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DWARF_CHILD(3)             Library Functions Manual             DWARF_CHILD(3)

NAME
     dwarf_child, dwarf_offdie, dwarf_offdie_b, dwarf_siblingof,
     dwarf_siblingof_b - retrieve DWARF Debugging Information Entry
     descriptors

LIBRARY
     DWARF Access Library (libdwarf, -ldwarf)

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 DWARF Access Library (libdwarf, -ldwarf).
     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()
                             and dwarf_siblingof_b(), the descriptor denoted
                             by argument die did not have a child or sibling.

                             For functions dwarf_offdie() and
                             dwarf_offdie_b(), there was no debugging
                             information entry at the offset specified by
                             argument offset.

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.

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);

SEE ALSO
     dwarf(3), dwarf_errmsg(3), dwarf_get_die_infotypes_flag.3,
     dwarf_next_cu_header(3)

NetBSD 8.0                     December 21, 2014                    NetBSD 8.0