build/config/linux/pkg_config.gni

# Copyright (c) 2013 The Chromium Authors. All rights reserved.
# Copyright (c) 2020-2024 Project CHIP Authors
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#    * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#    * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#    * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# Defines a config specifying the result of running pkg-config for the given
# packages. Put the package names you want to query in the "packages" variable
# inside the template invocation.
#
# You can also add defines via the "defines" variable. This can be useful to
# add this to the config to pass defines that the library expects to get by
# users of its headers.
#
# Example:
#   pkg_config("mything") {
#     packages = [ "mything1", "mything2" ]
#     defines = [ "ENABLE_AWESOME" ]
#   }
#
# You can also use "extra args" to filter out results (see pkg-config.py):
#   extra_args = [ "-v, "foo" ]
#
# To ignore libs and ldflags (only cflags/defines will be set, which is useful
# when doing manual dynamic linking), set:
#   ignore_libs = true
#
# To allow the build to proceed if (any of) the requested packages are absent, set:
#   optional = true
# In this case the resulting config object will be empty.

import("//build_overrides/build.gni")
import("${build_root}/config/sysroot.gni")

declare_args() {
  # A pkg-config wrapper to call instead of trying to find and call the right
  # pkg-config directly. Wrappers like this are common in cross-compilation
  # environments.
  # Leaving it blank defaults to searching PATH for 'pkg-config' and relying on
  # the sysroot mechanism to find the right .pc files.
  pkg_config = ""

  # A optional pkg-config wrapper to use for tools built on the host.
  host_pkg_config = ""

  system_libdir = "lib"
}

pkg_config_script = "${build_root}/config/linux/pkg-config.py"

# Define the args we pass to the pkg-config script for other build files that
# need to invoke it manually.
pkg_config_args = []

if (pkg_config != "") {
  pkg_config_args += [
    "-p",
    pkg_config,
  ]
}

if (host_pkg_config != "") {
  host_pkg_config_args = [
    "-p",
    host_pkg_config,
  ]
} else {
  host_pkg_config_args = pkg_config_args
}

if (sysroot != "") {
  pkg_config_args += [
    "-s",
    sysroot,
  ]

  if (system_libdir != "") {
    pkg_config_args += [
      "--system_libdir",
      system_libdir,
    ]
  }
}

template("pkg_config") {
  assert(defined(invoker.packages),
         "Variable |packages| must be defined to be a list in pkg_config.")
  config(target_name) {
    if (host_toolchain == current_toolchain) {
      args = host_pkg_config_args + invoker.packages
    } else {
      args = pkg_config_args + invoker.packages
    }
    if (defined(invoker.optional) && invoker.optional) {
      args += [ "-o" ]
    }
    if (defined(invoker.extra_args)) {
      args += invoker.extra_args
    }

    # pkgresult = [present, includes, cflags, libs, lib_dirs]
    pkgresult = exec_script(pkg_config_script, args, "value")
    if (pkgresult[0]) {
      cflags = pkgresult[2]

      foreach(include, pkgresult[1]) {
        cflags += [ "-I$include" ]
      }

      if (!defined(invoker.ignore_libs) || !invoker.ignore_libs) {
        libs = pkgresult[3]
        lib_dirs = pkgresult[4]
      }

      # Link libraries statically for OSS-Fuzz fuzzer build
      if (oss_fuzz) {
        # Output libs needed for static linking (direct + transitive/non-direct libs), we will re-execute the script to get those libs
        args += [ "--static" ]
        pkgresult_static = exec_script(pkg_config_script, args, "value")
        libs = []
        ldflags = [ "-Wl,-Bstatic" ]
        foreach(lib, pkgresult_static[3]) {
          # dl(dynamic loading) lib is not needed for linking statically and its presence triggers errors.
          # example of errors:
          #   ld.lld: error: undefined symbol: __dlsym
          #   >>> referenced by dlsym.o:(dlsym) in archive /lib/x86_64-linux-gnu/libdl.a
          if (lib != "dl") {
            ldflags += [ "-l$lib" ]
          }
        }
        ldflags += [ "-Wl,-Bdynamic" ]
        lib_dirs = pkgresult[4]
      }

      forward_variables_from(invoker, [ "defines" ])
    }
  }

  # Always forward visibility
  forward_variables_from(invoker, [ "visibility" ])
}