DOKK / manpages / debian 12 / libvistaio-dev / VistaIOReadFile.3.en
VistaIOReadFile(3) Library Functions Manual VistaIOReadFile(3)

VistaIOReadFile - read a Vista data file

#include <stdio>
#include <vistaio.h>
VistaIOAttrList VistaIOReadFile (file, filter)
FILE *file;
VistaIOReadFileFilterProc *filter;
typedef VistaIOBoolean VistaIOReadFileFilterProc (VistaIOBundle, VistaIORepnKind);

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

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.








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.








VistaIOReadObjects(3), VistaIOReadUbcIff(3),
    stdio(3),
  

  VistaIOBundle(3), VistaIOattribute(3), VistaIOtype(3)










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









  
``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.










Art Pope <pope@cs.ubc.ca>


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







  

    26 January 1994
    VistaIO Version 1.2.14