auto/types脚本分析-part11

本节我们主要分析auto/types目录下的4个脚本文件：sizeof脚本,typedef脚本,uintptr_t脚本以及value脚本。

顾名思义，auto/types目录下的这些脚本主要就是处理类型相关的一些工作。

1. auto/types/sizeof脚本

脚本内容如下：

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for $ngx_type size ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_type size

END

ngx_size=

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
#include <sys/time.h>
$NGX_INCLUDE_UNISTD_H
#include <signal.h>
#include <stdio.h>
#include <sys/resource.h>
$NGX_INCLUDE_INTTYPES_H
$NGX_INCLUDE_AUTO_CONFIG_H

int main() {
    printf("%d", (int) sizeof($ngx_type));
    return 0;
}

END


ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT $ngx_feature_libs"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"


if [ -x $NGX_AUTOTEST ]; then
    ngx_size=`$NGX_AUTOTEST`
    echo " $ngx_size bytes"
fi


case $ngx_size in
    4)
        ngx_max_value=2147483647
        ngx_max_len='(sizeof("-2147483648") - 1)'
    ;;

    8)
        ngx_max_value=9223372036854775807LL
        ngx_max_len='(sizeof("-9223372036854775808") - 1)'
    ;;

    *)
        echo
        echo "$0: error: can not detect $ngx_type size"

        echo "----------"    >> $NGX_AUTOCONF_ERR
        cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
        echo $ngx_test       >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR

        rm -rf $NGX_AUTOTEST*

        exit 1
esac


rm -rf $NGX_AUTOTEST*

下面我们对脚本进行分析：

1.1 打印相关提示信息

分别向控制台及autoconf.err文件中打印相应的提示信息：

echo $ngx_n "checking for $ngx_type size ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_type size

END

$ngx_n与$ngx_c我们前面讲述过，主要是为了禁止换行。$ngx_type为当前我们需要检查的数据类型。

1.2 生成并编译程序

ngx_size=

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
#include <sys/time.h>
$NGX_INCLUDE_UNISTD_H
#include <signal.h>
#include <stdio.h>
#include <sys/resource.h>
$NGX_INCLUDE_INTTYPES_H
$NGX_INCLUDE_AUTO_CONFIG_H

int main() {
    printf("%d", (int) sizeof($ngx_type));
    return 0;
}

END


ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT $ngx_feature_libs"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

将ngx_size值置为空，接着生成objs/autotest.c程序，然后编译。这里$NGX_LD_OPT与$ngx_feature_libs值为空.

NGX_INCLUDE_UNISTD_H与NGX_INCLUDE_INTTYPES_H通过在auto/headers脚本调用auto/include分别被设置为了#include<unistd.h>与#include <inttypes.h>。而NGX_INCLUDE_AUTO_CONFIG_H会在auto/unix脚本中根据需要进行设置。

1.3 执行程序，并根据执行结果进行处理

if [ -x $NGX_AUTOTEST ]; then
    ngx_size=`$NGX_AUTOTEST`
    echo " $ngx_size bytes"
fi


case $ngx_size in
    4)
        ngx_max_value=2147483647
        ngx_max_len='(sizeof("-2147483648") - 1)'
    ;;

    8)
        ngx_max_value=9223372036854775807LL
        ngx_max_len='(sizeof("-9223372036854775808") - 1)'
    ;;

    *)
        echo
        echo "$0: error: can not detect $ngx_type size"

        echo "----------"    >> $NGX_AUTOCONF_ERR
        cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
        echo $ngx_test       >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR

        rm -rf $NGX_AUTOTEST*

        exit 1
esac

判断生成的objs/autotest文件是否可执行，可执行的话则执行程序并将结果保存到ngx_size变量中。然后根据ngx_size的值计算出对应的最大值保存在ngx_max_value变量中，最大长度值保存在ngx_max_len变量中。

1.4 删除生成的测试程序

rm -rf $NGX_AUTOTEST*

2. auto/types/typedef脚本

脚本内容如下：

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for $ngx_type ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_type

END

ngx_found=no

for ngx_try in $ngx_type $ngx_types
do

    cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <netinet/in.h>
$NGX_INCLUDE_INTTYPES_H

int main() {
    $ngx_try i = 0;
    return (int) i;
}

END

    ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
              -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT $ngx_feature_libs"

    eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

    if [ -x $NGX_AUTOTEST ]; then
        if [ $ngx_try = $ngx_type ]; then
            echo " found"
            ngx_found=yes
        else
            echo ", $ngx_try used"
            ngx_found=$ngx_try
        fi
    fi

    if [ $ngx_found = no ]; then
        if [ $ngx_try = $ngx_type ]; then
            echo $ngx_n " $ngx_try not found$ngx_c"
        else
            echo $ngx_n ", $ngx_try not found$ngx_c"
        fi

        echo "----------"    >> $NGX_AUTOCONF_ERR
        cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
        echo $ngx_test       >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
    fi

    rm -rf $NGX_AUTOTEST*

    if [ $ngx_found != no ]; then
        break
    fi
done

if [ $ngx_found = no ]; then
    echo
    echo "$0: error: can not define $ngx_type"

    exit 1
fi

if [ $ngx_found != yes ]; then
    echo "typedef $ngx_found  $ngx_type;"   >> $NGX_AUTO_CONFIG_H
fi

