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 ei‐
       ther 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. Howev‐
              er,  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>

VistaIO Version 1.2.14                           26 January 1994                              VistaIOReadFile(3)