ida_offset

Functions that deal with offsets.

“Being an offset” is a characteristic of an operand. This means that operand or its part represent offset from some address in the program. This linear address is called “offset base”. Some operands may have 2 offsets simultaneously. Generally, IDA doesn’t handle this except for Motorola outer offsets. Thus there may be two offset values in an operand: simple offset and outer offset. Outer offsets are handled by specifying special operand number: it should be ORed with OPND_OUTER value. See bytes.hpp for further explanation of operand numbers.

Attributes

SWIG_PYTHON_LEGACY_BOOL

Functions

get_default_reftype(→ reftype_t)

Get default reference type depending on the segment.

op_offset_ex(→ bool)

Convert operand to a reference. To delete an offset, use clr_op_type() function.

op_offset(→ bool)

See op_offset_ex()

op_plain_offset(→ bool)

Convert operand to a reference with the default reference type.

get_offbase(→ ida_idaapi.ea_t)

Get offset base value

get_offset_expression(→ str)

Get offset expression (in the form "offset name+displ"). This function uses offset translation function ( processor_t::translate) if your IDP module has such a function. Translation function is used to map linear addresses in the program (only for offsets).

get_offset_expr(→ str)

See get_offset_expression()

can_be_off32(→ ida_idaapi.ea_t)

Does the specified address contain a valid OFF32 value?. For symbols in special segments the displacement is not taken into account. If yes, then the target address of OFF32 will be returned. If not, then BADADDR is returned.

calc_offset_base(→ ida_idaapi.ea_t)

Try to calculate the offset base This function takes into account the fixup information, current ds and cs values.

calc_probable_base_by_value(→ ida_idaapi.ea_t)

Try to calculate the offset base. 2 bases are checked: current ds and cs. If fails, return BADADDR

calc_reference_data(→ bool)

Calculate the target and base addresses of an offset expression. The calculated target and base addresses are returned in the locations pointed by 'base' and 'target'. In case 'ri.base' is BADADDR, the function calculates the offset base address from the referencing instruction/data address. The target address is copied from ri.target. If ri.target is BADADDR then the target is calculated using the base address and 'opval'. This function also checks if 'opval' matches the full value of the reference and takes in account the memory-mapping.

add_refinfo_dref(→ ida_idaapi.ea_t)

Add xrefs for a reference from the given instruction ( insn_t::ea). This function creates a cross references to the target and the base. insn_t::add_off_drefs() calls this function to create xrefs for 'offset' operand.

calc_target(→ ida_idaapi.ea_t)

This function has the following signatures:

calc_basevalue(→ ida_idaapi.ea_t)

Calculate the value of the reference base.

Module Contents

ida_offset.SWIG_PYTHON_LEGACY_BOOL
ida_offset.get_default_reftype(ea: ida_idaapi.ea_t) → reftype_t

Get default reference type depending on the segment.

Returns:

one of REF_OFF8, REF_OFF16, REF_OFF32, REF_OFF64

ida_offset.op_offset_ex(ea: ida_idaapi.ea_t, n: int, ri: refinfo_t) → bool

Convert operand to a reference. To delete an offset, use clr_op_type() function.

Parameters:

ea – linear address. if ‘ea’ has unexplored bytes, try to convert them to

  • no segment: fail

  • 16bit segment: to 16bit word data

  • 32bit segment: to dword

Parameters:

n – operand number (may be ORed with OPND_OUTER)

  • 0: first

  • 1: second

  • …

  • 7: eighth operand

  • OPND_MASK: all operands

Parameters:

ri – reference information

Returns:

success

ida_offset.op_offset(*args) → bool

See op_offset_ex()

ida_offset.op_plain_offset(ea: ida_idaapi.ea_t, n: int, base: ida_idaapi.ea_t) → bool

Convert operand to a reference with the default reference type.

ida_offset.get_offbase(ea: ida_idaapi.ea_t, n: int) → ida_idaapi.ea_t

Get offset base value

Parameters:

  • ea – linear address

  • n – 0..UA_MAXOP-1 operand number

Returns:

offset base or BADADDR

ida_offset.get_offset_expression(ea: ida_idaapi.ea_t, n: int, _from: ida_idaapi.ea_t, offset: adiff_t, getn_flags: int = 0) → str

Get offset expression (in the form “offset name+displ”). This function uses offset translation function ( processor_t::translate) if your IDP module has such a function. Translation function is used to map linear addresses in the program (only for offsets). Example: suppose we have instruction at linear address 0x00011000: `mov ax, [bx+7422h] ` and at ds:7422h: `array dw … ` We want to represent the second operand with an offset expression, so then we call: `get_offset_expresion(0x001100, 1, 0x001102, 0x7422, buf);

| | | |
| | | +output buffer
| | +value of offset expression
| +address offset value in the instruction
+the second operand

+address of instruction` and the function will return a colored string: `offset array `

Parameters:

  • ea – start of instruction or data with the offset expression

  • n – operand number (may be ORed with OPND_OUTER)

  • 0: first operand

  • 1: second operand

  • …

  • 7: eighth operand

Parameters:

  • offset – value of operand or its part. The function will return text representation of this value as offset expression.

