LogoLogo
IDA 8.4
IDA 8.4
  • Welcome to Hex-Rays docs
  • User Guide
    • User Interface
      • Menu Bar
        • File
          • Load file
          • Script File
          • Script command
          • Produce output files
          • Invoke OS Shell
          • Take database snapshot
          • Save database
          • Save database as...
          • Abort IDA
          • Exit IDA
        • Edit
          • Export data
          • Undo an action
          • Redo an action
          • Clear undo history
          • Disable undo
          • Convert to instruction
          • Convert to data
          • Convert to string literal
          • Convert to array
          • Undefine a byte
          • Give Name to the Location
          • Operand types
            • Offset
            • Number
            • Perform en masse operation
            • Convert operand to character
            • Convert operand to segment
            • Complex Offset Expression
            • Convert operand to symbolic constant (enum)
            • Convert operand to stack variable
            • Change operand sign
            • Bitwise negate operand
            • User-defined operand
            • Set operand type
          • Comments
          • Functions
          • Structures
            • Enums
          • Segments
          • Patch core
          • Other
            • Rename Any Address
          • Plugins
        • Jump
          • Center current line in window
          • Problems List
        • Search
          • REGULAR EXPRESSION SYNTAX SUMMARY
        • View
          • Open subviews
          • Graphs
          • Message Window
          • Arrows window
          • Database snapshot manager
          • Highlighting identifiers
          • Browser options
          • Lumina options
          • Assembler level and C level types
          • C++ type details
          • Bookmarks window
          • Calculator
          • View segment registers
          • View Internal Flags
          • Hide
          • Unhide
          • Del hidden range
          • Hide all items
          • Unhide all items
          • Setup hidden items
        • Debugger
          • Debugger window
          • Process Control
            • Start process
            • Process options
            • Pause process
            • Terminate process
            • Step into
            • Step over
            • Run to cursor
            • Run until return
            • Attach to process
            • Detach from process
            • Set current ip
            • Show application screen
          • Breakpoints
          • Watches
          • Tracing
          • Source code view
            • Watch view (source level)
          • Process Memory
            • Take memory snapshot
            • Manual memory regions
            • Refresh memory
          • Thread list
          • Module list
          • Stack trace
          • Exceptions
          • Debugger options
          • Switch debugger
        • Lumina
        • Options
          • Low & High Suspicious Operand Limits
        • Windows
          • Rename a stack variable
          • Miscellanous Options
          • Environment variables
          • Reset Hidden Messages
          • Various dialog help messages
        • List of all menu options
      • Desktops
      • Command line
      • How To Use List Viewers in IDA
      • Licenses
        • Apache License for Ghidra
        • Apache License for LLVM
        • Common Public License Version 1.0
        • APPLE PUBLIC SOURCE LICENSE
        • PCRE2 LICENCE
        • GNU Lesser General Public License v2.1 for libiberty
      • Database conversion from idb to i64
    • Disassembler
      • Interactivity
      • Background Analysis
      • Graph view
        • Graphing tutorial
      • Proximity view
      • Navigation
        • Anchor
        • How to Enter a Segment Value
        • How to Enter a Number
        • How to Enter an Identifier
        • How to enter text
        • How to Enter an Address
      • Disassembly Gallery
        • Philips 51XA-G3
        • 6502 and 65C02 Disassembler
        • 6301, 6303, 6800, 6801 and 6803 Disassembler
        • 68040, Amiga
        • 6805 Disassembler
        • 6808 Disassembler
        • 6809 OS9 Flex Disassembler
        • 6809 Disassembler
        • 6811 Disassembler
        • 68HC12 Disassembler
        • 68HC16 Disassembler
        • 68k Amiga Disassembler
        • 68k Mac OS
