dwarf_expand_frame_instructions —
expand frame instructions
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()
translates DWARF frame instruction bytes into an array of
Dwarf_Frame_Op descriptors.
Argument
cie should reference the CIE
descriptor associated with the instructions to be translated.
Arugment
instructions should point to an array
of frame instruction bytes, as returned by the functions
dwarf_get_cie_info(3)
or
dwarf_get_fde_instr_bytes(3).
Argument
len should specify the number of the
frame instruction bytes to be translated.
Argument
ret_ops should point to a location
that will be set to a pointer to an array of translated
Dwarf_Frame_Op descriptors.
Argument
ret_opcnt should point to a location
that will hold the total number of the returned descriptors.
If argument
err is not NULL, it will be used to
store error information in case of an error.
The memory area used for the descriptor array returned in argument
ret_ops is allocated by
DWARF Access Library (libdwarf, -ldwarf).
Application code should use function
dwarf_dealloc(3) with
type
DW_DLA_FRAME_BLOCK
to free the memory
area when the descriptor array is no longer needed.
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.
dwarf(3),
dwarf_frame_instructions_dealloc(3),
dwarf_get_cie_index(3),
dwarf_get_cie_info(3),
dwarf_get_cie_of_fde(3),
dwarf_get_fde_at_pc(3),
dwarf_get_fde_info_for_all_regs(3),
dwarf_get_fde_info_for_all_regs3(3),
dwarf_get_fde_info_for_cfa_reg3(3),
dwarf_get_fde_info_for_reg(3),
dwarf_get_fde_info_for_reg3(3),
dwarf_get_fde_instr_bytes(3),
dwarf_get_fde_list(3),
dwarf_get_fde_list_eh(3),
dwarf_get_fde_n(3)