Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
DWARF_NEW_EXPR(3)	 BSD Library Functions Manual	     DWARF_NEW_EXPR(3)

NAME
     dwarf_new_expr -- create a	location expression descriptor

LIBRARY
     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS
     #include <libdwarf.h>

     Dwarf_P_Expr
     dwarf_new_expr(Dwarf_P_Debug dbg, Dwarf_Error *err);

DESCRIPTION
     Function dwarf_new_expr() allocates a DWARF location expression descrip-
     tor used to build up a location expression	stream.

     The application can use the functions dwarf_add_expr_gen(3) and
     dwarf_add_expr_addr_b(3) to add location expression operators to the cre-
     ated descriptor.  When done, the application can call the function
     dwarf_expr_into_block(3) to retrieve the generated	byte stream for	the
     location expression, or call the function dwarf_add_AT_location_expr(3)
     to	create an attribute with the location expression stream	as its value.

     Argument dbg should reference a DWARF producer instance allocated using
     dwarf_producer_init(3) or dwarf_producer_init_b(3).

     If	argument err is	not NULL, it will be used to store error information
     in	case of	an error.

RETURN VALUES
     On	success, function dwarf_new_expr() returns the created location	ex-
     pression descriptor.  In case of an error,	function dwarf_new_expr() re-
     turns DW_DLV_BADADDR and sets the argument	err.

ERRORS
     Function dwarf_new_expr() can fail	with:

     [DW_DLE_ARGUMENT]	Argument dbg was NULL.

     [DW_DLE_MEMORY]	An out of memory condition was encountered during the
			execution of the function.

EXAMPLES
     To	create a location expression descriptor, add location expression oper-
     ators to it and to	retrieve the generated byte stream, use:

	   Dwarf_P_Debug dbg;
	   Dwarf_Error de;
	   Dwarf_P_Expr	pe;
	   Dwarf_Addr buf;
	   Dwarf_Unsigned len;

	   /* ...Assume	that `dbg' refers to a DWARF producer instance... */

	   if ((pe = dwarf_new_expr(dbg, &de)) == DW_DLV_BADADDR) {
		   warnx("dwarf_new_expr failed: %s", dwarf_errmsg(-1));
		   return;
	   }

	   if (dwarf_add_expr_gen(pe, DW_OP_regx, 55, 0, &de) ==
	       DW_DLV_NOCOUNT) {
		   warnx("dwarf_add_expr_gen failed: %s", dwarf_errmsg(-1));
		   return;
	   }

	   if ((buf = dwarf_expr_into_block(pe,	&len, &de)) ==
	       DW_DLV_BADADDR) {
		   warnx("dwarf_expr_into_block	failed:	%s",
		       dwarf_errmsg(-1));
		   return;
	   }

SEE ALSO
     dwarf(3), dwarf_add_AT_location_expr(3), dwarf_add_expr_gen(3),
     dwarf_add_expr_addr(3), dwarf_add_expr_addr_b(3),
     dwarf_expr_current_offset(3), dwarf_expr_into_block(3),
     dwarf_producer_init(3), dwarf_producer_init_b(3)

BSD			       September 8, 2011			   BSD

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | EXAMPLES | SEE ALSO

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=dwarf_new_expr&sektion=3&manpath=FreeBSD+12.0-RELEASE+and+Ports>

home | help