Xau(3)

     NAME
          Xau library: XauFileName, XauReadAuth, XauLockAuth,
          XauUnlockAuth, XauWriteAuth, XauDisposeAuth,
          XauGetAuthByAddr, XauGetBestAuthByAddr - X authority
          database routines

     SYNOPSIS
          #include <X11/Xauth.h>

          typedef struct xauth {
               unsigned short family;
               unsigned short address_length;
               char           *address;
               unsigned short number_length;
               char           *number;
               unsigned short name_length;
               char           *name;
               unsigned short data_length;
               char           *data;
          } Xauth;

          char *XauFileName ()

          Xauth *XauReadAuth (auth_file)
               FILE *auth_file;

          int XauWriteAuth (auth_file, auth)
               FILE *auth_file;
               Xauth *auth;

          Xauth *XauGetAuthByAddr (family,
                                   address_length, address,
                                   number_length, number)
               unsigned short family;
               unsigned short address_length;
               char *address;
               unsigned short number_length;
               char *number;

          Xauth *XauGetBestAuthByAddr (family,
                                       address_length, address,
                                       number_length, number,
                                       types_length, types, type_lengths)
               unsigned short family;
               unsigned short address_length;
               char *address;
               unsigned short number_length;
               char *number;
               int types_length;
               char **types;
               int *type_lengths;

          int XauLockAuth (file_name, retries, timeout, dead)
               char *file_name;
               int retries;
               int timeout;
               long dead;

          int XauUnlockAuth (file_name)
               char *file_name;

          XauDisposeAuth (auth)
               Xauth *auth;


     DESCRIPTION
          XauFileName generates the default authorization file name by
          first checking the XAUTHORITY environment variable if set,
          else it returns $HOME/.Xauthority.  This name is statically
          allocated and should not be freed.

          XauReadAuth reads the next entry from auth_file.  The entry
          is not statically allocated and should be freed by calling
          XauDisposeAuth.

          XuWriteAuth writes an authorization entry to auth_file.  It
          returns 1 on success, 0 on failure.

          XauGetAuthByAddr searches for an entry which matches the
          given network address/display number pair.  The entry is not
          statically allocated and should be freed by calling
          XauDisposeAuth.

          XauGetBestAuthByAddr is similar to XauGetAuthByAddr, except
          that a list of acceptable authentication methods is
          specified.  Xau will choose the file entry which matches the
          earliest entry in this list (e.g., the most secure
          authentication method).  The types argument is an array of
          strings, one string for each authentication method.
          types_length specifies how many elements are in the types
          array.  types_lengths is an array of integers representing
          the length of each string.

          XauLockAuth does the work necessary to synchronously update
          an authorization file.  First it makes two file names, one
          with ``-c'' appended to file_name, the other with ``-l''
          appended.  If the ``-c'' file already exists and is more
          than dead seconds old, XauLockAuth removes it and the
          associated ``-l'' file.  To prevent possible synchronization
          troubles with NFS, a dead value of zero forces the files to
          be removed.  XauLockAuth makes retries attempts to create
          and link the file names, pausing timeout seconds between
          each attempt.  XauLockAuth returns a collection of values
          depending on the results:
               LOCK_ERROR     A system error occurred, either a file_name
                              which is too long, or an unexpected failure from
                              a system call.  errno may prove useful.

               LOCK_TIMEOUT   retries attempts failed

               LOCK_SUCCESS   The lock succeeded.


          XauUnlockAuth undoes the work of XauLockAuth by unlinking
          both the ``-c'' and ``-l'' file names.

          XauDisposeAuth frees storage allocated to hold an
          authorization entry.

     SEE ALSO
          xauth(1), xdm(1)

     AUTHOR
          Keith Packard, MIT X Consortium