使用MinGW 与 MSYS 编译 ffmpeg 的问题说明

本文的目的是记录一下，Windows上搭建MinGW与MSYS开发环境并且编译ffmpeg并进行简单测试的过程中遇见的奇怪问题。

从MinGW官网http://www.mingw.org，下载并安装mingw

安装项：

Basic Setup
mingw-developer-toolkit Version:2013072300
mingw32-base Version:2013072200
msys-base Version:2013072300

特意记录一下unistd.h所在的包：

mingw-mingwrt dev3.21

应该是存在问题的.

将MSYS/etc/fstab.sample 复制一份叫fstab，并且fstab内c:mingw改为自己的mingw安装目录

打开MSYS，进入ffmpeg所在目录，并且进行configure --disable-all

然后make

出错：


分析了一下出错的地方，发现是_cdecl这个宏的问题，搜索了一下MinGW的所有代码，发现这个宏是在windef.h中定义的，而且只在几处地方有引用，
应该是因为什么特殊原因需要避免使用__cdecl，才引入这个宏.

原始unistd.h

#ifndef _UNISTD_H
/*
* unistd.h
*
* Standard header file declaring MinGW's POSIX compatibility features.
*
* $Id$
*
* Written by Rob Savoye <rob@cygnus.com>
* Modified by Earnie Boyd <earnie@users.sourceforge.net>
*   Danny Smith <dannysmith@users.sourceforge.net>
*   Ramiro Polla <ramiro@lisha.ufsc.br>
*   Gregory McGarry  <gregorymcgarry@users.sourceforge.net>
*   Keith Marshall  <keithmarshall@users.sourceforge.net>
* Copyright (C) 1997, 1999, 2002-2004, 2007-2009, 2014, MinGW.org Project.
*
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice, this permission notice, and the following
* disclaimer shall be included in all copies or substantial portions of
* the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OF OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*/
#define _UNISTD_H  1
#pragma GCC system_header

/* All MinGW headers MUST include _mingw.h before anything else,
* to ensure proper initialization of feature test macros.
*/
#include <_mingw.h>

/* unistd.h maps (roughly) to io.h
* Other headers included by unistd.h may be selectively processed;
* __UNISTD_H_SOURCED__ enables such selective processing.
*/
#define __UNISTD_H_SOURCED__ 1

#include <io.h>
#include <process.h>
#include <getopt.h>

/* These are defined in stdio.h.  POSIX also requires that they
* are to be consistently defined here; don't guard against prior
* definitions, as this might conceal inconsistencies.
*/
#define SEEK_SET   0
#define SEEK_CUR   1
#define SEEK_END   2

#if _POSIX_C_SOURCE
/*
* POSIX process/thread suspension functions; all are supported by a
* common MinGW API in libmingwex.a, providing for suspension periods
* ranging from mean values of ~7.5 milliseconds, (see comments below),
* extending up to a maximum of ~136 years.
*
* Note that, whereas POSIX supports early wake-up of any suspended
* process/thread, in response to a signal, this implementation makes
* no attempt to emulate this signalling behaviour, (since signals are
* not well supported by Windows); thus, unless impeded by an invalid
* argument, this implementation always returns an indication as if
* the sleeping period ran to completion.
*/
_EXTERN_C _cdecl __MINGW_NOTHROW
int __mingw_sleep( unsigned long, unsigned long );

/* Structure timespec is mandated by POSIX, for specification of
* intervals with the greatest precision supported by the OS kernel.
* Although this allows for specification to nanosecond precision, do
* not be deluded into any false expectation that such short intervals
* can be realized on Windows; on Win9x derivatives, the metronome used
* by the process scheduler has a period of ~55 milliseconds, while for
* WinNT derivatives, the corresponding period is ~15 milliseconds; thus,
* the shortest intervals which can be realistically timed will range
* from 0..55 milliseconds on Win9x hosts, and from 0..15 ms on WinNT,
* with period values normally distributed around means of ~27.5 ms
* and ~7.5 ms, for the two system types respectively.
*/
#define _FAKE_TIME_H_SOURCED	1
#define __need_struct_timespec	1
#include <parts/time.h>

_BEGIN_C_DECLS

/* The nanosleep() function provides the most general purpose API for
* process/thread suspension; it provides for specification of periods
* ranging from ~7.5 ms mean, (on WinNT derivatives; ~27.5 ms on Win9x),
* extending up to ~136 years, (effectively eternity).
*/
_cdecl __MINGW_NOTHROW
int nanosleep( const struct timespec *, struct timespec * );

