Add tool to namespace Objective-C classes at link time
The feature is enabled by CONFIG += unsupported/objc_namespace, but can be easily integrated into other build systems such as CMake or native Xcode by modifying the LD and LDFLAGS equivalent for each build system. This is a less resource-intensive alternative to using multiple Qt builds with different -qtnamespace settings. Note: The feature is not supported in any way, and should be used with care. Change-Id: Ibb8ba1159db36efd7106c117cc2210c7e2e24784 Reviewed-by: Martin Smith <martin.smith@theqtcompany.com> Reviewed-by: Morten Johan Sørvig <morten.sorvig@theqtcompany.com> Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>
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Tor Arne Vestbø
parent
50489f2e41
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216
mkspecs/features/data/mac/objc_namespace.sh
Executable file
216
mkspecs/features/data/mac/objc_namespace.sh
Executable file
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#!/bin/bash
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#############################################################################
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##
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## Copyright (C) 2015 The Qt Company Ltd.
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## Contact: http://www.qt.io/licensing/
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##
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## This file is the build configuration utility of the Qt Toolkit.
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##
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## $QT_BEGIN_LICENSE:LGPL21$
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## Commercial License Usage
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## Licensees holding valid commercial Qt licenses may use this file in
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## accordance with the commercial license agreement provided with the
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## Software or, alternatively, in accordance with the terms contained in
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## a written agreement between you and The Qt Company. For licensing terms
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## and conditions see http://www.qt.io/terms-conditions. For further
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## information use the contact form at http://www.qt.io/contact-us.
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##
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## GNU Lesser General Public License Usage
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## Alternatively, this file may be used under the terms of the GNU Lesser
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## General Public License version 2.1 or version 3 as published by the Free
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## Software Foundation and appearing in the file LICENSE.LGPLv21 and
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## LICENSE.LGPLv3 included in the packaging of this file. Please review the
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## following information to ensure the GNU Lesser General Public License
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## requirements will be met: https://www.gnu.org/licenses/lgpl.html and
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## http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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##
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## As a special exception, The Qt Company gives you certain additional
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## rights. These rights are described in The Qt Company LGPL Exception
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## version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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##
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## $QT_END_LICENSE$
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##
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#############################################################################
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script_argument_prefix="-Wobjc_namespace,--"
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required_arguments="target suffix original_ld"
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optional_arguments="exclude_list exclude_regex slient"
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for argument in $required_arguments $optional_arguments; do
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declare "$argument="
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done
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declare -i silent=0
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declare -a linker_arguments
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for i in "$@"; do
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case $1 in
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$script_argument_prefix*)
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declare "${1#$script_argument_prefix}"
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;;
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-o)
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if [ -n "$2" ]; then
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target="$2"
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fi
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linker_arguments+=("$1")
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;;
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*)
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linker_arguments+=("$1")
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;;
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esac
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shift
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done
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get_entry() {
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local map=$1 key=$2
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local i="${map}_map_${2}"
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printf '%s' "${!i}"
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}
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error() {
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echo "$0: error: $*" >&2
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exit 1
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}
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for argument in $required_arguments; do
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if [ -z "${!argument}" ]; then
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error "missing argument --${argument}"
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fi
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done
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# Normalize suffix so we can use it as a bash variable
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suffix=${suffix//[-. ]/_}
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link_binary() {
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(PS4=; test $silent -ne 1 && set -x; $original_ld "${linker_arguments[@]}" "$@") 2>&1 || exit 1
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}
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sanitize_address() {
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local address="$1"
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address=${address#0x} # Remove hex prefix
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address=${address: ${#address} < 8 ? 0 : -8} # Limit to 32-bit
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echo "0x$address"
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}
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read_binary() {
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local address=$1
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local length=$2
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dd if="$target" bs=1 iseek=$address count=$length 2>|/dev/null
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}
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read_32bit_value() {
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local address=$1
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read_binary $address 4 | xxd -p | dd conv=swab 2>/dev/null | rev
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}
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inspect_binary() {
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inspect_mode="$1"
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echo -n "🔎 Inspecting binary '$target', "
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if [ ! -f "$target" ]; then
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echo "target does not exist!"
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exit 1
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fi
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read -a mach_header <<< "$(otool -h "$target" -v | tail -n 1)"
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if [ "${mach_header[1]}" != "X86_64" ]; then
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echo "binary is not 64-bit, only 64-bit binaries are supported!"
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exit 1
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fi
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classnames_section="__objc_classname"
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classnames=$(otool -v -s __TEXT $classnames_section "$target" | tail -n +3)
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while read -a classname; do
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address=$(sanitize_address ${classname[0]})
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name=${classname[1]}
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declare "address_to_classname_map_$address=$name"
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declare "classname_to_address_map_$name=$address"
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done <<< "$classnames"
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extra_classnames_file="$(mktemp -t ${classnames_section}_additions).S"
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if [ "$inspect_mode" == "inject_classnames" ]; then
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echo "class names have not been namespaced, adding suffix '$suffix'..."
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printf ".section __TEXT,$classnames_section,cstring_literals,no_dead_strip\n" > $extra_classnames_file
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elif [ "$inspect_mode" == "patch_classes" ]; then
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echo "found namespaced class names, updating class entries..."
