NAME
dwarf_expand_frame_instructions —
expand frame instructions
LIBRARY
DWARF Access Library (libdwarf, -ldwarf)
SYNOPSIS
#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);
DESCRIPTION
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.
Memory Management
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.
RETURN VALUES
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.
ERRORS
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.
EXAMPLE
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);
SEE ALSO
dwarf(3),
dwarf_frame_instructions_dealloc(3),
dwarf_get_cie_info(3),
dwarf_get_cie_index(3),
dwarf_get_cie_of_fde,
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)