#ifndef __NO_INLINE__
__CRT_INLINE __LIBIMPL__(( FUNCTION = nanosleep ))
int nanosleep( const struct timespec *period, struct timespec *residual )
{
if( residual != (void *)(0) )
residual->tv_sec = (long long)(residual->tv_nsec = 0);
return __mingw_sleep((unsigned)(period->tv_sec), (period->tv_sec < 0LL)
? (unsigned)(-1) : (unsigned)(period->tv_nsec));
}
#endif

/* The usleep() function, and its associated useconds_t type specifier
* were made obsolete in POSIX.1-2008; declared here, only for backward
* compatibility, its continued use is not recommended.  (It is limited
* to specification of suspension periods ranging from ~7.5 ms mean up
* to a maximum of 999,999 microseconds only).
*/
typedef unsigned long useconds_t __MINGW_ATTRIB_DEPRECATED;
int _cdecl __MINGW_NOTHROW usleep( useconds_t )__MINGW_ATTRIB_DEPRECATED;

#ifndef __NO_INLINE__
__CRT_INLINE __LIBIMPL__(( FUNCTION = usleep ))
int usleep( useconds_t period ){ return __mingw_sleep( 0, 1000 * period ); }
#endif

/* The sleep() function is, perhaps, the most commonly used of all the
* process/thread suspension APIs; it provides support for specification
* of suspension periods ranging from 1 second to ~136 years.  (However,
* POSIX recommends limiting the maximum period to 65535 seconds, to
* maintain portability to platforms with only 16-bit ints).
*/
unsigned _cdecl __MINGW_NOTHROW sleep( unsigned );

#ifndef __NO_INLINE__
__CRT_INLINE __LIBIMPL__(( FUNCTION = sleep ))
unsigned sleep( unsigned period ){ return __mingw_sleep( period, 0 ); }
#endif

/* POSIX ftruncate() function.
*
* Microsoft's _chsize() function is incorrectly described, on MSDN,
* as a preferred replacement for the POSIX chsize() function.  There
* never was any such POSIX function; the actual POSIX equivalent is
* the ftruncate() function.
*/
int _cdecl ftruncate( int, off_t );

#ifndef __NO_INLINE__
__CRT_INLINE __JMPSTUB__(( FUNCTION = ftruncate, REMAPPED = _chsize ))
int ftruncate( int __fd, off_t __length ){ return _chsize( __fd, __length ); }
#endif

_END_C_DECLS

#endif /* _POSIX_C_SOURCE */

#undef __UNISTD_H_SOURCED__
#endif /* ! _UNISTD_H: $RCSfile$: end of file */

修
4000
改以后的unistd.h：

#ifndef _UNISTD_H
/*
* unistd.h
*
* Standard header file declaring MinGW's POSIX compatibility features.
*
* $Id$
*
* Written by Rob Savoye <rob@cygnus.com>
* Modified by Earnie Boyd <earnie@users.sourceforge.net>
*   Danny Smith <dannysmith@users.sourceforge.net>
*   Ramiro Polla <ramiro@lisha.ufsc.br>
*   Gregory McGarry  <gregorymcgarry@users.sourceforge.net>
*   Keith Marshall  <keithmarshall@users.sourceforge.net>
* Copyright (C) 1997, 1999, 2002-2004, 2007-2009, 2014, MinGW.org Project.
*
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice, this permission notice, and the following
* disclaimer shall be included in all copies or substantial portions of
* the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OF OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*/
#define _UNISTD_H  1
#pragma GCC system_header

/* All MinGW headers MUST include _mingw.h before anything else,
* to ensure proper initialization of feature test macros.
*/
#include <_mingw.h>

/* unistd.h maps (roughly) to io.h
* Other headers included by unistd.h may be selectively processed;
* __UNISTD_H_SOURCED__ enables such selective processing.
*/
#define __UNISTD_H_SOURCED__ 1

#include <io.h>
#include <process.h>
#include <getopt.h>

/* These are defined in stdio.h.  POSIX also requires that they
* are to be consistently defined here; don't guard against prior
* definitions, as this might conceal inconsistencies.
*/
#define SEEK_SET   0
#define SEEK_CUR   1
#define SEEK_END   2

#if _POSIX_C_SOURCE
#ifdef __GNUC__
#ifndef _cdecl
#define _cdecl __attribute__((cdecl))
#endif
#else
#define _cdecl
#endif
/*
* POSIX process/thread suspension functions; all are supported by a
* common MinGW API in libmingwex.a, providing for suspension periods
* ranging from mean values of ~7.5 milliseconds, (see comments below),
* extending up to a maximum of ~136 years.
*
* Note that, whereas POSIX supports early wake-up of any suspended
* process/thread, in response to a signal, this implementation makes
* no attempt to emulate this signalling behaviour, (since signals are
* not well supported by Windows); thus, unless impeded by an invalid
* argument, this implementation always returns an indication as if
* the sleeping period ran to completion.
*/
_EXTERN_C _cdecl __MINGW_NOTHROW
int __mingw_sleep( unsigned long, unsigned long );

