dwarf_add_at_location_expr(3) [freebsd man page]

DWARF_ADD_AT_LOCATION_EXPR(3)				   BSD Library Functions Manual 			     DWARF_ADD_AT_LOCATION_EXPR(3)

NAME

     dwarf_add_AT_location_expr -- create an attribute descriptor for a location expression

LIBRARY

     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS

     #include <libdwarf.h>

     Dwarf_P_Attribute
     dwarf_add_AT_location_expr(Dwarf_P_Debug dbg, Dwarf_P_Die die, Dwarf_Half attr, Dwarf_P_Expr loc_expr, Dwarf_Error *err);

DESCRIPTION

     Function dwarf_add_AT_location_expr() creates an attribute descriptor for a location expression and attaches it to the debugging information
     entry referenced by argument die.

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

     Argument die should reference a debugging information entry allocated using dwarf_new_die(3).

     Argument attr specifies the attribute code of the created attribute descriptor.

     Argument loc_expr should reference a location expression descriptor allocated using dwarf_new_expr(3).

     The attribute created by function dwarf_add_AT_location_expr() will have one of the DWARF forms DW_FORM_block, DW_FORM_block1, DW_FORM_block2
     or DW_FORM_block4, depending on the size of the byte stream generated by the location expression descriptor referenced by argument loc_expr.

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

RETURN VALUES

     On success, function dwarf_add_AT_location_expr() returns the created attribute descriptor.  In case of an error, function
     dwarf_add_AT_location_expr() returns DW_DLV_BADADDR and sets the argument err.

ERRORS

     Function dwarf_add_AT_location_expr() can fail with:

     [DW_DLE_ARGUMENT]	One of the arguments dbg, die or loc_expr was NULL.

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

SEE ALSO

     dwarf(3), dwarf_new_die(3), dwarf_new_expr(3), dwarf_producer_init(3), dwarf_producer_init_b(3)

BSD
								 September 5, 2011							       BSD

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 descriptor 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 created
     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 expression descriptor.	In case of an error, function dwarf_new_expr()
     returns 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 operators 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