unistd.h

Linux.Programming.by example 的源代码绝对经典

/* Copyright (C) 1991-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/*
 *	POSIX Standard: 2.10 Symbolic Constants		<unistd.h>
 */

#ifndef	_UNISTD_H
#define	_UNISTD_H	1

#include <features.h>

__BEGIN_DECLS

/* These may be used to determine what facilities are present at compile time.
   Their values can be obtained at run time from `sysconf'.  */

/* POSIX Standard approved as ISO/IEC 9945-1 as of August, 1988 and
   extended by POSIX-1b (aka POSIX-4) and POSIX-1c (aka POSIX threads).  */
#define	_POSIX_VERSION	199506L

/* These are not #ifdef __USE_POSIX2 because they are
   in the theoretically application-owned namespace.  */

/* POSIX Standard approved as ISO/IEC 9945-2 as of December, 1993.  */
#define	_POSIX2_C_VERSION	199209L

/* The utilities on GNU systems also correspond to this version.  */
#define _POSIX2_VERSION	199209L

/* If defined, the implementation supports the
   C Language Bindings Option.  */
#define	_POSIX2_C_BIND	1

/* If defined, the implementation supports the
   C Language Development Utilities Option.  */
#define	_POSIX2_C_DEV	1

/* If defined, the implementation supports the
   Software Development Utilities Option.  */
#define	_POSIX2_SW_DEV	1

/* If defined, the implementation supports the
   creation of locales with the localedef utility.  */
#define _POSIX2_LOCALEDEF       1

/* X/Open version number to which the library conforms.  It is selectable.  */
#ifdef __USE_UNIX98
# define _XOPEN_VERSION	500
#else
# define _XOPEN_VERSION	4
#endif

/* Commands and utilities from XPG4 are available.  */
#define _XOPEN_XCU_VERSION	4

/* We are compatible with the old published standards as well.  */
#define _XOPEN_XPG2	1
#define _XOPEN_XPG3	1
#define _XOPEN_XPG4	1

/* The X/Open Unix extensions are available.  */
#define _XOPEN_UNIX	1

/* Encryption is present.  */
#define	_XOPEN_CRYPT	1

/* The enhanced internationalization capabilities according to XPG4.2
   are present.  */
#define	_XOPEN_ENH_I18N	1

/* The legacy interfaces are also available.  */
#define _XOPEN_LEGACY	1


/* Get values of POSIX options:

   If these symbols are defined, the corresponding features are
   always available.  If not, they may be available sometimes.
   The current values can be obtained with `sysconf'.

   _POSIX_JOB_CONTROL		Job control is supported.
   _POSIX_SAVED_IDS		Processes have a saved set-user-ID
				and a saved set-group-ID.
   _POSIX_REALTIME_SIGNALS	Real-time, queued signals are supported.
   _POSIX_PRIORITY_SCHEDULING	Priority scheduling is supported.
   _POSIX_TIMERS		POSIX.4 clocks and timers are supported.
   _POSIX_ASYNCHRONOUS_IO	Asynchronous I/O is supported.
   _POSIX_PRIORITIZED_IO	Prioritized asynchronous I/O is supported.
   _POSIX_SYNCHRONIZED_IO	Synchronizing file data is supported.
   _POSIX_FSYNC			The fsync function is present.
   _POSIX_MAPPED_FILES		Mapping of files to memory is supported.
   _POSIX_MEMLOCK		Locking of all memory is supported.
   _POSIX_MEMLOCK_RANGE		Locking of ranges of memory is supported.
   _POSIX_MEMORY_PROTECTION	Setting of memory protections is supported.
   _POSIX_MESSAGE_PASSING	POSIX.4 message queues are supported.
   _POSIX_SEMAPHORES		POSIX.4 counting semaphores are supported.
   _POSIX_SHARED_MEMORY_OBJECTS	POSIX.4 shared memory objects are supported.
   _POSIX_THREADS		POSIX.1c pthreads are supported.
   _POSIX_THREAD_ATTR_STACKADDR	Thread stack address attribute option supported.
   _POSIX_THREAD_ATTR_STACKSIZE	Thread stack size attribute option supported.
   _POSIX_THREAD_SAFE_FUNCTIONS	Thread-safe functions are supported.
   _POSIX_THREAD_PRIORITY_SCHEDULING
				POSIX.1c thread execution scheduling supported.
   _POSIX_THREAD_PRIO_INHERIT	Thread priority inheritance option supported.
   _POSIX_THREAD_PRIO_PROTECT	Thread priority protection option supported.
   _POSIX_THREAD_PROCESS_SHARED	Process-shared synchronization supported.
   _POSIX_PII			Protocol-independent interfaces are supported.
   _POSIX_PII_XTI		XTI protocol-indep. interfaces are supported.
   _POSIX_PII_SOCKET		Socket protocol-indep. interfaces are supported.
   _POSIX_PII_INTERNET		Internet family of protocols supported.
   _POSIX_PII_INTERNET_STREAM	Connection-mode Internet protocol supported.
   _POSIX_PII_INTERNET_DGRAM	Connectionless Internet protocol supported.
   _POSIX_PII_OSI		ISO/OSI family of protocols supported.
   _POSIX_PII_OSI_COTS		Connection-mode ISO/OSI service supported.
   _POSIX_PII_OSI_CLTS		Connectionless ISO/OSI service supported.
   _POSIX_POLL			Implementation supports `poll' function.
   _POSIX_SELECT		Implementation supports `select' and `pselect'.

