fcntl.h

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/* The <fcntl.h> header is needed by the open() and fcntl() system calls,
 * which  have a variety of parameters and flags.  They are described here.  
 * The formats of the calls to each of these are:
 *
 *      open(path, oflag [,mode])       open a file
 *      fcntl(fd, cmd [,arg])           get or set file attributes
 * 
 */

#ifndef _FCNTL_H
#define _FCNTL_H

#ifndef _TYPES_H
#include <sys/types.h>
#endif

/* These values are used for cmd in fcntl().  POSIX Table 6-1.  */
#define F_DUPFD            0    /* duplicate file descriptor */
#define F_GETFD            1    /* get file descriptor flags */
#define F_SETFD            2    /* set file descriptor flags */
#define F_GETFL            3    /* get file status flags */
#define F_SETFL            4    /* set file status flags */
#define F_GETLK            5    /* get record locking information */
#define F_SETLK            6    /* set record locking information */
#define F_SETLKW           7    /* set record locking info; wait if blocked */
#define F_FREESP           8    /* free a section of a regular file */

/* File descriptor flags used for fcntl().  POSIX Table 6-2. */
#define FD_CLOEXEC         1    /* close on exec flag for third arg of fcntl */

/* L_type values for record locking with fcntl().  POSIX Table 6-3. */
#define F_RDLCK            1    /* shared or read lock */
#define F_WRLCK            2    /* exclusive or write lock */
#define F_UNLCK            3    /* unlock */

/* Oflag values for open().  POSIX Table 6-4. */
#define O_CREAT        00100    /* creat file if it doesn't exist */
#define O_EXCL         00200    /* exclusive use flag */
#define O_NOCTTY       00400    /* do not assign a controlling terminal */
#define O_TRUNC        01000    /* truncate flag */

/* File status flags for open() and fcntl().  POSIX Table 6-5. */
#define O_APPEND       02000    /* set append mode */
#define O_NONBLOCK     04000    /* no delay */

/* File access modes for open() and fcntl().  POSIX Table 6-6. */
#define O_RDONLY           0    /* open(name, O_RDONLY) opens read only */
#define O_WRONLY           1    /* open(name, O_WRONLY) opens write only */
#define O_RDWR             2    /* open(name, O_RDWR) opens read/write */

/* Mask for use with file access modes.  POSIX Table 6-7. */
#define O_ACCMODE         03    /* mask for file access modes */

/* Struct used for locking.  POSIX Table 6-8. */
struct flock {
  short l_type;                 /* type: F_RDLCK, F_WRLCK, or F_UNLCK */
  short l_whence;               /* flag for starting offset */
  off_t l_start;                /* relative offset in bytes */
  off_t l_len;                  /* size; if 0, then until EOF */
  pid_t l_pid;                  /* process id of the locks' owner */
};

/* Function Prototypes. */
_PROTOTYPE( int creat, (const char *_path, _mnx_Mode_t _mode)           );
_PROTOTYPE( int fcntl, (int _filedes, int _cmd, ...)                    );
_PROTOTYPE( int open,  (const char *_path, int _oflag, ...)             );

/* For locking files. */
#define LOCK_SH         F_RDLCK         /* Shared lock */
#define LOCK_EX         F_WRLCK         /* Exclusive lock */
#define LOCK_NB         0x0080          /* Do not block when locking */
#define LOCK_UN         F_UNLCK         /* Unlock */

_PROTOTYPE(  int flock, (int fd, int mode)                              );

#endif /* _FCNTL_H */

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