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LDOPEN(3X-SysV)     RISC/os Reference Manual      LDOPEN(3X-SysV)



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

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

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

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

     ldreadst (ldptr, flags)
     LDFILE *ldptr;
     intflags;

DESCRIPTION
     ldopen and ldclose(3X) provide uniform access to simple
     object files and to object files that are members of archive
     files.  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, ldopen opens filename, allo-
     cates and initializes the LDFILE structure, and returns a
     pointer to the structure to the calling program.

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

     ldopen and ldclose work in concert.  ldclose returns 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, and particularly when 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:











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LDOPEN(3X-SysV)     RISC/os Reference Manual      LDOPEN(3X-SysV)



          /* 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 );

     If the value of oldptr is not NULL, ldaopen opens filename
     anew and allocates and initializes a new LDFILE structure,
     copying the fields from oldptr.  ldaopen returns a pointer
     to the new LDFILE structure.  This new pointer is indepen-
     dent of the old pointer, oldptr.  The two pointers can be
     used concurrently to read separate parts of the object file.
     For example, one pointer can be used to step sequentially
     through the relocation information while the other is used
     to read indexed symbol table entries.

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

     ldopen causes the symbol table header and file descriptor
     table to be read.  Further access, using ldptr, causes other
     appropriate sections of the symbol table to be read (for
     example, if you call ldtbread, the symbols or externals are
     read). To force sections for the symbol table in memory,
     call ldreadst with ST_P* constants ORed together from
     st_support.h.

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

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














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