Consume official GStreamer binaries on MacOS

This PR re-enables support for the gstreamer mediastack
in macOS by consuming the official binary '.pkg' files
from gstreamer.freedesktop.org

To maintain symmetry with other platforms, the '.pkg'
files are uploaded to servo-build-deps and fetched from
there using the new script 'etc/install_macos_gstreamer.sh'.

Unlike the Homebrew version, the official GStreamer is
distributed as a 'relocatable' framework i.e the dylibs all
have @rpath-relative install names and also link to other
dylibs using @rpath relative path. To address this difference
the 'servo' binary needs to be patched with 'install_name_tool'
to add an LC_RPATH command that sets the relative paths
that the dynamic linker should search when trying to satify
dependencies. In Servo's case, this will be a path relative to
the 'servo' binary itself i.e '@executable_path/lib/'

The additional 'lib' is due to a flaw in the gstreamer
packaging where the install names of some of the dylibs
have the prefix '@rpath/lib' and some of them just have '@rpath'.

This PR also fixes a couple of issues present in the
`mach build` process on MacOS:
1. `mach build` process was not copying transitive dependencies
   of servo binary but only the first level dylibs
2. `mach build` process didn't patch the links to dylibs
   in servo binary (and dependencies). This meant though
   (some) dylibs were copied to local path, the binary
   still loaded the dylibs from system GStreamer installation
   i.e homebrew instead of the copieds dylibs

The build and runtime dependencies in etc/homebrew/Brewfile
and etc/homebrew/Brewfile-build have also been removed in This
PR.

Signed-off-by: Mukilan Thiyagarajan <me@mukilan.in>

1 files changed, 16 insertions, 65 deletions

diff --git a/python/servo/package_commands.py b/python/servo/package_commands.py
index 4f19c8dea19..1f4e87f9830 100644
--- a/python/servo/package_commands.py
+++ b/python/servo/package_commands.py
@@ -40,7 +40,8 @@ from servo.command_base import (
     is_macosx,
     is_windows,
 )
-from servo.gstreamer import macos_dylibs, macos_plugins
+from servo.build_commands import copy_dependencies, change_rpath_in_binary
+from servo.gstreamer import macos_gst_root
 from servo.util import delete
 
 # Note: mako cannot be imported at the top level because it breaks mach bootstrap
@@ -99,66 +100,11 @@ else:
             raise e
 
 
-def otool(s):
-    o = subprocess.Popen(['/usr/bin/otool', '-L', s], stdout=subprocess.PIPE)
-    for line in map(lambda s: s.decode('ascii'), o.stdout):
-        if line[0] == '\t':
-            yield line.split(' ', 1)[0][1:]
-
-
 def listfiles(directory):
     return [f for f in os.listdir(directory)
             if path.isfile(path.join(directory, f))]
 
 
-def install_name_tool(old, new, binary):
-    try:
-        subprocess.check_call(['install_name_tool', '-change', old, '@executable_path/' + new, binary])
-    except subprocess.CalledProcessError as e:
-        print("install_name_tool exited with return value %d" % e.returncode)
-
-
-def is_system_library(lib):
-    return lib.startswith("/System/Library") or lib.startswith("/usr/lib")
-
-
-def change_non_system_libraries_path(libraries, relative_path, binary):
-    for lib in libraries:
-        if is_system_library(lib):
-            continue
-        new_path = path.join(relative_path, path.basename(lib))
-        install_name_tool(lib, new_path, binary)
-
-
-def copy_dependencies(binary_path, lib_path):
-    relative_path = path.relpath(lib_path, path.dirname(binary_path)) + "/"
-
-    # Update binary libraries
-    binary_dependencies = set(otool(binary_path))
-    binary_dependencies = binary_dependencies.union(macos_dylibs())
-    binary_dependencies = binary_dependencies.union(macos_plugins())
-    change_non_system_libraries_path(binary_dependencies, relative_path, binary_path)
-
-    # Update dependencies libraries
-    need_checked = binary_dependencies
-    checked = set()
-    while need_checked:
-        checking = set(need_checked)
-        need_checked = set()
-        for f in checking:
-            # No need to check these for their dylibs
-            if is_system_library(f):
-                continue
-            need_relinked = set(otool(f))
-            new_path = path.join(lib_path, path.basename(f))
-            if not path.exists(new_path):
-                shutil.copyfile(f, new_path)
-            change_non_system_libraries_path(need_relinked, relative_path, new_path)
-            need_checked.update(need_relinked)
-        checked.update(checking)
-        need_checked.difference_update(checked)
-
-
 def copy_windows_dependencies(binary_path, destination):
     for f in os.listdir(binary_path):
         if os.path.isfile(path.join(binary_path, f)) and f.endswith(".dll"):
@@ -336,15 +282,16 @@ class PackageCommands(CommandBase):
             shutil.copy2(path.join(dir_to_root, 'Info.plist'), path.join(dir_to_app, 'Contents', 'Info.plist'))
 
             content_dir = path.join(dir_to_app, 'Contents', 'MacOS')
-            os.makedirs(content_dir)
+            lib_dir = path.join(content_dir, 'lib')
+            os.makedirs(lib_dir)
             shutil.copy2(binary_path, content_dir)
 
             change_prefs(dir_to_resources, "macosx")
 
             print("Finding dylibs and relinking")
-            # TODO(mrobinson): GStreamer dependencies don't need to be packaged
-            # with servo until the media backend is re-enabled.
-            # copy_dependencies(path.join(content_dir, 'servo'), content_dir)
+            dmg_binary = path.join(content_dir, "servo")
+            dir_to_gst_lib = path.join(macos_gst_root(), 'lib', '')
+            copy_dependencies(dmg_binary, lib_dir, dir_to_gst_lib)
 
             print("Adding version to Credits.rtf")
             version_command = [binary_path, '--version']
@@ -401,13 +348,17 @@ class PackageCommands(CommandBase):
                 os.remove(tar_path)
             shutil.copytree(path.join(dir_to_root, 'resources'), path.join(dir_to_brew, 'resources'))
             os.makedirs(path.join(dir_to_brew, 'bin'))
-            shutil.copy2(binary_path, path.join(dir_to_brew, 'bin', 'servo'))
             # Note that in the context of Homebrew, libexec is reserved for private use by the formula
             # and therefore is not symlinked into HOMEBREW_PREFIX.
-            os.makedirs(path.join(dir_to_brew, 'libexec'))
-            # TODO(mrobinson): GStreamer dependencies don't need to be packaged
-            # with servo until the media backend is re-enabled.
-            # copy_dependencies(path.join(dir_to_brew, 'bin', 'servo'), path.join(dir_to_brew, 'libexec'))
+            # The 'lib' sub-directory within 'libexec' is necessary to satisfy
+            # rpath relative install_names in the gstreamer packages
+            brew_servo_bin = path.join(dir_to_brew, 'bin', 'servo')
+            shutil.copy2(binary_path, brew_servo_bin)
+            change_rpath_in_binary(
+                brew_servo_bin, '@executable_path/lib/', '@executable_path/../libexec/lib/')
+            dir_to_lib = path.join(dir_to_brew, 'libexec', 'lib')
+            os.makedirs(dir_to_lib)
+            copy_dependencies(brew_servo_bin, dir_to_lib, dir_to_gst_lib)
             archive_deterministically(dir_to_brew, tar_path, prepend_path='servo/')
             delete(dir_to_brew)
             print("Packaged Servo into " + tar_path)