        • 68k Palm Pilot
        • Unix COFF
        • NEC 78k0 and 78k0s Processor
        • 80196 Processor
        • 8051 Disassembler
        • Analog Devices 218x.
        • Alpha Processor – NT COFF
        • Alpha Processor – Unix ELF
        • Android ARM Executables (.elf)
        • ARC Processor
        • ARM Processor EPOC App
        • ARM Processor EPOC PE File
        • ARM Processor EPOC ROMFile
        • EPOC SIS File Handler
        • ARM Processor iOS (iPhone): Unlock
        • ARM Processor iOS (iPhone): Objective-C metadata
        • ARM Processor iOS (iPhone): Objective-C Instance variables
        • ARM Processor iOS (iPhone): Parameter Identification & Tracking (PIT)
        • ARM Processor iOS (iPhone): Start
        • ARM Processor iOS (iPhone): Switch statements
        • ARM Processor iOS (iPhone): C++ signatures
        • ARM Processor iOS (iPhone): Write
        • ARM Processor: Linux ELF
        • ARM Processor: AOF SDK
        • ARM Processor: Windows CE COFF Format
        • ARM Processor: Windows CE PE Format
        • ATMEL AVR Disassembler
        • C166 Processor
        • C166 Processor with ELF file
        • Rockwell C39
        • Microsoft .NET CLI Disassembler. VisualBasic library
        • CR16
        • Android Dalvik Executables (.dex)
        • Microsoft .NET CLI Disassembler
        • DSP56K
        • Fujitsu FR (.elf)
        • Gameboy
        • H8 300: COFF FILE Format
        • H8 300s: COFF FILE Format
        • H8 500
        • HPPA Risc Processor: HP-UX SOM
        • i51
        • i860
        • Intel i960
        • Intel IA-64 (Itanium)
        • Java Bytecode
        • Angstrem KR 1878
        • Renesas/Hitachi M16C
        • Renesas/Hitachi M32R
        • M740
        • M7700
        • M7900
        • MIPS Processor: Nintendo N64
        • MIPS R5900 Processor : Sony bin
        • MIPS Processor: Sony ELF
        • MIPS Processor: Sony PSX
        • MIPS Processor: Sony PSX
        • MIPS Processor: Unix COFF File Format
        • MIPS Processor: Unix ELF File Format
        • MIPS Processor: Windows CE PE File Format
        • MIPS Processor: Windows CE PE2 File Format
        • Panasonic MN102
        • Atmel OAK DSP
        • 80×86 Architecture: DOS Extender
        • 80×86 Architecture: Watcom Runtime
        • 80×86 Architecture: Geos APP
        • 80×86 Architecture: Geos DRV
        • 80×86 Architecture: Geos LIB
        • 80×86 Architecture: GNU COFF Format
        • 80×86 Architecture: OS/2 Linear Executable Format
        • 80×86 Architecture: Netware NLM
        • 80×86 Architecture: QNX Executable
        • 80×86 Architecture: Watcom Runtime
        • 80×86 Architecture: Windows OMF
        • 80×86 Architecture: Windows Portable Executable Format
        • 80×86 Architecture: Windows Virtual Device Driver
        • 80×86 Architecture: Windows 16 bits DLL
        • X-Box Disassembler
        • PDP 11: SAV File
        • PIC
        • PIC 12xx
        • Power PC AIF ECOFF file Format
        • Power PC Linux ELF
        • Mac OS PEF File
        • Mac OS X File
        • Windows NT PE File
        • Hitachi SH-1 Processor
        • Hitachi SH-3 Processor: Windows CE COFF format
        • Hitachi SH-3 Processor: Windows CE PE format
        • Hitachi SH-4 Processor: ELF File Format
        • Hitachi SH-4 Processor: Windows CE PE File Format
        • Super Nintendo Entertainement System (SNES)
        • SPARC Solaris COFF
        • SPARC Solaris ELF
        • SPARC Sun ELF
        • SPARC Sun ELF SO
        • ST 20C4
        • ST 7
        • ST 9
        • Toshiba TLCS 900
        • TMS 320c2 COFF
        • TMS 320c5
        • TMS 320c54
        • TMS 320c6 COFF File Format
        • TRICORE
        • SunPlus unSP
        • NEC V850
        • Z180 COFF File Format
        • Z380 COFF File Format
        • Z8
        • Z80
      • Supported processors
      • Supported file formats
        • Windmp file loader
      • Bitfields
        • Bit Fields tutorial
      • Structures tutorial
      • Union tutorial
      • Variable length structures tutorial
      • Data types, operands and constructs
      • Packed executables
    • Decompiler
      • Prerequisites
      • Quick primer
      • Exception handler
      • Introduction to Decompilation vs. Disassembly
        • Comparisons of ARM disassembly and decompilation
        • Comparisons of PowerPC disassembly and decompilation
        • Comparisons of MIPS disassembly and decompilation