   _XOPEN_REALTIME		X/Open realtime support is available.
   _XOPEN_REALTIME_THREADS	X/Open realtime thread support is available.
   _XOPEN_SHM			Shared memory interface according to XPG4.2.

   _XBS5_ILP32_OFF32		Implementation provides environment with 32-bit
				int, long, pointer, and off_t types.
   _XBS5_ILP32_OFFBIG		Implementation provides environment with 32-bit
				int, long, and pointer and off_t with at least
				64 bits.
   _XBS5_LP64_OFF64		Implementation provides environment with 32-bit
				int, and 64-bit long, pointer, and off_t types.
   _XBS5_LPBIG_OFFBIG		Implementation provides environment with at
				least 32 bits int and long, pointer, and off_t
				with at least 64 bits.

   If any of these symbols is defined as -1, the corresponding option is not
   true for any file.  If any is defined as other than -1, the corresponding
   option is true for all files.  If a symbol is not defined at all, the value
   for a specific file can be obtained from `pathconf' and `fpathconf'.

   _POSIX_CHOWN_RESTRICTED	Only the super user can use `chown' to change
				the owner of a file.  `chown' can only be used
				to change the group ID of a file to a group of
				which the calling process is a member.
   _POSIX_NO_TRUNC		Pathname components longer than
				NAME_MAX generate an error.
   _POSIX_VDISABLE		If defined, if the value of an element of the
				`c_cc' member of `struct termios' is
				_POSIX_VDISABLE, no character will have the
				effect associated with that element.
   _POSIX_SYNC_IO		Synchronous I/O may be performed.
   _POSIX_ASYNC_IO		Asynchronous I/O may be performed.
   _POSIX_PRIO_IO		Prioritized Asynchronous I/O may be performed.

   Support for the Large File Support interface is not generally available.
   If it is available the following constants are defined to one.
   _LFS64_LARGEFILE		Low-level I/O supports large files.
   _LFS64_STDIO			Standard I/O supports large files.
   */

#include <bits/posix_opt.h>

/* Get the environment definitions from Unix98.  */
#ifdef __USE_UNIX98
# include <bits/environments.h>
#endif

/* Standard file descriptors.  */
#define	STDIN_FILENO	0	/* Standard input.  */
#define	STDOUT_FILENO	1	/* Standard output.  */
#define	STDERR_FILENO	2	/* Standard error output.  */


/* All functions that are not declared anywhere else.  */

#include <bits/types.h>

#ifndef	__ssize_t_defined
typedef __ssize_t ssize_t;
# define __ssize_t_defined
#endif

#define	__need_size_t
#define __need_NULL
#include <stddef.h>

#ifdef __USE_XOPEN
/* The Single Unix specification says that some more types are
   available here.  */
# ifndef __gid_t_defined
typedef __gid_t gid_t;
#  define __gid_t_defined
# endif

