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DWARF_NEXT_CU_HEADER(3)    Library Functions Manual    DWARF_NEXT_CU_HEADER(3)

NAME
     dwarf_next_cu_header, dwarf_next_cu_header_b, dwarf_next_cu_header_c -
     step through compilation units in a DWARF debug context

LIBRARY
     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS
     #include <libdwarf.h>

     int
     dwarf_next_cu_header(Dwarf_Debug dbg, Dwarf_Unsigned *cu_length,
         Dwarf_Half *cu_version, Dwarf_Off *cu_abbrev_offset,
         Dwarf_Half *cu_pointer_size, Dwarf_Unsigned *cu_next_offset,
         Dwarf_Error *err);

     int
     dwarf_next_cu_header_b(Dwarf_Debug dbg, Dwarf_Unsigned *cu_length,
         Dwarf_Half *cu_version, Dwarf_Off *cu_abbrev_offset,
         Dwarf_Half *cu_pointer_size, Dwarf_Half *cu_offset_size,
         Dwarf_Half *cu_extension_size, Dwarf_Unsigned *cu_next_offset,
         Dwarf_Error *err);

     int
     dwarf_next_cu_header_c(Dwarf_Debug dbg, Dwarf_Bool is_info,
         Dwarf_Unsigned *cu_length, Dwarf_Half *cu_version,
         Dwarf_Off *cu_abbrev_offset, Dwarf_Half *cu_pointer_size,
         Dwarf_Half *cu_offset_size, Dwarf_Half *cu_extension_size,
         Dwarf_Sig8 *type_signature, Dwarf_Unsigned *type_offset,
         Dwarf_Unsigned *cu_next_offset, Dwarf_Error *err);

DESCRIPTION
     These functions are used to step through compilation or type units
     associated with a DWARF debug context, optionally returning information
     about the unit.

     Function dwarf_next_cu_header_c() is the API recommended for new
     application code.  Function dwarf_next_cu_header() and
     dwarf_next_cu_header_b() can only operate on compilation units associated
     with the ".debug_info" section.  They are less general than function
     dwarf_next_cu_header_c(), and are deprecated for use by new application
     code.

     Argument dbg should reference a DWARF debug context allocated using
     dwarf_init(3).  If argument is_info is set to 1, the function returns
     information for compilation units found in the ".debug_info" section.  If
     argument is_info is set to 0, the function returns information for type
     units found in the ".debug_types" sections.  Argument cu_length should
     point to a location that will be set to the length of the compilation or
     type unit.  Argument cu_version should point to a location that will be
     set to the version number for the compilation or type unit.  Argument
     cu_abbrev_offset should point to a location that will be set to the
     starting offset (in the ".debug_abbrev" section) of the set of debugging
     information entry abbreviations associated with this compilation or type
     unit.  Argument cu_pointer_size should point to a location that will be
     set to the size in bytes of an address for the machine architecture of
     the underlying object being debugged.  Argument cu_offset_size should
     point to a location that will be set to the size in bytes for a DWARF
     offset in the compilation or type unit.  Argument cu_extension_size is
     only needed for processing MIPS/IRIX objects that use a non-standard
     DWARF format.  It should point to a location that will be set to 4 for
     normal objects and to 0 for non-standard ones.  Argument type_signature
     and type_offset is only needed for processing type units.  Argument
     type_signature should point to a location that will be set to the 64-bit
     unique signature of the type described in the type unit.  Argument
     type_offset should point to a location that will be set to the offset of
     the debugging information entry that describes the type.  Argument
     cu_next_offset should point to a location that will be set to the offset
     of the next compilation unit header in the ".debug_info" section, or the
     offset of the next type unit header in the ".debug_types" section.
     Argument err should point to a location that will hold an error
     descriptor in case of an error.

     Function dwarf_next_cu_header_b() is identical to function
     dwarf_next_cu_header_c() except that it does not provide arguments
     is_info, type_signature and type_offset.

     Function dwarf_next_cu_header() is identical to function
     dwarf_next_cu_header_b() except that it does not provide arguments
     cu_offset_size and cu_extension_size.

     A value of NULL may be used for any of the arguments cu_length,
     cu_version, cu_abbrev_offset, cu_pointer_size, cu_offset_size,
     cu_extension_size, type_signature, type_offset, cu_next_offset and err if
     the caller is not interested in the respective value.

   Iterating Through Compilation Units in a Debug Context
     The first call to function dwarf_next_cu_header_c() for a given debug
     context with argument is_info set to 1 will return information about the
     first compilation unit in the ".debug_info" section.  Subsequent calls to
     the function will iterate through the remaining compilation units in the
     section.  On stepping past the last compilation unit in the section,
     function dwarf_next_cu_header_c() returns DW_DLV_NO_ENTRY and resets its
     internal state.  The next call to the function will restart from the
     first compilation unit in the section.

   Iterating Through Type Units in a Debug Context
     When a DWARF debug context is allocated using dwarf_init(3), an internal
     pointer associated with the context will point to the first
     ".debug_types" section found in the debug object.  The first call to
     function dwarf_next_cu_header_c() for the debug context with argument
     is_info set to 0 will return information about the first type unit in
     that ".debug_types" section.  Subsequent calls to the function will
     iterate through the remaining type units in the section.  On stepping
     past the last type unit in the debug context, function
     dwarf_next_cu_header_c() returns DW_DLV_NO_ENTRY and resets its internal
     state.  The next call to the function will restart from the first type
     unit in the ".debug_types" section.

     If the debug object contains multiple ".debug_types" sections, the
     function dwarf_next_types_section() can be called to move the internal
     pointer to the next ".debug_types" section.  As a result, subsequent
     calls of the function dwarf_next_cu_header_c() will operate on the new
     ".debug_types" section.  Function dwarf_next_types_section() returns
     DW_DLV_NO_ENTRY when there are no more ".debug_types" sections left in
     the debug object.

RETURN VALUES
     On success, these functions return DW_DLV_OK.  In case of an error, they
     return DW_DLV_ERROR and set argument err.  When there are no more
     compilation units left to traverse, they return DW_DLV_NO_ENTRY.

ERRORS
     These functions can fail with the following error:

     [DW_DLE_ARGUMENT]       Argument dbg was NULL.

SEE ALSO
     dwarf(3), dwarf_get_cu_die_offset_given_cu_header_offset(3),
     dwarf_init(3), dwarf_next_types_section(3), dwarf_siblingof(3)

NetBSD 8.0                     December 21, 2014                    NetBSD 8.0