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fi
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classes=$(otool -o "$target" | grep class_ro_t)
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while read -a class; do
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address="$(sanitize_address ${class[1]})"
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class_flags="0x$(read_32bit_value $address)"
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if [ -z "$class_flags" ]; then
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echo " 💥 failed to read class flags for class at $address"
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continue
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fi
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is_metaclass=$(($class_flags & 0x1))
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name_offset=$(($address + 24))
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classname_address="0x$(read_32bit_value $name_offset)"
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if [ -z "$classname_address" ]; then
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echo " 💥 failed to read class name address for class at $address"
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continue
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fi
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classname=$(get_entry address_to_classname $classname_address)
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if [ -z "$classname" ]; then
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echo " 💥 failed to resolve class name for address '$classname_address'"
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continue
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fi
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if [[ $exclude_list =~ $classname || $classname =~ $exclude_regex ]]; then
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if [ $is_metaclass -eq 1 ]; then
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class_type="meta class"
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else
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class_type="class"
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fi
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echo " 🚽 skipping excluded $class_type '$classname'"
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continue
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fi
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newclassname="${classname}_${suffix}"
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if [ "$inspect_mode" == "inject_classnames" ]; then
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if [ $is_metaclass -eq 1 ]; then
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continue
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fi
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echo " 💉 injecting $classnames_section entry '$newclassname' for '$classname'"
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printf ".asciz \"$newclassname\"\n" >> $extra_classnames_file
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elif [ "$inspect_mode" == "patch_classes" ]; then
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newclassname_address=$(get_entry classname_to_address ${newclassname})
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if [ -z "$newclassname_address" ]; then
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echo " 💥 failed to resolve class name address for class '$newclassname'"
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continue
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fi
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if [ $is_metaclass -eq 1 ]; then
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class_type="meta"
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else
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class_type="class"
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fi
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echo " 🔨 patching class_ro_t at $address ($class_type) from $classname_address ($classname) to $newclassname_address ($newclassname)"
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echo ${newclassname_address: -8} | rev | dd conv=swab 2>/dev/null | xxd -p -r -seek $name_offset -l 4 - "$target"
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fi
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done <<< "$classes"
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}
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echo "🔩 Linking binary using '$original_ld'..."
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link_binary
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inspect_binary inject_classnames
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echo "🔩 Re-linking binary with extra __objc_classname section..."
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link_binary $extra_classnames_file
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inspect_binary patch_classes
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50
mkspecs/features/mac/unsupported/objc_namespace.prf
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50
mkspecs/features/mac/unsupported/objc_namespace.prf
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#
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# W A R N I N G
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# -------------
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#
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# This file is not part of the Qt API. It exists purely as an
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# implementation detail. It may change from version to version
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# without notice, or even be removed.
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#
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# We mean it.
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#
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# The Objective-C runtime will complain when loading a binary that
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# introduces as class name that already exists in the global namespace.
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# This may happen when linking Qt statically into a plugin, and then
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# loading more than two plugins into the same host, both using Qt.
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#
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# We work around this by doing a bit of post-processing on the final
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# binary, adding new suffixed class name entries to the __objc_classname
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# section of the __TEXT segment, and then patching the class_ro_t
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# entries to point to the newly added class names.
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#
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# By linking the binary between these two steps we avoid having to
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# manually remap all the offsets in the Mach-O binary due to the
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# added class names, instead relying on the linker to do this
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# for us by linking in an assembly file with the added names.
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objc_namespace_script = $$clean_path($$PWD/../../data/mac/objc_namespace.sh)
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isEmpty(QMAKE_OBJC_NAMESPACE_SUFFIX) {
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QMAKE_OBJC_NAMESPACE_SUFFIX = $$TARGET
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!isEmpty(QMAKE_TARGET_BUNDLE_PREFIX): \
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QMAKE_OBJC_NAMESPACE_SUFFIX = $${QMAKE_TARGET_BUNDLE_PREFIX}.$${QMAKE_OBJC_NAMESPACE_SUFFIX}
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}
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QMAKE_LFLAGS += \
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-Wobjc_namespace,--target=$$shell_quote($$TARGET) \
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-Wobjc_namespace,--suffix=$$shell_quote($$QMAKE_OBJC_NAMESPACE_SUFFIX) \
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-Wobjc_namespace,--original_ld=$$shell_quote($$QMAKE_LINK)
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!isEmpty(QMAKE_OBJC_NAMESPACE_EXCLUDE): \
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QMAKE_LFLAGS += -Wobjc_namespace,--exclude_list=$$shell_quote($$QMAKE_OBJC_NAMESPACE_EXCLUDE)
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!isEmpty(QMAKE_OBJC_NAMESPACE_EXCLUDE_REGEX) {
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equals(MAKEFILE_GENERATOR, UNIX): \
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QMAKE_OBJC_NAMESPACE_EXCLUDE_REGEX ~= s/\\$/\$\$/
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QMAKE_LFLAGS += -Wobjc_namespace,--exclude_regex=$$shell_quote($$QMAKE_OBJC_NAMESPACE_EXCLUDE_REGEX)
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}
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slient: QMAKE_LFLAGS += -Wobjc_namespace,--silent=1
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QMAKE_LINK = $$objc_namespace_script
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