add the syscall and create a test

lib/emscripten/emtests/test_getcwd.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <unistd.h>
+
+int main() {
+    const unsigned int size = 256;
+    char cwd[size] = {};
+    char* buf = getcwd(cwd, size);
+    printf("getcwd\n");
+    return 0;
+}

lib/emscripten/emtests/test_getcwd.out

@@ -0,0 +1 @@
+getcwd

lib/emscripten/src/lib.rs

@@ -502,6 +502,7 @@ pub fn generate_emscripten_env(globals: &mut EmscriptenGlobals) -> ImportObject
             "___syscall168" => func!(crate::syscalls::___syscall168),
             "___syscall180" => func!(crate::syscalls::___syscall180),
             "___syscall181" => func!(crate::syscalls::___syscall181),
+            "___syscall183" => func!(crate::syscalls::___syscall183),
             "___syscall191" => func!(crate::syscalls::___syscall191),
             "___syscall192" => func!(crate::syscalls::___syscall192),
             "___syscall194" => func!(crate::syscalls::___syscall194),

lib/emscripten/src/syscalls/mod.rs

@@ -48,6 +48,10 @@ use std::slice;
 // Other platforms do otherwise.
 #[cfg(target_os = "darwin")]
 use libc::SO_NOSIGPIPE;
+use crate::utils::copy_cstr_into_wasm;
+use crate::env::get_emscripten_data;
+use std::ffi::CString;
+
 #[cfg(not(target_os = "darwin"))]
 const SO_NOSIGPIPE: c_int = 0;
 
@@ -186,6 +190,25 @@ pub fn ___syscall110(_ctx: &mut Ctx, _one: i32, _two: i32) -> i32 {
     -1
 }
 
+// getcwd
+pub fn ___syscall183(ctx: &mut Ctx, buf: u32, _size: u32) -> u32 {
+    debug!("emscripten::___syscall183");
+    use std::env;
+    let path = env::current_dir();
+    match path {
+        Ok(path_buf) => {
+            // write path into buffer
+            let path_string = path_buf.display().to_string();
+            let path_c_string = CString::new(path_string).unwrap();
+            let offset = unsafe { copy_cstr_into_wasm(ctx, path_c_string.as_ptr()) };
+            offset
+        }
+        Err(e) => {
+            unimplemented!()
+        }
+    }
+}
+
 // mmap2
 pub fn ___syscall192(ctx: &mut Ctx, which: c_int, mut varargs: VarArgs) -> c_int {
     debug!("emscripten::___syscall192 (mmap2) {}", which);

lib/emscripten/tests/emtests/test_getcwd.rs

@@ -0,0 +1,9 @@
+#[test]
+fn test_getcwd() {
+    assert_emscripten_output!(
+        "../../emtests/test_getcwd.wasm",
+        "getcwd",
+        vec![],
+        "../../emtests/test_getcwd.out"
+    );
+}