LDOPEN(3x,L)                AIX Technical Reference                LDOPEN(3x,L)



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ldopen, ldaopen



PURPOSE

Opens a common object file for reading.

LIBRARY

Object File Access Routine Library (libld.a)

SYNTAX

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

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

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

DESCRIPTION

The ldopen and ldclose subroutines are designed to provide 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, ldopen opens filename, allocates and initializes
the LDFILE structure, and returns a pointer to the structure to the calling
program.

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

The ldopen and ldclose subroutines are designed to work in concert.  The
ldclose subroutine 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,
in particular whenever a new filename is opened, ldopen should be called with a
NULL ldptr argument.

The following example illustrates the use of the ldopen and ldclose
subroutines:




Processed November 7, 1990       LDOPEN(3x,L)                                 1

LDOPEN(3x,L)                AIX Technical Reference                LDOPEN(3x,L)



       /* 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 again, and allocates
and initializes a new LDFILE structure, copying the TYPE, OFFSET, and HEADER
fields from oldptr.  The ldaopen subroutine returns a pointer to the new LDFILE
structure.  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 successful open does not insure that the given file is a common
object file or an archived object file.

RELATED INFORMATION

In this book:  "fopen, freopen, fdopen," "ldclose, ldaclose," and "ldfcn."


























Processed November 7, 1990       LDOPEN(3x,L)                                 2