From 06f34a1aed2541866f32438d7bbc75e35c1d5dc3 Mon Sep 17 00:00:00 2001
From: Casper Beyer <caspervonb@pm.me>
Date: Mon, 29 Jun 2020 21:34:18 +0800
Subject: [PATCH] feat(std/wasi) implement fd_filestat_get (#6555)

---
 std/wasi/README.md                        |  2 +-
 std/wasi/snapshot_preview1.ts             | 71 ++++++++++++++++++++++-
 std/wasi/testdata/std_fs_file_metadata.rs | 23 ++++++++
 3 files changed, 94 insertions(+), 2 deletions(-)
 create mode 100644 std/wasi/testdata/std_fs_file_metadata.rs

diff --git a/std/wasi/README.md b/std/wasi/README.md
index 3848ae9a62..b81279dbfb 100644
--- a/std/wasi/README.md
+++ b/std/wasi/README.md
@@ -19,7 +19,7 @@ This module provides an implementation of the WebAssembly System Interface
 - [x] fd_fdstat_get
 - [ ] fd_fdstat_set_flags
 - [ ] fd_fdstat_set_rights
-- [ ] fd_filestat_get
+- [x] fd_filestat_get
 - [ ] fd_filestat_set_size
 - [x] fd_filestat_set_times
 - [x] fd_pread
diff --git a/std/wasi/snapshot_preview1.ts b/std/wasi/snapshot_preview1.ts
index 0067499cc4..78b29b968e 100644
--- a/std/wasi/snapshot_preview1.ts
+++ b/std/wasi/snapshot_preview1.ts
@@ -523,7 +523,76 @@ export default class Module {
       },
 
       fd_filestat_get: (fd: number, buf_out: number): number => {
-        return ERRNO_NOSYS;
+        const entry = this.fds[fd];
+        if (!entry) {
+          return ERRNO_BADF;
+        }
+
+        const view = new DataView(this.memory.buffer);
+
+        try {
+          const info = Deno.fstatSync(entry.handle.rid);
+
+          if (entry.type === undefined) {
+            switch (true) {
+              case info.isFile:
+                entry.type = FILETYPE_REGULAR_FILE;
+                break;
+
+              case info.isDirectory:
+                entry.type = FILETYPE_DIRECTORY;
+                break;
+
+              case info.isSymlink:
+                entry.type = FILETYPE_SYMBOLIC_LINK;
+                break;
+
+              default:
+                entry.type = FILETYPE_UNKNOWN;
+                break;
+            }
+          }
+
+          view.setBigUint64(buf_out, BigInt(info.dev ? info.dev : 0), true);
+          buf_out += 8;
+
+          view.setBigUint64(buf_out, BigInt(info.ino ? info.ino : 0), true);
+          buf_out += 8;
+
+          view.setUint8(buf_out, entry.type);
+          buf_out += 8;
+
+          view.setUint32(buf_out, Number(info.nlink), true);
+          buf_out += 8;
+
+          view.setBigUint64(buf_out, BigInt(info.size), true);
+          buf_out += 8;
+
+          view.setBigUint64(
+            buf_out,
+            BigInt(info.atime ? info.atime.getTime() * 1e6 : 0),
+            true
+          );
+          buf_out += 8;
+
+          view.setBigUint64(
+            buf_out,
+            BigInt(info.mtime ? info.mtime.getTime() * 1e6 : 0),
+            true
+          );
+          buf_out += 8;
+
+          view.setBigUint64(
+            buf_out,
+            BigInt(info.birthtime ? info.birthtime.getTime() * 1e6 : 0),
+            true
+          );
+          buf_out += 8;
+        } catch (err) {
+          return errno(err);
+        }
+
+        return ERRNO_SUCCESS;
       },
 
       fd_filestat_set_size: (fd: number, size: bigint): number => {
diff --git a/std/wasi/testdata/std_fs_file_metadata.rs b/std/wasi/testdata/std_fs_file_metadata.rs
new file mode 100644
index 0000000000..93149fd1c7
--- /dev/null
+++ b/std/wasi/testdata/std_fs_file_metadata.rs
@@ -0,0 +1,23 @@
+// { "preopens": { "/fixture": "fixture" } }
+
+fn main() {
+  let file = std::fs::File::open("/fixture/file").unwrap();
+  let metadata = file.metadata().unwrap();
+  assert!(metadata.is_file());
+  assert!(metadata.len() == 5);
+
+  let file = std::fs::File::open("/fixture/symlink_to_file").unwrap();
+  let metadata = file.metadata().unwrap();
+  assert!(metadata.is_file());
+  assert!(metadata.len() == 5);
+
+  let file = std::fs::File::open("/fixture/directory/file").unwrap();
+  let metadata = file.metadata().unwrap();
+  assert!(metadata.is_file());
+  assert!(metadata.len() == 15);
+
+  let file = std::fs::File::open("/fixture/directory/symlink_to_file").unwrap();
+  let metadata = file.metadata().unwrap();
+  assert!(metadata.is_file());
+  assert!(metadata.len() == 15);
+}