swupdate: add upstream patch to fix build error

When building SWUpdate with the following defconfig:

```
CONFIG_DOWNLOAD=y
```

.. the build process breaks with:

```
corelib/channel_curl.c:27:10: fatal error: json-c/json.h: No such file or directory
 #include <json-c/json.h>
```

Looking at the SWUpdate Kconfig based build system shows that `CONFIG_DOWNLOAD`
depends on `HAVE_LIBCURL`, which selects CURL, which eventually enables the
(unnecessary) build of channel_curl.o.

The upstream fixes the condition for building channel_curl.o by adding a new
hidden config option `CHANNEL_CURL`, which is only selected by the
dependent options.

Backported from:
https://github.com/sbabic/swupdate/commit/37a6666a532e9cbc42b56301f27919ae7c00d2eb

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

diff --git a/package/swupdate/0002-Fix-build-if-DOWNLOAD-is-set-but-no-JSON.patch b/package/swupdate/0002-Fix-build-if-DOWNLOAD-is-set-but-no-JSON.patch
new file mode 100644 (file)
index 0000000..5e07995
--- /dev/null
+++ b/package/swupdate/0002-Fix-build-if-DOWNLOAD-is-set-but-no-JSON.patch
@@ -0,0 +1,107 @@
+From 37a6666a532e9cbc42b56301f27919ae7c00d2eb Mon Sep 17 00:00:00 2001
+From: Stefano Babic <sbabic@denx.de>
+Date: Tue, 23 Jan 2018 16:52:32 +0100
+Subject: [PATCH] Fix build if DOWNLOAD is set, but no JSON
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+The downloader does not require JSON, but channel_curl is built
+even if not called. Build fails with the error:
+
+corelib/channel_curl.c:27:10: fatal error: json-c/json.h: No such file or directory
+
+Add a CONFIG_CHANNEL_CURL that is automatically set by the modules
+reuiring it (suricatta and swuforwarder).
+
+Backported from: 37a6666a532e9cbc42b56301f27919ae7c00d2eb
+
+Signed-off-by: Stefano Babic <sbabic@denx.de>
+Reported-by: Jörg Krause <joerg.krause@embedded.rocks>
+Acked-by: Jörg Krause <joerg.krause@embedded.rocks>
+Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
+---
+ Kconfig             | 7 +++++++
+ corelib/Makefile    | 2 +-
+ handlers/Config.in  | 8 +++++---
+ suricatta/Config.in | 3 +--
+ 4 files changed, 14 insertions(+), 6 deletions(-)
+
+diff --git a/Kconfig b/Kconfig
+index 4469096..e344572 100644
+--- a/Kconfig
++++ b/Kconfig
+@@ -294,6 +294,13 @@ config DOWNLOAD
+ comment "Image downloading support needs libcurl"
+       depends on !HAVE_LIBCURL
+ 
++config CHANNEL_CURL
++      bool
++      depends on HAVE_LIBCURL
++      depends on HAVE_JSON_C
++      select CURL
++      select JSON
++
+ config HASH_VERIFY
+       bool "Allow to add sha256 hash to each image"
+       depends on HAVE_LIBSSL
+diff --git a/corelib/Makefile b/corelib/Makefile
+index 282bffd..4b30f9c 100644
+--- a/corelib/Makefile
++++ b/corelib/Makefile
+@@ -17,4 +17,4 @@ lib-$(CONFIG_ENCRYPTED_IMAGES)       += swupdate_decrypt.o
+ lib-$(CONFIG_LIBCONFIG)               += swupdate_settings.o \
+                                  parsing_library_libconfig.o
+ lib-$(CONFIG_JSON)            += parsing_library_libjson.o
+-lib-$(CONFIG_CURL)            += channel_curl.o
++lib-$(CONFIG_CHANNEL_CURL)    += channel_curl.o
+diff --git a/handlers/Config.in b/handlers/Config.in
+index 596f069..6226b59 100644
+--- a/handlers/Config.in
++++ b/handlers/Config.in
+@@ -54,7 +54,6 @@ config UBIVIDOFFSET
+         if your NAND driver incorrectly reports that it can handle
+         sub-page accesses when it should not.
+ 
+-
+ config CFI
+       bool "cfi"
+       depends on MTD
+@@ -164,8 +163,8 @@ comment "remote handler needs zeromq"
+ config SWUFORWARDER_HANDLER
+       bool "SWU forwarder"
+       depends on HAVE_LIBCURL
+-      select CURL
+-      select JSON
++      depends on HAVE_JSON_C
++      select CHANNEL_CURL
+       default n
+       help
+         This allows to build a chain of updater. A
+@@ -174,6 +173,9 @@ config SWUFORWARDER_HANDLER
+         embedded SWU to the other devices using the
+         Webserver REST API.
+ 
++comment "swuforward handler needs json-c and curl"
++      depends on !HAVE_JSON_C || !HAVE_LIBCURL
++
+ comment "SWU forwarder requires libcurl"
+       depends on !HAVE_LIBCURL
+ 
+diff --git a/suricatta/Config.in b/suricatta/Config.in
+index 62e448a..2586169 100644
+--- a/suricatta/Config.in
++++ b/suricatta/Config.in
+@@ -71,8 +71,7 @@ config SURICATTA_HAWKBIT
+       bool "hawkBit support"
+       depends on HAVE_LIBCURL
+       depends on HAVE_JSON_C
+-      select JSON
+-      select CURL
++      select CHANNEL_CURL
+       help
+         Support for hawkBit server.
+         https://projects.eclipse.org/projects/iot.hawkbit
+-- 
+2.16.1
+