wasi: Implement fd_write for stdout

benediktwerner · Jul 26, 2019 · 31bf702 · 31bf702
1 parent 624d487
commit 31bf702
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Showing 2 changed files with 37 additions and 5 deletions.
diff --git a/src/vm.rs b/src/vm.rs
@@ -340,15 +340,15 @@ impl VM {
         &mut self.memory
     }
 
-    fn push(&mut self, val: Value) -> VMResult<()> {
+    pub(crate) fn push(&mut self, val: Value) -> VMResult<()> {
         if self.value_stack.len() >= VALUE_STACK_LIMIT {
             return Err(Trap::ValueStackOverflow);
         }
         self.value_stack.push(val);
         Ok(())
     }
 
-    fn pop(&mut self) -> VMResult<Value> {
+    pub(crate) fn pop(&mut self) -> VMResult<Value> {
         self.value_stack.pop().ok_or(Trap::PopFromEmptyStack)
     }
 
@@ -651,7 +651,17 @@ impl VM {
         let func = self.module.get_func(self.ip.func_index).unwrap();
         if func.is_imported() {
             if let Some(wasi_func) = func.wasi_function() {
-                return wasi_func.handle(self);
+                wasi_func.handle(self)?;
+                loop {
+                    if let Some(Label::Return) = self.label_stack.pop() {
+                        if !self.label_stack.is_empty() {
+                            let frame = self.function_stack.pop().unwrap();
+                            self.ip = frame.ret_addr;
+                        }
+                        break;
+                    }
+                }
+                return Ok(());
             }
             return Err(Trap::UnsupportedCallToImportedFunction(self.ip.func_index));
         }

diff --git a/src/wasi.rs b/src/wasi.rs
@@ -26,7 +26,7 @@ impl WasiFunction {
             // "fd_prestat_dir_name" => WasiFunction::FdPrestatDirName,
             // "fd_seek" => WasiFunction::FdSeek,
             // "fd_read" => WasiFunction::FdRead,
-            // "fd_write" => WasiFunction::FdWrite,
+            "fd_write" => WasiFunction::FdWrite,
             // "fd_close" => WasiFunction::FdClose,
             // "path_open" => WasiFunction::PathOpen,
             "proc_exit" => WasiFunction::ProcExit,
@@ -46,7 +46,29 @@ impl WasiFunction {
             WasiFunction::FdPrestatDirName => (),
             WasiFunction::FdSeek => (),
             WasiFunction::FdRead => (),
-            WasiFunction::FdWrite => (),
+            WasiFunction::FdWrite => {
+                let fd = vm.locals()?[0].to::<u32>().unwrap();
+                let iovs = vm.locals()?[1].to::<u32>().unwrap();
+                let iovs_len = vm.locals()?[2].to::<u32>().unwrap();
+                let nwritten_out = vm.locals()?[3].to::<u32>().unwrap();
+                let mut nwritten = 0;
+                if fd != 1 {
+                    panic!("wasi.fd_write call with fd != stdout");
+                }
+                for i in 0..iovs_len {
+                    let iov = iovs + i * 8;
+                    let str_addr: u32 = vm.memory().load(iov)?;
+                    let len: u32 = vm.memory().load(iov + 4)?;
+                    let start = str_addr as usize;
+                    let end = (str_addr + len) as usize;
+                    let s = &vm.memory().data()[start..end];
+                    print!("{}", String::from_utf8(s.to_vec()).unwrap());
+                    nwritten += len;
+                }
+                let errno: u32 = 0;
+                vm.push(errno.into())?;
+                vm.memory_mut().store(nwritten_out, nwritten)?;
+            }
             WasiFunction::FdClose => (),
             WasiFunction::PathOpen => (),
             WasiFunction::ProcExit => return Err(Trap::WasiExit(vm.pop_as()?)),