Add getdents64

Author: godsarmy

README.md

@@ -10,6 +10,7 @@ linux system lib by zig namespace [std.os.linux](https://ziglang.org/documentati
 | [execve.zig](src/execve.zig)               | [execve](https://ziglang.org/documentation/master/std/#std.os.linux.execve) |
 | [fork_waitpid.zig](src/fork_waitpid.zig)   | [fork](https://ziglang.org/documentation/master/std/#std.os.linux.fork) [waitpid](https://ziglang.org/documentation/master/std/#std.os.linux.waitpid) |
 | [getcwd.zig](src/getcwd.zig)               | [getcwd](https://ziglang.org/documentation/master/std/#std.os.linux.getcwd) [chdir](https://ziglang.org/documentation/master/std/#std.os.linux.chdir) |
+| [getdents64](src/getdents64.zig)           | [getdents64](https://ziglang.org/documentation/master/std/#std.os.linux.getdents64) |
 | [getgroups.zig](src/getgroups.zig)         | [getgroups](https://ziglang.org/documentation/master/std/#std.os.linux.getgroups) |
 | [getrandom.zig](src/getrandom.zig)         | [getrandom](https://ziglang.org/documentation/master/std/#std.os.linux.getrandom) |
 | [lstat.zig](src/lstat.zig)                 | [lstat](https://ziglang.org/documentation/master/std/#std.os.linux.lstat) |

src/getdents64.zig

@@ -0,0 +1,33 @@
+const std = @import("std");
+
+const mem = std.mem;
+const stdout = std.io.getStdOut().writer();
+const linux = std.os.linux;
+const buf_size = 1024;
+
+pub fn main() !void {
+    const tmp_dir = "/tmp";
+    var buf: [buf_size]u8 = undefined;
+
+    const open_rc = linux.open(tmp_dir, linux.O{}, 0);
+    const err = linux.E.init(open_rc);
+    if (err != linux.E.SUCCESS) {
+        try stdout.print("Error is {}\n", .{err});
+    }
+    defer _ = linux.close(@intCast(open_rc));
+
+    while (true) {
+        const nread = linux.getdents64(@intCast(open_rc), &buf, buf.len);
+        if (nread == 0) {
+            break;
+        }
+        var index: u32 = 0;
+        while (index < nread) {
+            const entry = @as(*align(1) linux.dirent64, @ptrCast(&buf[index]));
+            const name = mem.sliceTo(@as([*:0]u8, @ptrCast(&entry.name)), 0);
+            try stdout.print("{} {s}\n", .{ entry.ino, name });
+            index += entry.reclen;
+        }
+        try stdout.print("total entries: {}\n", .{nread});
+    }
+}