ndk编译安卓openssl静态库

1、使用编译工具android-ndk-r14b，本来用的android-ndk-r16，虽然编译成功了，但使用的时候链接有错误，error: undefined reference to 'stderr'，百度了一下，有人说是｛源文件里面使用了大量的标准IO设备：stderr 等，在NDK15以后，这些都不被支持了，见https://android.googlesource.com/platform/ndk/+/ndk-r15-release/docs/UnifiedHeaders.md｝，换成r14b后，编译成功，使用时链接也成功。

2、android-ndk-r14b解压到了/root/android-ndk-r14b/，设置环境变量

export ANDROID_NDK_ROOT=/root/android-ndk-r14b

3、cd /root/，下载设置安卓环境的脚本，

wget https://wiki.openssl.org/images/7/70/Setenv-android.sh

脚本内容如下，也可直接复制，

#!/bin/bash
# Cross-compile environment for Android on ARMv7 and x86
#
# Contents licensed under the terms of the OpenSSL license
# http://www.openssl.org/source/license.html
#
# See http://wiki.openssl.org/index.php/FIPS_Library_and_Android
#   and http://wiki.openssl.org/index.php/Android

#####################################################################

# Set ANDROID_NDK_ROOT to you NDK location. For example,
# /opt/android-ndk-r8e or /opt/android-ndk-r9. This can be done in a
# login script. If ANDROID_NDK_ROOT is not specified, the script will
# try to pick it up with the value of _ANDROID_NDK_ROOT below. If
# ANDROID_NDK_ROOT is set, then the value is ignored.
# _ANDROID_NDK="android-ndk-r8e"
_ANDROID_NDK="android-ndk-r14b"
# _ANDROID_NDK="android-ndk-r10"

# Set _ANDROID_EABI to the EABI you want to use. You can find the
# list in $ANDROID_NDK_ROOT/toolchains. This value is always used.
# _ANDROID_EABI="x86-4.6"
#_ANDROID_EABI="aarch64-linux-android-4.9"
_ANDROID_EABI="arm-linux-androideabi-4.9"

# Set _ANDROID_ARCH to the architecture you are building for.
# This value is always used.
# _ANDROID_ARCH=arch-x86
_ANDROID_ARCH=arch-arm

# Set _ANDROID_API to the API you want to use. You should set it
# to one of: android-14, android-9, android-8, android-14, android-5
# android-4, or android-3. You can't set it to the latest (for
# example, API-17) because the NDK does not supply the platform. At
# Android 5.0, there will likely be another platform added (android-22?).
# This value is always used.
# _ANDROID_API="android-14"
_ANDROID_API="android-16"
# _ANDROID_API="android-19"

#####################################################################

# If the user did not specify the NDK location, try and pick it up.
# We expect something like ANDROID_NDK_ROOT=/opt/android-ndk-r8e
# or ANDROID_NDK_ROOT=/usr/local/android-ndk-r8e.

if [ -z "$ANDROID_NDK_ROOT" ]; then

  _ANDROID_NDK_ROOT=""
  if [ -z "$_ANDROID_NDK_ROOT" ] && [ -d "/usr/local/$_ANDROID_NDK" ]; then
    _ANDROID_NDK_ROOT="/usr/local/$_ANDROID_NDK"
  fi

  if [ -z "$_ANDROID_NDK_ROOT" ] && [ -d "/opt/$_ANDROID_NDK" ]; then
    _ANDROID_NDK_ROOT="/opt/$_ANDROID_NDK"
  fi

  if [ -z "$_ANDROID_NDK_ROOT" ] && [ -d "$HOME/$_ANDROID_NDK" ]; then
    _ANDROID_NDK_ROOT="$HOME/$_ANDROID_NDK"
  fi

  if [ -z "$_ANDROID_NDK_ROOT" ] && [ -d "$PWD/$_ANDROID_NDK" ]; then
    _ANDROID_NDK_ROOT="$PWD/$_ANDROID_NDK"
  fi

  # If a path was set, then export it
  if [ ! -z "$_ANDROID_NDK_ROOT" ] && [ -d "$_ANDROID_NDK_ROOT" ]; then
    export ANDROID_NDK_ROOT="$_ANDROID_NDK_ROOT"
  fi
fi

# Error checking
# ANDROID_NDK_ROOT should always be set by the user (even when not running this script)
# http://groups.google.com/group/android-ndk/browse_thread/thread/a998e139aca71d77
if [ -z "$ANDROID_NDK_ROOT" ] || [ ! -d "$ANDROID_NDK_ROOT" ]; then
  echo "Error: ANDROID_NDK_ROOT is not a valid path. Please edit this script."
  # echo "$ANDROID_NDK_ROOT"
  # exit 1
fi

# Error checking
if [ ! -d "$ANDROID_NDK_ROOT/toolchains" ]; then
  echo "Error: ANDROID_NDK_ROOT/toolchains is not a valid path. Please edit this script."
  # echo "$ANDROID_NDK_ROOT/toolchains"
  # exit 1
fi

