LevelDB-course-Lab/build_detect_platform

#!/bin/sh
#
# Detects OS we're compiling on and outputs a file specified by the first
# argument, which in turn gets read while processing Makefile.
#
# The output will set the following variables:
#   PLATFORM_LDFLAGS            Linker flags
#   PLATFORM_SHARED_EXT         Extension for shared libraries
#   PLATFORM_SHARED_LDFLAGS     Flags for building shared library
#   PLATFORM_SHARED_CFLAGS      Flags for compiling objects for shared library
#   PLATFORM_CCFLAGS            C compiler flags
#   PLATFORM_CXXFLAGS           C++ compiler flags.  Will contain:
#       -DLEVELDB_PLATFORM_POSIX if cstdatomic is present
#       -DLEVELDB_PLATFORM_NOATOMIC if it is not

OUTPUT=$1
if test -z "$OUTPUT"; then
  echo "usage: $0 <output-filename>"
  exit 1
fi

# Delete existing output, if it exists
rm -f $OUTPUT
touch $OUTPUT

if test -z "$CXX"; then
    CXX=g++
fi

# Detect OS
if test -z "$TARGET_OS"; then
    TARGET_OS=`uname -s`
fi

COMMON_FLAGS=
PLATFORM_CCFLAGS=
PLATFORM_CXXFLAGS=
PLATFORM_LDFLAGS=
PLATFORM_SHARED_EXT="so"
PLATFORM_SHARED_LDFLAGS="-shared -Wl,-soname -Wl,"
PLATFORM_SHARED_CFLAGS="-fPIC"

# On GCC, we pick libc's memcmp over GCC's memcmp via -fno-builtin-memcmp
case "$TARGET_OS" in
    Darwin)
        PLATFORM=OS_MACOSX
        COMMON_FLAGS="-fno-builtin-memcmp -DOS_MACOSX"
        PLATFORM_SHARED_EXT=dylib
        PLATFORM_SHARED_LDFLAGS="-dynamiclib -install_name "
        PORT_FILE=port/port_posix.cc
        ;;
    Linux)
        PLATFORM=OS_LINUX
        COMMON_FLAGS="-fno-builtin-memcmp -pthread -DOS_LINUX"
        PLATFORM_LDFLAGS="-pthread"
        PORT_FILE=port/port_posix.cc
        ;;
    SunOS)
        PLATFORM=OS_SOLARIS
        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_SOLARIS"
        PLATFORM_LDFLAGS="-lpthread -lrt"
        PORT_FILE=port/port_posix.cc
        ;;
    FreeBSD)
        PLATFORM=OS_FREEBSD
        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_FREEBSD"
        PLATFORM_LDFLAGS="-lpthread"
        PORT_FILE=port/port_posix.cc
        ;;
    NetBSD)
        PLATFORM=OS_NETBSD
        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_NETBSD"
        PLATFORM_LDFLAGS="-lpthread -lgcc_s"
        PORT_FILE=port/port_posix.cc
        ;;
    OpenBSD)
        PLATFORM=OS_OPENBSD
        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_OPENBSD"
        PLATFORM_LDFLAGS="-pthread"
        PORT_FILE=port/port_posix.cc
        ;;
    DragonFly)
        PLATFORM=OS_DRAGONFLYBSD
        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_DRAGONFLYBSD"
        PLATFORM_LDFLAGS="-lpthread"
        PORT_FILE=port/port_posix.cc
        ;;
    OS_ANDROID_CROSSCOMPILE)
        PLATFORM="$TARGET_OS"
        COMMON_FLAGS=""
        PLATFORM_LDFLAGS=""
        PORT_FILE=port/port_android.cc
        ;;
    *)
        echo "Unknown platform!"
        exit 1
esac

# We want to make a list of all cc files within util, db, table, and helpers
# except for the test and benchmark files. By default, find will output a list
# of all files matching either rule, so we need to append -print to make the
# prune take effect.
DIRS="util db table"
set -f # temporarily disable globbing so that our patterns aren't expanded
PRUNE_TEST="-name *test*.cc -prune"
PRUNE_BENCH="-name *_bench.cc -prune"
PORTABLE_FILES=`find $DIRS $PRUNE_TEST -o $PRUNE_BENCH -o -name '*.cc' -print | sort | tr "\n" " "`
set +f # re-enable globbing

# The sources consist of the portable files, plus the platform-specific port
# file.
echo "SOURCES=$PORTABLE_FILES $PORT_FILE" >> $OUTPUT
echo "MEMENV_SOURCES=helpers/memenv/memenv.cc" >> $OUTPUT

if [ "$PLATFORM" = "OS_ANDROID_CROSSCOMPILE" ]; then
    # Cross-compiling; do not try any compilation tests.
    true
else
    # If -std=c++0x works, use <cstdatomic>.  Otherwise use port_posix.h.
    $CXX $CFLAGS -std=c++0x -x c++ - -o /dev/null 2>/dev/null  <<EOF
      #include <cstdatomic>
      int main() {}
EOF
    if [ "$?" = 0 ]; then
        COMMON_FLAGS="$COMMON_FLAGS -DLEVELDB_PLATFORM_POSIX -DLEVELDB_CSTDATOMIC_PRESENT"
        PLATFORM_CXXFLAGS="-std=c++0x"
    else
        COMMON_FLAGS="$COMMON_FLAGS -DLEVELDB_PLATFORM_POSIX"
    fi

    # Test whether Snappy library is installed
    # http://code.google.com/p/snappy/
    $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
      #include <snappy.h>
      int main() {}
EOF
    if [ "$?" = 0 ]; then
        COMMON_FLAGS="$COMMON_FLAGS -DSNAPPY"
        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lsnappy"
    fi

    # Test whether tcmalloc is available
    $CXX $CFLAGS -x c++ - -o /dev/null -ltcmalloc 2>/dev/null  <<EOF
      int main() {}
EOF
    if [ "$?" = 0 ]; then
        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -ltcmalloc"
    fi
fi

PLATFORM_CCFLAGS="$PLATFORM_CCFLAGS $COMMON_FLAGS"
PLATFORM_CXXFLAGS="$PLATFORM_CXXFLAGS $COMMON_FLAGS"

echo "PLATFORM=$PLATFORM" >> $OUTPUT
echo "PLATFORM_LDFLAGS=$PLATFORM_LDFLAGS" >> $OUTPUT
echo "PLATFORM_CCFLAGS=$PLATFORM_CCFLAGS" >> $OUTPUT
echo "PLATFORM_CXXFLAGS=$PLATFORM_CXXFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_CFLAGS=$PLATFORM_SHARED_CFLAGS" >> $OUTPUT
echo "PLATFORM_SHARED_EXT=$PLATFORM_SHARED_EXT" >> $OUTPUT
echo "PLATFORM_SHARED_LDFLAGS=$PLATFORM_SHARED_LDFLAGS" >> $OUTPUT