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DWARF_LOCLIST_FROM_EXPR(3)                            Library Functions Manual

NAME
     dwarf_loclist_from_expr, dwarf_loclist_from_expr_a,
     dwarf_loclist_from_expr_b - translate DWARF location expression bytes

LIBRARY
     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS
     #include <libdwarf.h>

     int
     dwarf_loclist_from_expr(Dwarf_Debug dbg, Dwarf_Ptr bytes_in,
         Dwarf_Unsigned bytes_len, Dwarf_Locdesc **llbuf,
         Dwarf_Signed *listlen, Dwarf_Error *err);

     int
     dwarf_loclist_from_expr_a(Dwarf_Debug dbg, Dwarf_Ptr bytes_in,
         Dwarf_Unsigned bytes_len, Dwarf_Half addr_size,
         Dwarf_Locdesc **llbuf, Dwarf_Signed *listlen, Dwarf_Error *err);

     int
     dwarf_loclist_from_expr_b(Dwarf_Debug dbg, Dwarf_Ptr bytes_in,
         Dwarf_Unsigned bytes_len, Dwarf_Half addr_size,
         Dwarf_Half offset_size, Dwarf_Small version, Dwarf_Locdesc **llbuf,
         Dwarf_Signed *listlen, Dwarf_Error *error);

DESCRIPTION
     Function dwarf_loclist_from_expr() translates DWARF location expression
     bytes into a Dwarf_Locdesc descriptor.  The size for address related data
     is taken to be the default address size for the object being read.

     Argument dbg should reference a DWARF debug context allocated using
     dwarf_init(3).

     Argument bytes_in should point to an array of DWARF location expression
     bytes.

     Argument bytes_len should specify the number of the location expression
     bytes to be translated.

     Argument llbuf should point to a location which will be set to a pointer
     to a returned Dwarf_Locdesc descriptor.

     Argument listlen should point to a location which will hold the number of
     the Dwarf_Locdesc descriptors returned.  In this case it is always set to
     1.

     If argument err is not NULL, it will be used to store error information
     in case of an error.

     Function dwarf_loclist_from_expr_a() is identical to function
     dwarf_loclist_from_expr(), except that it requires one additional
     argument addr_size, which specifies the address size to use when
     translating the location expression bytes.

     Function dwarf_loclist_from_expr_b() is identical to function
     dwarf_loclist_from_expr_a() except that it requires two additional
     arguments for translating the location expression bytes.  Argument
     offset_size specifies the offset size, and argument version specifies the
     DWARF version.  These values are required to correctly translate the
     DW_OP_GNU_implicit_pointer opcode.

   Memory Management
     The memory area used for the descriptor returned in argument llbuf is
     allocated by DWARF Access Library (libdwarf, -ldwarf).  When the
     descriptor is no longer needed, application code should use function
     dwarf_dealloc(3) to free the memory area in two steps:
     1.   First, the array of Dwarf_Loc descriptors pointed to by the ld_s
          field of the Dwarf_Locdesc descriptor should be deallocated using
          the allocation type DW_DLA_LOC_BLOCK.
     2.   Next, the application should free the llbuf pointer using the
          allocation type DW_DLA_LOCDESC.

RETURN VALUES
     On success, these functions returns DW_DLV_OK.  In case of an error, they
     return DW_DLV_ERROR and set the argument err.

ERRORS
     These functions may fail with the following errors:

     [DW_DLE_ARGUMENT]           One of the arguments dbg, bytes_in, llbuf or
                                 listlen was NULL.

     [DW_DLE_ARGUMENT]           Argument bytes_len was 0.

     [DW_DLE_ARGUMENT]           The value of argument addr_size was invalid.

     [DW_DLE_LOC_EXPR_BAD]       An unknown or invalid operation was found in
                                 the location expression bytes provided in
                                 argument bytes_in.

     [DW_DLE_MEMORY]             An out of memory condition was encountered
                                 during the execution of this function.

SEE ALSO
     dwarf(3), dwarf_dealloc(3), dwarf_loclist_n(3),
     dwarf_get_fde_info_for_all_regs3(3), dwarf_get_fde_info_for_cfa_reg3(3),
     dwarf_get_fde_info_for_reg3(3), dwarf_get_loclist_entry(3)

NetBSD 8.0                     December 21, 2014                    NetBSD 8.0