c - 什么是nameser_compat.h，为什么不包括在内？

Question

我正在尝试获取一些代码来编译，这些代码试图在 nameser_compat.h 头文件中使用一些定义。如果设置了某些 BIND 兼容性，则该文件显然包含在 nameser.h 中。

我正在尝试在 OSX 上编译，但显然未设置此值，因为它没有将文件拉入。除了 nameser.h 之外，我是否应该手动将 nameser_compat.h 导入到我的代码中？

Answer 1

在我的 Mac OS X 10.7.4 机器上，我可以找到三个相关的文件：

/usr/include/arpa/nameser.h
/usr/include/arpa/nameser_compat.h
/usr/include/nameser.h

我采用了这段微不足道的代码（在文件中xx.c）：

#include <nameser.h>
int main(void) { return 0; }

并像这样编译它以获得显示的输出：

$ /usr/bin/gcc -O3 -g -std=c99 -Wall -Wextra -DBIND_8_COMPAT -H -c xx.c
. /usr/include/nameser.h
.. /usr/include/arpa/nameser_compat.h
... /usr/include/machine/endian.h
.... /usr/include/i386/endian.h
..... /usr/include/sys/cdefs.h
...... /usr/include/sys/_symbol_aliasing.h
...... /usr/include/sys/_posix_availability.h
..... /usr/include/sys/_endian.h
...... /usr/include/libkern/_OSByteOrder.h
....... /usr/include/sys/_types.h
........ /usr/include/machine/_types.h
......... /usr/include/i386/_types.h
....... /usr/include/libkern/i386/_OSByteOrder.h
.. /usr/include/sys/param.h
... /usr/include/sys/types.h
.... /usr/include/sys/appleapiopts.h
.... /usr/include/machine/types.h
..... /usr/include/i386/types.h
...... /usr/include/i386/_types.h
.... /usr/include/sys/_structs.h
... /usr/include/sys/syslimits.h
... /usr/include/machine/param.h
.... /usr/include/i386/param.h
..... /usr/include/i386/_param.h
... /usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/include/limits.h
.... /usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/include/syslimits.h
.... /Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/include/limits.h
..... /Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/include/syslimits.h
..... /usr/include/limits.h
...... /usr/include/machine/limits.h
....... /usr/include/i386/limits.h
........ /usr/include/i386/_limits.h
... /usr/include/sys/signal.h
.... /usr/include/machine/signal.h
..... /usr/include/i386/signal.h
...... /usr/include/i386/_structs.h
.... /usr/include/sys/_structs.h
..... /usr/include/machine/_structs.h
...... /usr/include/i386/_structs.h
....... /usr/include/mach/i386/_structs.h
Multiple include guards may be useful for:
/usr/include/sys/_symbol_aliasing.h
$

这表明使用-DBIND_8_COMPATset，nameser_compat.h包含标题。源代码显示这是预期的：

#ifndef _NAMESER_9_H_
#define _NAMESER_9_H_

#ifdef BIND_8_COMPAT
#include <arpa/nameser_compat.h>
#endif