  • getn_flags – combination of:

  • GETN_APPZERO: meaningful only if the name refers to a structure. appends the struct field name if the field offset is zero

  • GETN_NODUMMY: do not generate dummy names for the expression but pretend they already exist (useful to verify that the offset expression can be represented)

Returns:

0: can’t convert to offset expression

Returns:

1: ok, a simple offset expression

Returns:

2: ok, a complex offset expression

ida_offset.get_offset_expr(ea: ida_idaapi.ea_t, n: int, ri: refinfo_t, _from: ida_idaapi.ea_t, offset: adiff_t, getn_flags: int = 0) → str

See get_offset_expression()

ida_offset.can_be_off32(ea: ida_idaapi.ea_t) → ida_idaapi.ea_t

Does the specified address contain a valid OFF32 value?. For symbols in special segments the displacement is not taken into account. If yes, then the target address of OFF32 will be returned. If not, then BADADDR is returned.

ida_offset.calc_offset_base(ea: ida_idaapi.ea_t, n: int) → ida_idaapi.ea_t

Try to calculate the offset base This function takes into account the fixup information, current ds and cs values.

Parameters:

  • ea – the referencing instruction/data address

  • n – operand number

  • 0: first operand

  • 1: second operand

  • …

  • 7: eighth operand

Returns:

output base address or BADADDR

ida_offset.calc_probable_base_by_value(ea: ida_idaapi.ea_t, off: int) → ida_idaapi.ea_t

Try to calculate the offset base. 2 bases are checked: current ds and cs. If fails, return BADADDR

ida_offset.calc_reference_data(target: ea_t *, base: ea_t *, _from: ida_idaapi.ea_t, ri: refinfo_t, opval: adiff_t) → bool

Calculate the target and base addresses of an offset expression. The calculated target and base addresses are returned in the locations pointed by ‘base’ and ‘target’. In case ‘ri.base’ is BADADDR, the function calculates the offset base address from the referencing instruction/data address. The target address is copied from ri.target. If ri.target is BADADDR then the target is calculated using the base address and ‘opval’. This function also checks if ‘opval’ matches the full value of the reference and takes in account the memory-mapping.

Parameters:

  • target – output target address

  • base – output base address

  • ri – reference info block from the database

  • opval – operand value (usually op_t::value or op_t::addr)

Returns:

success

ida_offset.add_refinfo_dref(insn: insn_t const &, _from: ida_idaapi.ea_t, ri: refinfo_t, opval: adiff_t, type: dref_t, opoff: int) → ida_idaapi.ea_t

Add xrefs for a reference from the given instruction ( insn_t::ea). This function creates a cross references to the target and the base. insn_t::add_off_drefs() calls this function to create xrefs for ‘offset’ operand.

Parameters:

  • insn – the referencing instruction

  • ri – reference info block from the database

  • opval – operand value (usually op_t::value or op_t::addr)

  • type – type of xref

  • opoff – offset of the operand from the start of instruction

Returns:

the target address of the reference

ida_offset.calc_target(*args) → ida_idaapi.ea_t

This function has the following signatures:

  1. calc_target(from: ida_idaapi.ea_t, opval: adiff_t, ri: const refinfo_t &) -> ida_idaapi.ea_t

  2. calc_target(from: ida_idaapi.ea_t, ea: ida_idaapi.ea_t, n: int, opval: adiff_t) -> ida_idaapi.ea_t

# 0: calc_target(from: ida_idaapi.ea_t, opval: adiff_t, ri: const refinfo_t &) -> ida_idaapi.ea_t

Calculate the target using the provided refinfo_t.

# 1: calc_target(from: ida_idaapi.ea_t, ea: ida_idaapi.ea_t, n: int, opval: adiff_t) -> ida_idaapi.ea_t

Retrieve refinfo_t structure and calculate the target.

ida_offset.calc_basevalue(target: ida_idaapi.ea_t, base: ida_idaapi.ea_t) → ida_idaapi.ea_t

Calculate the value of the reference base.