wasi: allow to close preopens

cf. WebAssembly/WASI#522

Author: yamt

libwasi/wasi.c

@@ -880,7 +880,7 @@ wasi_fd_close(struct exec_context *ctx, struct host_instance *hi,
                 toywasm_mutex_unlock(&wasi->lock);
                 goto fail;
         }
-        if (fdinfo->hostfd == -1) {
+        if (wasi_fdinfo_unused(fdinfo)) {
                 toywasm_mutex_unlock(&wasi->lock);
                 ret = EBADF;
                 goto fail;
@@ -1576,11 +1576,7 @@ wasi_fd_renumber(struct exec_context *ctx, struct host_instance *hi,
         if (ret != 0) {
                 goto fail_locked;
         }
-        if (wasi_fdinfo_is_prestat(fdinfo_from)) {
-                ret = ENOTSUP;
-                goto fail_locked;
-        }
-        if (fdinfo_from->hostfd == -1) {
+        if (!wasi_fdinfo_is_prestat(fdinfo_from) && fdinfo_from->hostfd == -1) {
                 ret = EBADF;
                 goto fail_locked;
         }

libwasi/wasi_fdtable.c

@@ -153,10 +153,6 @@ wasi_fd_lookup_locked_for_close(struct exec_context *ctx,
         if (ret != 0) {
                 goto fail;
         }
-        if (wasi_fdinfo_is_prestat(fdinfo)) {
-                ret = ENOTSUP;
-                goto fail;
-        }
 
         /*
          * it should have at least two references for

test/wasi-testsuite-skip.json

@@ -3,7 +3,6 @@
         "fd_filestat_get": "https://github.com/WebAssembly/wasi-testsuite/pull/59",
         "fd_filestat_set": "intentional limitations due to the use of legacy (non openat family) functions.",
         "fd_flags_set": "rights system not implemented.",
-        "close_preopen": "https://github.com/WebAssembly/WASI/pull/522",
         "interesting_paths": "loose implementation of path_open."
     }
 }

test/wasmtime-wasi-tests-blacklist.txt

@@ -20,3 +20,6 @@ interesting_paths
 # Note: wasmtime behavior is intentional:
 # https://github.com/bytecodealliance/wasmtime/commit/b84c4d748826837fb532fa64bf32ac6b50690d77
 poll_oneoff_files
+
+# https://github.com/WebAssembly/WASI/pull/522
+close_preopen