unistd.h

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/* Set the process group of PID to PGRP.  */
extern int setpgrp __P ((__pid_t __pid, __pid_t __pgrp));
#endif /* Use BSD.  */

/* Create a new session with the calling process as its leader.
   The process group IDs of the session and the calling process
   are set to the process ID of the calling process, which is returned.  */
extern __pid_t __setsid __P ((void));
extern __pid_t setsid __P ((void));

/* Get the real user ID of the calling process.  */
extern __uid_t __getuid __P ((void));
extern __uid_t getuid __P ((void));

/* Get the effective user ID of the calling process.  */
extern __uid_t __geteuid __P ((void));
extern __uid_t geteuid __P ((void));

/* Get the real group ID of the calling process.  */
extern __gid_t __getgid __P ((void));
extern __gid_t getgid __P ((void));

/* Get the effective group ID of the calling process.  */
extern __gid_t __getegid __P ((void));
extern __gid_t getegid __P ((void));

/* If SIZE is zero, return the number of supplementary groups
   the calling process is in.  Otherwise, fill in the group IDs
   of its supplementary groups in LIST and return the number written.  */
extern int __getgroups __P ((int __size, __gid_t __list[]));
extern int getgroups __P ((int __size, __gid_t __list[]));

/* Set the user ID of the calling process to UID.
   If the calling process is the super-user, set the real
   and effective user IDs, and the saved set-user-ID to UID;
   if not, the effective user ID is set to UID.  */
extern int __setuid __P ((__uid_t __uid));
extern int setuid __P ((__uid_t __uid));

#ifdef	__USE_BSD
/* Set the real user ID of the calling process to RUID,
   and the effective user ID of the calling process to EUID.  */
extern int __setreuid __P ((__uid_t __ruid, __uid_t __euid));
extern int setreuid __P ((__uid_t __ruid, __uid_t __euid));

/* Set the effective user ID of the calling process to UID.  */
extern int seteuid __P ((__uid_t __uid));
#endif /* Use BSD.  */

/* Set the group ID of the calling process to GID.
   If the calling process is the super-user, set the real
   and effective group IDs, and the saved set-group-ID to GID;
   if not, the effective group ID is set to GID.  */
extern int __setgid __P ((__gid_t __gid));
extern int setgid __P ((__gid_t __gid));

#ifdef	__USE_BSD
/* Set the real group ID of the calling process to RGID,
   and the effective group ID of the calling process to EGID.  */
extern int __setregid __P ((__gid_t __rgid, __gid_t __egid));
extern int setregid __P ((__gid_t __rgid, __gid_t __egid));

/* Set the effective group ID of the calling process to GID.  */
extern int setegid __P ((__gid_t __gid));
#endif /* Use BSD.  */


/* Clone the calling process, creating an exact copy.
   Return -1 for errors, 0 to the new process,
   and the process ID of the new process to the old process.  */
extern __pid_t __fork __P ((void));
extern __pid_t fork __P ((void));

#ifdef	__USE_BSD
/* Clone the calling process, but without copying the whole address space.
   The the calling process is suspended until the the new process exits or is
   replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
   and the process ID of the new process to the old process.  */
extern __pid_t __vfork __P ((void));
extern __pid_t vfork __P ((void));
#endif /* Use BSD. */


/* Return the pathname of the terminal FD is open on, or NULL on errors.
   The returned storage is good only until the next call to this function.  */
extern char *ttyname __P ((int __fd));

/* Return 1 if FD is a valid descriptor associated
   with a terminal, zero if not.  */
extern int __isatty __P ((int __fd));
extern int isatty __P ((int __fd));


/* Make a link to FROM named TO.  */
extern int __link __P ((__const char *__from, __const char *__to));
extern int link __P ((__const char *__from, __const char *__to));

#ifdef	__USE_BSD
/* Make a symbolic link to FROM named TO.  */
extern int __symlink __P ((__const char *__from, __const char *__to));
extern int symlink __P ((__const char *__from, __const char *__to));

/* Read the contents of the symbolic link PATH into no more than
   LEN bytes of BUF.  The contents are not null-terminated.
   Returns the number of characters read, or -1 for errors.  */
extern int __readlink __P ((__const char *__path, char *__buf, size_t __len));
extern int readlink __P ((__const char *__path, char *__buf, size_t __len));
#endif /* Use BSD.  */

/* Remove the link NAME.  */
extern int __unlink __P ((__const char *__name));
extern int unlink __P ((__const char *__name));

/* Remove the directory PATH.  */
extern int __rmdir __P ((__const char *__path));
extern int rmdir __P ((__const char *__path));


/* Return the foreground process group ID of FD.  */
extern __pid_t tcgetpgrp __P ((int __fd));

/* Set the foreground process group ID of FD set PGRP_ID.  */
extern int tcsetpgrp __P ((int __fd, __pid_t __pgrp_id));


/* Return the login name of the user.  */
extern char *getlogin __P ((void));

#ifdef	__USE_BSD
/* Set the login name returned by `getlogin'.  */
extern int setlogin __P ((__const char *__name));
#endif


#ifdef	__USE_POSIX2
/* Process the arguments in ARGV (ARGC of them, minus
   the program name) for options given in OPTS.

   If `opterr' is zero, no messages are generated
   for invalid options; it defaults to 1.
   `optind' is the current index into ARGV.
   `optarg' is the argument corresponding to the current option.
   Return the option character from OPTS just read.
   Return -1 when there are no more options.
   For unrecognized options, or options missing arguments,
   `optopt' is set to the option letter, and '?' is returned.

   The OPTS string is a list of characters which are recognized option
   letters, optionally followed by colons, specifying that that letter
   takes an argument, to be placed in `optarg'.

