ultrix man page for ldfcn

ldfcn(5)							File Formats Manual							  ldfcn(5)

Name
       ldfcn - common object file access routines

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

Description
       The  common  object  file  access  routines are a collection of functions that read an object file that is in common object file form.  The
       calling program must know the detailed structure of the parts of the object file that it processes, but the calling program does  not  have
       to know the overall structure of the object file as the routines handle this function.

       The interface between the calling program and the object file access routines is based on the defined type (defined as which is declared in
       the header file Primarily, this structure provides uniform access to simple object files and object files that are members  of  an  archive
       file.

       The  function allocates and initializes the structure, reads in the symbol table header, if present, and returns a pointer to the structure
       to the calling program.	The fields of the structure can be accessed individually through macros defined in The fields contain the  follow-
       ing information:

       LDFILE	 *ldptr;

       TYPE(ldptr)    The file magic number, used to distinguish between archive members and simple object files.

       IOPTR(ldptr)   The file pointer returned by and used by the standard input/output functions.

       OFFSET(ldptr)  The  file  address  of  the  beginning  of the object file; if the object file is a member of an archive file, the offset is
		      nonzero.

       HEADER(ldptr)  The file header structure of the object file.

       SYMHEADER(ldptr)
		      The symbolic header structure for the symbol table associated with the object file.

       PFD(ldptr)     The file table associated with the symbol table.

       SYMTAB(ldptr)  A pointer to a copy of the symbol table in memory. It is accessed through the pCHDR structure (see If  no  symbol  table	is
		      present, this field is NULL.  This macro causes the whole symbol table to be read.

       LDSWAP(ldptr)  If the header and symbol table structures are swapped within the object file and all access requires using this field is set
		      to true.	Note that if you use routines, all structures, except the optional header and auxiliaries, are swapped.

       The object file access functions can be divided into four categories:(1)  Functions that open or close an object file

		     and
			    open a common object file
		     and
			    close a common object file(2)  Functions that return header or symbol table information

			    read the archive header of a member of an archive file
			    read the file header of a common object file
		     and
			    read a section header of a common object file
			    read a symbol table entry of a common object file
			    retrieve a symbol name from a symbol table entry or from the string table
			    retrieve a pointer into the aux table for the specified ldptr
			    create a type string (for example, C declarations) for the specified symbol
			    retrieve a procedure descriptor
			    retrieve a relative file table entry(3)  Functions that position (seek to) an object file at the start of the section, relocation, or line number information for a par-
	      ticular section

			    seek to the optional file header of a common object file
		     and
			    seek to a section of a common object file
		     and
			    seek to the relocation information for a section of a common object file
		     and
			    seek to the line number information for a section of a common object file
			    seek to the symbol table of a common object file(4) Miscellaneous functions
			    return the index of a particular common object file symbol table entry
			    initialize the tables and constants so that the archive hash and lookup routines can work
			    give a string return the hash index for it
			    return an archive hash bucket that is empty or matches the string argument
			    print MIPS assembly instructions
			    cause a section of the symbol table to be read

	      These functions are described in detail in the manual pages identified for each function.

	      The and functions both return pointers to a structure.

Macros
       Additional  access  to  an  object  file is provided through a set of macros defined in These macros parallel the standard inputoutput file
       reading and manipulating functions.  They translate a reference of the structure into a reference to its file descriptor field.

       The following macros are provided:

	      GETC(ldptr)
	      FGETC(ldptr)
	      GETW(ldptr)
	      UNGETC(c, ldptr)
	      FGETS(s, n, ldptr)
	      FREADM((char *) ptr, sizeof (*ptr), nitems, ldptr)
	      FSEEK(ldptr, offset, ptrname)
	      FTELL(ldptr)
	      REWIND(ldptr)
	      FEOF(ldptr)
	      FERROR(ldptr)
	      FILENO(ldptr)
	      SETBUF(ldptr, buf)
	      STROFFSET(ldptr)

       The STROFFSET macro calculates the address of the local symbol's string table in an object file.  See the manual  entries  for  the  corre-
       sponding  standard input/output library functions for details on the use of these macros.  (The functions are identified as 3s in Section 3
       of the reference pages.)

Restrictions
       The macro defined in the header file translates into a call to the standard input/output function should not be used to seek from  the  end
       of an archive file since the end of an archive file cannot be the same as the end of one of its object file members.

See Also
       ar(1),  fopen(3s),  fseek(3s),  ldahread(3x), ldclose(3x), ldfhread(3x), ldgetname(3x), ldlread(3x), ldlseek(3x), ldohseek(3x), ldopen(3x),
       ldrseek(3x), ldlseek(3x), ldshread(3x), ldtbindex(3x), ldtbread(3x), ldtbseek(3x)

								       RISC								  ldfcn(5)