fix(std/archive): untar (#6217)

- Fix `Untar` for tarballs with multiple files (Currently throwing `"checksum error"`)
- Fix parsing, now all `ustar` versions should be supported. Linux `tar -cvf deno.tar dir/` is not working on master. 
- Added `asyncIterator`
- Added README.md

1 files changed, 60 insertions, 0 deletions

diff --git a/std/archive/README.md b/std/archive/README.md
new file mode 100644
index 000000000..efa258ca4
--- /dev/null
+++ b/std/archive/README.md
@@ -0,0 +1,60 @@
+# Usage
+
+## Tar
+
+```ts
+import { Tar } from "https://deno.land/std/archive/tar.ts";
+
+const tar = new Tar();
+const content = new TextEncoder().encode("Deno.land");
+await tar.append("deno.txt", {
+  reader: new Deno.Buffer(content),
+  contentSize: content.byteLength,
+});
+
+// Or specifying a filePath
+await tar.append("land.txt", {
+  filePath: "./land.txt",
+});
+
+// use tar.getReader() to read the contents
+
+const writer = await Deno.open("./out.tar", { write: true, create: true });
+await Deno.copy(tar.getReader(), writer);
+writer.close();
+```
+
+## Untar
+
+```ts
+import { Untar } from "https://deno.land/std/archive/tar.ts";
+import { ensureFile } from "https://deno.land/std/fs/ensure_file.ts";
+import { ensureDir } from "https://deno.land/std/fs/ensure_dir.ts";
+
+const reader = await Deno.open("./out.tar", { read: true });
+const untar = new Untar(reader);
+
+for await (const entry of untar) {
+  console.log(entry); // metadata
+  /*
+    fileName: "archive/deno.txt",
+    fileMode: 33204,
+    mtime: 1591657305,
+    uid: 0,
+    gid: 0,
+    size: 24400,
+    type: 'file'
+  */
+
+  if (entry.type === "directory") {
+    await ensureDir(entry.fileName);
+    continue;
+  }
+
+  await ensureFile(entry.fileName);
+  const file = await Deno.open(entry.fileName, { write: true });
+  // <entry> is a reader
+  await Deno.copy(entry, file);
+}
+reader.close();
+```