From 92803a2db3818995bee6ee4d5113ff2e99e6e075 Mon Sep 17 00:00:00 2001
From: Glauber Costa <glommer@cloudius-systems.com>
Date: Wed, 17 Jun 2015 14:45:53 -0400
Subject: [PATCH] touch_directory: EEXIST-ignoring make directory

There are many situations in which we would like to make sure a directory
exists.  We can do that by creating the directory we want, and just ignoring
the relevant error.

It is a lot of code though, and I believe it is an idiom common enough to exist
on its own.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
---
 core/reactor.cc | 12 ++++++++++++
 core/seastar.hh |  1 +
 2 files changed, 13 insertions(+)

diff --git a/core/reactor.cc b/core/reactor.cc
index f035caf64b..6ce1eec136 100644
--- a/core/reactor.cc
+++ b/core/reactor.cc
@@ -1917,6 +1917,18 @@ future<> make_directory(sstring name) {
     return engine().make_directory(std::move(name));
 }
 
+future<> touch_directory(sstring name) {
+    return make_directory(name).then_wrapped([] (future<> f) {
+        try {
+            f.get();
+        } catch (std::system_error& e) {
+            if (e.code() != std::error_code(EEXIST, std::system_category())) {
+                throw;
+            }
+        }
+    });
+}
+
 future<> remove_file(sstring pathname) {
     return engine().remove_file(std::move(pathname));
 }
diff --git a/core/seastar.hh b/core/seastar.hh
index 9c6017b493..4b15860946 100644
--- a/core/seastar.hh
+++ b/core/seastar.hh
@@ -108,5 +108,6 @@ future<connected_socket> connect(socket_address sa);
 future<file> open_file_dma(sstring name, open_flags flags);
 future<file> open_directory(sstring name);
 future<> make_directory(sstring name);
+future<> touch_directory(sstring name);
 future<> remove_file(sstring pathname);