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.\" Id: dwarf_get_vars.3 3963 2022-03-12 16:07:32Z jkoshy
.\"
.Dd April 2, 2011
.Dt DWARF_GET_VARS 3
.Os
.Sh NAME
.Nm dwarf_get_vars ,
.Nm dwarf_var_cu_offset ,
.Nm dwarf_var_die_offset ,
.Nm dwarf_var_name_offsets ,
.Nm dwarf_varname
.Nd retrieve information about static variables
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_vars
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Var **vars"
.Fa "Dwarf_Signed *nvars"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_var_cu_offset
.Fa "Dwarf_Var var"
.Fa "Dwarf_Off *cu_offset"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_var_die_offset
.Fa "Dwarf_Var var"
.Fa "Dwarf_Off *die_offset"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_var_name_offsets
.Fa "Dwarf_Var var"
.Fa "char **name"
.Fa "Dwarf_Off *die_offset"
.Fa "Dwarf_Off *cu_die_offset"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_varname
.Fa "Dwarf_Var var"
.Fa "char **name"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
These functions retrieve information about the file scope static
variables associated with a DWARF debug context.
Information about these static variables is returned using opaque
descriptors of type
.Vt Dwarf_Var .
Applications need to use the functions described below to retrieve
the name and offset information contained in these descriptors.
.Pp
Function
.Fn dwarf_get_vars
retrieves descriptors for all the static variables associated with the
DWARF debug context specified by argument
.Fa dbg .
The argument
.Fa vars
should point to a location that will be set to a pointer to an array
of
.Vt Dwarf_Var
descriptors.
The argument
.Fa nvars
should point to a location that will be set to the number of
descriptors returned.
.Pp
Function
.Fn dwarf_var_cu_offset
returns the section-relative offset, relative to the
.Dq ".debug_info"
section, of the compilation unit that
contains the debugging information entry associated with the argument
.Fa var .
Argument
.Fa cu_offset
should point to a location that will hold the returned offset.
.Pp
Function
.Fn dwarf_var_die_offset
retrieves the section-relative offset, relative to the
.Dq ".debug_info"
section, of the debugging information
entry associated with the argument
.Fa var ,
and stores it into the location pointed to by the argument
.Fa die_offset .
.Pp
Function
.Fn dwarf_var_name_offsets
retrieves both the name and the associated offsets for the debugging
information entry for argument
.Fa var .
Argument
.Fa name
should point to a location which will be set to a pointer to a
NUL-terminated string containing the name of the associated debugging
information entry.
Argument
.Fa die_offset
should point to a location which will be set to a section-relative
offset, relative to the
.Dq ".debug_info"
section, of the associated debugging information entry.
Argument
.Fa cu_die_offset
should point to a location which will be set to a
section-relative offset, relative to the
.Dq ".debug_info"
section, of the first debugging information entry in
the compilation unit associated with argument
.Fa var .
.Pp
Function
.Fn dwarf_varname
sets the location pointed to by argument
.Fa name
to a pointer to a NUL-terminated string holding the name of the
debugging information entry associated with the argument
.Fa var .
.Ss Memory Management
The memory area used for the array of
.Vt Dwarf_Var
descriptors returned in argument
.Fa vars
by function
.Fn dwarf_get_vars
is owned by the
.Lb libdwarf .
Application code should not attempt to directly free this pointer.
Portable code should instead use the function
.Xr dwarf_vars_dealloc 3
to indicate that the memory area may be freed.
.Pp
The memory area used for the string returned in the
.Fa name
argument to functions
.Fn dwarf_var_name_offsets
and
.Fn dwarf_varname
is owned by the
.Lb libdwarf .
Portable code should indicate that the memory area can
be freed using the
.Xr dwarf_dealloc 3
function.
.Ss Error Returns
If argument
.Fa err
is not
.Dv NULL ,
these functions will use it to store error information,
in case of an error.
.Sh RETURN VALUES
On success, these functions returns
.Dv DW_DLV_OK .
In case of an error, they return
.Dv DW_DLV_ERROR
and set the argument
.Fa err .
.Sh ERRORS
These functions may fail with the following errors:
.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Va cu_die_offset ,
.Va cu_offset ,
.Va dbg ,
.Va die_offset ,
.Va var ,
.Va vars ,
.Va name ,
or
.Va nvars
was
.Dv NULL .
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_dealloc 3 ,
.Xr dwarf_get_cu_die_offset_given_cu_header_offset 3 ,
.Xr dwarf_vars_dealloc 3