From f5a9474952f459a5095e0aae68e0984fdd84b210 Mon Sep 17 00:00:00 2001
From: Casper Beyer <caspervonb@pm.me>
Date: Sun, 11 Apr 2021 20:05:22 +0800
Subject: feat: stabilize Deno.ftruncate and Deno.ftruncateSync (#10126)

This stabilizes Deno.ftruncate and Deno.ftruncateSync.

This is a well known system call and the interface is
not going to change. Implicitly requires write permissions
as the file has to be opened with write to be truncated.
---
 cli/dts/lib.deno.ns.d.ts | 51 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

(limited to 'cli/dts/lib.deno.ns.d.ts')

diff --git a/cli/dts/lib.deno.ns.d.ts b/cli/dts/lib.deno.ns.d.ts
index 09f39d6b8..931d28877 100644
--- a/cli/dts/lib.deno.ns.d.ts
+++ b/cli/dts/lib.deno.ns.d.ts
@@ -2335,4 +2335,55 @@ declare namespace Deno {
     newpath: string,
     options?: SymlinkOptions,
   ): Promise<void>;
+
+  /**
+   * Synchronously truncates or extends the specified file stream, to reach the
+   * specified `len`.
+   *
+   * If `len` is not specified then the entire file contents are truncated as if len was set to 0.
+   *
+   * if the file previously was larger than this new length, the extra  data  is  lost.
+   *
+   * if  the  file  previously  was shorter, it is extended, and the extended part reads as null bytes ('\0').
+   * 
+   * ```ts
+   * // truncate the entire file
+   * const file = Deno.open("my_file.txt", { read: true, write: true, truncate: true, create: true });
+   * Deno.ftruncateSync(file.rid);
+   *
+   * // truncate part of the file
+   * const file = Deno.open("my_file.txt", { read: true, write: true, create: true });
+   * Deno.write(file.rid, new TextEncoder().encode("Hello World"));
+   * Deno.ftruncateSync(file.rid, 7);
+   * const data = new Uint8Array(32);
+   * Deno.readSync(file.rid, data);
+   * console.log(new TextDecoder().decode(data)); // Hello W
+   * ```
+   */
+  export function ftruncateSync(rid: number, len?: number): void;
+
+  /**
+   * Truncates or extends the specified file stream, to reach the specified `len`.
+   *
+   * If `len` is not specified then the entire file contents are truncated as if len was set to 0.
+   *
+   * If the file previously was larger than this new length, the extra  data  is  lost.
+   *
+   * If  the  file  previously  was shorter, it is extended, and the extended part reads as null bytes ('\0').
+   *
+   * ```ts
+   * // truncate the entire file
+   * const file = Deno.open("my_file.txt", { read: true, write: true, create: true });
+   * await Deno.ftruncate(file.rid);
+   *
+   * // truncate part of the file
+   * const file = Deno.open("my_file.txt", { read: true, write: true, create: true });
+   * await Deno.write(file.rid, new TextEncoder().encode("Hello World"));
+   * await Deno.ftruncate(file.rid, 7);
+   * const data = new Uint8Array(32);
+   * await Deno.read(file.rid, data);
+   * console.log(new TextDecoder().decode(data)); // Hello W
+   * ```
+   */
+  export function ftruncate(rid: number, len?: number): Promise<void>;
 }
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