如何使用autoconf检查POSIX一致性

问题描述

我的项目遵循 POSIX.1-2008 标准，并且我想确保用户的实现符合该标准.

My project follows the POSIX.1-2008 standard and I would like to ensure that the user's implementation conforms to this standard.

到目前为止，我一直在使用 AC_DEFINE 定义 _POSIX_C_SOURCE 宏.

So far I've been using AC_DEFINE to define the _POSIX_C_SOURCE macro as specified in the POSIX standard.

AC_DEFINE([_POSIX_C_SOURCE], [200809L], [Define the POSIX version])

但是，由于这是一个简单的C预处理器 #define 宏，因此它无济于事，无法阻止不符合POSIX的实现编译.

However, since this is a simple C preprocessor #define macro , it does nothing to prevent an implementation that isn't POSIX-compliant from compiling.

Autoconf 是否提供标准宏来检查实现是否符合特定POSIX标准?

Does Autoconf offer a standard macro to check for the implementation's conformance to a specific POSIX standard?

推荐答案

要可移植地检查用户的实现是否符合特定的POSIX标准，请使用 AC_EGREP_CPP 来检查 _POSIX_VERSION :

To portably check if the user's implementation conforms to a specific POSIX standard, use AC_EGREP_CPP to check the existence and value of _POSIX_VERSION:

AC_EGREP_CPP(posix_200809L_supported,
             [#define _POSIX_C_SOURCE 200809L
              #include <unistd.h>
              #ifdef _POSIX_VERSION
              #if _POSIX_VERSION == 200809L
              posix_200809L_supported
              #endif
              #endif
             ],
             [],
             [AC_MSG_FAILURE([*** Implementation must conform to the POSIX.1-2008 standard.])]
)

这是由于POSIX做出的一些保证.

This works due to several guarantees made by POSIX.

我们首先将 _POSIX_C_SOURCE 设置为 200809L .

#define _POSIX_C_SOURCE 200809L

POSIX.1-2008 指出，当应用程序包含 POSIX.1-2008 描述的标头时，以及此功能测试宏时( _POSIX_C_SOURCE )定义为具有值 200809L ，然后 POSIX.1-2008要求在包含标头时显示的所有符号都应可见 .

POSIX.1-2008 states that when an application includes a header described by POSIX.1-2008, and when this feature test macro (_POSIX_C_SOURCE) is defined to have the value 200809L, then all symbols required by POSIX.1-2008 to appear when the header is included shall be made visible.

因此，当我们在下一行中包含 unistd.h 时， POSIX.1-2008 所需的所有符号将出现在 unistd.h 将可见.

So when we include unistd.h in the next line, all symbols required by POSIX.1-2008 to appear in unistd.h will be made visible.

#include <unistd.h>

自 _POSIX_VERSION 必须显示在 unistd.h 中，现在也可以看到.

Since _POSIX_VERSION is required to appear in unistd.h, it too is now visible.

_POSIX_VERSION 为设置为 200809L 的值.

因此，我们现在要做的就是测试是否定义了 _POSIX_VERSION ，如果已定义，则将其设置为等于 200809L 的值.

So all we have to do now is test if _POSIX_VERSION is defined, and if so, whether it's set to a value equal to 200809L.

#ifdef _POSIX_VERSION
#if _POSIX_VERSION == 200809L

检查是否定义了 _POSIX_VERSION 有助于我们确定实施中是否支持任何 POSIX 标准.检查 _POSIX_VERSION 的值有助于我们缩小是否支持 POSIX 标准的特定版本.

Checking whether _POSIX_VERSION is defined helps us determine if there is support for any POSIX standard on the implementation. Checking the value of _POSIX_VERSION helps us narrow down whether a specific version of the POSIX standard is supported.

如果这两个条件均成立，则该实现几乎可以肯定支持 POSIX.1-2008 .

If both of these conditions are true, then the implementation almost certainly supports POSIX.1-2008.

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