NAME
dwarf_child
,
dwarf_offdie
,
dwarf_offdie_b
,
dwarf_siblingof
,
dwarf_siblingof_b
—
retrieve DWARF Debugging Information
Entry descriptors
LIBRARY
library “libdwarf”
SYNOPSIS
#include
<libdwarf.h>
int
dwarf_child
(Dwarf_Die
die, Dwarf_Die
*ret_die, Dwarf_Error
*err);
int
dwarf_offdie
(Dwarf_Debug dbg,
Dwarf_Off offset, Dwarf_Die
*ret_die, Dwarf_Error *err);
int
dwarf_offdie_b
(Dwarf_Debug dbg,
Dwarf_Off offset, Dwarf_Bool
is_info, Dwarf_Die *ret_die,
Dwarf_Error *err);
int
dwarf_siblingof
(Dwarf_Debug dbg,
Dwarf_Die die, Dwarf_Die
*ret_die, Dwarf_Error *err);
int
dwarf_siblingof_b
(Dwarf_Debug
dbg, Dwarf_Die die, Dwarf_Die
*ret_die, Dwarf_Bool is_info,
Dwarf_Error *err);
DESCRIPTION
These functions are used to retrieve and traverse DWARF Debugging Information Entry (DIE) descriptors associated with a compilation unit. These descriptors are arranged in the form of a tree, traversable using “child” and “sibling” links; see dwarf(3) for more information. DWARF Debugging Information Entry descriptors are represented by the Dwarf_Die opaque type.Function
dwarf_child
()
retrieves the child of descriptor denoted by argument
die, and stores it in the location pointed to by
argument ret_die.
Function
dwarf_siblingof
()
retrieves the sibling of the descriptor denoted by argument
die, and stores it in the location pointed to by
argument ret_die. If argument
die is NULL, the first debugging information entry
descriptor for the current compilation unit will be returned. This function
and function dwarf_child
() may be used together to
traverse the tree of debugging information entry descriptors for a
compilation unit.
Function
dwarf_siblingof_b
()
is identical to the function dwarf_siblingof
()
except that it can retrieve the sibling descriptor from either the current
compilation unit or type unit. If argument is_info is
non-zero, the function behaves identically to function
dwarf_siblingof
(). If argument
is_info is zero, the descriptor referred by argument
die should be associated with a debugging information
entry in the type unit. The function will store the sibling of the
descriptor in the location pointed to by argument
ret_die. If argument is_info is
zero and argument die is NULL
,
the first debugging information entry descriptor for the current type unit
will be returned.
Function
dwarf_offdie
()
retrieves the debugging information entry descriptor at global offset
offset in the “.debug_info” section of
the object associated with argument dbg. The returned
descriptor is written to the location pointed to by argument
ret_die.
Function
dwarf_offdie_b
()
is identical to the function dwarf_offdie
() except
that it can retrieve the debugging information entry descriptor at global
offset offset from either of the
“.debug_info” and “.debug_types” sections of the
object associated with argument dbg. If argument
is_info is non-zero, the function will retrieve the
debugging information entry from the “.debug_info” section,
otherwise the function will retrieve the debugging information entry from
the “.debug_types” section. The returned descriptor is written
to the location pointed to by argument ret_die.
Memory Management
The memory area used for the Dwarf_Die
descriptor returned in argument ret_die is allocated
by the library “libdwarf”. Application
code should use function
dwarf_dealloc
()
with the allocation type DW_DLA_DIE
to free the
memory area when the Dwarf_Die descriptor is no longer
needed.
RETURN VALUES
These functions return the following values:
- [
DW_DLV_OK
] - The call succeeded.
- [
DW_DLV_ERROR
] - The requested operation failed. Additional information about the error encountered will be recorded in argument err, if it is not NULL.
- [
DW_DLV_NO_ENTRY
] - For functions
dwarf_child
(),dwarf_siblingof
() anddwarf_siblingof_b
(), the descriptor denoted by argument die did not have a child or sibling.For functions
dwarf_offdie
() anddwarf_offdie_b
(), there was no debugging information entry at the offset specified by argument offset.
EXAMPLES
To retrieve the first DWARF Debugging Information Entry descriptor for the first compilation unit associated with a Dwarf_Debug instance, and to traverse all its children, use:
Dwarf_Debug dbg; Dwarf_Die die, die0; Dwarf_Error de; ... allocate dbg using dwarf_init() etc ... if (dwarf_next_cu_header(dbg, NULL, NULL, NULL, NULL, NULL, &de) != DW_DLV_OK) errx(EXIT_FAILURE, "dwarf_next_cu_header: %s", dwarf_errmsg(de)); /* Get the first DIE for the current compilation unit. */ die = NULL; if (dwarf_siblingof(dbg, die, &die0, &de) != DW_DLV_OK) errx(EXIT_FAILURE, "dwarf_siblingof: %s", dwarf_errmsg(de)); /* Get the first child of this DIE. */ die = die0; if (dwarf_child(die, &die0, &de) != DW_DLV_OK) errx(EXIT_FAILURE, "dwarf_child: %s", dwarf_errmsg(de)); /* Get the rest of children. */ do { die = die0; if (dwarf_siblingof(dbg, die, &die0, &de) == DW_DLV_ERROR) errx(EXIT_FAILURE, "dwarf_siblingof: %s", dwarf_errmsg(de)); } while (die0 != NULL);
ERRORS
These functions may fail with the following errors:
- [
DW_DLE_ARGUMENT
] - Arguments dbg, die or ret_die were NULL.
- [
DW_DLE_DIE_NO_CU_CONTEXT
] - Argument dbg was not associated with a compilation unit.
- [
DW_DLE_NO_ENTRY
] - The descriptor denoted by argument die had no child or sibling, or there was no DWARF debugging information entry at the offset specified by argument offset.
SEE ALSO
dwarf(3), dwarf_errmsg(3), dwarf_get_die_infotypes_flag(3), dwarf_next_cu_header(3)