# Error checking
if [ ! -d "$ANDROID_NDK_ROOT/toolchains/$_ANDROID_EABI" ]; then
  echo "Error: ANDROID_EABI is not a valid path. Please edit this script."
  # echo "$ANDROID_NDK_ROOT/toolchains/$_ANDROID_EABI"
  # exit 1
fi

#####################################################################

# Based on ANDROID_NDK_ROOT, try and pick up the required toolchain. We expect something like:
# /opt/android-ndk-r83/toolchains/arm-linux-androideabi-4.7/prebuilt/linux-x86_64/bin
# Once we locate the toolchain, we add it to the PATH. Note: this is the 'hard way' of
# doing things according to the NDK documentation for Ice Cream Sandwich.
# https://android.googlesource.com/platform/ndk/+/ics-mr0/docs/STANDALONE-TOOLCHAIN.html

ANDROID_TOOLCHAIN=""
for host in "linux-x86_64" "linux-x86" "darwin-x86_64" "darwin-x86"
do
  if [ -d "$ANDROID_NDK_ROOT/toolchains/$_ANDROID_EABI/prebuilt/$host/bin" ]; then
    ANDROID_TOOLCHAIN="$ANDROID_NDK_ROOT/toolchains/$_ANDROID_EABI/prebuilt/$host/bin"
    break
  fi
done

# Error checking
if [ -z "$ANDROID_TOOLCHAIN" ] || [ ! -d "$ANDROID_TOOLCHAIN" ]; then
  echo "Error: ANDROID_TOOLCHAIN is not valid. Please edit this script."
  # echo "$ANDROID_TOOLCHAIN"
  # exit 1
fi

case $_ANDROID_ARCH in
	arch-arm)	  
      ANDROID_TOOLS="arm-linux-androideabi-gcc arm-linux-androideabi-ranlib arm-linux-androideabi-ld"
	  ;;
	arch-x86)	  
      ANDROID_TOOLS="i686-linux-android-gcc i686-linux-android-ranlib i686-linux-android-ld"
	  ;;
	arch-arm64)	  
      ANDROID_TOOLS="aarch64-linux-android-gcc aarch64-linux-android-ranlib aarch64-linux-android-ld"
	  ;;	  
	*)
	  echo "ERROR ERROR ERROR"
	  ;;
esac

for tool in $ANDROID_TOOLS
do
  # Error checking
  if [ ! -e "$ANDROID_TOOLCHAIN/$tool" ]; then
    echo "Error: Failed to find $tool. Please edit this script."
    # echo "$ANDROID_TOOLCHAIN/$tool"
    # exit 1
  fi
done

# Only modify/export PATH if ANDROID_TOOLCHAIN good
if [ ! -z "$ANDROID_TOOLCHAIN" ]; then
  export ANDROID_TOOLCHAIN="$ANDROID_TOOLCHAIN"
  export PATH="$ANDROID_TOOLCHAIN":"$PATH"
fi

#####################################################################

# For the Android SYSROOT. Can be used on the command line with --sysroot
# https://android.googlesource.com/platform/ndk/+/ics-mr0/docs/STANDALONE-TOOLCHAIN.html
export ANDROID_SYSROOT="$ANDROID_NDK_ROOT/platforms/$_ANDROID_API/$_ANDROID_ARCH"
export CROSS_SYSROOT="$ANDROID_SYSROOT"
export NDK_SYSROOT="$ANDROID_SYSROOT"

# Error checking
if [ -z "$ANDROID_SYSROOT" ] || [ ! -d "$ANDROID_SYSROOT" ]; then
  echo "Error: ANDROID_SYSROOT is not valid. Please edit this script."
  # echo "$ANDROID_SYSROOT"
  # exit 1
fi

#####################################################################

# If the user did not specify the FIPS_SIG location, try and pick it up
# If the user specified a bad location, then try and pick it up too.
if [ -z "$FIPS_SIG" ] || [ ! -e "$FIPS_SIG" ]; then

  # Try and locate it
  _FIPS_SIG=""
  if [ -d "/usr/local/ssl/$_ANDROID_API" ]; then
    _FIPS_SIG=`find "/usr/local/ssl/$_ANDROID_API" -name incore`
  fi

  if [ ! -e "$_FIPS_SIG" ]; then
    _FIPS_SIG=`find $PWD -name incore`
  fi

  # If a path was set, then export it
  if [ ! -z "$_FIPS_SIG" ] && [ -e "$_FIPS_SIG" ]; then
    export FIPS_SIG="$_FIPS_SIG"
  fi
fi

# Error checking. Its OK to ignore this if you are *not* building for FIPS
if [ -z "$FIPS_SIG" ] || [ ! -e "$FIPS_SIG" ]; then
  echo "Error: FIPS_SIG does not specify incore module. Please edit this script."
  # echo "$FIPS_SIG"
  # exit 1
fi

