NAME

       atOpenExpand,  atReadExpand, atCloseExpand - read version objects with attribute citations
       expanded
       atGetWriteName - get bound version name of a version object opened with atOpenExpand

SYNOPSIS

       #include <atfs.h>
       #include <atfstk.h>

       int   atOpenExpand(char *version, int expand_busy) ;

       int   atReadExpand(int desc, char *bufp, int nbytes) ;

       void  atCloseExpand(int desc) ;

       char *atGetWriteName(int desc) ;

       extern int  atBindError ;
       extern char atBindErrorMsg[] ;

DESCRIPTION

       atOpenExpand, atReadExpand, and atCloseExpand are designed  as  a  nearly  plug-compatible
       replacement  for  the  system  calls  open(2),  read(2),  and close(2) for reading of AtFS
       version objects with attribute citations expanded.

       atOpenExpand opens the file or AtFS version object version for reading with  atReadExpand.
       Version  points to the pathname of a file or AtFS version object.  If the flag expand_busy
       is non-zero, attribute citations are expanded in busy versions also.  atOpenExpand returns
       a  descriptor  that  is  valid  as  argument  to  successive  calls  to  atReadExpand  and
       atCloseExpand.

       atReadExpand attempts to read nbytes of data from the object referenced by the  descriptor
       desc  into  the  buffer  pointed to by bufp.  If desc is zero, atReadExpand reads from the
       standard input.  atReadExpand returns the number of bytes actually read.

       atCloseExpand frees the resources associated with the descriptor desc.

       atGetWriteName returns a pointer to the bound version name of the version object for which
       atOpenExpand returned the descriptor desc.

DIAGNOSTICS

       On  error  atOpenExpand and atReadExpand return -1 and set errno appropriately.  If one of
       these returns an error and  errno  is  set  to  ENOMEM,  the  application  may  retry  the
       operation, possibly after freeing some memory.

       If  atOpenExpand returns an error and atBindError has a non-zero value, the string version
       did not  select  a  version  object  or  not  a  unique  version  object.   In  this  case
       atBindErrorMsg contains an appropriate error message.

       Possible Values of errno after a call to atOpenExpand:

       ENOMEM Not enough memory could be allocated.

       EMFILE All available descriptors are in use.

       All errno values returned by open(2) or read(2).

       Possible Values of errno after a call to atReadExpand:

       ENOMEM Not enough memory could be allocated.

       EBADF  Invalid descriptor.

BUGS

       Since  atOpenExpand  reads  the complete contents of version into memory, it fails on very
       large version objects.

SEE ALSO

       intro(2), open(2), read(2), close(2), errno(3), atattribute(3), atbind(3).