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grantpt(3) [freebsd man page]

PTSNAME(3)						   BSD Library Functions Manual 						PTSNAME(3)

NAME
grantpt, ptsname, unlockpt -- pseudo-terminal access functions LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <stdlib.h> int grantpt(int fildes); char * ptsname(int fildes); int unlockpt(int fildes); DESCRIPTION
The grantpt(), ptsname(), and unlockpt() functions allow access to pseudo-terminal devices. These three functions accept a file descriptor that references the master half of a pseudo-terminal pair. This file descriptor is created with posix_openpt(2). The grantpt() function is used to establish ownership and permissions of the slave device counterpart to the master device specified with fildes. The slave device's ownership is set to the real user ID of the calling process, and the permissions are set to user readable- writable and group writable. The group owner of the slave device is also set to the group ``tty''. The ptsname() function returns the full pathname of the slave device counterpart to the master device specified with fildes. This value can be used to subsequently open the appropriate slave after posix_openpt(2) and grantpt() have been called. The unlockpt() function clears the lock held on the pseudo-terminal pair for the master device specified with fildes. RETURN VALUES
The grantpt() and unlockpt() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. The ptsname() function returns a pointer to the name of the slave device on success; otherwise a NULL pointer is returned. ERRORS
The grantpt(), ptsname() and unlockpt() functions may fail and set errno to: [EBADF] fildes is not a valid open file descriptor. [EINVAL] fildes is not a master pseudo-terminal device. In addition, the grantpt() function may set errno to: [EACCES] The slave pseudo-terminal device could not be accessed. SEE ALSO
posix_openpt(2), pts(4), tty(4) STANDARDS
The ptsname() function conforms to IEEE Std 1003.1-2008 (``POSIX.1''). This implementation of grantpt() and unlockpt() does not conform to IEEE Std 1003.1-2008 (``POSIX.1''), because it depends on posix_openpt(2) to create the pseudo-terminal device with proper permissions in place. It only validates whether fildes is a valid pseudo-terminal master device. Future revisions of the specification will likely allow this behaviour, as stated by the Austin Group. HISTORY
The grantpt(), ptsname() and unlockpt() functions appeared in FreeBSD 5.0. BSD
August 20, 2008 BSD

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GRANTPT(3)						   BSD Library Functions Manual 						GRANTPT(3)

NAME
grantpt, posix_openpt, ptsname, ptsname_r, unlockpt -- pseudo-terminal access functions SYNOPSIS
#include <stdlib.h> int grantpt(int fildes); char * ptsname(int fildes); int ptsname_r(int fildes, char *buffer, size_t buflen); int unlockpt(int fildes); #include <stdlib.h> #include <fcntl.h> int posix_openpt(int oflag); DESCRIPTION
The grantpt(), ptsname(), ptsname_r(), unlockpt(), and posix_openpt() functions allow access to pseudo-terminal devices. The first four functions accept a file descriptor that references the master half of a pseudo-terminal pair. This file descriptor is created with posix_openpt(). The grantpt() function is used to establish ownership and permissions of the slave device counterpart to the master device specified with fildes. The slave device's ownership is set to the real user ID of the calling process; its permissions are set to user readable-writable and group writable. The group owner of the slave device is also set to the group ``tty'' if it exists on the system; otherwise, it is left untouched. The ptsname() and ptsname_r() functions return the full pathname of the slave device counterpart to the master device specified with fildes. This value can be used to subsequently open the appropriate slave after posix_openpt() and grantpt() have been called. The ptsname() function is not guaranteed to be reentrant or thread safe. The ptsname_r() function takes a buffer and length as arguments to avoid this problem. The unlockpt() function unlocks the slave pseudo-terminal device associated with the master device to which fildes refers. The posix_openpt() function opens the first available master pseudo-terminal device and returns a descriptor to it. The oflag argument spec- ifies the flags used for opening the device: O_RDWR Open for reading and writing. O_NOCTTY If set, do not allow the terminal to become the controlling terminal for the calling process. RETURN VALUES
The grantpt() and unlockpt() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. The ptsname() function returns a pointer to the name of the slave device on success; otherwise a NULL pointer is returned and the global variable errno is set to indicate the error. The ptsname_r() function returns 0 if successful. On failure, it returns -1 and the global variable errno is set to indicate the error. The posix_openpt() function returns a file descriptor to the first available master pseudo-terminal device on success; otherwise -1 is returned and the global variable errno is set to indicate the error. ERRORS
The grantpt(), ptsname(), ptsname_r(), and unlockpt() functions may fail and set errno to: [EINVAL] fildes is not a master pseudo-terminal device. In addition, the ptsname_r() function may set errno to: [EINVAL] The buffer argument is NULL. [ERANGE] The bufsize argument is smaller than the length of the string to be returned. In addition, the grantpt() function may set errno to: [EACCES] The slave pseudo-terminal device could not be accessed. The posix_openpt() function may fail and set errno to: [EINVAL] oflag consists of an invalid mode bit. [EAGAIN] The system has no available pseudo-terminal devices. The grantpt(), ptsname(), ptsname_r(), and unlockpt() functions may also fail and set errno for any of the errors specified for the fstat(2) system call. The posix_openpt() function may also fail and set errno for any of the errors specified for the open(2) system call. LEGACY SYNOPSIS
#include <stdlib.h> #include <fcntl.h> int grantpt(int fildes); char * ptsname(int fildes); int unlockpt(int fildes); #include <fcntl.h> int posix_openpt(int oflag); SEE ALSO
open(2), pty(4), tty(4), compat(5) STANDARDS
The grantpt(), ptsname(), unlockpt(), and posix_openpt() functions conform to IEEE Std 1003.1-2001 (``POSIX.1''). BSD
February 2, 2005 BSD

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