XauGetAuthByAddr

Xau(3)								       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 (void);

       Xauth *XauReadAuth (FILE *auth_file);

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

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

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

       int XauUnlockAuth (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 autho-
       rization 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 syn-
       chronization 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



								       Xau(3)