LDOPEN(3X)           INTERACTIVE UNIX System           LDOPEN(3X)



          NAME
               ldopen, ldaopen - open a common object file for reading

          SYNOPSIS
               #include <stdio.h>
               #include <filehdr.h>
               #include <ldfcn.h>

               LDFILE *ldopen (filename, ldptr)
               char *filename;
               LDFILE *ldptr;

               LDFILE *ldaopen (filename, oldptr)
               char *filename;
               LDFILE *oldptr;

          DESCRIPTION
               The ldopen and ldclose(3X)  functions are designed to pro-
               vide uniform access to both simple object files and object
               files that are members of archive files.  Thus an archive of
               common object files can be processed as if it were a series
               of simple common object files.

               If ldptr has the value NULL, then ldopen will open filename
               and allocate and initialize the LDFILE structure, and return
               a pointer to the structure to the calling program.

               If ldptr is valid and if TYPE(ldptr) is the archive magic
               number, ldopen will reinitialize the LDFILE structure for
               the next archive member of filename.

               The ldopen and ldclose(3X) functions are designed to work in
               concert.  Ldclose will return FAILURE only when TYPE(ldptr)
               is the archive magic number and there is another file in the
               archive to be processed.  Only then should ldopen be called
               with the current value of ldptr.  In all other cases, in
               particular whenever a new filename is opened, ldopen should
               be called with a NULL ldptr argument.

               The following is a prototype for the use of ldopen and
               ldclose(3X).

                    /* for each filename to be processed */
                    ldptr = NULL;
                    do
                    {
                         if ( (ldptr = ldopen(filename, ldptr)) != NULL )
                         {
                              /* check magic number */
                              /* process the file */
                         }
                    } while (ldclose(ldptr) == FAILURE );



          Rev. C Software Development Set                            Page 1

          LDOPEN(3X)           INTERACTIVE UNIX System           LDOPEN(3X)



               If the value of  oldptr  is  not  NULL,  ldaopen  will  open
               filename  anew  and  allocate  and  initialize  a new LDFILE
               structure, copying the TYPE, OFFSET, and HEADER fields  from
               oldptr.   Ldaopen returns a pointer to the new LDFILE struc-
               ture.  This new pointer is independent of the  old  pointer,
               oldptr.   The  two pointers may be used concurrently to read
               separate parts of the object file.  For example, one pointer
               may  be  used  to  step  sequentially through the relocation
               information, while the other is used to read indexed  symbol
               table entries.

               Both ldopen and ldaopen open  filename  for  reading.   Both
               functions  return  NULL  if filename cannot be opened, or if
               memory for the LDFILE structure cannot be allocated.  A suc-
               cessful open does not ensure that the given file is a common
               object file or an archived object file.

               The program must be loaded with the object file access  rou-
               tine library libld.a.

          SEE ALSO
               fopen(3S), ldclose(3X), ldfcn(4).

































          Rev. C Software Development Set                            Page 2