/* Structure timespec is mandated by POSIX, for specification of
* intervals with the greatest precision supported by the OS kernel.
* Although this allows for specification to nanosecond precision, do
* not be deluded into any false expectation that such short intervals
* can be realized on Windows; on Win9x derivatives, the metronome used
* by the process scheduler has a period of ~55 milliseconds, while for
* WinNT derivatives, the corresponding period is ~15 milliseconds; thus,
* the shortest intervals which can be realistically timed will range
* from 0..55 milliseconds on Win9x hosts, and from 0..15 ms on WinNT,
* with period values normally distributed around means of ~27.5 ms
* and ~7.5 ms, for the two system types respectively.
*/
#define _FAKE_TIME_H_SOURCED	1
#define __need_struct_timespec	1
#include <parts/time.h>

_BEGIN_C_DECLS

/* The nanosleep() function provides the most general purpose API for
* process/thread suspension; it provides for specification of periods
* ranging from ~7.5 ms mean, (on WinNT derivatives; ~27.5 ms on Win9x),
* extending up to ~136 years, (effectively eternity).
*/
_cdecl __MINGW_NOTHROW
int nanosleep( const struct timespec *, struct timespec * );

#ifndef __NO_INLINE__
__CRT_INLINE __LIBIMPL__(( FUNCTION = nanosleep ))
int nanosleep( const struct timespec *period, struct timespec *residual )
{
if( residual != (void *)(0) )
residual->tv_sec = (long long)(residual->tv_nsec = 0);
return __mingw_sleep((unsigned)(period->tv_sec), (period->tv_sec < 0LL)
? (unsigned)(-1) : (unsigned)(period->tv_nsec));
}
#endif

/* The usleep() function, and its associated useconds_t type specifier
* were made obsolete in POSIX.1-2008; declared here, only for backward
* compatibility, its continued use is not recommended.  (It is limited
* to specification of suspension periods ranging from ~7.5 ms mean up
* to a maximum of 999,999 microseconds only).
*/
typedef unsigned long useconds_t __MINGW_ATTRIB_DEPRECATED;
int _cdecl __MINGW_NOTHROW usleep( useconds_t )__MINGW_ATTRIB_DEPRECATED;

#ifndef __NO_INLINE__
__CRT_INLINE __LIBIMPL__(( FUNCTION = usleep ))
int usleep( useconds_t period ){ return __mingw_sleep( 0, 1000 * period ); }
#endif

/* The sleep() function is, perhaps, the most commonly used of all the
* process/thread suspension APIs; it provides support for specification
* of suspension periods ranging from 1 second to ~136 years.  (However,
* POSIX recommends limiting the maximum period to 65535 seconds, to
* maintain portability to platforms with only 16-bit ints).
*/
unsigned _cdecl __MINGW_NOTHROW sleep( unsigned );

#ifndef __NO_INLINE__
__CRT_INLINE __LIBIMPL__(( FUNCTION = sleep ))
unsigned sleep( unsigned period ){ return __mingw_sleep( period, 0 ); }
#endif

/* POSIX ftruncate() function.
*
* Microsoft's _chsize() function is incorrectly described, on MSDN,
* as a preferred replacement for the POSIX chsize() function.  There
* never was any such POSIX function; the actual POSIX equivalent is
* the ftruncate() function.
*/
int _cdecl ftruncate( int, off_t );

#ifndef __NO_INLINE__
__CRT_INLINE __JMPSTUB__(( FUNCTION = ftruncate, REMAPPED = _chsize ))
int ftruncate( int __fd, off_t __length ){ return _chsize( __fd, __length ); }
#endif

_END_C_DECLS

#endif /* _POSIX_C_SOURCE */

#undef __UNISTD_H_SOURCED__
#endif /* ! _UNISTD_H: $RCSfile$: end of file */

再进行make，通过了



一点分析：
通过以后，思考了一下原因，
将两个头文件使用gcc -E进行预编译以后，发现结果除了文件名以外完全一致；
使用原始头文件单独对出错的file.c进行编译：
gcc -I.. -c file.c -o file.o
发现编译，竟然成功了。
因此这个错误一定就是与make有关系了，但是其中流程不清楚，等到以后有时间了再深究吧。