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dwarf_attrval_signed.3
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dwarf_attrval_signed.3
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.\" Copyright (c) 2011 Kai Wang
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $Id: dwarf_attrval_signed.3 2072 2011-10-27 03:26:49Z jkoshy $
.\"
.Dd January 29, 2011
.Os
.Dt DWARF_ATTRVAL_SIGNED 3
.Sh NAME
.Nm dwarf_attrval_flag ,
.Nm dwarf_attrval_signed ,
.Nm dwarf_attrval_string ,
.Nm dwarf_attrval_unsigned
.Nd retrieve the value of an attribute within a DWARF debugging information entry
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_attrval_flag
.Fa "Dwarf_Die die"
.Fa "Dwarf_Half attr"
.Fa "Dwarf_Bool *ret"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_attrval_signed
.Fa "Dwarf_Die die"
.Fa "Dwarf_Half attr"
.Fa "Dwarf_Signed *ret"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_attrval_string
.Fa "Dwarf_Die die"
.Fa "Dwarf_Half attr"
.Fa "const char **ret"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_attrval_unsigned
.Fa "Dwarf_Die die"
.Fa "Dwarf_Half attr"
.Fa "Dwarf_Unsigned *ret"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
These functions search the debugging information entry referenced
by argument
.Ar die
for the attribute named by argument
.Ar attr .
If the named attribute is found, the functions set the location
pointed to by argument
.Ar ret
to the value of the attribute.
The argument
.Ar err ,
if non NULL,
will be used to return an error descriptor in case of an error.
.Pp
Function
.Fn dwarf_attrval_flag
sets the location pointed to by argument
.Ar ret
to 1 if the attribute named by argument
.Ar attr
has a non-zero value, or to 0 otherwise.
The form of the attribute named by argument
.Ar attr
must be
.Dv DW_FORM_flag .
.Pp
Function
.Fn dwarf_attrval_signed
stores the value for the attribute named by argument
.Ar attr ,
into the location pointed to by argument
.Ar ret .
The attribute's value is treated as a signed integral quantity and is
sign-extended as needed.
The attribute named by the argument
.Ar attr
must belong to the
.Dv CONSTANT
class and must have one of the following forms:
.Dv DW_FORM_data1 ,
.Dv DW_FORM_data2 ,
.Dv DW_FORM_data4 ,
.Dv DW_FORM_data8
or
.Dv DW_FORM_sdata .
.Pp
Function
.Fn dwarf_attrval_string
sets the location pointed to by argument
.Ar ret
to a pointer to a NUL-terminated string that is the value of the
attribute named by argument
.Ar attr .
The form of the attribute must be one of
.Dv DW_FORM_string
or
.Dv DW_FORM_strp .
.Pp
Function
.Fn dwarf_attrval_unsigned
stores the value for the attribute named by argument
.Ar attr
into the location pointed to by argument
.Ar 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
.Dv CONSTANT ,
.Dv ADDRESS
or
.Dv REFERENCE
classes and must have one of the following forms:
.Dv DW_FORM_addr ,
.Dv DW_FORM_data1 ,
.Dv DW_FORM_data2 ,
.Dv DW_FORM_data4 ,
.Dv DW_FORM_data8 ,
.Dv DW_FORM_udata ,
.Dv DW_FORM_ref1 ,
.Dv DW_FORM_ref2 ,
.Dv DW_FORM_ref4 ,
.Dv DW_FORM_ref8 ,
or
.Dv DW_FORM_ref_udata .
.Pp
If the attribute named by argument
.Ar attr
is not present in the debugging information entry referenced by
argument
.Ar die ,
and if a
.Dv DW_AT_abstract_origin
attribute is present in the debugging information entry,
function
.Fn dwarf_attrval_unsigned
will search for the named attribute in the debugging information entry
referenced by the
.Dv DW_AT_abstract_origin
attribute.
.Sh RETURN VALUES
On success, these functions returns
.Dv DW_DLV_OK .
If the named attribute was not found in the specified debugging
information entry descriptor these functions return
.Dv DW_DLV_NO_ENTRY
and set argument
.Ar err .
For other errors, these functions return
.Dv DW_DLV_ERROR
and set argument
.Ar err .
.Sh COMPATIBILITY
These functions are extensions added by this implementation of the
DWARF(3) API.
.Sh ERRORS
These functions may fail with the following errors:
.Bl -tag -width ".Bq Er DW_DLE_ATTR_FORM_BAD"
.It Bq Er DW_DLE_ARGUMENT
Either of the arguments
.Va die
or
.Va ret
was NULL.
.It Bq Er DW_DLE_NO_ENTRY
Argument
.Ar die
did not contain an attribute corresponding to the value in argument
.Ar attr .
.It Bq Er DW_DLE_ATTR_FORM_BAD
The attribute named by argument
.Ar attr
was not of a permitted form.
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_attr 3 ,
.Xr dwarf_hasattr 3