Click above to get retro games delivered to your door ever month!

Synopsis:
    #include <io.h>
    #include <fcntl.h>
    #include <sys\stat.h>
    #include <sys\types.h>
    #include <share.h>
    int sopen( const char *filename,
               int access, int share, ... );
    int _wsopen( const wchar_t *filename,
               int access, int share, ... );

Description:
    The sopen function opens a file at the operating system level for shared
    access.  The name of the file to be opened is given by filename.  The
    file will be accessed according to the access mode specified by access.
    When the file is to be created, the optional argument must be given
    which establishes the future access permissions for the file.
     Additionally, the sharing mode of the file is given by the share
    argument.  The optional argument is the file permissions to be used when
     O_CREAT flag is on in the access mode.

    The _wsopen function is identical to sopen except that it accepts a wide
    character string argument.

    The access mode is established by a combination of the bits defined in
    the <fcntl.h> header file.  The following bits may be set:

    Mode     Meaning

O_RDONLY
    permit the file to be only read.

O_WRONLY
    permit the file to be only written.

O_RDWR
    permit the file to be both read and written.

O_APPEND
    causes each record that is written to be written at the end of the file.

O_CREAT
    has no effect when the file indicated by filename already exists;
    otherwise, the file is created;

O_TRUNC
    causes the file to be truncated to contain no data when the file exists;
    has no effect when the file does not exist.

O_BINARY
    causes the file to be opened in binary mode which means that data will
    be transmitted to and from the file unchanged.

O_TEXT
    causes the file to be opened in text mode which means that
    carriage-return characters are written before any linefeed character
    that is written and causes carriage-return characters to be removed when
    encountered during reads.

O_NOINHERIT
    indicates that this file is not to be inherited by a child process.

O_EXCL
    indicates that this file is to be opened for exclusive access.  If the
    file exists and  O_CREAT was also specified then the open will fail
    (i.e., use  O_EXCL to ensure that the file does not already exist).

    When neither  O_TEXT nor  O_BINARY are specified, the default value in
    the global variable  _fmode is used to set the file translation mode.
     When the program begins execution, this variable has a value of
     O_TEXT.

     O_CREAT must be specified when the file does not exist and it is to be
    written.

    When the file is to be created ( O_CREAT is specified), an additional
    argument must be passed which contains the file permissions to be used
    for the new file.  The access permissions for the file or directory are
    specified as a combination of bits (defined in the <sys\stat.h> header
    file).

    The following bits define permissions for the owner.

    Permission     Meaning

S_IRWXU
    Read, write, execute/search

S_IRUSR
    Read permission

S_IWUSR
    Write permission

S_IXUSR
    Execute/search permission

    The following bits define permissions for the group.

    Permission     Meaning

S_IRWXG
    Read, write, execute/search

S_IRGRP
    Read permission

S_IWGRP
    Write permission

S_IXGRP
    Execute/search permission

    The following bits define permissions for others.

    Permission     Meaning

S_IRWXO
    Read, write, execute/search

S_IROTH
    Read permission

S_IWOTH
    Write permission

S_IXOTH
    Execute/search permission

    The following bits define miscellaneous permissions used by other
    implementations.

    Permission     Meaning

S_IREAD
    is equivalent to S_IRUSR (read permission)

S_IWRITE
    is equivalent to S_IWUSR (write permission)

S_IEXEC
    is equivalent to S_IXUSR (execute/search permission)

    All files are readable with DOS; however, it is a good idea to set
     S_IREAD when read permission is intended for the file.

    The sopen function applies the current file permission mask to the
    specified permissions (see  umask).

    The shared access for the file, share, is established by a combination
    of bits defined in the <share.h> header file.  The following values may
    be set:

    Value     Meaning

SH_COMPAT
    Set compatibility mode.

SH_DENYRW
    Prevent read or write access to the file.

SH_DENYWR
    Prevent write access of the file.

SH_DENYRD
    Prevent read access to the file.

SH_DENYNO
    Permit both read and write access to the file.

    You should consult the technical documentation for the DOS system that
    you are using for more detailed information about these sharing modes.

Returns:
    If successful, sopen returns a handle for the file.  When an error
    occurs while opening the file, -1 is returned.  When an error has
    occurred,  errno contains a value indicating the type of error that has
    been detected.

Errors:
    When an error has occurred,  errno contains a value indicating the type
    of error that has been detected.

    Constant     Meaning

EACCES
    Access denied because path specifies a directory or a volume ID, or
    sharing mode denied due to a conflicting open.

EMFILE
    No more handles available (too many open files)

ENOENT
    Path or file not found


    #include <sys\stat.h>
    #include <sys\types.h>
    #include <fcntl.h>
    #include <share.h>

    void main()
      {
        int handle;

        /* open a file for output                  */
        /* replace existing file if it exists      */

        handle = sopen( "file",
                    O_WRONLY | O_CREAT | O_TRUNC,
                    SH_DENYWR,
                    S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP );

        /* read a file which is assumed to exist   */

        handle = sopen( "file", O_RDONLY, SH_DENYWR );

        /* append to the end of an existing file   */
        /* write a new file if file does not exist */

        handle = sopen( "file",
                    O_WRONLY | O_CREAT | O_APPEND,
                    SH_DENYWR,
                    S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP );
      }

Classification:
    WATCOM

Systems:
     sopen - All, Netware

    _wsopen - DOS, Windows, Win386, Win32, OS/2 1.x(all), OS/2-32

See Also:
    chsize, close, creat, dup, dup2, eof, exec Functions, filelength,
    fileno, fstat, isatty, lseek, open, read, setmode, stat, tell, write,
    umask
Example: