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
library “libdwarf”
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)