        • Hex-Rays v7.4 vs. v7.3 Decompiler Comparison Page
        • Hex-Rays v7.3 vs. v7.2 Decompiler Comparison Page
        • Hex-Rays v7.2 vs. v7.1 Decompiler Comparison Page
      • Interactive operation
        • Rename
        • Set type
        • Set number representation
        • Edit indented comment
        • Edit block comment
        • Hide/unhide C statements
        • Split/unsplit expression
        • Force call type
        • Set call type
        • Add/del variadic arguments
        • Del function argument
        • Add/delete function return type
        • Jump to cross reference
        • Jump to cross reference globally
        • Generate HTML file
        • Mark/unmark as decompiled
        • Copy to assembly
        • Show/hide casts
        • Reset pointer type
        • Convert to struct *
        • Create new struct type
        • Split variable
        • Select union field
        • Jump to paired paren
        • Collapse/uncollapse item
        • Map to another variable
      • Batch operation
      • Configuration
      • Third party plugins
      • Floating point support
      • Support for intrinsic functions
      • Overlapped variables
      • gooMBA
      • Failures and troubleshooting
      • FAQ
      • Limitations
      • Tips and tricks
    • Debugger
      • Instant debugger
      • Remote debugging
        • Remote iOS Debugger
        • Android debugger
        • Dalvik debugger
        • Remote GDB Debugger
          • Remote GDB Debugger options
          • Debugging with gdbserver
          • Debugging with VMWare
          • Debugging with OpenOCD
          • Debugging with QEMU
          • External programs and GDB Debugger
          • Debugging code snippets with QEMU
        • PIN debugger
          • Building the PIN tool
          • Connecting a remote PIN tool instance from IDA
          • PIN support for MacOSX
        • Replayer debugger
        • Bochs debugger
          • Bochs Disk Image operation mode
          • Bochs IDB operation mode
          • Bochs PE operation mode
          • Bochs debugger FAQ
      • Local debugging
        • WinDbg Debugger
        • Linux debugger
        • Intel/ARM macOS debugger
      • Debugger tutorials
        • Debugging Dalvik Programs
        • IDA Win32 Local Debugging
        • IDA Linux Local Debugging
        • IDA Win32 to Win32 Debugging
        • IDA Win32 to Win64 Debugging
        • Debugging Mac OSX Applications with IDA Pro
        • Debugging iOS Applications with IDA Pro
        • Debugging Linux Applications locally
        • Debugging Linux/Windows Applications with PIN Tracer module
        • Debugging Windows Applications with IDA Bochs Plugin
        • Debugging Windows Applications with IDA WinDbg Plugin
        • Using the Bochs debugger plugin in Linux
        • Debugging Windows Kernel with VMWare and IDA WinDbg Plugin
        • Debugging Linux Kernel under VMWare using IDA GDB debugger
        • Windows Debugger Hub
        • Linux Debugger
        • Debugging a Windows executable locally and remotely
        • Debugging the XNU Kernel with IDA Pro
        • Remote debugging with IDA Pro
        • IDA Scriptable Debugger: overview
          • IDA Scriptable Debugger: scriptability
        • Debugging code snippets with QEMU debugger (a la IDA Bochs debugger)
        • Trace Replayer and managing traces
        • Using IDA Pro's tracing features
        • Working with PIN
        • Appcall
    • Signatures
      • FLIRT
        • IDA F.L.I.R.T. Technology: In-Depth
        • Supported Compilers
          • Turbo Pascal
          • Delphi
      • Makesig
    • Type Libraries
      • IDAClang
      • TILIB
    • Configuration
      • Configuration files
      • Command line switches
      • Keyboard macros
    • Teams
      • IDA Teams Licenses
      • Diffing and Merging Databases with IDA Teams
      • Teams lc command reference manual
      • hv command reference manual
      • Hex-Rays Vault’s visual client user manual
    • Lumina
      • lc command reference manual
    • Plugins
      • Open Plugin Architecture
      • Plugin options
      • Plugins Shipped with IDA
        • Swift plugin
        • Golang plugin
        • Rust plugin
        • picture_search
        • Objective-C Analysis Plugin
        • DYLD Shared Cache Utils
      • Plugin Contest
      • How to write your own plugin?
    • Helper Tools
  • Developer Guide
    • C++ SDK