# ifndef __uid_t_defined
typedef __uid_t uid_t;
#  define __uid_t_defined
# endif

# ifndef __off_t_defined
#  ifndef __USE_FILE_OFFSET64
typedef __off_t off_t;
#  else
typedef __off64_t off_t;
#  endif
#  define __off_t_defined
# endif
# if defined __USE_LARGEFILE64 && !defined __off64_t_defined
typedef __off64_t off64_t;
#  define __off64_t_defined
# endif

# ifndef __useconds_t_defined
typedef __useconds_t useconds_t;
#  define __useconds_t_defined
# endif

# ifndef __pid_t_defined
typedef __pid_t pid_t;
#  define __pid_t_defined
# endif
#endif	/* X/Open */

#if defined __USE_MISC || defined __USE_XOPEN_EXTENDED
# ifndef __intptr_t_defined
typedef __intptr_t intptr_t;
#  define __intptr_t_defined
# endif
#endif

#if defined __USE_BSD || defined __USE_XOPEN
# ifndef __socklen_t_defined
typedef __socklen_t socklen_t;
#  define __socklen_t_defined
# endif
#endif

/* Values for the second argument to access.
   These may be OR'd together.  */
#define	R_OK	4		/* Test for read permission.  */
#define	W_OK	2		/* Test for write permission.  */
#define	X_OK	1		/* Test for execute permission.  */
#define	F_OK	0		/* Test for existence.  */

/* Test for access to NAME using the real UID and real GID.  */
extern int access (__const char *__name, int __type) __THROW;

#ifdef __USE_GNU
/* Test for access to NAME using the effective UID and GID
   (as normal file operations use).  */
extern int euidaccess (__const char *__name, int __type) __THROW;
#endif


/* Values for the WHENCE argument to lseek.  */
#ifndef	_STDIO_H		/* <stdio.h> has the same definitions.  */
# define SEEK_SET	0	/* Seek from beginning of file.  */
# define SEEK_CUR	1	/* Seek from current position.  */
# define SEEK_END	2	/* Seek from end of file.  */
#endif

#if defined __USE_BSD && !defined L_SET
/* Old BSD names for the same constants; just for compatibility.  */
# define L_SET		SEEK_SET
# define L_INCR		SEEK_CUR
# define L_XTND		SEEK_END
#endif


/* Move FD's file position to OFFSET bytes from the
   beginning of the file (if WHENCE is SEEK_SET),
   the current position (if WHENCE is SEEK_CUR),
   or the end of the file (if WHENCE is SEEK_END).
   Return the new file position.  */
#ifndef __USE_FILE_OFFSET64
extern __off_t lseek (int __fd, __off_t __offset, int __whence) __THROW;
#else
# ifdef __REDIRECT
extern __off64_t __REDIRECT (lseek,
			     (int __fd, __off64_t __offset, int __whence)
			     __THROW,
			     lseek64);
# else
#  define lseek lseek64
# endif
#endif
#ifdef __USE_LARGEFILE64
extern __off64_t lseek64 (int __fd, __off64_t __offset, int __whence) __THROW;
#endif

/* Close the file descriptor FD.  */
extern int close (int __fd) __THROW;

/* Read NBYTES into BUF from FD.  Return the
   number read, -1 for errors or 0 for EOF.  */
extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __THROW;

/* Write N bytes of BUF to FD.  Return the number written, or -1.  */
extern ssize_t write (int __fd, __const void *__buf, size_t __n) __THROW;

#ifdef __USE_UNIX98
# ifndef __USE_FILE_OFFSET64
extern ssize_t pread (int __fd, void *__buf, size_t __nbytes, __off_t __offset)
     __THROW;
extern ssize_t pwrite (int __fd, __const void *__buf, size_t __n,
		       __off_t __offset) __THROW;
# else
#  ifdef __REDIRECT
extern ssize_t __REDIRECT (pread, (int __fd, void *__buf, size_t __nbytes,
				   __off64_t __offset) __THROW,
			   pread64);
extern ssize_t __REDIRECT (pwrite, (int __fd, __const void *__buf,
				    size_t __nbytes, __off64_t __offset)
			   __THROW,
			pwrite64);
#  else
#   define pread pread64
#   define pwrite pwrite64
#  endif
# endif

# ifdef __USE_LARGEFILE64
/* Read NBYTES into BUF from FD at the given position OFFSET without