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DWARF_GET_RANGES(3) 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
representable address offset, and
dwr_addr2 is a base address for the
beginning and ending address offsets
of subsequent 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.
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.
EXAMPLES
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 ..
*/
}
}
}
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
argument die is ignored, and function dwarf_get_ranges_a() is only
provided for compatibility with other implementations of the DWARF(3)
API.
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.
SEE ALSO
dwarf(3), dwarf_ranges_dealloc(3)
NetBSD 10.99 November 9, 2011 NetBSD 10.99