Open System Services System Calls Reference Manual (G06.25+, H06.03+)

System Functions (n - p) open(2)
RELATED INFORMATION
Functions: chmod(2), close(2), creat(2), fcntl(2), lseek(2), mknod(2), read(2), stat(2),
umask(2), write(2).
STANDARDS CONFORMANCE
The POSIX standards leave some features to the implementing vendor to define. These features
are affected in the HP implementation:
• The O_RDWR flag is supported for FIFO files.
• The group ID of the new file is determined by the value of the O_ISGID flag in the
parent directory.
• The O_NONBLOCK flag is ignored for regular disk files and directory files.
• The O_NOCTTY flag is ignored for regular disk files and directory files.
• The O_CREAT flag is ignored for FIFOs and tty files.
• If the O_CREAT flag is specified and bits other than the file permission and appropriate
file type flags are set in the mode parameter, errno is set to [EINVAL].
• If the O_TRUNC flag is specified and the O_RDONLY access flag is specified, the open
fails.
• The O_TRUNC flag is ignored for files other than regular files.
• Attempting to open an OSS directory with an access flag of O_WRONLY or O_RDWR
fails.
• Specifying the O_NONBLOCK flag when opening character special devices that sup-
port nonblocking opens is supported.
HP extensions to the XPG4 Version 2 specification are:
• Opening Guardian files (that is, files in the /G file system) is supported, as described
under Opening Guardian Files in DESCRIPTION.
• The errno values [EFAULT], [EFILEBAD], [EFSBAD], [EGUARDIANOPEN], [EIO],
[ELOOP], [ENETDOWN], [EOSSNOTRUNNING], and [EPERM] can be returned.
• The file type S_NONSTOP is supported.
527186-003 Hewlett-Packard Company 5−13