Manual Pages  — DWARF_EXPAND_FRAME_INSTRUCTIONS

dwarf_expand_frame_instructions – expand frame instructions

LIBRARY SYNOPSIS DESCRIPTION Memory Management RETURN VALUES EXAMPLES ERRORS SEE ALSO

DWARF Access Library (libdwarf, -ldwarf)

#include <libdwarf.h>

int
dwarf_expand_frame_instructions(Dwarf_Cie cie, Dwarf_Ptr instructions, Dwarf_Unsigned len, Dwarf_Frame_Op **ret_ops, Dwarf_Signed *ret_opcnt, Dwarf_Error *error);

Function dwarf_expand_frame_instructions() returns DW_DLV_OK when it succeeds. In case of an error, it returns DW_DLV_ERROR and sets the argument err.

To retrieve and expand the frame instructions for a given FDE descriptor, use:

Dwarf_Dbg dbg;
Dwarf_Cie cie;
Dwarf_Fde fde;
Dwarf_Ptr fde_inst;
Dwarf_Unsigned fde_instlen;
Dwarf_Frame_Op *ops;
Dwarf_Signed opcnt;
Dwarf_Error de;

/* ... assuming `dbg` references a valid DWARF debugging context,
  `fde` references a valid FDE descriptor and `cie` holds the CIE
  descriptor associated with the FDE descriptor ... */

if (dwarf_get_fde_instr_bytes(fde, &fde_inst, &fde_instlen,
    &de) != DW_DLV_OK)
        errx(EXIT_FAILURE, "dwarf_get_fde_instr_bytes failed: %s",
            dwarf_errmsg(de));

if (dwarf_expand_frame_instructions(cie, fde_inst, fde_instlen,
    &ops, &opcnt, &de) != DW_DLV_OK)
        errx(EXIT_FAILURE,
            "dwarf_expand_frame_instructions failed: %s",
            dwarf_errmsg(de));

for (i = 0; i < opcnt; i++) {
        /* ... use ops[i] ... */
}

/* Free the memory area when no longer needed. */
dwarf_dealloc(dbg, ops, DW_DLA_FRAME_BLOCK);

Function dwarf_expand_frame_instructions() can fail with:

[DW_DLE_ARGUMENT]	One of the arguments cie, instructions, ret_ops or ret_opcnt was NULL.
[DW_DLE_ARGUMENT]	Argument len was 0.
[DW_DLE_MEMORY]	An out of memory condition was encountered during the execution of this function.
[DW_DLE_FRAME_INSTR_EXEC_ERROR]
	An unknown instruction was found in the instruction bytes provided in argument instructions.