2.1 打印相关提示信息

echo $ngx_n "checking for $ngx_type ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_type

END

$ngx_n与$ngx_c我们前面讲述过，主要是为了禁止换行。$ngx_type为当前我们需要检查的数据类型。

2.2 循环检查对应的类型

ngx_found=no

for ngx_try in $ngx_type $ngx_types
do

    cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <netinet/in.h>
$NGX_INCLUDE_INTTYPES_H

int main() {
    $ngx_try i = 0;
    return (int) i;
}

END

    ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
              -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT $ngx_feature_libs"

    eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

    if [ -x $NGX_AUTOTEST ]; then
        if [ $ngx_try = $ngx_type ]; then
            echo " found"
            ngx_found=yes
        else
            echo ", $ngx_try used"
            ngx_found=$ngx_try
        fi
    fi

    if [ $ngx_found = no ]; then
        if [ $ngx_try = $ngx_type ]; then
            echo $ngx_n " $ngx_try not found$ngx_c"
        else
            echo $ngx_n ", $ngx_try not found$ngx_c"
        fi

        echo "----------"    >> $NGX_AUTOCONF_ERR
        cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
        echo $ngx_test       >> $NGX_AUTOCONF_ERR
        echo "----------"    >> $NGX_AUTOCONF_ERR
    fi

    rm -rf $NGX_AUTOTEST*

    if [ $ngx_found != no ]; then
        break
    fi
done

上面循环检查$ngx_type与$ngx_types，尝试找到一个可用的类型。

2.3 后续处理

if [ $ngx_found = no ]; then
    echo
    echo "$0: error: can not define $ngx_type"

    exit 1
fi

if [ $ngx_found != yes ]; then
    echo "typedef $ngx_found  $ngx_type;"   >> $NGX_AUTO_CONFIG_H
fi

如果找到的可用类型不是$ngx_type的话，则用typedef定义之，并将结果写到objs/ngx_auto_config.h头文件中。

3. auto/types/uintptr_t脚本

脚本内容如下：

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for uintptr_t ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for uintptr_t

END

found=no

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
$NGX_INTTYPES_H

int main() {
    uintptr_t i = 0;
    return (int) i;
}

END

ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

if [ -x $NGX_AUTOTEST ]; then
    echo " uintptr_t found"
    found=yes
else
    echo $ngx_n " uintptr_t not found" $ngx_c
fi

rm -rf $NGX_AUTOTEST*


if [ $found = no ]; then
    found="uint`expr 8 \* $ngx_ptr_size`_t"
    echo ", $found used"

    echo "typedef $found  uintptr_t;"                   >> $NGX_AUTO_CONFIG_H
    echo "typedef $found  intptr_t;" | sed -e 's/u//g'  >> $NGX_AUTO_CONFIG_H
fi

下面进行脚本分析：

3.1 打印相关提示信息

echo $ngx_n "checking for uintptr_t ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for uintptr_t

END

$ngx_n与$ngx_c我们前面讲述过，主要是为了禁止换行。

3.2 生成并编译程序

found=no

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
$NGX_INTTYPES_H

int main() {
    uintptr_t i = 0;
    return (int) i;
}

END

ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

NGX_INTTYPES_H在auto/headers脚本调用中被设置:

auto/include脚本如下行：

eval "NGX_$ngx_name='#include <$ngx_include>'"

3.3 执行程序，并根据结果进行处理

if [ -x $NGX_AUTOTEST ]; then
    echo " uintptr_t found"
    found=yes
else
    echo $ngx_n " uintptr_t not found" $ngx_c
fi

rm -rf $NGX_AUTOTEST*


if [ $found = no ]; then
    found="uint`expr 8 \* $ngx_ptr_size`_t"
    echo ", $found used"

    echo "typedef $found  uintptr_t;"                   >> $NGX_AUTO_CONFIG_H
    echo "typedef $found  intptr_t;" | sed -e 's/u//g'  >> $NGX_AUTO_CONFIG_H
fi

判断生成的程序是否可执行，可执行的话将found置为yes，否则会用调用如下语句：

found="uint`expr 8 \* $ngx_ptr_size`_t"

这里$ngx_ptr_size为我们在文章开头auto/types/sizeof脚本求的当前机器字长（在/auto/unix脚本中调用获得）。

然后将found通过typedef的方式定义成uintptr_t并写入到objs/ngx_auto_config.h头文件中。

4. auto/types/value脚本

脚本内容如下：

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $ngx_param
#define $ngx_param  $ngx_value
#endif

END

向objs/ngx_auto_config.h头文件写入相应的宏定义。

Ivanzz

发上等愿，结中等缘，享下等福；择高处立，寻平处住，向宽处行

auto/types脚本分析-part11

1. auto/types/sizeof脚本

1.1 打印相关提示信息

1.2 生成并编译程序

1.3 执行程序，并根据执行结果进行处理

1.4 删除生成的测试程序

2. auto/types/typedef脚本

2.1 打印相关提示信息

2.2 循环检查对应的类型

2.3 后续处理

3. auto/types/uintptr_t脚本

3.1 打印相关提示信息

3.2 生成并编译程序

3.3 执行程序，并根据结果进行处理

4. auto/types/value脚本