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Introduction

WBBlades is a tool set based on Mach-O file parsing, including one-click detection for app (supports OC and Swift), package size analysis (supports a single static library/dynamic library), point-to-point crash analysis ( analyse system crash log, based on symbol file and without symbol files), Class automatic extraction and Hook capability based on Mach-O file. It mainly uses __Text assembly code analysis, architecture extraction, DYSM file stripping, symbol table stripping, crash file (ips) analysis technology.Support big method/small method parsing and iOS 15 above about dyld_chained_Fixups processing.

Tool Overview

Tool Name	Function Overview	Related Technologies
One-Click Detection for App	Swift & OC useless class detection, useless resource detection, and package downsizing optimization suggestions.	Disassembly, __Text instruction extraction, Mach-O parsing, symbol table and Swift class structure in Mach-O
Package Size Analysis	Detecting the actual size occupied by static & dynamic libraries in .ipa file.	Architecture stripping, static library structure analysis
Crash Analysis	Using .app or dYSM file to parse the system crash log.	DYSM file parsing, lightweight symbol table extraction, ips file parsing, with/without symbol table crash parsing
Mach-O Class Hook	Automatically extract classes from any Mach-O file, and then hook them.	dyld_ chained_ Fixups, binding, rebase, and big/small method parsing

The new version implements a comprehensive visual implementation of the toolset based on the original command-line-based operation of the above tools, and is designed for R&D efficiency improvement. In addition, in the analysis of difficult crashes, for some crashes that are not easy to reproduce and cannot be collected by general tools (the app process is directly killed by the operating system), a point-to-point crash analysis is provided.

Installation

$ git clone https://github.com/wuba/WBBlades.git
$ cd WBBlades
$ pod install

Usage of Visualization Tool

Target selects "WBBladesCrashApp".

Click the button on the left function area, select a tool such as Useless Classes Detection,Application Size Analysis,etc., and operate according to the prompts in the tool, and the result will be output to the text box;

Detailed introduction to visualization tool: Detailed introduction to visualization tool

Usage for Mac Command Line

Target selects "WBBlades"，Compile and build to generate command line tools Copy the generated product "blades" to /usr/local/bin，as follows： sudo cp ${Your_BUILD_DIR}/blades /usr/local/bin

• Unused Code Detection ObjC & Swift

  $ blades -unused xxx.app -from xxx.a xxx.a ....

  -from indicating that only the unused code in the following static libraries is analyzed. Without this parameter, the default is all classes in the APP.

• App Size Analysis (Directly measure the size of .a or .framework after linking)

  $ blades -size xxx.a xxx.framework ....

  Supporting input a folder path, all static libraries under the folder will be analyzed.

• Log Recovery without dSYM File (In the case of missing dSYM file, try ObjC crash stack symbolization, Swift is not supported)

  $ blades -symbol xxx.app -logPath xxx.ips

Tool Features

Unused code (unused class) detection support range

Description	Support	Code Example
ObjC classes's static call	✅	[MyClass new]
ObjC classes's dynamic call	✅	NSClassFromString(@"MyClass")
ObjC dynamic call througn string concatenation	❌	NSClassFromString(@"My" + @"Class")
ObjC load method	✅	+load{...}
ObjC & Swift being inherited	✅	SomClass : MyClass
ObjC & Swift being properties	✅	@property (strong,atomic) MyClass *obj;
Swift class direct call	✅	MyClass.init()
Swift call using runtime	❌	objc_getClass("Demo.MyClass")
Swift generic parameters	✅	SomeClass<MyClass>.init()
Swfit class dynamic call in ObjC	✅	NSClassFromString("Demo.MyClass")
Swift type declaration in the container	❌	var array:[MyClass]
Swift multiple nesting	✅	class SomeClass {class MyClass {...} ...}

App Size Analysis Tool

Supports quick detection of the linked size of a static library. No need to compile and link. For example: If you want to know how much app size will increase when an SDK is imported or updated, you can use blades -size to estimate the size, without the need to connect the SDK to compile and link successfully to calculate.

Crash Log Symbolization Tool Without dSYM File

In the case of losing the dSYM file, try to restore the log via blades -symbol. **For example, in an app packaging, the dSYM file is cleared after a period of time, but the app file is retained. In this case, you can consider using blades for symbolization. **Before using the tool, pay attention to a few points:

• If your app is a debug package or a package that does not strip the symbol table, you can use dsymutil app -o xx.dSYM to extract the symbol table. Then use the symbol table to symbolize the log.

• This tool only supports ObjC, and its principle is to determine the function of the crash by analyzing the address of the ObjC method in Mach-O. Therefore, it is not suitable for Swfit, C, and C++. In addition, tools are not omnipotent, and are only used as emergency supplementary technical means. In daily situations, it is recommended to use symbol tables for log symbolization.

Contributing & Feedback

We sincerely hope that developers can provide valuable comments and suggestions, and developers can provide feedback on suggestions and problems by submitting PR or Issue.

If you are interested in WBBlades, you can join the WBBlades development group and discuss technical issues together. Please add the wechat account "zqlong320" or scan the QR code below as your friend and then we will invite you to join the group.

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• Unused Class Detection Based on Mach-O Disassembly
• Open Source｜WBBlades：APP Analysis Tool Set Based on Mach-O File Analysis
• The Storage Difference between Swift and ObjC from the Perspective of Mach-O
• New Approach to Swift Hook - Virtual Method Table

Thanks

GitHub: https://github.com/aquynh/capstone

GitHub: https://github.com/Sunnyyoung/SYFlatButton

GitHub: https://github.com/nygard/class-dump

GitHub: https://github.com/alexrozanski/PXListView

GitHub: https://github.com/steventroughtonsmith/cartool

DWARF: https://www.prevanders.net/dwarf.html#releases