1# Copyright 2014 The Chromium Authors 2# Use of this source code is governed by a BSD-style license that can be 3# found in the LICENSE file. 4 5import("//build/config/c++/c++.gni") 6import("//build/config/compiler/compiler.gni") 7import("//build/config/sanitizers/sanitizers.gni") 8import("//build/config/sysroot.gni") 9import("//build/toolchain/toolchain.gni") 10 11declare_args() { 12 # When non empty, overrides the target rpath value. This allows a user to 13 # make a Chromium build where binaries and shared libraries are meant to be 14 # installed into separate directories, like /usr/bin/chromium and 15 # /usr/lib/chromium for instance. It is useful when a build system that 16 # generates a whole target root filesystem (like Yocto) is used on top of gn, 17 # especially when cross-compiling. 18 # Note: this gn arg is similar to gyp target_rpath generator flag. 19 gcc_target_rpath = "" 20 ldso_path = "" 21} 22 23# This config causes functions not to be automatically exported from shared 24# libraries. By default, all symbols are exported but this means there are 25# lots of exports that slow everything down. In general we explicitly mark 26# which functions we want to export from components. 27# 28# Some third_party code assumes all functions are exported so this is separated 29# into its own config so such libraries can remove this config to make symbols 30# public again. 31# 32# See http://gcc.gnu.org/wiki/Visibility 33config("symbol_visibility_hidden") { 34 cflags = [ "-fvisibility=hidden" ] 35 rustflags = [ "-Zdefault-visibility=hidden" ] 36 37 # Visibility attribute is not supported on AIX. 38 if (current_os != "aix") { 39 cflags_cc = [ "-fvisibility-inlines-hidden" ] 40 cflags_objcc = cflags_cc 41 } 42} 43 44# This config is usually set when :symbol_visibility_hidden is removed. 45# It's often a good idea to set visibility explicitly, as there're flags 46# which would error out otherwise (e.g. -fsanitize=cfi-unrelated-cast) 47config("symbol_visibility_default") { 48 cflags = [ "-fvisibility=default" ] 49} 50 51# The rpath is the dynamic library search path. Setting this config on a link 52# step will put the directory where the build generates shared libraries into 53# the rpath. 54# 55# This is required for component builds since the build generates many shared 56# libraries in the build directory that we expect to be automatically loaded. 57# It will be automatically applied in this case by :executable_config. 58# 59# In non-component builds, certain test binaries may expect to load dynamic 60# libraries from the current directory. As long as these aren't distributed, 61# this is OK. For these cases use something like this: 62# 63# if ((is_linux || is_chromeos) && !is_component_build) { 64# configs += [ "//build/config/gcc:rpath_for_built_shared_libraries" ] 65# } 66config("rpath_for_built_shared_libraries") { 67 if (!is_android && current_os != "aix" && !is_castos) { 68 # Note: Android, Aix don't support rpath. Chromecast has its own logic for 69 # setting the rpath in //build/config/chromecast. 70 if (current_toolchain != default_toolchain || gcc_target_rpath == "") { 71 ldflags = [ 72 # Want to pass "\$". GN will re-escape as required for ninja. 73 "-Wl,-rpath=\$ORIGIN", 74 ] 75 } else { 76 ldflags = [ "-Wl,-rpath=${gcc_target_rpath}" ] 77 } 78 if (current_toolchain == default_toolchain && ldso_path != "") { 79 ldflags += [ "-Wl,--dynamic-linker=${ldso_path}" ] 80 } 81 } 82} 83 84if (is_component_build && !is_android) { 85 # See the rpath_for... config above for why this is necessary for component 86 # builds. 87 executable_and_shared_library_configs_ = 88 [ ":rpath_for_built_shared_libraries" ] 89} else { 90 executable_and_shared_library_configs_ = [] 91} 92 93# Settings for executables. 94config("executable_config") { 95 configs = executable_and_shared_library_configs_ 96 ldflags = [ "-pie" ] 97 if (is_android) { 98 ldflags += [ 99 "-Bdynamic", 100 "-Wl,-z,nocopyreloc", 101 ] 102 } 103 104 if (!is_android && current_os != "aix") { 105 ldflags += [ 106 # TODO(GYP): Do we need a check on the binutils version here? 107 # 108 # Newer binutils don't set DT_RPATH unless you disable "new" dtags 109 # and the new DT_RUNPATH doesn't work without --no-as-needed flag. 110 "-Wl,--disable-new-dtags", 111 ] 112 } 113} 114 115# Settings for shared libraries. 116config("shared_library_config") { 117 configs = executable_and_shared_library_configs_ 118} 119