An improved nm + objc/swift class-dump (writeup)
Works great on Objective-C classes
... and Swift types
dsdump(1) BSD General Commands Manual dsdump(1)
NAME
dsdump -- An improved nm + objc/swift class-dump
SYNOPSIS
dsdump [option...] <mach-o-file>
DESCRIPTION
Provides an "nm-improved" experience when working with Mach-O executa-
bles. dsdump has 3 "primary" modes: Symbol table (--sym), Objective-C
(--objc), and Swift (--swift, -s). Omitting all of these options will
default to the Swift mode.
OPTIONS
-c, --color
Adds color to output
-d, --demangle
Demangle Swift and C++ symbols in print symbol mode
-l, --library
Instead of dumping symbols, search all procs for library
-O, --opcs
Dump the DYLD opcodes used to bind external symbols at load time
-f, --filter FilterWord
Specify classes to filter by (case insensitive, can be used mul-
tiple times)
-a, --arch architecture
Specify the arichtecture if file is FAT. Understands x86_64h,
x86_64, arm64, arm64e
-u, --undefined
Only display undefined (externally referenced) symbols or classes
-U, --defined
Only display defined (internally implemented) symbols or classes
-v, --verbose
Specifies the verbosity level. The -v option can be used multiple
times, while the long argument sets the exact level 0-5. Kind of
like codesign(1)'s verbosity that everyone complains about...
--objc Dump the Objective-C classes
-o Sets mode to Objective-C mode and verbosity to level 4
--swift
Dump the Swift type descriptors (classes, structs, enums)
-s Sets mode to Swift mode and verbosity to level 4
-h, --help
Print out this beautiful, helpful document
EXAMPLES
List ObjC internal/external classes referenced/implemented by vmmap:
dsdump --objc $(which vmmap)
List all alive processes that have the MobileDevice loaded
sudo dsdump -l /S*/L*/P*/MobileDevice.framework/MobileDevice
List the Objective-C external classes called by vmmap:
dsdump --objc $(which vmmap) -u
List the Objective-C internal classes implemented by vmmap:
dsdump --objc $(which vmmap) -U
Perform an Objective-C "class-dump" in color of vmmap
dsdump --objc $(which vmmap) -U -vvvc
Thoroughly dump the Swift content in color in the Console app
dsdump --swift
/Applications/Utilities/Console.app/Contents/MacOS/Console -cvvvv
VERBOSITY
dsdump can output a range of verbosity between the 3 different modes
(--sym, --swift, --objc). The verbosity level can be set by the long form
(--verbose=3) or by specifying a count via short form (-vvv). The break-
down of these levels are shown below:
--sym:
0. Print symbol
1. 0 + library path or Mach-O section
2. 1 + fullpath to library
3. 2 + nlist struct output
4. Same as 3... for now
5. Same as 3... for now
--swift:
0. List swift types
1. 0 + Parent classes
2. 1 + Protocols
3. 2 + Swift type dump
4. 3 + Extended type dump, ObjC bridge methods
5. 4 + Commenting in methods
--objc:
0. List Objective-C classes
1. 0 + Parent classes & library basename for external
2. 1 + Fullpath to libraries for external + protocols
3. 2 + Objective-C class dump
4. 3 + Print properties
5. 4 + Print ivars & offsets
ENVIRONMENT
DSCOLOR Enables color. Alternatively, use -c
ARCH <arch> Specify the architecture if inspecting a FAT executable,
Alternatively use --arch
SEE ALSO
nm(1), objdump(1), vmmap(1)
BUGS
There's a situation where occassionally dsdump will think the parent
class is a RO_ROOT where it will in fact won't be. I'll print this out
for now so I can hunt it down
ARM64e still needs some luv, especially on the Swift side, especially
with Protocols... and not crashing
AUTHORS
Derek Selander @LOLgrep
Darwin March 26, 2020 Darwin
Compiling this will be a bit of a pain in the butt on your end. You'll need to clone the Swift language in the same directory. Swift can't be a submodule to this repo since some of their git cloning scripts won't work :|
# cd into the dsdump repo
cd dsdump/
# make a directory called swift-source, yes, name it exactly that
mkdir swift-source
cd swift-source/
# clone the Swift repository into swift-source
git clone https://github.com/apple/swift.git
# checkout
cd swift
git checkout 75670c17272a993ed798cee7e31c20590e94118b
# Use the Swift update helper script to grab everything else
./swift/utils/update-checkout --clone-with-ssh --tag swift-5.1.4-RELEASEComment out any remaining problematic code after a build, remove methods in Metadata.h as needed (i.e. problematic ARC bridging code on line 700)
I've included the libSwiftDemangling.a static lib that I built into dsdump/dsdump. If you want to build entirely from Swift source, you'll need to build this yourself. Otherwise you should be good to go to build dsdump via Xcode.
Alternatively, you can skip all of this by simply grabbing the compiled dsdump version in the compiled directory found here. Make sure the SHA256 matches below if you're paranoid.
Compiled SHA256
SHA256: 83eebd025b43b58a486235e1bec70a3239995be409605e3ff19bdae07adff917
- https://opensource.apple.com/source/dyld/dyld-635.2/src/dyldInitialization.cpp.auto.html Specifically the THREADED code for ARM64e
- https://opensource.apple.com/source/objc4/ Specifically, the objc_class swift_class structs (and all the property, protocol, method, ivar, etc structs)
- https://github.com/apple/swift
- Full ARM64e support
- M1 support
- Crashes
- iOS 15/Monterey support
- In process support (TODO TODO guess that means a libdsdump.a)
- Basic dsc listing with options to
dlopenfrom cmdline
- Basic dsc listing with options to
- header files