contrib: add sample Android.bp to build within an Android tree

Add an Android.bp file for Soong, the Android build system, to build
the library including C++ bindings along with all the CLI tools.

This reference Android build file will live in a contrib/ folder to
indiciate it is a less-maintained part of libgpiod. It will need to
be moved to the root directory in order to use it, though, as Soong
doesn't let Blueprint files reference sources in a parent directory.

  error: external/libgpiod/contrib/Android.bp:5:1: module "libgpiod" variant "...": Path is outside directory: ../include
  error: external/libgpiod/contrib/Android.bp:5:1: module "libgpiod" variant "...": Path is outside directory: ../bindings/cxx
  error: external/libgpiod/contrib/Android.bp:5:1: module "libgpiod" variant "...": Path is outside directory: ../lib/*.c
  error: external/libgpiod/contrib/Android.bp:5:1: module "libgpiod" variant "...": Path is outside directory: ../bindings/cxx/*.cpp

Signed-off-by: Benjamin Li <benl@squareup.com>
[Bartosz: add the build file to the release tarball generated by 'make dist']
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

4 files changed, 142 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index 59d87626..3807dca5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,7 +3,7 @@
 
 ACLOCAL_AMFLAGS = -I m4
 AUTOMAKE_OPTIONS = foreign
-SUBDIRS = include lib
+SUBDIRS = include lib contrib
 
 EXTRA_DIST = \
 	LICENSES/GPL-2.0-or-later.txt \
diff --git a/configure.ac b/configure.ac
index 131655b1..7d72c247 100644
--- a/configure.ac
+++ b/configure.ac
@@ -267,6 +267,7 @@ AC_CONFIG_FILES([Makefile
 		 include/Makefile
 		 lib/Makefile
 		 lib/libgpiod.pc
+		 contrib/Makefile
 		 tools/Makefile
 		 tests/Makefile
 		 tests/gpiosim/Makefile
diff --git a/contrib/Android.bp b/contrib/Android.bp
new file mode 100644
index 00000000..fbc21961
--- /dev/null
+++ b/contrib/Android.bp
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Benjamin Li <benl@squareup.com>
+
+// Instructions:
+// - Check out this repository as external/libgpiod.
+// - Move this build file to the project's root directory.
+
+//
+// libgpiod main library
+//
+
+cc_library {
+    name: "libgpiod",
+    defaults: [
+        "libgpiod_defaults",
+    ],
+    srcs: [
+        "lib/*.c",
+        "bindings/cxx/*.cpp",
+    ],
+    export_include_dirs: [
+        "include",
+        "bindings/cxx",
+    ],
+}
+
+cc_defaults {
+    name: "libgpiod_defaults",
+    device_specific: true,
+    cpp_std: "gnu++17",
+    cflags: [
+        // You may want to edit this with the version from configure.ac of
+        // the release you are using.
+        "-DGPIOD_VERSION_STR=\"unstable\"",
+    ],
+    cppflags: [
+        // Google C++ style is to not use exceptions, but this library does
+        // use them.
+        "-fexceptions",
+    ],
+    // Google C++ style is to not use runtime type information, but this
+    // library does use it.
+    rtti: true,
+}
+
+//
+// libgpiod tools
+//
+
+phony {
+    name: "libgpiod_tools",
+    required: [
+        "gpiodetect",
+        "gpioget",
+        "gpioinfo",
+        "gpiomon",
+        "gpionotify",
+        "gpioset",
+    ],
+}
+
+cc_binary {
+    name: "gpiodetect",
+    defaults: [
+        "libgpiod_defaults",
+        "libgpiod_tools_defaults",
+    ],
+    srcs: [
+        "tools/gpiodetect.c",
+    ],
+}
+
+cc_binary {
+    name: "gpioget",
+    defaults: [
+        "libgpiod_defaults",
+        "libgpiod_tools_defaults",
+    ],
+    srcs: [
+        "tools/gpioget.c",
+    ],
+}
+
+cc_binary {
+    name: "gpioinfo",
+    defaults: [
+        "libgpiod_defaults",
+        "libgpiod_tools_defaults",
+    ],
+    srcs: [
+        "tools/gpioinfo.c",
+    ],
+}
+
+cc_binary {
+    name: "gpiomon",
+    defaults: [
+        "libgpiod_defaults",
+        "libgpiod_tools_defaults",
+    ],
+    srcs: [
+        "tools/gpiomon.c",
+    ],
+}
+
+cc_binary {
+    name: "gpionotify",
+    defaults: [
+        "libgpiod_defaults",
+        "libgpiod_tools_defaults",
+    ],
+    srcs: [
+        "tools/gpionotify.c",
+    ],
+}
+
+cc_binary {
+    name: "gpioset",
+    defaults: [
+        "libgpiod_defaults",
+        "libgpiod_tools_defaults",
+    ],
+    srcs: [
+        "tools/gpioset.c",
+    ],
+}
+
+cc_defaults {
+    name: "libgpiod_tools_defaults",
+    srcs: [
+        "tools/tools-common.c",
+    ],
+    shared_libs: [
+        "libgpiod",
+    ],
+}
diff --git a/contrib/Makefile.am b/contrib/Makefile.am
new file mode 100644
index 00000000..1b50e86b
--- /dev/null
+++ b/contrib/Makefile.am
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2023 Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
+
+EXTRA_DIST = Android.bp