Bug 1728436 - Added libasound2 dependency to the sysroot r=glandium

This is required to build the midir crate on Linux. The Dockerfile change is
needed to run the just built xpcshell executable on the build host.

Differential Revision: https://phabricator.services.mozilla.com/D124641

dom/midi/AlsaCompatibility.cpp

@@ -0,0 +1,35 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+
+// The code in this file is a workaround for building with ALSA versions prior
+// to 1.0.29. The snd_pcm_sw_params_set_tstamp_type() and
+// snd_pcm_sw_params_get_tstamp_type() functions are missing from those versions
+// and we need them for the alsa crate which in turn is a dependency of the
+// midir crate. The functions are not actually used so we provide dummy
+// implementations that return an error. This file can be safely removed when
+// the Linux sysroot will be updated to Debian 9 (or higher)
+#include <alsa/asoundlib.h>
+
+#if (SND_LIB_MAJOR == 1) && (SND_LIB_MINOR == 0) && (SND_LIB_SUBMINOR < 29)
+
+extern "C" {
+
+int snd_pcm_sw_params_set_tstamp_type(void) {
+  MOZ_CRASH(
+      "The replacement for snd_pcm_sw_params_set_tstamp_type() should never be "
+      "called");
+  return -1;
+}
+
+int snd_pcm_sw_params_get_tstamp_type(void) {
+  MOZ_CRASH(
+      "The replacement for snd_pcm_sw_params_get_tstamp_type() should never be "
+      "called");
+  return -1;
+}
+}
+
+#endif

dom/midi/moz.build

@@ -55,6 +55,9 @@ UNIFIED_SOURCES = [
 
 include("/ipc/chromium/chromium-config.mozbuild")
 
+if CONFIG["OS_TARGET"] == "Linux":
+    UNIFIED_SOURCES += ["AlsaCompatibility.cpp"]
+
 FINAL_LIBRARY = "xul"
 LOCAL_INCLUDES += [
     "/dom/base",

media/libcubeb/src/moz.build

@@ -92,7 +92,9 @@ if CONFIG['OS_TARGET'] == 'Android':
 
 FINAL_LIBRARY = 'gkmedias'
 
-CFLAGS += CONFIG['MOZ_ALSA_CFLAGS']
+if CONFIG['MOZ_ALSA']:
+    CFLAGS += CONFIG['MOZ_ALSA_CFLAGS']
+
 CFLAGS += CONFIG['MOZ_JACK_CFLAGS']
 CFLAGS += CONFIG['MOZ_PULSEAUDIO_CFLAGS']
 

taskcluster/docker/debian-build/Dockerfile

@@ -15,7 +15,8 @@ RUN /usr/local/sbin/setup_packages.sh $TASKCLUSTER_ROOT_URL $DOCKER_IMAGE_PACKAG
 # libc6-i386 and lib32gcc1 are needed for wine.
 # libdbus-glib-1-2 and libgtk-3-0 are needed to run xpcshell during the build.
 # lib32atomic1, lib32stdc++6 and lib32z1 are needed to run some 32-bits
-# spidermonkey tests.
+# spidermonkey tests. libasound2 is needed to run xpcshell after we introduced
+# the dependencies on alsa via Web MIDI.
 RUN apt-get update && \
     apt-get dist-upgrade && \
     apt-get install \
@@ -30,6 +31,7 @@ RUN apt-get update && \
       'lib32gcc(1|-s1)$' \
       lib32stdc++6 \
       lib32z1 \
+      libasound2 \
       libc6-i386 \
       libdbus-glib-1-2 \
       libgtk-3-0 \

taskcluster/scripts/misc/build-sysroot.sh

@@ -31,6 +31,7 @@ esac
 
 packages="
   linux-libc-dev
+  libasound2-dev
   libstdc++-${gcc_version}-dev
   libdbus-glib-1-dev
   libdrm-dev

toolkit/moz.configure

@@ -171,12 +171,23 @@ imply_option("--enable-replace-malloc", dmd, when=compile_environment)
 
 # ALSA cubeb backend
 # ==============================================================
-system_lib_option("--enable-alsa", env="MOZ_ALSA", help="Enable ALSA audio backend.")
+@depends(target)
+def alsa_default_check(target):
+    return target.kernel == "Linux" and target.os != "Android"
 
-alsa = pkg_check_modules("MOZ_ALSA", "alsa", when="--enable-alsa")
 
-set_config("MOZ_ALSA", depends_if(alsa)(lambda _: True))
-set_define("MOZ_ALSA", depends_if(alsa)(lambda _: True))
+option("--enable-alsa", env="MOZ_ALSA", help="Enable ALSA audio backend.")
+
+
+@depends("--enable-alsa", alsa_default_check)
+def enable_alsa_or_alsa_default_check(alsa_enabled, alsa_default_check):
+    return alsa_enabled or alsa_default_check
+
+
+pkg_check_modules("MOZ_ALSA", "alsa", when=enable_alsa_or_alsa_default_check)
+
+set_config("MOZ_ALSA", True, when="--enable-alsa")
+set_define("MOZ_ALSA", True, when="--enable-alsa")
 
 # JACK cubeb backend
 # ==============================================================