      • C++ SDK reference
      • Using the Decompiler SDK: Decompiler Plug-In
    • IDAPython
      • IDAPython API Reference
    • IDC
      • Core concepts
        • Expressions
        • Statements
        • Functions
        • Variables
        • Constants
        • Exceptions
        • Classes
        • Predefined symbols
        • loader_input_t class
        • Slices
      • IDC API Reference
        • Index of debugger related IDC functions
        • Alphabetical list of IDC functions
          • set_selector
          • enable_tracing
          • get_prev_fixup_ea
          • del_segm
          • get_bmask_cmt
          • end_type_updating
          • Find
          • toggle_bnot
          • patch_byte
          • get_module_info
          • set_member_name
          • create_float
          • del_struc_member
          • read_dbg_memory
          • get_enum_width
          • getn_thread_name
          • del_struc
          • filelength
          • set_manual_insn
          • is_value...() functions
          • get_ip_val
          • del_extra_cmt
          • create_insn
          • op_offset_high16
          • get_cmt
          • expand_struc
          • get_idb_path
          • set_frame_size
          • get_file_ext
          • has_value
          • readshort
          • sanitize_file_name
          • get_member_flag
          • create_struct
          • ARM specific
          • Disk Write Error
          • set_enum_member_cmt
          • rename
          • set_ida_state
          • get_member_size
          • msg
          • qbasename
          • get_enum_member_enum
          • auto_mark_range
          • plan_to_apply_idasgn
          • set_named_type
          • op_offset
          • rename_entry
          • strlen
          • get_extra_cmt
          • get_enum_flag
          • fgetc
          • Internal Error
          • op_stkvar
          • get_last_index
          • get_field_ea
          • get_last_struc_idx
          • How to use the help subsystem
          • get_struc_id
          • select_thread
          • create_array
          • get_struc_cmt
          • set_array_string
          • set_func_attr
          • set_storage_type
          • get_struc_size
          • demangle_name
          • get_next_fixup_ea
          • get_next_bmask
          • delattr
          • gen_simple_call_chart
          • patch_qword
          • get_enum_name
          • loader_input_t.getc
          • get_first_struc_idx
          • get_debugger_event_cond
          • read_dbg_qword
          • define_local_var
          • generate_disasm_line
          • add_idc_hotkey
          • tolower
          • del_selector
          • set_debugger_event_cond
          • get_imagebase
          • gen_file
          • get_entry
          • find_custom_data_format
          • get_debug_name_ea
          • add_default_til
          • set_func_end
          • exit_process
          • delete_array
          • xtol
          • get_exception_code
          • detach_process
          • set_enum_cmt
          • get_wide_word
          • put_bookmark
          • is_loaded
          • add_enum_member
          • parse_decls
          • readstr
          • get_entry_qty
          • ord
          • sprintf
          • get_root_filename
          • get_enum_member_cmt
          • create_word
          • set_func_flags
          • loader_input_t.tell
          • create_align
          • read_dbg_dword
          • get_struc_idx
          • next_addr
          • get_bytes
          • batch
          • start_process
          • Cannot Create File
          • process_config_line
          • del_user_info
          • qmakefile
          • set_struc_name
          • print_decls
          • create_custom_data
          • del_enum_member
          • format_cdata
          • get_fixup_target_sel
          • get_item_size
          • loader_input_t.gets
          • get_last_bmask
          • Step Tracing Options
          • get_enum_idx
          • selector_by_name
          • Already recording a macro for...
          • get_enum_cmt
          • next_not_tail
          • prev_head
          • set_color
          • set_numbered_type
          • get_member_name
          • auto_wait
          • get_enum_member_bmask
          • fseek
          • get_segm_start
          • attach_process
          • Trace file functions
          • get_enum_member_value
          • op_stroff
          • get_next_offset
