Android ndk-build 源碼分析

一、可以利用如下命令

bash -x ndk-build根據調試信息來分析

二、

PROGDIR=`dirname $0`
PROGDIR=`cd $PROGDIR && pwd`
# Check if absolute NDK path contain space
#
case $PROGDIR in
    *\ *) echo "ERROR: NDK path cannot contain space"
          exit 1
        ;;
esac

# If NDK_LOG is set to 1 or true in the environment, or the command-line
# then enable log messages below
# Also normalize NDK_HOST_32BIT and NDK_ANALYZE to 1 or 0
if [ -z "$NDK_LOG" ]; then
  NDK_LOG=0
fi

if [ -z "$NDK_HOST_32BIT" ]; then
  NDK_HOST_32BIT=0
fi

if [ -z "$NDK_ANALYZE" ]; then
  NDK_ANALYZE=0
fi

PROGDIR為/home/jltxgcy/android-ndk-r8e

然後檢查這個目錄是否有空格

如果下面的變量長度為0，則都賦值為0

PROJECT_PATH=
PROJECT_PATH_NEXT=
for opt; do
    if [ -z "$PROJECT_PATH" -a "$PROJECT_PATH_NEXT" = "yes" ] ; then
        PROJECT_PATH=$opt
        PROJECT_PATH_NEXT=
    else
        case $opt in
          NDK_LOG=1|NDK_LOG=true)
            NDK_LOG=1
            ;;
          NDK_LOG=*)
            NDK_LOG=0
            ;;
          NDK_HOST_32BIT=1|NDK_HOST_32BIT=true)
            NDK_HOST_32BIT=1
            ;;
          NDK_HOST_32BIT=*)
            NDK_HOST_32BIT=0
            ;;
          NDK_ANALYZE=1|NDK_ANALYZE=true)
            NDK_ANALYZE=1
            ;;
          NDK_ANALYZE=*)
            NDK_ANALYZE=0
            ;;
          NDK_TOOLCHAIN_VERSION=*)
            NDK_TOOLCHAIN_VERSION=${opt#NDK_TOOLCHAIN_VERSION=}
            ;;
          APP_ABI=*)
            APP_ABI=${opt#APP_ABI=}
            ;;
          -C)
            PROJECT_PATH_NEXT="yes"
            ;;
        esac
    fi
done

此段代碼沒有執行，暫不分析

if [ "$NDK_LOG" = "true" ]; then
  NDK_LOG=1
fi

if [ "$NDK_HOST_32BIT" = "true" ]; then
  NDK_HOST_32BIT=1
fi

if [ "$NDK_ANALYZE" = "true" ]; then
  NDK_ANALYZE=1
fi

if [ "$NDK_LOG" = "1" ]; then
  log () {
    echo "$@"
  }
else
  log () {
    : # nothing
  }
fi

此段代碼均為假，不執行

# Detect host operating system and architecture
# The 64-bit / 32-bit distinction gets tricky on Linux and Darwin because
# uname -m returns the kernel's bit size, and it's possible to run with
# a 64-bit kernel and a 32-bit userland.
#
HOST_OS=$(uname -s)
case $HOST_OS in
  Darwin) HOST_OS=darwin;;
  Linux) HOST_OS=linux;;
  FreeBsd) HOST_OS=freebsd;;
  CYGWIN*|*_NT-*) HOST_OS=cygwin;;
  *) echo "ERROR: Unknown host operating system: $HOST_OS"
     exit 1
esac
log "HOST_OS=$HOST_OS"

HOST_OS為Linux，所以HOST_OS為linux

HOST_ARCH=$(uname -m)
case $HOST_ARCH in
    i?86) HOST_ARCH=x86;;
    x86_64|amd64) HOST_ARCH=x86_64;;
    *) echo "ERROR: Unknown host CPU architecture: $HOST_ARCH"
       exit 1
esac
log "HOST_ARCH=$HOST_ARCH"

