cerbero: Use Android NDK LD when building Cargo recipes

Also needs a patch to cargo-c to pass -soname instead of -Wl,-soname
when using the Android linker because ld.gold cannot handle the
spurious -Wl prefix.

Part-of: <https://gitlab.freedesktop.org/gstreamer/cerbero/-/merge_requests/915>

3 files changed, 54 insertions, 2 deletions

diff --git a/cerbero/build/build.py b/cerbero/build/build.py
index da0e0d08..e30bb56d 100644
--- a/cerbero/build/build.py
+++ b/cerbero/build/build.py
@@ -18,6 +18,7 @@
 
 import os
 import re
+import glob
 import copy
 import shutil
 import shlex
@@ -1138,13 +1139,13 @@ class Cargo(Build, ModifyEnvBase):
         self.cargo = os.path.join(self.config.cargo_home, 'bin',
                 'cargo' + self.config._get_exe_suffix())
         try:
-            target_triple = self.config.rust_triple(self.config.target_arch,
+            self.target_triple = self.config.rust_triple(self.config.target_arch,
                     self.config.target_platform, self.using_msvc())
         except FatalError as e:
             raise InvalidRecipeError(self.name, e.msg)
         self.cargo_args = [
             '--verbose', '--offline',
-            '--target', target_triple,
+            '--target', self.target_triple,
             '--target-dir', self.cargo_dir,
         ]
 
@@ -1156,6 +1157,27 @@ class Cargo(Build, ModifyEnvBase):
                 os.makedirs(self.cargo_dir)
         else:
             os.makedirs(self.cargo_dir)
+        if self.config.target_platform == Platform.ANDROID:
+            dot_cargo = os.path.join(self.config_src_dir, '.cargo')
+            os.makedirs(dot_cargo, exist_ok=True)
+            linker = self.env['LD']
+            link_args = []
+            args = iter(shlex.split(self.env['LDFLAGS']))
+            # We need to extract necessary linker flags from LDFLAGS which is
+            # passed to the compiler
+            for arg in args:
+                if arg.startswith('-L'):
+                    link_args.append(arg)
+                elif arg == '-gcc-toolchain':
+                    arg = next(args)
+                    for l in glob.glob(f'{arg}/lib/gcc/*/*/libgcc.a'):
+                        d = os.path.dirname(l)
+                        link_args.append(f'-L{d}')
+            # Append so we don't overwrite cargo vendor settings
+            with open(os.path.join(dot_cargo, 'config.toml'), 'a') as f:
+                f.write(f'[target.{self.target_triple}]\n')
+                f.write(f'linker = "{linker}"\n')
+                f.write(f'rustflags = {link_args!r}\n')
         # No configure step with cargo
 
     async def compile(self):
diff --git a/recipes/build-tools/cargo-c.recipe b/recipes/build-tools/cargo-c.recipe
index 82770885..143a5e09 100644
--- a/recipes/build-tools/cargo-c.recipe
+++ b/recipes/build-tools/cargo-c.recipe
@@ -11,6 +11,9 @@ class Recipe(recipe.Recipe):
     # Need system openssl on Linux
     use_system_libs = True
 
+    # https://github.com/lu-zero/cargo-c/pull/277
+    patches = [name + '/0001-Fix-linking-with-Android-NDK-linker.patch']
+
     deps = ['pkg-config']
     # Need openssl on macOS. On Windows, a prebuilt openssl crate is downloaded.
     platform_deps = {
diff --git a/recipes/build-tools/cargo-c/0001-Fix-linking-with-Android-NDK-linker.patch b/recipes/build-tools/cargo-c/0001-Fix-linking-with-Android-NDK-linker.patch
new file mode 100644
index 00000000..38fbb7ed
--- /dev/null
+++ b/recipes/build-tools/cargo-c/0001-Fix-linking-with-Android-NDK-linker.patch
@@ -0,0 +1,27 @@
+From 1f25fb1c4c69a845b01afe0e6619c2a10c890522 Mon Sep 17 00:00:00 2001
+From: Nirbheek Chauhan <nirbheek@centricular.com>
+Date: Thu, 1 Sep 2022 21:33:29 +0530
+Subject: [PATCH] Fix linking with Android NDK linker
+
+Android ld.gold cannot handle -Wl, and it's incorrect anyway since all
+the other linker arguments passed by cargo do not have a -Wl prefix.
+---
+ src/target.rs | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/target.rs b/src/target.rs
+index 7b1c43e..03a0d4c 100644
+--- a/src/target.rs
++++ b/src/target.rs
+@@ -70,7 +70,7 @@ impl Target {
+         let env = &self.env;
+ 
+         if os == "android" {
+-            lines.push(format!("-Wl,-soname,lib{}.so", lib_name));
++            lines.push(format!("-soname,lib{}.so", lib_name));
+         } else if os == "linux"
+             || os == "freebsd"
+             || os == "dragonfly"
+-- 
+2.37.1
+