DWARF_GET_RANGES(3)					   BSD Library Functions Manual 				       DWARF_GET_RANGES(3)

NAME

     dwarf_get_ranges -- retrieve non-contiguous address ranges

LIBRARY

     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS

     #include <libdwarf.h>

     int
     dwarf_get_ranges(Dwarf_Debug dbg, Dwarf_Off offset, Dwarf_Ranges **ranges, Dwarf_Signed *cnt, Dwarf_Unsigned *byte_cnt, Dwarf_Error *err);

     int
     dwarf_get_ranges_a(Dwarf_Debug dbg, Dwarf_Off offset, Dwarf_Die die, Dwarf_Ranges **ranges, Dwarf_Signed *cnt, Dwarf_Unsigned *byte_cnt,
	 Dwarf_Error *err);

DESCRIPTION

     Function dwarf_get_ranges() retrieves information about the non-contiguous address ranges associated with a DWARF debugging information
     entry.  Information about address ranges is returned as an array of descriptors of type Dwarf_Ranges, with each Dwarf_Ranges descriptor
     describing one address range entry.

     Argument dbg should reference a DWARF debug context allocated using dwarf_init(3).

     Argument offset is an offset, relative to the ``.debug_ranges'' section, to the start of the desired list of address ranges.  The offset of
     an address ranges list is indicated by the DW_AT_ranges attribute of a debugging information entry.

     Argument die (function dwarf_get_ranges_a() only) is ignored in this implementation; see the section Compatibility Notes below.

     Argument ranges should point to a location that will be set to a pointer to an array of Dwarf_Ranges descriptors.

     Argument cnt should point to a location that will be set to the number of entries returned.  If argument byte_cnt is not NULL, it will be set
     to the number of bytes occupied by the returned entries in the ``.debug_ranges'' section.

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

     Dwarf_Ranges descriptors are defined in the header file <libdwarf.h>, and consists of the following fields:

     dwr_addr1	The first address offset, whose meaning depends on the type of the entry.

     dwr_addr2	The second address offset, whose meaning depends on the type of the entry.

     dwr_type	The type of this address range entry:
		DW_RANGES_ENTRY  A range list entry.  For this type of entry, the fields dwr_addr1 and dwr_addr2 hold the beginning and ending
				 offsets of the address range, respectively.
		DW_RANGES_ADDRESS_SELECTION
				 A base address selection entry.  For this type of entry, the field dwr_addr1 is the value of the largest repre-
				 sentable address offset, and dwr_addr2 is a base address for the begining and ending address offsets of subse-
				 quent address range entries in the list.
		DW_RANGES_END	 An end of list mark.  Both dwr_addr1 and dwr_addr2 are set to 0.

   Memory Management
     The memory area used for the array of Dwarf_Ranges descriptors returned in argument ranges is owned by the DWARF Access Library (libdwarf,
     -ldwarf).	The application should not attempt to directly free this pointer.  Portable code should instead use dwarf_ranges_dealloc() to
     indicate that the memory may be freed.

COMPATIBILITY

     Function dwarf_get_ranges_a() is identical to dwarf_get_ranges(), except that it requires one additional argument die denoting the debugging
     information entry associated with the address range list.	In this implementation of the DWARF Access Library (libdwarf, -ldwarf), the argu-
     ment die is ignored, and function dwarf_get_ranges_a() is only provided for compatibility with other implementations of the DWARF(3) API.

RETURN VALUES

     These functions return DW_DLV_OK when they succeed.  They return DW_DLV_NO_ENTRY if there is no address range list at the specified offset
     offset.  In case of an error, they return DW_DLV_ERROR and set the argument err.

ERRORS

     These function can fail with:

     [DW_DLE_ARGUMENT]	One of the arguments dbg, ranges or cnt was NULL.

     [DW_DLE_NO_ENTRY]	There is no address range list at the specified offset offset.

EXAMPLE

     To retrieve the address range list associated with a debugging information entry, use:

	   Dwarf_Debug dbg;
	   Dwarf_Die die;
	   Dwarf_Error de;
	   Dwarf_Addr base;
	   Dwarf_Attribute *attr_list;
	   Dwarf_Ranges *ranges;
	   Dwarf_Signed cnt;
	   Dwarf_Unsigned off, attr_count, bytecnt;
	   int i, j;

	   if ((ret = dwarf_attrlist(die, &attr_list, &attr_count, &de)) !=
	       DW_DLV_OK)
		   errx(EXIT_FAILURE, "dwarf_attrlist failed: %s",
		       dwarf_errmsg(de));

	   for (i = 0; (Dwarf_Unsigned) i < attr_count; i++) {
		   if (dwarf_whatattr(attr_list[i], &attr, &de) != DW_DLV_OK) {
			   warnx("dwarf_whatattr failed: %s",
			       dwarf_errmsg(de));
			   continue;
		   }
		   if (attr != DW_AT_ranges)
			   continue;
		   if (dwarf_formudata(attr_list[i], &off, &de) != DW_DLV_OK) {
			   warnx("dwarf_formudata failed: %s",
			       dwarf_errmsg(de));
			   continue;
		   }
		   if (dwarf_get_ranges(dbg, (Dwarf_Off) off, &ranges, &cnt,
		       &bytecnt, &de) != DW_DLV_OK)
			   continue;
		   for (j = 0; j < cnt; j++) {
			   if (ranges[j].dwr_type == DW_RANGES_END)
				   break;
			   else if (ranges[j].dwr_type ==
			       DW_RANGES_ADDRESS_SELECTION)
				   base = ranges[j].dwr_addr2;
			   else {
				   /*
				    * DW_RANGES_ENTRY entry.
				    * .. Use dwr_addr1 and dwr_addr2 ..
				    */
			   }
		   }
	   }

SEE ALSO

     dwarf(3), dwarf_ranges_dealloc(3)

BSD
								 November 9, 2011							       BSD