为什么我找不到 ioctl() 的文档？

如何解决为什么我找不到 ioctl() 的文档？

我正在搜索 ioctl() 的文档，我在 POSIX 标准中找到了一些东西： https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/

但看起来这只是一小部分...

例如，我找不到有关此 TIocgWINSZ 的任何信息，显然人们正在使用： Getting terminal width in C?

在我的 C 程序中只包含这个头文件 sys/ioctl.h，我猜在我的 Debian 机器上这是实际包含的文件：

┌───┐
│ $ │ ziga > ziga--workstation > usr
└─┬─┘
  └─> cat /usr/include/linux/ioctl.h 
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _LINUX_IOCTL_H
#define _LINUX_IOCTL_H

#include <asm/ioctl.h>

现在我尝试找到包含的标头 asm/ioctl.h 并且我再次猜测就是这样：

┌───┐
│ $ │ ziga > ziga--workstation > usr
└─┬─┘
  └─> cat /usr/include/asm-generic/ioctl.h 
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _ASM_GENERIC_IOCTL_H
#define _ASM_GENERIC_IOCTL_H

/* ioctl command encoding: 32 bits total,command in lower 16 bits,* size of the parameter structure in the lower 14 bits of the
 * upper 16 bits.
 * Encoding the size of the parameter structure in the ioctl request
 * is useful for catching programs compiled with old versions
 * and to avoid overwriting user space outside the user buffer area.
 * The highest 2 bits are reserved for indicating the ``access mode''.
 * NOTE: This limits the max parameter size to 16kB -1 !
 */

/*
 * The following is for compatibility across the varIoUs Linux
 * platforms.  The generic ioctl numbering scheme doesn't really enforce
 * a type field.  De facto,however,the top 8 bits of the lower 16
 * bits are indeed used as a type field,so we might just as well make
 * this explicit here.  Please be sure to use the decoding macros
 * below from Now on.
 */
#define _IOC_NRBITS 8
#define _IOC_TYPEBITS   8

/*
 * Let any architecture override either of the following before
 * including this file.
 */

#ifndef _IOC_SIZEBITS
# define _IOC_SIZEBITS  14
#endif

#ifndef _IOC_DIRBITS
# define _IOC_DIRBITS   2
#endif

#define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
#define _IOC_TYPEMASK   ((1 << _IOC_TYPEBITS)-1)
#define _IOC_SIZEMASK   ((1 << _IOC_SIZEBITS)-1)
#define _IOC_DIRMASK    ((1 << _IOC_DIRBITS)-1)

#define _IOC_NRSHIFT    0
#define _IOC_TYPESHIFT  (_IOC_NRSHIFT+_IOC_NRBITS)
#define _IOC_SIZESHIFT  (_IOC_TYPESHIFT+_IOC_TYPEBITS)
#define _IOC_DirsHIFT   (_IOC_SIZESHIFT+_IOC_SIZEBITS)

/*
 * Direction bits,which any architecture can choose to override
 * before including this file.
 *
 * NOTE: _IOC_WRITE means userland is writing and kernel is
 * reading. _IOC_READ means userland is reading and kernel is writing.
 */

#ifndef _IOC_NONE
# define _IOC_NONE  0U
#endif

#ifndef _IOC_WRITE
# define _IOC_WRITE 1U
#endif

#ifndef _IOC_READ
# define _IOC_READ  2U
#endif

#define _IOC(dir,type,nr,size) \
    (((dir)  << _IOC_DirsHIFT) | \
     ((type) << _IOC_TYPESHIFT) | \
     ((nr)   << _IOC_NRSHIFT) | \
     ((size) << _IOC_SIZESHIFT))

#define _IOC_TYPECHECK(t) (sizeof(t))

/*
 * Used to create numbers.
 *
 * NOTE: _IOW means userland is writing and kernel is reading. _IOR
 * means userland is reading and kernel is writing.
 */
#define _IO(type,nr)        _IOC(_IOC_NONE,(type),(nr),0)
#define _IOR(type,size)  _IOC(_IOC_READ,(_IOC_TYPECHECK(size)))
#define _IOW(type,size)  _IOC(_IOC_WRITE,(_IOC_TYPECHECK(size)))
#define _IOWR(type,size) _IOC(_IOC_READ|_IOC_WRITE,(_IOC_TYPECHECK(size)))
#define _IOR_BAD(type,sizeof(size))
#define _IOW_BAD(type,sizeof(size))
#define _IOWR_BAD(type,sizeof(size))

/* used to decode ioctl numbers.. */
#define _IOC_DIR(nr)        (((nr) >> _IOC_DirsHIFT) & _IOC_DIRMASK)
#define _IOC_TYPE(nr)       (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
#define _IOC_NR(nr)     (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
#define _IOC_SIZE(nr)       (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)

/* ...and for the drivers/sound files... */

#define IOC_IN      (_IOC_WRITE << _IOC_DirsHIFT)
#define IOC_OUT     (_IOC_READ << _IOC_DirsHIFT)
#define IOC_INOUT   ((_IOC_WRITE|_IOC_READ) << _IOC_DirsHIFT)
#define IOCSIZE_MASK    (_IOC_SIZEMASK << _IOC_SIZESHIFT)
#define IOCSIZE_SHIFT   (_IOC_SIZESHIFT)

#endif /* _ASM_GENERIC_IOCTL_H */


#endif /* _LINUX_IOCTL_H */

此文件不包含任何内容！这是一个死胡同，仍然没有丝毫TIocgWINSZ...

发生了什么？我一无所知...

POSIX 编程正在成为一门失传的艺术吗？文档在哪里？如果标准如此杂乱无章，任何人怎么能指望程序员新手学习任何东西...

对我来说，似乎每个人都喜欢将编码作为一种爱好……即使他们的代码在没有文档的情况下对世界毫无用处。我知道一些孤独的狼可以做到这一点，但我永远无法从 POSIX 标准中想象这样的事情......

正如我所建议的，我也尝试过手册页，但什么也没有：