   If a letter in OPTS is followed by two colons, its argument is optional.
   This behavior is specific to the GNU `getopt'.

   The argument `--' causes premature termination of argument scanning,
   explicitly telling `getopt' that there are no more options.

   If OPTS begins with `--', then non-option arguments
   are treated as arguments to the option '\0'.
   This behavior is specific to the GNU `getopt'.  */
extern int getopt __P ((int __argc, char *__const * __argv,
			__const char *__opts));
extern int opterr;
extern int optind;
extern int optopt;
extern char *optarg;
#endif


#ifdef	__USE_BSD

/* Put the name of the current host in no more than LEN bytes of NAME.
   The result is null-terminated if LEN is large enough for the full
   name and the terminator.  */
extern int __gethostname __P ((char *__name, size_t __len));
extern int gethostname __P ((char *__name, size_t __len));

/* Set the name of the current host to NAME, which is LEN bytes long.
   This call is restricted to the super-user.  */
extern int sethostname __P ((__const char *__name, size_t __len));

/* Return the current machine's Internet number.  */
extern long int gethostid __P ((void));

/* Set the current machine's Internet number to ID.
   This call is restricted to the super-user.  */
extern int sethostid __P ((long int __id));


/* Return the number of bytes in a page.  This is the system's page size,
   which is not necessarily the same as the hardware page size.  */
extern size_t __getpagesize __P ((void));
extern size_t getpagesize __P ((void));


/* Return the maximum number of file descriptors
   the current process could possibly have.  */
extern int __getdtablesize __P ((void));
extern int getdtablesize __P ((void));


/* Truncate FILE to LENGTH bytes.  */
extern int truncate __P ((__const char *__file, __off_t __length));

/* Truncate the file FD is open on to LENGTH bytes.  */
extern int ftruncate __P ((int __fd, __off_t __length));


/* Make all changes done to FD actually appear on disk.  */
extern int fsync __P ((int __fd));

/* Make all changes done to all files actually appear on disk.  */
extern int sync __P ((void));


/* Revoke access permissions to all processes currently communicating
   with the control terminal, and then send a SIGHUP signal to the process
   group of the control terminal.  */
extern int vhangup __P ((void));


/* Turn accounting on if NAME is an existing file.  The system will then write
   a record for each process as it terminates, to this file.  If NAME is NULL,
   turn accounting off.  This call is restricted to the super-user.  */
extern int acct __P ((__const char *__name));

/* Make PATH be the root directory (the starting point for absolute paths).
   This call is restricted to the super-user.  */
extern int chroot __P ((__const char *__path));

/* Make the block special device PATH available to the system for swapping.
   This call is restricted to the super-user.  */
extern int swapon __P ((__const char *__path));

/* Reboot or halt the system.  */
extern int reboot __P ((int __howto));


/* Successive calls return the shells listed in `/etc/shells'.  */
extern char *getusershell __P ((void));
extern void endusershell __P ((void)); /* Discard cached info.  */
extern void setusershell __P ((void)); /* Rewind and re-read the file.  */


/* Prompt with PROMPT and read a string from the terminal without echoing.
   Uses /dev/tty if possible; otherwise stderr and stdin.  */
extern char *getpass __P ((const char *__prompt));

#endif /* Use BSD.  */


#ifdef __USE_MISC

/* Generate a unique temporary file name from TEMPLATE.
   The last six characters of TEMPLATE must be "XXXXXX";
   they are replaced with a string that makes the file name unique.
   Returns TEMPLATE, or a null pointer if it cannot get a unique file name.  */
extern char *mktemp __P ((char *__template));

/* Generate a unique temporary file name from TEMPLATE.
   The last six characters of TEMPLATE must be "XXXXXX";
   they are replaced with a string that makes the filename unique.
   Returns a file descriptor open on the file for reading and writing,
   or -1 if it cannot create a uniquely-named file.  */
extern int mkstemp __P ((char *__template));


/* Invoke `system call' number SYSNO, passing it the remaining arguments.
   This is completely system-dependent, and not often useful.

   In Unix, `syscall' sets `errno' for all errors and most calls return -1
   for errors; in many systems you cannot pass arguments or get return
   values for all system calls (`pipe', `fork', and `getppid' typically
   among them).

   In Mach, all system calls take normal arguments and always return an
   error code (zero for success).  */
extern int syscall __P ((int __sysno, ...));

#endif	/* Use misc.  */


#if defined (__USE_MISC) && !defined (F_LOCK)
/* NOTE: These declarations also appear in <fcntl.h>; be sure to keep both
   files consistent.  Some systems have them there and some here, and some
   software depends on the macros being defined without including both.  */

/* `lockf' is a simpler interface to the locking facilities of `fcntl'.
   LEN is always relative to the current file position.
   The CMD argument is one of the following.  */

#define F_ULOCK 0       /* Unlock a previously locked region.  */
#define F_LOCK  1       /* Lock a region for exclusive use.  */ 
#define F_TLOCK 2       /* Test and lock a region for exclusive use.  */
#define F_TEST  3       /* Test a region for other processes locks.  */

extern int lockf __P ((int __fd, int __cmd, __off_t __len));
#endif /* Use misc and F_LOCK not already defined.  */


#ifdef __USE_GNU

/* Evaluate EXPRESSION, and repeat as long as it returns -1 with `errno'
   set to EINTR.  */

#define TEMP_FAILURE_RETRY(expression) \
  ({ long int __result;							      \
       do __result = (long int) (expression);				      \
       while (__result == -1L && errno == EINTR);			      \
       __result; })
          
#endif

__END_DECLS

#endif /* unistd.h  */