app-backup/casync: add initial ebuild

This is a fairly boring meson ebuild. I had to apply a patch to make it
build.

This is included in the sdk for the torcx packaging work, where we'd
like to get a digest of a given torcx pkg. `casync digest` works well
for that and can be pointed at a directory easily enough.

sdk_container/src/third_party/coreos-overlay/app-backup/casync/Manifest

@@ -0,0 +1 @@
+DIST v2.tar.gz 1250776 SHA256 a5f79ee3ccae2df42cce662c36edc7047aebacd3a9c029ee9a859adfa7a68d00 SHA512 d3f27a8af75c07030cbd465bc716f74b1389234ff03c4043f76e898a2c2633ca6352618c89330aca6b83ff8d09082ff7d7a3d835035665c4f9eab9dc643fd3cf WHIRLPOOL 19ecfeac16c2f519a8e2abf4aed65d4331b57e7fbf58386ea0fd0441f58a1306d67103885dd662e5f1e8320add995625687830f4cbdb6535a917979e682b6121

sdk_container/src/third_party/coreos-overlay/app-backup/casync/casync-2.ebuild

@@ -0,0 +1,33 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=6
+
+DESCRIPTION="casync - Content-Addressable Data Synchronization Tool - is a tool similar to rsync for backing up and updating directory trees"
+HOMEPAGE="https://github.com/systemd/casync"
+SRC_URI="https://github.com/systemd/casync/archive/v${PV}.tar.gz"
+
+inherit meson eutils
+
+LICENSE="LGPL-2.1"
+SLOT="0"
+KEYWORDS="amd64"
+IUSE="fuse selinux doc"
+
+DEPEND="app-arch/zstd
+fuse? ( sys-fs/fuse )
+"
+RDEPEND="${DEPEND}"
+
+PATCHES=(
+	"${FILESDIR}/fix-selinux-build.patch"
+)
+
+src_configure() {
+	local emesonargs=(
+		-Dfuse=$(usex fuse true false)
+		-Dselinux=$(usex selinux true false)
+		-Dman=$(usex doc true false)
+	)
+	meson_src_configure
+}

sdk_container/src/third_party/coreos-overlay/app-backup/casync/files/fix-selinux-build.patch

@@ -0,0 +1,126 @@
+From ab7ef83b5aef07af6e8628eeab353a3fb043fadd Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
+Date: Wed, 26 Jul 2017 09:52:40 -0400
+Subject: [PATCH 1/2] Fix build without selinux and refuse --with=selinux when
+ compiled without
+
+Fixes #73.
+
+The output is pretty crappy:
+
+  $ build/casync --with=selinux make ...
+  Failed to run synchronizer: Operation not supported
+
+but that's being tracked as #44.
+---
+ src/cadecoder.c |  2 +-
+ src/caencoder.c | 13 ++++++++++---
+ 2 files changed, 11 insertions(+), 4 deletions(-)
+
+diff --git a/src/cadecoder.c b/src/cadecoder.c
+index 5deca52..aad8e31 100644
+--- a/src/cadecoder.c
++++ b/src/cadecoder.c
+@@ -13,7 +13,7 @@
+ #include <linux/msdos_fs.h>
+ 
+ #if HAVE_SELINUX
+-#include <selinux/selinux.h>
++#  include <selinux/selinux.h>
+ #endif
+ 
+ #include "cadecoder.h"
+diff --git a/src/caencoder.c b/src/caencoder.c
+index eb58bbb..63fd4e2 100644
+--- a/src/caencoder.c
++++ b/src/caencoder.c
+@@ -21,7 +21,7 @@
+ #include <linux/msdos_fs.h>
+ 
+ #if HAVE_SELINUX
+-#include <selinux/selinux.h>
++#  include <selinux/selinux.h>
+ #endif
+ 
+ #include "caencoder.h"
+@@ -264,10 +264,12 @@ static void ca_encoder_node_free(CaEncoderNode *n) {
+ 
+         n->fcaps = mfree(n->fcaps);
+ 
++#if HAVE_SELINUX
+         if (n->selinux_label) {
+                 freecon(n->selinux_label);
+                 n->selinux_label = NULL;
+         }
++#endif
+ 
+         n->device_size = UINT64_MAX;
+ 
+@@ -658,18 +660,20 @@ static int ca_encoder_node_read_selinux_label(
+                 CaEncoder *e,
+                 CaEncoderNode *n) {
+ 
++#if HAVE_SELINUX
+         char *label;
+         int r;
++#endif
+ 
+         assert(e);
+         assert(n);
+ 
+         if ((e->feature_flags & CA_FORMAT_WITH_SELINUX) == 0)
+                 return 0;
++#if HAVE_SELINUX
+         if (n->selinux_label_valid)
+                 return 0;
+ 
+-#if HAVE_SELINUX
+         if (n->fd >= 0)
+                 r = fgetfilecon(n->fd, &label) < 0 ? -errno : 0;
+         else {
+@@ -706,10 +710,13 @@ static int ca_encoder_node_read_selinux_label(
+ 
+                 n->selinux_label = label;
+         }
+-#endif
+ 
+         n->selinux_label_valid = true;
+         return 0;
++
++#else
++        return -EOPNOTSUPP;
++#endif
+ }
+ 
+ static int compare_xattr(const void *a, const void *b) {
+
+From 42b8c68addc8aed0a829b7678ef0ceefd47dc113 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
+Date: Wed, 26 Jul 2017 10:34:03 -0400
+Subject: [PATCH 2/2] Fix segv in ca_remote_forget_chunk
+
+With gcc-7.1.1-6.fc27:
+
+In file included from ../src/caformat-util.h:7:0,
+                 from ../src/caremote.c:8:
+../src/caremote.c: In function 'ca_remote_forget_chunk':
+../src/util.h:471:13: error: argument 1 null where non-null expected [-Werror=nonnull]
+         if (strncmp(s, prefix, l) == 0)
+             ^~~~~~~~~~~~~~~~~~~~~
+---
+ src/caremote.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/caremote.c b/src/caremote.c
+index 7d49923..755c3a6 100644
+--- a/src/caremote.c
++++ b/src/caremote.c
+@@ -2729,7 +2729,7 @@ int ca_remote_forget_chunk(CaRemote *rr, const CaChunkID *id) {
+ 
+                 p = startswith(qpos, "low-priority/");
+                 if (!p) {
+-                        p = startswith(p, "high-priority/");
++                        p = startswith(qpos, "high-priority/");
+                         if (!p) {
+                                 r = -EBADMSG;
+                                 goto finish;