解决的timespec的重新定义在time.h中 [英] resolving redefinition of timespec in time.h

问题描述

我写一个程序，它包括 /usr/include/linux/time.h 和 /usr/include/stdlib.h。

I am writing a program which includes both /usr/include/linux/time.h and /usr/include/stdlib.h.

问题是：

文件stdlib.h 包括 /usr/include/time.h ，它定义了结构的timespec 和 /usr/include/linux/time.h 还定义了一个。这就引入了重新定义的编译错误。

stdlib.h includes /usr/include/time.h, which defines 'struct timespec', and /usr/include/linux/time.h also defines one. This introduces a compilation error of redefinition.

我检查'结构的timespec的定义，在这两个头文件：

I've examined the definitions of 'struct timespec' in these two header files:

在/usr/include/time.h：

in /usr/include/time.h:

struct timespec
{
    __time_t tv_sec;            /* Seconds.  */
    long int tv_nsec;           /* Nanoseconds.  */
};

在/usr/include/linux/time.h：

in /usr/include/linux/time.h:

struct timespec {
    __kernel_time_t tv_sec;                 /* seconds */
    long            tv_nsec;                /* nanoseconds */
}; 

看来，这些定义确实等价的，但我不能证明这一点。

It seems that these definitions are indeed equivalent, but I can't prove it.

我的问题是：有没有解决这个重新定义一个可靠的方法。

My question is: is there a robust way to resolve this redefinition?

其他有关这个问题的讨论也非常AP preciated。谢谢你。

Links to discussions on this problem are also highly appreciated. Thanks.

推荐答案

要解决双重定义错误的一种方法是重命名这些定义之一：

One way to resolve the double-definition error is to rename one of these definitions:

#include <time.h>
#define timespec linux_timespec
#include <linux/time.h>
#undef timespec

和则断言在编译时，这两个定义具有相同的布局：

And then assert at compile time that both definitions have the same layout:

typedef int assert_same_size[sizeof(struct linux_timespec) == sizeof(timespec) ? 1 : -1];
typedef int assert_same_alignment[__alignof(struct linux_timespec) == __alignof(timespec) ? 1 : -1];
typedef int assert_same_tv_sec[offsetof(struct linux_timespec, tv_sec) == offsetof(struct timespec, tv_sec) ? 1 : -1];
typedef int assert_same_tv_nsec[offsetof(struct linux_timespec, tv_nsec) == offsetof(struct timespec, tv_nsec) ? 1 : -1];

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