#####################################################################

# Most of these should be OK (MACHINE, SYSTEM, ARCH). RELEASE is ignored.
export MACHINE=armv7
export RELEASE=2.6.37
export SYSTEM=android
export ARCH=arm
export CROSS_COMPILE="arm-linux-androideabi-"

if [ "$_ANDROID_ARCH" == "arch-x86" ]; then
	export MACHINE=i686
	export RELEASE=2.6.37
	export SYSTEM=android
	export ARCH=x86
	export CROSS_COMPILE="i686-linux-android-"
fi
if [ "$_ANDROID_ARCH" == "arch-arm64" ]; then
	export MACHINE=aarch64
	export RELEASE=2.6.37
	export SYSTEM=android
	export ARCH=arm64
	export CROSS_COMPILE="aarch64-linux-android-"
fi

# For the Android toolchain
# https://android.googlesource.com/platform/ndk/+/ics-mr0/docs/STANDALONE-TOOLCHAIN.html
export ANDROID_SYSROOT="$ANDROID_NDK_ROOT/platforms/$_ANDROID_API/$_ANDROID_ARCH"
export SYSROOT="$ANDROID_SYSROOT"
export NDK_SYSROOT="$ANDROID_SYSROOT"
export ANDROID_NDK_SYSROOT="$ANDROID_SYSROOT"
export ANDROID_API="$_ANDROID_API"

# CROSS_COMPILE and ANDROID_DEV are DFW (Don't Fiddle With). Its used by OpenSSL build system.
# export CROSS_COMPILE="arm-linux-androideabi-"
export ANDROID_DEV="$ANDROID_NDK_ROOT/platforms/$_ANDROID_API/$_ANDROID_ARCH/usr"
export HOSTCC=gcc

VERBOSE=1
if [ ! -z "$VERBOSE" ] && [ "$VERBOSE" != "0" ]; then
  echo "ANDROID_NDK_ROOT: $ANDROID_NDK_ROOT"
  echo "ANDROID_ARCH: $_ANDROID_ARCH"
  echo "ANDROID_EABI: $_ANDROID_EABI"
  echo "ANDROID_API: $ANDROID_API"
  echo "ANDROID_SYSROOT: $ANDROID_SYSROOT"
  echo "ANDROID_TOOLCHAIN: $ANDROID_TOOLCHAIN"
  echo "FIPS_SIG: $FIPS_SIG"
  echo "CROSS_COMPILE: $CROSS_COMPILE"
  echo "ANDROID_DEV: $ANDROID_DEV"
fi

修改脚本里面的个别变量以匹配我们的环境，

_ANDROID_NDK="android-ndk-r14b"
_ANDROID_EABI="arm-linux-androideabi-4.9"
_ANDROID_API="android-16"

 运行脚本

source ./setenv-android.sh

 如果提示语法错误，可能是脚本的编码不对，执行

dos2unix Setenv-android.sh

脚本运行后会输出

Error: FIPS_SIG does not specify incore module. Please edit this script.
ANDROID_NDK_ROOT: /root/android-ndk-r14b
ANDROID_ARCH: arch-arm
ANDROID_EABI: arm-linux-androideabi-4.9
ANDROID_API: android-16
ANDROID_SYSROOT: /root/android-ndk-r14b/platforms/android-16/arch-arm
ANDROID_TOOLCHAIN: /root/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin
FIPS_SIG: /root/openssl-1.1.0e/util/incore
CROSS_COMPILE: arm-linux-androideabi-
ANDROID_DEV: /root/android-ndk-r14b/platforms/android-16/arch-arm/usr

不用理会FIPS_SIG错误。

4、

# cd /root/openssl-1.0.2p/
配置openssl
# ./config shared no-ssl2 no-ssl3 no-comp no-hw no-engine --openssldir=/tmp/openssl-output --prefix=/tmp/openssl-output
编译
# make depend
# make all
安装
# make install

 

关于 "libcrypto.a(ui_openssl.o):ui_openssl.c:function read_string_inner: error: undefined reference to 'signal' " 报错解决

当你将编译好的 OpenSSL 静态库链接进你的安卓工程时，可能会遇到如下报错

libcrypto.a(ui_openssl.o):ui_openssl.c:function read_string_inner: error: undefined reference to 'signal' 

libcrypto.a(ui_openssl.o):ui_openssl.c:function read_string_inner: error: undefined reference to 'tcsetattr' 

这时你需要使用低版本的 API 重新编译 OpenSSL 静态库，推荐使用 android-16 或以下版本的 API 来重新编译

用低版本 API 编译的副作用是你无法编译出支持 64 位架构的静态库，只能编译出支持 32 位架构的静态库

具体信息可以参考：

https://github.com/openssl/openssl/issues/988

http://stackoverflow.com/questions/37122126/whats-the-exact-significance-of-android-ndk-platform-version-compared-to-api-le