wcs_open(2)                                                 wcs_open(2)

  open()

  NAME

    open(), wcs_open() - open or create a file for reading or writing

  SYNOPSIS

    #include 

    int open (const char *path, int o_flag, ...)
    int wcs_open (const wchar_t *path, int o_flag, ...)

  DESCRIPTION

    The open(2) and wcs_open(2) functions are identical, except that
    wcs_open(2) accepts wide characters in the path argument.

    The file name specified by path is opened for reading and/or writing as
    specified by the argument o_flag and the file descriptor returned to the
    calling process. The o_flag argument may indicate the file is to be
    created if it does not exist (by specifying the O_CREAT flag), and
    modified by the process' umask value (see umask(2)).

    The o_flag is a bitwise inclusive OR of the values from the following two
    tables.

    You must include one of the three values (file access modes) from the
    following table in the value of o_flag.

    Symbol       Meaning

    O_RDONLY     Open for reading only

    O_RDWR       Open for reading and writing

    O_WRONLY     Open for writing only

    You can specify any combination of the remaining flags.

    Symbol         Meaning

    O_APPEND       Append on each write

    O_CREAT        Create file if it does not exist

    O_EXCL         Error if create and file exists

    O_NOCTTY       Do not acquire as a controlling terminal

    O_NONBLOCK     Do not block on open

    O_TRUNC        Truncate size to 0

    O_SYNC         Perform synchronous I/O operations

    When the file is opened with the O_CREAT flag set and it doesn't already
    exist, open(2) or wcs_open(2) requires a third argument, which it treats
    as a mode of type mode_t. This argument specifies the mode of the newly-
    created file. (For a description of a mode see the reference page for
    chmod(2).)

    Opening a file with O_APPEND set causes each write on the file to be
    appended to the end. If O_TRUNC is specified and the file exists, the file
    is truncated to zero length. If O_EXCL is set with O_CREAT and the file
    already exists, open(2) or wcs_open(2) returns an error. This may be used
    to implement a simple exclusive access locking mechanism. If O_EXCL is set
    and the last component of the pathname is a symbolic link, open(2) or
    wcs_open(2) will fail even if the symbolic link points to a non-existent
    name. If the O_NONBLOCK flag is specified and the open(2) or wcs_open(2)
    call would result in the process being blocked for some reason (e.g.,
    waiting for carrier on a dialup line), open(2) or wcs_open(2) returns
    immediately. The first time the process attempts to perform I/O on the
    open file it will block (not currently implemented).

    If successful, open(2) or wcs_open(2) returns a non-negative integer,
    termed a file descriptor. It returns -1 on failure. The file pointer used
    to mark the current position within the file is set to the beginning of
    the file.

    When a new file is created it is given the group of the directory which
    contains it.

    The new descriptor is set to remain open across execve(2) system calls;
    see close(2) and fcntl(2).

    The system imposes a limit on the number of file descriptors open
    simultaneously by one process.

  RETURN VALUES

    On success, the open(2) or wcs_open(2) call returns an integer file
    descriptor which refers to the file. On failure, the call returns -1 and
    sets errno

  ERRORS

    The named file is opened unless:

    [EACCES]
        Search permission is denied for a component of the path prefix.

    [EACCES]
        The required permissions (for reading and/or writing) are denied for
        the given flags.

    [EACCES]
        O_CREAT is specified, the file does not exist, and the directory in
        which it is to be created does not permit writing.

    [EEXIST]
        O_CREAT and O_EXCL were specified and the file exists.

    [EFAULT]
        Path points outside the process's allocated address space.

    [EINTR]
        The open(2) operation was interrupted by a signal.

    [EINVAL]
        The value of the oflag argument is not valid.

    [EIO]
        An I/O error occurred while making the directory entry or allocating
        the file serial number for O_CREAT.

    [EISDIR]
        The named file is a directory, and the arguments specify it is to be
        opened for writing.

    [ELOOP]
        Too many symbolic links were encountered in translating the pathname.

    [EMFILE]
        The process has already reached its limit for open file descriptors.

    [ENAMETOOLONG]
        A component of a pathname exceeded {NAME_MAX} characters, or an entire
        pathname exceeded {PATH_MAX} characters.

    [ENFILE]
        The system has already reached its limit for open file descriptors.

    [ENOENT]
        O_CREAT is not set and the named file does not exist.

    [ENOENT]
        A component of the pathname that must exist does not exist.

    [ENOSPC]
        O_CREAT is specified, the file does not exist, and the directory in
        which the entry for the new file is being placed cannot be extended
        because there is no space left on the file system containing the
        directory.

    [ENOSPC]
        O_CREAT is specified, the file does not exist, and there are no free
        file serial numbers on the file system on which the file is being
        created.

    [ENOTDIR]
        A component of the path prefix is not a directory.

    [ENXIO]
        The named file is a character special or block special file, and the
        device associated with this special file does not exist.

    [EROFS]
        The named file resides on a read-only file system, and the file is to
        be modified.

  SEE ALSO

    chmod(2)

    close(2)

    creat(2)

    dup(2)

    fcntl(2)

    lseek(2)

    read(2)

    write(2)

    umask(2)

  USAGE NOTES

    All of these functions are thread safe.

    All of these functions are async-signal safe.