Add open()

Author: lupyuen

docs/tcc-wasm.wasm

@@ -45,10 +45,14 @@ extern fn main(_argc: c_int, argv: [*:null]const ?[*:0]const u8) c_int;
 //  File Functions
 
 export fn open(path: [*:0]const u8, oflag: c_uint, ...) c_int {
-    debug("open: path={s}, oflag={}", .{ path, oflag });
-    @panic("TODO: open");
+    debug("open: path={s}, oflag={}, return fd={}", .{ path, oflag, fd });
+    const ret = fd;
+    fd += 1;
+    return ret;
 }
 
+var fd: c_int = 3;
+
 ///////////////////////////////////////////////////////////////////////////////
 //  Memory Allocator for malloc