qt5base-lts/mkspecs/macx-ios-clang/rename_main.sh
Tor Arne Vestbø b52b5fa082 iOS: Gracefully fail main()-renaming when link-time optimizations are enabled
We don't have a way to rename main() inside a LLVM bit-code file yet, so we
error out if we detect that LTO is enabled (which causes object files to be
written as LLVM bit-code), and inform the user about a workaround.

Task-number: QTBUG-40184
Change-Id: I89c927a3a7f075c65e54442c4f7e6bb25175b6f7
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>
2014-07-23 13:46:44 +02:00

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#!/bin/bash
#############################################################################
##
## Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
## Contact: http://www.qt-project.org/legal
##
## This file is the build configuration utility of the Qt Toolkit.
##
## $QT_BEGIN_LICENSE:LGPL$
## Commercial License Usage
## Licensees holding valid commercial Qt licenses may use this file in
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## use the contact form at http://qt.digia.com/contact-us.
##
## GNU Lesser General Public License Usage
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## General Public License version 2.1 as published by the Free Software
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## packaging of this file. Please review the following information to
## ensure the GNU Lesser General Public License version 2.1 requirements
## will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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## rights. These rights are described in the Digia Qt LGPL Exception
## version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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## GNU General Public License Usage
## Alternatively, this file may be used under the terms of the GNU
## General Public License version 3.0 as published by the Free Software
## Foundation and appearing in the file LICENSE.GPL included in the
## packaging of this file. Please review the following information to
## ensure the GNU General Public License version 3.0 requirements will be
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##
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## $QT_END_LICENSE$
##
#############################################################################
if [ $# -eq 0 ]; then
echo "usage: $0 <path to object files>"
else
for f in $(find $1 -name '*.o'); do
# Skip object files without the _main symbol
nm $f 2>/dev/null | grep -q 'T _main$' || continue
fname=${f#$1/}
file -b $f | grep -qi 'llvm bit-code' && \
(cat \
<<EOF >&2
$f:: error: The file '$fname' contains LLVM bitcode, not object code. Automatic main() redirection could not be applied.
note: This is most likely due to the use of link-time optimization (-flto). Please disable LTO, or work around the \
issue by manually renaming your main() function to qtmn():
#ifdef Q_OS_IOS
extern "C" int qtmn(int argc, char *argv[])
#else
int main(int argc, char *argv[])
#endif
EOF
) && exit 1
echo "Found main() in $fname"
strings -t d - $f | grep '_main\(\.eh\)\?$' | while read match; do
offset=$(echo $match | cut -d ' ' -f 1)
symbol=$(echo $match | cut -d ' ' -f 2)
echo " Renaming '$symbol' at offset $offset to '${symbol/main/qtmn}'"
# In-place rename the string (keeping the same length)
printf '_qtmn' | dd of=$f bs=1 seek=$offset conv=notrunc >/dev/null 2>&1
done
done
fi