feat: Implement clock_res_get, fd_pwrite, and fd_tell (#55)

bjorn3 · Dec 5, 2023 · 66fded0 · 66fded0
1 parent f3c5567
commit 66fded0
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Showing 2 changed files with 45 additions and 2 deletions.
diff --git a/src/fs_fd.ts b/src/fs_fd.ts
@@ -83,6 +83,10 @@ export class OpenFile extends Fd {
     return { ret: 0, offset: this.file_pos };
   }
 
+  fd_tell(): { ret: number; offset: bigint } {
+    return { ret: 0, offset: this.file_pos };
+  }
+
   fd_write(
     view8: Uint8Array,
     iovs: Array<wasi.Ciovec>,
@@ -108,6 +112,28 @@ export class OpenFile extends Fd {
     return { ret: 0, nwritten };
   }
 
+  fd_pwrite(view8: Uint8Array, iovs: Array<wasi.Ciovec>, offset: bigint) {
+    let nwritten = 0;
+    if (this.file.readonly) return { ret: wasi.ERRNO_BADF, nwritten };
+    for (const iovec of iovs) {
+      const buffer = view8.slice(iovec.buf, iovec.buf + iovec.buf_len);
+      if (offset + BigInt(buffer.byteLength) > this.file.size) {
+        const old = this.file.data;
+        this.file.data = new Uint8Array(
+          Number(offset + BigInt(buffer.byteLength)),
+        );
+        this.file.data.set(old);
+      }
+      this.file.data.set(
+        buffer.slice(0, Number(this.file.size - offset)),
+        Number(offset),
+      );
+      offset += BigInt(buffer.byteLength);
+      nwritten += iovec.buf_len;
+    }
+    return { ret: 0, nwritten };
+  }
+
   fd_filestat_get(): { ret: number; filestat: wasi.Filestat } {
     return { ret: 0, filestat: this.file.stat() };
   }

diff --git a/src/wasi.ts b/src/wasi.ts
@@ -134,14 +134,31 @@ export default class WASI {
 
       // eslint-disable-next-line @typescript-eslint/no-unused-vars
       clock_res_get(id: number, res_ptr: number): number {
-        throw "unimplemented";
+        let resolutionValue: bigint;
+        switch (id) {
+          case wasi.CLOCKID_MONOTONIC: {
+            // https://developer.mozilla.org/en-US/docs/Web/API/Performance/now
+            // > Resolution in isolated contexts: 5 microseconds
+            resolutionValue = 5_000n; // 5 microseconds
+            break;
+          }
+          case wasi.CLOCKID_REALTIME: {
+            resolutionValue = 1_000_000n; // 1 millisecond?
+            break;
+          }
+          default:
+            return wasi.ERRNO_NOSYS;
+        }
+        const view = new DataView(self.inst.exports.memory.buffer);
+        view.setBigUint64(res_ptr, resolutionValue, true);
+        return wasi.ERRNO_SUCCESS;
       },
       clock_time_get(id: number, precision: bigint, time: number): number {
         const buffer = new DataView(self.inst.exports.memory.buffer);
         if (id === wasi.CLOCKID_REALTIME) {
           buffer.setBigUint64(
             time,
-            BigInt(new Date().getTime()) * 1000000n,
+            BigInt(new Date().getTime()) * 1_000_000n,
             true,
           );
         } else if (id == wasi.CLOCKID_MONOTONIC) {