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1# Copyright 2014 The Chromium Authors. All rights reserved.
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
36  # Visibility attribute is not supported on AIX.
37  if (current_os != "aix") {
38    cflags_cc = [ "-fvisibility-inlines-hidden" ]
39    cflags_objcc = cflags_cc
40  }
41}
42
43config("symbol_visibility_inline_hidden") {
44  cflags_cc = [ "-fvisibility-inlines-hidden" ]
45}
46
47# This config is usually set when :symbol_visibility_hidden is removed.
48# It's often a good idea to set visibility explicitly, as there're flags
49# which would error out otherwise (e.g. -fsanitize=cfi-unrelated-cast)
50config("symbol_visibility_default") {
51  cflags = [ "-fvisibility=default" ]
52}
53
54# The rpath is the dynamic library search path. Setting this config on a link
55# step will put the directory where the build generates shared libraries into
56# the rpath.
57#
58# This is required for component builds since the build generates many shared
59# libraries in the build directory that we expect to be automatically loaded.
60# It will be automatically applied in this case by :executable_ldconfig.
61#
62# In non-component builds, certain test binaries may expect to load dynamic
63# libraries from the current directory. As long as these aren't distributed,
64# this is OK. For these cases use something like this:
65#
66#  if (is_linux && !is_component_build) {
67#    configs += [ "//build/config/gcc:rpath_for_built_shared_libraries" ]
68#  }
69config("rpath_for_built_shared_libraries") {
70  if (!is_ohos) {
71    # Note: ohos doesn't support rpath.
72    rpath_link = "."
73    if (current_toolchain != default_toolchain || gcc_target_rpath == "") {
74      ldflags = [
75        # Want to pass "\$". GN will re-escape as required for ninja.
76        "-Wl,-rpath=\$ORIGIN/${rpath_link}",
77        "-Wl,-rpath-link=${rpath_link}",
78      ]
79    } else {
80      ldflags = [
81        "-Wl,-rpath=${gcc_target_rpath}",
82        "-Wl,-rpath-link=${rpath_link}",
83      ]
84    }
85  }
86
87  if (!is_ohos) {
88    if (!defined(ldflags)) {
89      ldflags = []
90    }
91    if (current_toolchain == default_toolchain && ldso_path != "") {
92      ldflags += [ "-Wl,--dynamic-linker=${ldso_path}" ]
93    }
94  }
95}
96
97# Settings for executables.
98config("executable_ldconfig") {
99  ldflags = []
100
101  if (is_ohos) {
102    ldflags += [
103      "-Bdynamic",
104      "-Wl,-z,nocopyreloc",
105    ]
106  }
107
108  if (!is_ohos) {
109    # See the rpath_for... config above for why this is necessary for component
110    # builds.
111    if (is_component_build) {
112      configs = [ ":rpath_for_built_shared_libraries" ]
113    }
114  }
115
116  if (!is_ohos && current_os != "aix") {
117    # Find the path containing shared libraries for this toolchain
118    # relative to the build directory. ${root_out_dir} will be a
119    # subdirectory of ${root_build_dir} when cross compiling.
120    _rpath_link = rebase_path(root_out_dir, root_build_dir)
121    ldflags += [
122      "-Wl,-rpath-link=$_rpath_link",
123
124      # Newer binutils don't set DT_RPATH unless you disable "new" dtags
125      # and the new DT_RUNPATH doesn't work without --no-as-needed flag.
126      "-Wl,--disable-new-dtags",
127    ]
128  }
129}
130