          • set_processor_type
          • get_bookmark_desc
          • Entering String for Search
          • create_data
          • lastattr
          • get_operand_value
          • collect_stack_trace
          • toupper
          • get_fixup_target_dis
          • set_cmt
          • add_entry
          • set_segm_addressing
          • qmake_full_path
          • get_source_linnum
          • fputc
          • resume_thread
          • get_func_attr
          • get_first_enum_member
          • add_sourcefile
          • get_first_bmask
          • read_selection_start
          • hasattr
          • get_member_cmt
          • gen_flow_graph
          • get_array_element
          • get_tinfo
          • loader_input_t
          • tinfo_errstr
          • TRUNC
          • add_segm_ex
          • Not enough memory available to complete operation.
          • Local types information and manipulation helpers
          • set_source_linnum
          • get_next_enum_member
          • loader_input_t.readbytes
          • set_array_params
          • jumpto
          • get_bookmark
          • set_enum_bf
          • prev_not_tail
          • toggle_sign
          • loader_input_t.size
          • Trace events functions
          • get_func_flags
          • get_gotea
          • Bad BIOS & DOS Comments Base
          • set_segm_attr
          • get_item_head
          • set_default_sreg_value
          • print_insn_mnem
          • set_member_cmt
          • get_ordinal_qty
          • set_target_assembler
          • add_user_stkpnt
          • set_local_type
          • Hidden ranges
          • del_items
          • compile_idc_text
          • Dalvik debugger extension functions
          • byte_value
          • create_dword
          • is_code
          • del_func
          • get_enum
          • make_array
          • rotate_left
          • recalc_spd
          • search_path
          • CommonBits
          • get_processor_name
          • set_func_cmt
          • get_prev_bmask
          • Hashes
          • split_sreg_range
          • process_ui_action
          • set_fixup
          • get_fixup_target_type
          • create_oword
          • get_flags
          • get_func_name
          • create_strlit
          • add_struc
          • atol
          • load_debugger
          • mkdir
          • set_struc_idx
          • sizeof
          • get_enum_member_by_name
          • save_database
          • guess_type
          • get_segm_name
          • print_operand
          • qisabspath
          • get_member_qty
          • set_struc_cmt
          • get_fixup_target_flags
          • idadir
          • object.retrieve
          • add_auto_stkpnt
          • get_numbered_type_name
          • get_enum_member_name
          • get_next_index
          • prev_addr
          • get_name_ea
          • get_sp_delta
          • set_bmask_cmt
          • get_struc_qty
          • readlong
          • set_segm_name
          • get_prev_offset
          • set_segm_alignment
          • get_strlit_contents
          • forget_exception
          • get_item_end
          • add_func
          • get_name
          • Asks
          • get_spd
          • Debugger: control
          • get_wide_byte
          • plan_and_wait
          • set_enum_flag
          • RunPythonStatement
          • del_sourcefile
          • get_prev_struc_idx
          • find_selector
          • get_frame_regs_size
          • op_num
          • define_exception
          • create_double
          • create_byte
          • read_selection_end
          • Disk Positioning Error
          • OpTypes
          • op_plain_offset
          • move_segm
          • get_member_id
          • set_segm_combination
          • get_current_thread
          • trim
          • Debugger: options
          • getn_thread
          • get_frame_id
          • typeinfo.print
          • to_ea
          • rebase_program
          • add_struc_member
          • get_exception_qty
          • get_first_index
          • import_type
          • set_segm_type
          • find_custom_data_type
          • get_next_seg
          • find_func_end
          • get_next_struc_idx
          • get_last_enum_member
          • getattr
          • get_frame_size
          • get_screen_ea
          • loader_input_t.read
          • Bad Macro
          • set_reg_value
          • Debugger: modules
          • create_pack_real
          • writestr
          • exec_idc
