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143 lines
4.4 KiB
Markdown
143 lines
4.4 KiB
Markdown
# `omath::MachOPatternScanner` — Scan Mach-O binaries for byte patterns
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> Header: `omath/utility/macho_pattern_scan.hpp`
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> Namespace: `omath`
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> Platform: **macOS / Mach-O binaries**
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> Depends on: `<cstdint>`, `<filesystem>`, `<optional>`, `<string_view>`, `omath/utility/section_scan_result.hpp`
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> Companion: works well with `omath::PatternScanner` (same pattern grammar)
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`MachOPatternScanner` searches **Mach-O** binaries for a hex pattern (with wildcards). You can scan:
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* a **loaded module** in the current process, or
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* a **Mach-O file on disk** (by section name; defaults to **`__text`**).
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---
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## Pattern string grammar (same as `PatternScanner`)
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* **Hex byte**: two hex digits → one byte (`90`, `4F`, `00`, `ff`).
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* **Wildcard byte**: `?` or `??` matches **any byte**.
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* **Whitespace**: ignored (use to group tokens).
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✔️ `"48 8B ?? ?? 89"`, `"55 48 89 E5"`, `"??"`
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❌ odd digit counts, non-hex characters (besides `?` and whitespace)
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---
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## API
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```cpp
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namespace omath {
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class MachOPatternScanner final {
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public:
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// Scan a module already loaded in *this* process.
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// module_base_address: base address of the loaded Mach-O image
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// Returns absolute address (process VA) of the first match, or nullopt.
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static std::optional<std::uintptr_t>
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scan_for_pattern_in_loaded_module(
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const void* module_base_address,
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const std::string_view& pattern,
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const std::string_view& target_section_name = "__text");
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// Scan a Mach-O file on disk, by section name (default "__text").
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// Returns section bases (virtual + raw) and match offset within the section, or nullopt.
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static std::optional<SectionScanResult>
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scan_for_pattern_in_file(
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const std::filesystem::path& path_to_file,
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const std::string_view& pattern,
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const std::string_view& target_section_name = "__text");
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};
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} // namespace omath
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```
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---
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## Return values
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* **Loaded module**: `std::optional<std::uintptr_t>`
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* `value()` = **process virtual address** of the first match.
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* `nullopt` = no match or parse/Mach-O error.
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* **File scan**: `std::optional<SectionScanResult>`
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* `virtual_base_addr` = virtual address base of the scanned section.
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* `raw_base_addr` = file offset of section start.
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* `target_offset` = offset from section base to the first matched byte.
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* To get addresses:
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* **Virtual address** of hit = `virtual_base_addr + target_offset`
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* **Raw file offset** of hit = `raw_base_addr + target_offset`
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---
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## Usage examples
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### Scan a loaded module (current process)
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```cpp
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#include <dlfcn.h>
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#include "omath/utility/macho_pattern_scan.hpp"
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using omath::MachOPatternScanner;
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void* handle = dlopen("libexample.dylib", RTLD_LAZY);
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if (handle) {
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auto addr = MachOPatternScanner::scan_for_pattern_in_loaded_module(
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handle, "55 48 89 E5 ?? ?? 48"
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);
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if (addr) {
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std::uintptr_t hit_va = *addr;
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// ...
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}
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dlclose(handle);
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}
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```
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### Scan a Mach-O file on disk
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```cpp
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#include "omath/utility/macho_pattern_scan.hpp"
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using omath::MachOPatternScanner;
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auto res = MachOPatternScanner::scan_for_pattern_in_file(
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"/usr/local/lib/libexample.dylib", "55 48 89 E5"
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);
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if (res) {
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auto va_hit = res->virtual_base_addr + res->target_offset;
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auto raw_hit = res->raw_base_addr + res->target_offset;
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}
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```
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### Scan another section (e.g., "__cstring")
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```cpp
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auto res = MachOPatternScanner::scan_for_pattern_in_file(
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"myapp", "48 8D 0D ?? ?? ?? ??", "__cstring"
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);
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```
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---
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## Notes & edge cases
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* **Mach-O only**: these functions assume a valid Mach-O layout. Non-Mach-O files or corrupted headers yield `nullopt`.
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* **Section name**: defaults to **`__text`** (note the double underscore, per Mach-O convention); pass a different name to target other sections.
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* **Performance**: Pattern matching is **O(N × M)** (sliding window with wildcards). For large binaries, prefer scanning only necessary sections.
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* **Architecture**: works for 64-bit Mach-O binaries (x86_64 and arm64).
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---
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## See also
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* [`omath::PatternScanner`](pattern_scan.md) — raw buffer/iterator scanning with the same pattern grammar.
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* [`omath::PePatternScanner`](pe_pattern_scan.md) — PE (Windows) binary scanner.
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* [`omath::ElfPatternScanner`](elf_pattern_scan.md) — ELF (Linux) binary scanner.
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* [`omath::SectionScanResult`](section_scan_result.md) — return type for file-based scans.
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---
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*Last updated: Feb 2026*
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