qt5base-lts/mkspecs/macx-ios-clang/rename_main.sh

#!/bin/bash

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##
## Copyright (C) 2015 The Qt Company Ltd.
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## This file is the build configuration utility of the Qt Toolkit.
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if [ $# -ne 2 ]; then
    echo "$0: wrong number of arguments for internal tool used by iOS mkspec"
else
    arch_paths=""
    for a in $2; do
        arch_paths="$arch_paths $1/$a"
    done
    for f in $(find $arch_paths -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