HOST_ARCH為x86_64

# Detect 32-bit userland on 64-bit kernels
HOST_TAG="$HOST_OS-$HOST_ARCH"
case $HOST_TAG in
  linux-x86_64|darwin-x86_64)
    # we look for x86_64 or x86-64 in the output of 'file' for our shell
    # the -L flag is used to dereference symlinks, just in case.
    file -L "$SHELL" | grep -q "x86[_-]64"
    if [ $? != 0 ]; then
      HOST_ARCH=x86
      log "HOST_ARCH=$HOST_ARCH (32-bit userland detected)"
    fi
    ;;
esac

檢查file -L "$SHELL" | grep -q "x86[_-]64"是否正確，如果不正確，那麼HOST_ARCH為x86

# Check that we have 64-bit binaries on 64-bit system, otherwise fallback
# on 32-bit ones. This gives us more freedom in packaging the NDK.
LOG_MESSAGE=
if [ $HOST_ARCH = x86_64 ]; then
  if [ ! -d $PROGDIR/prebuilt/$HOST_TAG ]; then
    HOST_ARCH=x86
    LOG_MESSAGE="(no 64-bit prebuilt binaries detected)"
  fi

  if [ "$NDK_HOST_32BIT" = "1" ]; then
    HOST_ARCH=x86
    LOG_MESSAGE="(force 32-bit host toolchain)"
  fi
fi

如果/home/jltxgcy/android-ndk-r8e/prebuilt/linux-x86_64不存在，那麼HOST_ARCH為x86

# If GNUMAKE is defined, check that it points to a valid file
if [ -n "$GNUMAKE" ] ; then
    ABS_GNUMAKE=`which $GNUMAKE 2> /dev/null`
    if [ $? != 0 ] ; then
        echo "ERROR: Your GNUMAKE variable is defined to an invalid name: $GNUMAKE"
        echo "Please fix it to point to a valid make executable (e.g. /usr/bin/make)"
        exit 1
    fi
    GNUMAKE="$ABS_GNUMAKE"
    log "GNUMAKE=$GNUMAKE (from environment variable)"
else
    # Otherwise use the prebuilt version for our host tag, if it exists
    # Note: we intentionally do not provide prebuilt make binaries for Cygwin
    # or MSys.
    GNUMAKE=$PROGDIR/prebuilt/$HOST_TAG/bin/make
    if [ ! -f "$GNUMAKE" ]; then
        # Otherwise, use 'make' and check that it is available
        GNUMAKE=`which make 2> /dev/null`
        if [ $? != 0 ] ; then
            echo "ERROR: Cannot find 'make' program. Please install Cygwin make package"
            echo "or define the GNUMAKE variable to point to it."
            exit 1
        fi
        log "GNUMAKE=$GNUMAKE (system path)"
    else
        log "GNUMAKE=$GNUMAKE (NDK prebuilt)"
    fi
fi

GNUMAKE長度為0，進入else，/home/jltxgcy/android-ndk-r8e/prebuilt/linux-x86_64/bin/make是否存在，如果存在，GNUMAKE就是它了。如果不存在，利用which make查找系統的make。

# On Windows, when running under cygwin, check that we are
# invoking a cygwin-compatible GNU Make binary. It is unfortunately
# common for app developers to have another non cygwin-compatible
# 'make' program in their PATH.
#
if [ "$OSTYPE" = "cygwin" ] ; then
    GNUMAKE=`cygpath -u $GNUMAKE`
    PROGDIR_MIXED=`cygpath -m $PROGDIR`
    CYGWIN_GNUMAKE=`$GNUMAKE -f "$PROGDIR_MIXED/build/core/check-cygwin-make.mk" 2>&1`
    if [ $? != 0 ] ; then
        echo "ERROR: You are using a non-Cygwin compatible Make program."
        echo "Currently using: `cygpath -m $GNUMAKE`"
        echo ""
        echo "To solve the issue, follow these steps:"
        echo ""
        echo "1. Ensure that the Cygwin 'make' package is installed."
        echo "   NOTE: You will need GNU Make 3.81 or later!"
        echo ""
        echo "2. Define the GNUMAKE environment variable to point to it, as in:"
        echo ""
        echo "     export GNUMAKE=/usr/bin/make"
        echo ""
        echo "3. Call 'ndk-build' again."
        echo ""
        exit 1
    fi
    log "Cygwin-compatible GNU make detected"
fi

if [ "$NDK_ANALYZE" = 1 ]; then
    . $PROGDIR/build/tools/dev-defaults.sh  # for DEFAULT_LLVM_VERSION

