feat: basic support of pipe sequences

mod.test.ts

@@ -1085,6 +1085,21 @@ Deno.test("command .lines()", async () => {
   assertEquals(result, ["1", "2"]);
 });
 
+Deno.test("piping in command", async () => {
+  {
+    const result = await $`echo 1 | cat -`.text();
+    assertEquals(result, "1");
+  }
+  {
+    const result = await $`echo 1 && echo 2 | cat -`.text();
+    assertEquals(result, "1\n2");
+  }
+  {
+    const result = await $`echo 1 || echo 2 | cat -`.text();
+    assertEquals(result, "1");
+  }
+});
+
 Deno.test("redirects", async () => {
   await withTempDir(async (tempDir) => {
     // absolute

mod.ts

@@ -33,7 +33,14 @@ import { createPathRef, PathRef } from "./src/path.ts";
 export type { Delay, DelayIterator } from "./src/common.ts";
 export { FsFileWrapper, PathRef } from "./src/path.ts";
 export type { ExpandGlobOptions, PathSymlinkOptions, SymlinkOptions, WalkEntry, WalkOptions } from "./src/path.ts";
-export { CommandBuilder, CommandChild, CommandResult, KillSignal, KillSignalController } from "./src/command.ts";
+export {
+  CommandBuilder,
+  CommandChild,
+  CommandResult,
+  KillSignal,
+  KillSignalController,
+  type KillSignalListener,
+} from "./src/command.ts";
 export type { CommandContext, CommandHandler, CommandPipeReader, CommandPipeWriter } from "./src/command_handler.ts";
 export type { Closer, Reader, ShellPipeReaderKind, ShellPipeWriterKind, WriterSync } from "./src/pipes.ts";
 export type {

src/command.ts

@@ -1075,7 +1075,7 @@ function validateCommandName(command: string) {
 const SHELL_SIGNAL_CTOR_SYMBOL = Symbol();
 
 interface KillSignalState {
-  aborted: boolean;
+  abortedCode: number;
   listeners: ((signal: Deno.Signal) => void)[];
 }
 
@@ -1086,7 +1086,7 @@ export class KillSignalController {
 
   constructor() {
     this.#state = {
-      aborted: false,
+      abortedCode: 0,
       listeners: [],
     };
     this.#killSignal = new KillSignal(SHELL_SIGNAL_CTOR_SYMBOL, this.#state);
@@ -1106,6 +1106,9 @@ export class KillSignalController {
   }
 }
 
+/** Listener for when a KillSignal is killed. */
+export type KillSignalListener = (signal: Deno.Signal) => void;
+
 /** Similar to `AbortSignal`, but for `Deno.Signal`.
  *
  * A `KillSignal` is considered aborted if its controller
@@ -1128,7 +1131,7 @@ export class KillSignal {
    * SIGKILL, SIGABRT, SIGQUIT, SIGINT, or SIGSTOP
    */
   get aborted(): boolean {
-    return this.#state.aborted;
+    return this.#state.abortedCode !== 0;
   }
 
   /**
@@ -1147,39 +1150,51 @@ export class KillSignal {
     };
   }
 
-  addListener(listener: (signal: Deno.Signal) => void) {
+  addListener(listener: KillSignalListener) {
     this.#state.listeners.push(listener);
   }
 
-  removeListener(listener: (signal: Deno.Signal) => void) {
+  removeListener(listener: KillSignalListener) {
     const index = this.#state.listeners.indexOf(listener);
     if (index >= 0) {
       this.#state.listeners.splice(index, 1);
     }
   }
+
+  /** @internal - DO NOT USE. Very unstable. Not sure about this. */
+  get _abortedExitCode() {
+    return this.#state.abortedCode;
+  }
 }
 
 function sendSignalToState(state: KillSignalState, signal: Deno.Signal) {
-  if (signalCausesAbort(signal)) {
-    state.aborted = true;
+  const code = getSignalAbortCode(signal);
+  if (code !== undefined) {
+    state.abortedCode = code;
   }
   for (const listener of state.listeners) {
     listener(signal);
   }
 }
 
-function signalCausesAbort(signal: Deno.Signal) {
+function getSignalAbortCode(signal: Deno.Signal) {
   // consider the command aborted if the signal is any one of these
   switch (signal) {
     case "SIGTERM":
+      return 128 + 15;
     case "SIGKILL":
+      return 128 + 9;
     case "SIGABRT":
+      return 128 + 6;
     case "SIGQUIT":
+      return 128 + 3;
     case "SIGINT":
+      return 128 + 2;
     case "SIGSTOP":
-      return true;
+      // should SIGSTOP be considered an abort?
+      return 128 + 19;
     default:
-      return false;
+      return undefined;
   }
 }
 

src/commands/cat.ts

@@ -21,17 +21,18 @@ export async function catCommand(
 
 async function executeCat(context: CommandContext) {
   const flags = parseCatArgs(context.args);
-  let exit_code = 0;
+  let exitCode = 0;
   const buf = new Uint8Array(1024);
 
   for (const path of flags.paths) {
     if (path === "-") { // read from stdin
       if (typeof context.stdin === "object") { // stdin is a Reader
-        while (true) {
+        while (!context.signal.aborted) {
           const size = await context.stdin.read(buf);
           if (!size || size === 0) break;
           else context.stdout.writeSync(buf.slice(0, size));
         }
+        exitCode = context.signal._abortedExitCode;
       } else {
         const _assertValue: "null" | "inherit" = context.stdin;
         throw new Error(`not supported. stdin was '${context.stdin}'`);
@@ -40,21 +41,22 @@ async function executeCat(context: CommandContext) {
       let file;
       try {
         file = await Deno.open(pathUtils.join(context.cwd, path), { read: true });
-        while (true) {
+        while (!context.signal.aborted) {
           // NOTE: rust supports cancellation here
           const size = file.readSync(buf);
           if (!size || size === 0) break;
           else context.stdout.writeSync(buf.slice(0, size));
         }
+        exitCode = context.signal._abortedExitCode;
       } catch (err) {
         context.stderr.writeLine(`cat ${path}: ${err}`);
-        exit_code = 1;
+        exitCode = 1;
       } finally {
         if (file) file.close();
       }
     }
   }
-  return exit_code;
+  return exitCode;
 }
 
 export function parseCatArgs(args: string[]): CatFlags {

src/pipes.ts

@@ -187,3 +187,45 @@ export class PipedBuffer implements WriterSync {
     this.#hasSet = true;
   }
 }
+
+export class PipeSequencePipe implements Reader, WriterSync {
+  #inner = new Buffer();
+  #readListener: (() => void) | undefined;
+  #closed = false;
+
+  close() {
+    this.#readListener?.();
+    this.#closed = true;
+  }
+
+  writeSync(p: Uint8Array): number {
+    const value = this.#inner.writeSync(p);
+    if (this.#readListener !== undefined) {
+      const listener = this.#readListener;
+      this.#readListener = undefined;
+      listener();
+    }
+    return value;
+  }
+
+  read(p: Uint8Array): Promise<number | null> {
+    if (this.#readListener !== undefined) {
+      // doesn't support multiple read listeners at the moment
+      throw new Error("Misuse of PipeSequencePipe");
+    }
+
+    if (this.#inner.length === 0) {
+      if (this.#closed) {
+        return Promise.resolve(null);
+      } else {
+        return new Promise((resolve) => {
+          this.#readListener = () => {
+            resolve(this.#inner.readSync(p));
+          };
+        });
+      }
+    } else {
+      return Promise.resolve(this.#inner.readSync(p));
+    }
+  }
+}