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 (void);

       Xauth *XauReadAuth (FILE *auth_file);

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

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

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

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

       int XauUnlockAuth (const char *file_name);

       int XauDisposeAuth (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.

       XauWriteAuth  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