("PRINTF {:?} {:?}", format, values);
-    return 0;
+extern "C" fn _printf(memory_offset: i32, extra: i32, vm_context: &mut VmCtx) -> i32 {
+    // println!("PRINTF");
+    let mem = &vm_context.user_data.instance.memories[0];
+    // let x = mem.carve_slice(memory_offset as u32, 16).unwrap();
+    return unsafe {
+        let base_memory_offset = mem.mmap.as_ptr().offset(memory_offset as isize) as *const i8;
+        printf(base_memory_offset, extra)
+    };
 }
 
 pub fn generate_libc_env<'a, 'b>() -> ImportObject<&'a str, &'b str> {
     let mut import_object = ImportObject::new();
-    import_object.set("env", "printf", printf as *const u8);
+    import_object.set("env", "printf", _printf as *const u8);
     import_object.set("env", "putchar", putchar as *const u8);
     import_object
 }
@@ -37,19 +44,19 @@ mod tests {
         main(&context);
     }
 
-    // #[test]
-    // fn test_printf() {
-    //     let wasm_bytes = include_wast2wasm_bytes!("tests/printf.wast");
-    //     let import_object = generate_libc_env();
-    //     let result_object = instantiate(wasm_bytes, import_object).expect("Not compiled properly");
-    //     let module = result_object.module;
-    //     let mut instance = result_object.instance;
-    //     let func_index = match module.info.exports.get("main") {
-    //         Some(&Export::Function(index)) => index,
-    //         _ => panic!("Function not found"),
-    //     };
-    //     let main: fn(&VmCtx) = get_instance_function!(instance, func_index);
-    //     let context = instance.generate_context();
-    //     main(&context);
-    // }
+    #[test]
+    fn test_print() {
+        let wasm_bytes = include_wast2wasm_bytes!("tests/printf.wast");
+        let import_object = generate_libc_env();
+        let result_object = instantiate(wasm_bytes, import_object).expect("Not compiled properly");
+        let module = result_object.module;
+        let mut instance = result_object.instance;
+        let func_index = match module.info.exports.get("main") {
+            Some(&Export::Function(index)) => index,
+            _ => panic!("Function not found"),
+        };
+        let main: fn(&VmCtx) = get_instance_function!(instance, func_index);
+        let context = instance.generate_context();
+        main(&context);
+    }
 }

src/integrations/tests/printf.wast

@@ -0,0 +1,19 @@
+(module
+ (type $FUNCSIG$ii (func (param i32) (result i32)))
+ (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
+ (import "env" "printf" (func $printf (param i32 i32) (result i32)))
+ (table 0 anyfunc)
+ (memory $0 1)
+ (data (i32.const 16) "Hello World\00")
+ (export "memory" (memory $0))
+ (export "main" (func $main))
+ (func $main (; 1 ;) (result i32)
+  (drop
+   (call $printf
+    (i32.const 16)
+    (i32.const 0)
+   )
+  )
+  (i32.const 0)
+ )
+)

src/webassembly/memory.rs

@@ -116,6 +116,18 @@ impl LinearMemory {
 
         Some(prev_pages as i32)
     }
+
+    pub fn carve_slice(&self, offset: u32, size: u32) -> Option<&[u8]> {
+        let start = offset as usize;
+        let end = start + size as usize;
+        let slice: &[u8] = &*self;
+
+        // if end <= self.mapped_size() {
+        Some(&slice[start..end])
+        // } else {
+        //     None
+        // }
+    }
 }
 
 impl fmt::Debug for LinearMemory {
@@ -151,3 +163,18 @@ impl DerefMut for LinearMemory {
         &mut *self.mmap
     }
 }
+
+// impl Clone for LinearMemory {
+//     fn clone(&self) -> LinearMemory {
+//         let mut mmap = MmapMut::map_anon(self.maximum.unwrap_or(self.current) as usize).unwrap();
+//         let mut base_mmap = &self.mmap;
+//         let to_init = &mut mmap[0..self.current as usize];
+//         to_init.copy_from_slice(&self.mmap);
+
+//         return LinearMemory {
+//             mmap: mmap,
+//             current: self.current,
+//             maximum: self.maximum,
+//         };
+//     }
+// }