.

wcfs/internal/wcfs_misc.cpp

@@ -21,6 +21,13 @@
 
 namespace os {
 
+tuple<File, error> open(const string &path) {
+    File f = {.fd = -1, path = path};
+    int err = std::open(path.c_str(), O_RDONLY);    // XXX mode
+    if (err != 0)
+        return f, f._errno();
+}
+
 error File::close() {
     File *f = this;
 
@@ -44,4 +51,5 @@ error File::_err(const char *op) {
     return errorf("%s %s: %s", op, f->path, strerror_r(errno));
 }
 
+
 }   // os::

wcfs/internal/wcfs_misc.h

@@ -25,6 +25,9 @@
 #include <string>
 using std::string;
 
+#include <tuple>
+using std::tuple;
+
 // error mimics error from Go.
 struct error {
     string err;
@@ -51,7 +54,9 @@ struct File {
     error stat(struct stat *st);
 };
 
-// XXX tuple<File, error> open(const string &path)
+// open opens file @path.
+// XXX mode
+tuple<File, error> open(const string &path);
 
 }   // os::
 

wcfs/internal/wcfs_virtmem.cpp

@@ -73,6 +73,7 @@ struct SrvReq;
 struct WCFS {
 
     Conn *connect(Tid at);
+    tuple<os::File, error> _open(const string &path /*, XXX mode*/);
 };
 
 // Conn represents logical connection that provides view of data on wcfs
@@ -264,3 +265,12 @@ void _Mapping::_remmapblk(int64_t blk, Tid at) {
         mm.map_into_ro(blkmem, fsfile.fd, blk*f->blksize);
     }
 }
+
+
+// ---- WCFS raw file access ----
+
+tuple<os::File, error> WCFS::_open(const string &path/*, XXX mode*/) {
+    WCFS *wc = this;
+    path_ = wc->_path(path);
+    return os::open(path_/*, XXX mode*/);
+}