NAME

       VistaIOReadFile - read a Vista data file

SYNOPSIS

       #include <stdio>
       #include <vistaio.h>

       VistaIOAttrList VistaIOReadFile (file, filter)
              FILE *file;
              VistaIOReadFileFilterProc *filter;

       typedef VistaIOBoolean VistaIOReadFileFilterProc (VistaIOBundle, VistaIORepnKind);

ARGUMENTS

       file      Specifies the open stream from which the data file should be read.

       filter    May  specify a function that determines which attributes' binary data is read from the file, or
                 it may be NULL to indicate that all binary data should be read.

DESCRIPTION

       VistaIOReadFile reads the contents of a Vista data file. It returns a list of the attributes found in the
       file.  Attribute  values  in  that  list  will  have  been  converted  to  internal form, as described by
       VistaIOattribute(3) and VistaIOtype(3).

       With the filter argument you may supply a function that gets to decide for each attribute value  that  is
       an object whether or not that object's binary data should be read. This mechanism allows you to avoid the
       expense of reading binary data that is not of interest (e.g., image pixel values when images are  not  of
       concern).  However,  you  need  only  supply  a  filter  function if you are particularly concerned about
       efficiency.  Your filter function should be declared:

              VistaIOBoolean MyFilter (bundle, repn)
                     VistaIOBundle bundle;
                     VistaIORepnKind repn;

       Your filter function will be called once for each object encountered at any level in the file. It will be
       passed  a  VistaIOBundle representing the object (including its type name and attribute list, but not its
       binary data), and the repn value obtained by looking up its  type  name  (i.e.,  the  value  returned  by
       VistaIOLookupType(3)  on the type name, which could be VistaIOUnknownRepn). The object's binary data will
       be read only if the filter function returns TRUE. If it returns FALSE, the object will be represented  in
       the  attribute  list  as a VistaIOBundle, without binary data — it will not be converted to internal form
       (e.g., not to a VistaIOImage). If no filter function is supplied (i.e., filter is NULL),  VistaIOReadFile
       will read all binary data associated with all objects.

       For  backwards  compatibility  VistaIOReadFile  will  recognize and read the contents of a UBC image file
       format (IFF) file.  If  the  first  character  read  from  the  stream  is  ``I'',  VistaIOReadFile  uses
       VistaIOReadUbcIff to read a single UBC IFF image. The image is returned as a VistaIOImage attribute value
       in a list containing a single attribute. In this case, the filter argument has no effect.

RETURN VALUE

       VistaIOReadData returns an attribute list representing the file's  contents,  or  NULL  if  an  error  is
       encountered. In the case of an error, the stream may not have been completely read.

SEE ALSO

       VistaIOReadObjects(3), VistaIOReadUbcIff(3), stdio(3),
       VistaIOBundle(3), VistaIOattribute(3), VistaIOtype(3)

NOTES

       Data  is  read  from  the stream sequentially, permitting the stream to be a pipe. No rewind is performed
       either before reading or after.

DIAGNOSTIC

       ``EOF encountered in name attribute.''
              The end-of-file was encountered unexpectedly while reading the value of the named attribute.

       ``File continues beyond expected EOF.''
              The end-of-file wasn't encountered immediately after all expected binary data.

       ``Invalid name attribute.''
              The named attribute is encoded incorrectly in the stream. It may,  for  example,  be  missing  the
              ``:'' that should separate its name and value.

       ``Missing {.''
              The ``{'' marking the start of an attribute list is missing.

       ``Missing }.''
              The ``}'' marking the end of an attribute list is missing.

       ``name attribute has data but not length.''
              The  named attribute's value is an object whose attribute list contains a data attribute but not a
              length attribute. Both attributes must be present to specify binary data. (A similar diagnostic is
              produced if there is a length attribute but no data attribute.)

       ``name attribute's attr attribute incorrect.''
              The  named  attribute's  value  is  an  object  whose attribute list indicates it has binary data.
              However, its data attribute specifies an offset too early in the binary data portion of the  file,
              or its data or length attribute has a non-integer value.

       ``Read from stream failed.''
              An attempt to read a block of binary data failed, perhaps because of a premature end-of-file.

       ``Vista data file delimiter not found.''
              The  FORMFEED  NEWLINE  sequence  terminating  the  attribute list portion of the data file wasn't
              found.

       ``Vista data file isn't version 2.''
              The data file's header indicates a file format version other than 2, the current version.

AUTHOR

       Art Pope <pope@cs.ubc.ca>

       Adaption to vistaio: Gert Wollny <gw.fossdev@gmail.com>