DWARF_ATTRVAL_SIGNED(3) | Library Functions Manual | DWARF_ATTRVAL_SIGNED(3)

# NAME

`dwarf_attrval_flag`, `dwarf_attrval_signed`, `dwarf_attrval_string`, `dwarf_attrval_unsigned` —
retrieve the value of an attribute within a DWARF debugging information entry

# LIBRARY

DWARF Access Library (libdwarf, -ldwarf)

# SYNOPSIS

`#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);

# DESCRIPTION

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 not present in the debugging information entry referenced by argument die, and if a `DW_AT_abstract_origin` 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` attribute.

# RETURN VALUES

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.

# COMPATIBILITY

These functions are extensions added by this implementation of the DWARF(3) API.

# ERRORS

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.

# SEE ALSO

dwarf(3), dwarf_attr(3), dwarf_hasattr(3)

January 18, 2014 | NetBSD 9.2