          • get_enum_size
          • set_enum_name
          • create_tbyte
          • sel2para
          • atoa
          • loader_input_t.close
          • add_enum
          • ltoa
          • set_enum_idx
          • substr
          • del_idc_hotkey
          • Breakpoint handling functions
          • loader_input_t.seek
          • cleanup_appcall
          • object.store
          • get_type
          • qexit
          • get_debug_name
          • get_array_id
          • Can't Open File
          • suspend_process
          • process_config_directive
          • get_entry_name
          • get_last_member
          • get_struc_name
          • clear_selection
          • fclose
          • firstattr
          • How to move/resize windows
          • create_yword
          • dbg_appcall
          • get_qword
          • patch_dword
          • begin_type_updating
          • read_dbg_byte
          • get_fpnum
          • qsleep
          • get_first_member
          • get_nsec_stamp
          • del_stkpnt
          • eval
          • savefile
          • eval_python
          • Xrefs
          • strstr
          • writeshort
          • get_sreg
          • get_segm_end
          • get_func_off_str
          • set_func_start
          • del_array_element
          • get_full_flags
          • set_exception_flags
          • rename_array
          • get_frame_args_size
          • op_flt
          • get_min_spd_ea
          • apply_type
          • get_prev_index
          • loadfile
          • retrieve_input_file_md5
          • get_wide_dword
          • patch_dbg_byte
          • Functions provided by the WinDbg debugger
          • get_original_byte
          • get_member_strid
          • call_system
          • writelong
          • get_thread_qty
          • nextattr
          • send_dbg_command
          • get_first_seg
          • get_processes
          • patch_word
          • get_manual_insn
          • ftell
          • get_entry_ordinal
          • set_array_long
          • delete_all_segments
          • TO_LONG
          • Function chunk related functions
          • Debugger: events
          • get_prev_func
          • op_seg
          • validate_idb_names
          • fprintf
          • fopen
          • strfill
          • del_fixup
          • get_bmask_name
          • Disk Read Error
          • inf_attr
          • is_bf
          • read_dbg_word
          • qdirname
          • get_segm_attr
          • func_contains
          • get_enum_qty
          • del_source_linnum
          • get_sourcefile
          • clr_database_flag
          • bTree Error
          • set_name
          • Refresh Screen
          • op_enum
          • getn_enum
          • get_db_byte
          • setattr
          • get_forced_operand
          • op_bin
          • Functions provided by the replayer debugger
          • prevattr
          • update_extra_cmt
          • get_str_type
          • op_man
          • choose_func
          • set_bmask_name
          • get_curline
          • decode_insn
          • set_segment_bounds
          • get_struc_by_idx
          • set_segm_class
          • write_dbg_memory
          • get_exception_name
          • get_enum_member
          • is_mapped
          • del_enum
          • get_frame_lvar_size
          • get_operand_type
          • set_root_filename
          • compile_idc_file
          • typeinfo.size
          • get_local_tinfo
          • get_fixup_target_off
          • is_union
          • unlink
          • get_segm_by_sel
          • set_enum_width
          • take_memory_snapshot
          • exec_python
          • get_next_func
          • get_member_offset
          • get_func_cmt
          • parse_decl
          • create_qword
          • next_head
          • suspend_thread
          • loader_input_t.getz
          • get_color
          • get_reg_value
          • load_and_run_plugin
          • set_database_flag
          • set_enum_member_name
          • set_member_type
          • get_prev_enum_member
      • IDC examples
        • Batch analysis
        • Device driver analysis
        • New file format definition
        • Structures manipulation
        • VxD analysis
        • Analyzing encrypted code
  • Admin Guide
    • Lumina server
    • Teams server
    • License server
      • Installing on Windows
      • Installing on Linux
      • Installing on OS X
Powered by GitBook
LogoLogo

