LDOPEN(3X)LDOPEN(3X)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;
int ldreadst (ldptr, flags)
LDFILE *ldptr;
int flags;
DESCRIPTIONldopen 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, allocates 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. It
handles individual object (or a.out) files and (via the while-loop) an
archive file (see ar(1)) of object files.
Page 1
LDOPEN(3X)LDOPEN(3X)
/* for each filename to be processed */
ldptr = NULL;
do {
if ( (ldptr = ldopen(filename, ldptr)) != NULL )
{
/* check magic number */
/* process a single object 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 independent 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 cannot 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. When calling
ldopen on a given a.out (rather than an archive) for the first time be
sure the second argument you pass is a NULL pointer ((LDFILE *)0) (this
is the only way to ensure the LDFILE * is initialized properly for that
a.out).
ldreadst reads in the portions of the symbol table implied by the flags
argument. A flags argument of -1 reads in the entire symbol table.
Since the other routines, for example ldtbread, ensure that the relevant
portions of the symbol table have been read in, you need not call
ldreadst to use the other routines. ldreadst(ldptr,-1) would simply
ensure the whole symbol table is read in at once, which is not necessary.
ldreadst returns SUCCESS if it has read in the symbol table successfully
or FAILURE if it cannot. If an symbol table has been truncated or
damaged there is a small probability that ldreadst will core dump rather
than return FAILURE .
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 of the symbol table
into memory, call ldreadst with ST_P* constants ORed together from
<cmplrs/stsupport.h>.
The program must be loaded with the object file access routine library
libmld.a.
Page 2
LDOPEN(3X)LDOPEN(3X)SEE ALSOfopen(3S), ldclose(3X), ldfcn(4).
Page 3
