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FreeBSD 11.0 - man page for dwarf_get_ranges_a (freebsd section 3)

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

dwarf_get_ranges -- retrieve non-contiguous address ranges
DWARF Access Library (libdwarf, -ldwarf)
#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);
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.
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.
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.
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.
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 .. */ } } }
dwarf(3), dwarf_ranges_dealloc(3)
November 9, 2011 BSD