    # Find perl.  If HOST_PERL is defined, check that it points to a valid file
    HOST_PERL_LIB=
    if [ -n "$HOST_PERL" ] ; then
        ABS_PERL=`which $HOST_PERL 2> /dev/null`
        if [ $? != 0 ] ; then
            echo "ERROR: Your HOST_PERL variable is defined to an invalid name: $HOST_PERL"
            echo "Please fix it to point to a valid perl executable (e.g. /usr/bin/perl)"
            exit 1
        fi
        HOST_PERL="$ABS_PERL"
        log "HOST_PERL=$HOST_PERL (from environment variable)"
    else
        # Otherwise use the prebuilt version for our host tag
        HOST_PERL="$PROGDIR/prebuilt/$HOST_TAG/bin/perl"
        if [ ! -f "$HOST_PERL" ]; then
            # Otherwise, use 'perl' and check that it is available
            HOST_PERL=`which perl 2> /dev/null`
            if [ $? != 0 ] ; then
                echo "ERROR: Cannot find 'perl' program. Please install perl package"
                echo "or define the HOST_PERL variable to point to it."
                exit 1
            fi
            log "HOST_PERL=$HOST_PERL (system path)"
        else
            HOST_PERL_LIB="$PROGDIR/prebuilt/$HOST_TAG/lib/perl5"
            log "HOST_PERL=$HOST_PERL (NDK prebuilt)"
        fi
    fi

    # Return flags send in env. or command line which are enough to retrive APP_ABI and TOOLCHAIN_PREFIX later
    gen_flags ()
    {
        local FLAGS=

        if [ -n "$PROJECT_PATH" ] ; then
            FLAGS=$FLAGS" -C $PROJECT_PATH"
        fi
        if [ -n "$APP_ABI" ] ; then
            FLAGS=$FLAGS" APP_ABI=$APP_ABI"
        fi
        if [ -n "$NDK_HOST_32BIT" ] ; then
            FLAGS=$FLAGS" NDK_HOST_32BIT=$NDK_HOST_32BIT"
        fi
        if [ -n "$NDK_TOOLCHAIN_VERSION" ] ; then
            FLAGS=$FLAGS" NDK_TOOLCHAIN_VERSION=$NDK_TOOLCHAIN_VERSION"
        fi
        echo "$FLAGS"
    }

    get_build_var ()
    {
        local VAR=$1
        local FLAGS=`gen_flags`
        $GNUMAKE --no-print-dir -f $PROGDIR/build/core/build-local.mk $FLAGS DUMP_${VAR} | tail -1
    }

    get_build_var_for_abi ()
    {
        local VAR=$1
        local ABI=$2
        local FLAGS=`gen_flags`
        $GNUMAKE --no-print-dir -f $PROGDIR/build/core/build-local.mk $FLAGS DUMP_${VAR} APP_ABI=${ABI} | tail -1
    }

    APP_ABIS=`get_build_var APP_ABI`
    for ABI in $APP_ABIS; do
        TOOLCHAIN_PREFIX=`get_build_var_for_abi TOOLCHAIN_PREFIX $ABI`
        PERL5LIB="$HOST_PERL_LIB" "$HOST_PERL" $PROGDIR/prebuilt/common/scan-build/scan-build \
            --use-analyzer $PROGDIR/toolchains/llvm-${DEFAULT_LLVM_VERSION}/prebuilt/$HOST_TAG/bin/${ABI}/analyzer \
            --use-cc ${TOOLCHAIN_PREFIX}gcc \
            --use-c++ ${TOOLCHAIN_PREFIX}g++ \
            --status-bugs -v -v \
            $GNUMAKE -f $PROGDIR/build/core/build-local.mk "$@" APP_ABI=$ABI
    done
else
    $GNUMAKE -f $PROGDIR/build/core/build-local.mk "$@"
fi

此段代碼只執行最後一句，/home/jltxgcy/android-ndk-r8e/prebuilt/linux-x86_64/bin/make /home/jltxgcy/android-ndk-r8e/build/core/build-local.mk