dwarf_attrval_flag,
dwarf_attrval_signed,
dwarf_attrval_string,
dwarf_attrval_unsigned —
retrieve the value of an attribute within a DWARF
debugging information entry
DWARF Access Library (libdwarf, -ldwarf)
#include
<libdwarf.h>
int
dwarf_attrval_flag(
Dwarf_Die
die,
Dwarf_Half attr,
Dwarf_Bool *ret,
Dwarf_Error *err);
int
dwarf_attrval_signed(
Dwarf_Die
die,
Dwarf_Half attr,
Dwarf_Signed *ret,
Dwarf_Error *err);
int
dwarf_attrval_string(
Dwarf_Die
die,
Dwarf_Half attr,
const char **ret,
Dwarf_Error *err);
int
dwarf_attrval_unsigned(
Dwarf_Die
die,
Dwarf_Half attr,
Dwarf_Unsigned *ret,
Dwarf_Error *err);
These functions search the debugging information entry referenced by argument
die for the attribute named by argument
attr. If the named attribute is found, the
functions set the location pointed to by argument
ret to the value of the attribute. The
argument
err, if non NULL, will be used to
return an error descriptor in case of an error.
Function
dwarf_attrval_flag() sets the location
pointed to by argument
ret to either 0 or 1.
If the form of the attribute named by argument
attr is
DW_FORM_flag
, function
dwarf_attrval_flag() sets the location pointed to
by argument
ret to 1 if the attribute has a
non-zero value, or to 0 otherwise. If the form of the attribute named by
argument
attr is
DW_FORM_flag_present
, function
dwarf_attrval_flag() unconditionally sets the
location pointed to by argument
ret to 1. The
form of the attribute must be one of
DW_FORM_flag
or
DW_FORM_flag_present
.
Function
dwarf_attrval_signed() stores the value
for the attribute named by argument
attr,
into the location pointed to by argument
ret.
The attribute's value is treated as a signed integral quantity and is
sign-extended as needed. The attribute named by the argument
attr must belong to the
CONSTANT
class and must have one of the
following forms:
DW_FORM_data1
,
DW_FORM_data2
,
DW_FORM_data4
,
DW_FORM_data8
or
DW_FORM_sdata
.
Function
dwarf_attrval_string() sets the location
pointed to by argument
ret to a pointer to a
NUL-terminated string that is the value of the attribute named by argument
attr. The form of the attribute must be one
of
DW_FORM_string
or
DW_FORM_strp
.
Function
dwarf_attrval_unsigned() stores the value
for the attribute named by argument
attr into
the location pointed to by argument
ret. The
attribute's value is treated as an unsigned integral quantity, and is
zero-extended as needed. The named attribute must belong to one of the
CONSTANT
,
ADDRESS
or
REFERENCE
classes and must have one of the
following forms:
DW_FORM_addr
,
DW_FORM_data1
,
DW_FORM_data2
,
DW_FORM_data4
,
DW_FORM_data8
,
DW_FORM_udata
,
DW_FORM_ref1
,
DW_FORM_ref2
,
DW_FORM_ref4
,
DW_FORM_ref8
, or
DW_FORM_ref_udata
.
If the attribute named by argument
attr is
DW_AT_type
and is not present in the
debugging information entry referenced by argument
die, and if a
DW_AT_abstract_origin
or
DW_AT_specification
attribute is present in
the debugging information entry, function
dwarf_attrval_unsigned() will search for the
named attribute in the debugging information entry referenced by the
DW_AT_abstract_origin
or
DW_AT_specification
attribute.
On success, these functions returns
DW_DLV_OK
. If the named attribute was not
found in the specified debugging information entry descriptor these functions
return
DW_DLV_NO_ENTRY
and set argument
err. For other errors, these functions return
DW_DLV_ERROR
and set argument
err.
These functions are extensions added by this implementation of the DWARF(3) API.
These functions may fail with the following errors:
-
-
- [
DW_DLE_ARGUMENT
]
- Either of the arguments
die or
ret was NULL.
-
-
- [
DW_DLE_NO_ENTRY
]
- Argument die did not
contain an attribute corresponding to the value in argument
attr.
-
-
- [
DW_DLE_ATTR_FORM_BAD
]
- The attribute named by argument
attr was not of a permitted form.
dwarf(3),
dwarf_attr(3),
dwarf_hasattr(3)