Need Help?

  • FAQs
  • Support

Community

  • Forum
  • Plugins

Resources

  • Blog
  • Download center

© 2025 Copyright Hex-Rays

On this page

Was this helpful?

Export as PDF
  1. Developer Guide
  2. C++ SDK

Using the Decompiler SDK: Decompiler Plug-In

Below is the full source code of a sample plugin. It performs a quite useful transformation of the pseudocode: replaces zeroes in pointer contexts with NULLs. A NULL immediately conveys the idea that the current expression is pointer-related. This is especially useful for unknown function arguments.

The plugin is fully automatic. It hooks to the decompiler events and waits for the pseudocode to be ready. At that moment it takes control and modifies the ctree.

The conversion is performed by the convert_zeroes() function. It visits all expressions of the ctree and checks for pointer contexts. If a expression has a pointer type, then the make_null_if_zero() function is called for it. This function checks if the expression is a zero constant and converts it if necessary.

The plugin can be turned on or off by its menu item in the Plugins submenu.

The code is short and straightforward. Use it as a template for your plugins.

\

/*
 *      Hex-Rays Decompiler project
 *      Copyright (c) 2007-2019 by Hex-Rays, support@hex-rays.com
 *      ALL RIGHTS RESERVED.
 *
 *      Sample plugin for Hex-Rays Decompiler.
 *      It automatically replaces zeroes in pointer contexts with NULLs.
 *      For example, expression like
 *
 *              funcptr = 0;
 *
 *      will be displayed as
 *
 *              funcptr = NULL;
 *
 *      Due to highly dynamic nature of the decompier output, we must
 *      use the decompiler events to accomplish the task. The plugin will
 *      wait for the ctree structure to be ready in the memory and will
 *      replace zeroes in pointer contexts with NULLs.
 *
 */

#include <hexrays.hpp>

// Hex-Rays API pointer
hexdsp_t *hexdsp = NULL;

static bool inited = false;

static const char nodename[] = “$ hexrays NULLs”;
static const char null_type[] = “MACRO_NULL”;
//————————————————————————–
// Is the plugin enabled?
// The user can disable it. The plugin will save the on/off switch in the
// current database.
static bool is_enabled(void)
{
  netnode n(nodename); // use a netnode to save the state
  return n.altval(0) == 0; // if the long value is positive, then disabled
}

//————————————————————————–
// If the expression is zero, convert it to NULL
static void make_null_if_zero(cexpr_t *e)
{
  if ( e->is_zero_const() && !e->type.is_ptr() )
  { // this is plain zero, convert it
    number_format_t &nf = e->n->nf;
    nf.flags = enum_flag();
    nf.serial = 0;
    nf.type_name = null_type;
    e->type = tinfo_t::get_stock(STI_PVOID);
  }
}

//————————————————————————–
// Convert zeroes of the ctree to NULLs
static void convert_zeroes(cfunc_t *cfunc)
{
  // To represent NULLs, we will use the MACRO_NULL enumeration
  // Normally it is present in the loaded tils but let’s verify it
  if ( !get_named_type(NULL, null_type, NTF_TYPE) )
  {
    msg(“%s type is missing, cannot convert zeroes to NULLs\n”, null_type);
    return;
  }

  // We derive a helper class from ctree_visitor_t
  // The ctree_visitor_t is a base class to derive
  // ctree walker classes.
  // You have to redefine some virtual functions
  // to do the real job. Here we redefine visit_expr() since we want
  // to examine and modify expressions.
  struct ida_local zero_converter_t : public ctree_visitor_t
  {
    zero_converter_t(void) : ctree_visitor_t(CV_FAST) {}
    int idaapi visit_expr(cexpr_t *e)
    {
      // verify if the current expression has pointer expressions
      // we handle the following patterns:
      //  A. ptr = 0;
      //  B. func(0); where argument is a pointer
      //  C. ptr op 0 where op is a comparison
      switch ( e->op )
      {
        case cot_asg:   // A
          if ( e->x->type.is_ptr() )
            make_null_if_zero(e->y);
          break;

