xref: /freebsd/contrib/elftoolchain/libdwarf/dwarf_formexprloc.3 (revision ae500c1ff8974130f7f2692772cf288b90349e0d)

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.\" $Id: dwarf_formexprloc.3 3640 2018-10-14 14:09:13Z jkoshy $
.\"
.Dd July 25, 2010
.Dt DWARF_FORMEXPRLOC 3
.Os
.Sh NAME
.Nm dwarf_formexprloc
.Nd return information about a location expression
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_formexprloc
.Fa "Dwarf_Attribute attr"
.Fa "Dwarf_Unsigned *retlen"
.Fa "Dwarf_Ptr *retexpr"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_formexprloc
allows an application to retrieve the length and the bytes of a
DWARF location expression.
.Pp
Argument
.Ar attr
should reference a DWARF attribute of the form
.Dv DW_FORM_exprloc .
Argument
.Ar retlen
should point to a location that will be set to the length of the
location expression.
Argument
.Ar retexpr
should point to a location that will be set to a pointer to the
content of the location expression itself.
.Pp
If argument
.Ar err
is not NULL, it will be used to return an error descriptor in case
of an error.
.Ss Memory Management
The application should not attempt to free the memory
area referenced by the pointer returned in argument
.Ar retexpr .
.Sh RETURN VALUES
Function
.Fn dwarf_formexprloc
returns
.Dv DW_DLV_OK
on success.
In case of an error, it returns
.Dv DW_DLV_ERROR
and sets argument
.Ar err .
.Sh ERRORS
Function
.Fn dwarf_formexprloc
may fail with the following errors:
.Bl -tag -width ".Bq Er DW_DLE_ATTR_FORM_BAD"
.It Bq Er DW_DLE_ARGUMENT
One of arguments
.Ar attr ,
.Ar retlen
or
.Ar retexpr
was NULL.
.It Bq Er DW_DLE_ATTR_FORM_BAD
The attribute referenced by argument
.Ar attr
was not of form
.Dv DW_FORM_exprloc .
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_attr 3 ,
.Xr dwarf_formblock 3 ,
.Xr dwarf_formflag 3 ,
.Xr dwarf_formref 3 ,
.Xr dwarf_formsdata 3 ,
.Xr dwarf_formsig8 3 ,
.Xr dwarf_formstring 3 ,
.Xr dwarf_formudata 3 ,
.Xr dwarf_hasattr 3