        case cot_call:  // B
          {
            carglist_t &args = *e->a;
            for ( int i=0; i < args.size(); i++ ) // check all arguments
            {
              carg_t &a = args[i];
              if ( a.formal_type.is_ptr_or_array() )
                make_null_if_zero(&a);
            }
          }
          break;

        case cot_eq:    // C
        case cot_ne:
        case cot_sge:
        case cot_uge:
        case cot_sle:
        case cot_ule:
        case cot_sgt:
        case cot_ugt:
        case cot_slt:
        case cot_ult:
          // check both sides for zeroes
          if ( e->y->type.is_ptr() )
            make_null_if_zero(e->x);
          if ( e->x->type.is_ptr() )
            make_null_if_zero(e->y);
          break;

        default:
          break;

      }
      return 0; // continue walking the tree
    }
  };
  zero_converter_t zc;
  // walk the whole function body
  zc.apply_to(&cfunc->body, NULL);
}

//————————————————————————–
// This callback will detect when the ctree is ready to be displayed
// and call convert_zeroes() to create NULLs
static ssize_t idaapi callback(void *, hexrays_event_t event, va_list va)
{
  if ( event == hxe_maturity )
  {
    cfunc_t *cfunc = va_arg(va, cfunc_t*);
    ctree_maturity_t mat = va_argi(va, ctree_maturity_t);
    if ( mat == CMAT_FINAL ) // ctree is ready, time to convert zeroes to NULLs
      convert_zeroes(cfunc);
  }
  return 0;
}

//————————————————————————–
// Initialize the plugin.
int idaapi init(void)
{
  if ( !init_hexrays_plugin() )
    return PLUGIN_SKIP; // no decompiler
  if ( is_enabled() ) // null plugin is enabled?
  {
    install_hexrays_callback(callback, NULL);
    const char *hxver = get_hexrays_version();
    msg(“Hex-rays version %s has been detected, %s ready to use\n”, hxver, PLUGIN.wanted_name);
  }
  inited = true;
  return PLUGIN_KEEP;
}

//————————————————————————–
void idaapi term(void)
{
  if ( inited )
  {
    // clean up
    remove_hexrays_callback(callback, NULL);
    term_hexrays_plugin();
  }
}

//————————————————————————–
bool idaapi run(size_t)
{
  // since all real work is done in the callbacks, use the main plugin entry
  // to turn it on and off.
  // display a message explaining the purpose of the plugin:
  int code = askbuttons(
       “~E~nable”,
       “~D~isable”,
       “~C~lose”,
       –1,
       “AUTOHIDE NONE\n”
       “Sample plugin for Hex-Rays decompiler.\n”
       “\n”
       “This plugin is fully automatic.\n”
       “It detects zeroes in pointer contexts and converts them into NULLs.\n”
       “\n”
       “The current state of the plugin is: %s\n”,
       is_enabled() ? “ENABLED” : “DISABLED”);
  switch ( code )
  {
    case –1:    // close
      break;
    case 0:     // disable
    case 1:     // enable
      netnode n;
      n.create(nodename);
      n.altset(0, code == 0);
      if ( code )
        install_hexrays_callback(callback, NULL);
      else
        remove_hexrays_callback(callback, NULL);
      info(“The %s plugin has been %s.”, PLUGIN.wanted_name, code ? “ENABLED” : “DISABLED”);
      break;
  }
  return true;
}

//————————————————————————–
static char comment[] = “Sample2 plugin for Hex-Rays decompiler”;

//————————————————————————–
//
//      PLUGIN DESCRIPTION BLOCK
//
//————————————————————————–
plugin_t PLUGIN =
{
  IDP_INTERFACE_VERSION,
  0,                    // plugin flags
  init,                 // initialize
  term,                 // terminate. this pointer may be NULL.
  run,                  // invoke plugin
  comment,              // long comment about the plugin
                        // it could appear in the status line
                        // or as a hint
  “”,                   // multiline help about the plugin
  “Hex-Rays NULL converter”, // the preferred short name of the plugin
  “”                    // the preferred hotkey to run the plugin
};

Last updated 6 months ago

Was this helpful?