ABI compliance checker

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ABI Compliance Checker (ACC) is a tool for checking backward binary and source-level compatibility of a C/C++ library. The tool checks header files and shared libraries of old and new versions and analyzes changes in API and ABI (ABI=API+compiler ABI) that may break binary and/or source compatibility: changes in calling stack, v-table changes, removed symbols, renamed fields, etc.

Binary incompatibility may result in crashing or incorrect behavior of applications built with an old version of a library if they run on a new one. Source incompatibility may result in recompilation errors with a new library version. The tool is intended for developers of software libraries and Linux maintainers who are interested in ensuring backward compatibility, i.e. allow old applications to run or to be recompiled with newer library versions.

Contents

Downloads

The tool can be downloaded from github.com.

License

This program is free software. You may use, redistribute and/or modify it under the terms of either the GNU GPL or LGPL.

Supported Platforms

GNU/Linux, FreeBSD, Mac OS X, MS Windows.

System Requirements

The tool requires:

  • G++ (3.0-4.7, 4.8.3, recommended 4.5 or newer)
  • GNU Binutils (readelf, c++filt, objdump)
  • Perl 5 (5.8 or newer)
  • Ctags (5.8 or newer)

WARNING: if you are using ccache program (i.e. gcc points to /usr/lib/ccache/gcc) then it should be newer than 3.1.2 or disabled.

On Mac OS X the tool also requires Xcode for g++, c++filt, nm and otool.

On MS Windows the tool also requires MinGW, MS Visual C++ (dumpbin, undname, cl), Active Perl 5, adding of tool locations to the PATH and execution of vsvars32.bat script (C:\Microsoft Visual Studio 9.0\Common7\Tools\).

Installation

The tool is ready-to-use after extracting the archive. You can also use a Makefile to install the tool into the system:
 cd abi-compliance-checker-x.y.z/ 
 sudo perl Makefile.pl -install --prefix=PREFIX [/usr, /usr/local, ...] 

This command will install the  abi-compliance-checker  program into the  PREFIX/bin  system directory and private modules into the  PREFIX/share .

To verify that the tool is installed correctly and it works on your host run:
 cd tmp/ 
 abi-compliance-checker -test 

Usage

For using the tool, you should provide the XML descriptors for two library versions: v1.xml and v2.xml files. Library descriptor is a simple XML-file that specifies version number, paths to header files and shared libraries and other optional information. An example of the descriptor is the following:

<version>
    0.3.4
</version>

<headers>
    /usr/local/libssh/0.3.4/include/
</headers>

<libs>
    /usr/local/libssh/0.3.4/lib/
</libs>

Command to compare two versions of a library:
   abi-compliance-checker -lib NAME -old V1.xml -new V2.xml 

The compatibility report will be generated to:
   compat_reports/NAME/V1_to_V2/compat_report.html 

Examples

Library Versions Report
NetCDF 4.0.1 to 4.1.1 report
MySQL++ 3.0.9 to 3.1.0 report
libssh 0.3.4 to 0.4.0 report

Detectable Compatibility Problems

The tool searches for the following list of changes in the API that may break binary/source-level compatibility. See “Binary Compatibility Issues With C++” from KDE TechBase and this list of articles for more info.

Binary Compatibility

  • Problems with Data Types
    • Structures and Classes
      • added/removed fields (change of a memory layout)
      • change of size
      • changed order of fields
      • change of a field type
      • changes in fields (recursive analysis)
    • Classes
      • added/removed virtual functions (change of a v-table layout)
      • change of virtual function position
      • overridden virtual functions
      • added/removed base classes
      • changes in base classes (recursive analysis)
    • Unions
      • added/removed fields
      • change of size
      • change of a field type
      • changes in fields (recursive analysis)
    • Enumerations
      • change of a member value
      • removed/renamed members
  • Problems with Symbols
    • removed symbols (functions and global data)
    • added/removed parameters
    • change of a parameter/return value type
    • change of default parameter value
    • renamed parameters
    • incorrect version change
    • changed attributes (const, volatile, static, etc.)
  • Problems with Constants (#defines)
    • changed value

Source Compatibility

  • Problems with Data Types
    • Structures, Classes and Unions
      • removed/renamed fields
      • change of a field type
      • changes in fields (recursive analysis)
    • Classes
      • added/removed base classes
      • change access level of a field or method
      • added pure virtual methods
    • Enumerations
      • removed/renamed members
  • Problems with Symbols
    • removed symbols (functions and global data)
    • added/removed parameters
    • change of a parameter type
    • removed default value
    • change of return value type
    • changed attributes (const, static, etc.)
  • Problems with Constants (#defines)
    • changed value

Adv. Usage

Create ABI Dumps

The library ABI is a representation of the library API at the binary level. The ABI dump is a dump of the model of the ABI used in the tool.

The ABI dump consists of:

  • Types Information
    • Attributes (name, size, header, access, base types, etc.)
    • Fields (name, type, size, position, alignment, access, specifiers, etc.)
    • V-table structure (offsets, entries)
    • Etc.
  • Symbols Information
    • Attributes (name, mangled name, header, access, specifiers, etc.)
    • Parameters (name, type, position, alignment, etc.)
    • Etc.
  • Etc.

The ABI dump can be used to create a snapshot of a library ABI in the particular environment and then compare it with any other state of the ABI changed due to changes in the environment (compiler version, external libraries, etc.) or changes in the library API (header files). The typical case is the comparing of two versions of the same library that require incompatible states of the environment (i.e. these versions cannot be installed simultaneously). In this case one can create a dump for one version of the library and then switch the environment and create ABI dump for other version of the library. Two ABI dumps can be compared by the tool to create the API compatibility report.

To create an ABI dump use -dump option:
   abi-compliance-checker -lib NAME -dump VER.xml 

The ABI dump will be generated to:
   abi_dumps/NAME/NAME_VER.abi.tar.gz 

To compare ABI dumps pass them as the descriptors:
   abi-compliance-checker -lib NAME -old V1.abi.tar.gz -new V2.abi.tar.gz 

Usage with ABI Dumper

Library should be compiled with "-g -Og" GCC options to contain DWARF debug info.

Create ABI dumps for both library versions using the ABI Dumper tool:

   abi-dumper OLD.so -o ABI-0.dump -lver 0 
   abi-dumper NEW.so -o ABI-1.dump -lver 1 

Compare ABI dumps:

   abi-compliance-checker -l NAME -old ABI-0.dump -new ABI-1.dump 

Usage as a Parser of API

The tool can be used as a parser of C/C++ API. Use -dump and -xml options to create ABI dump in the XML format:
   abi-compliance-checker -lib NAME -dump VER.xml -xml 

The ABI dump will be generated to:
   abi_dumps/NAME/NAME_VER.abi.tar.gz 

You can use additional -stdout option to print ABI dump on the screen instead of creating gzipped file:
   abi-compliance-checker -lib NAME -dump VER.xml -xml -stdout 

See examples of ABI dumps for MeeGo Touch library in XML and Perl (default) formats.

Compare Operating Systems

The detailed explanation on how to check compatibility between operating systems you can read on this page.

Check Applications Portability

The ACC tool can be used by independent software vendors (ISV) to check applications portability to new library versions by specifying of its binary using -app option:
   abi-compliance-checker -lib NAME -old V1.xml -new V2.xml -app APP 

Found issues can be taken into account when adapting the application to a new library version.

Command-Line Options

See the list of supported options in the output of -help and -info options.

Tutorial

An excellent tutorial "ABI: stability check" is available at Les RPM de Remi Blog. See also ABI compliance checker Notes at glibc wiki.

Report Format

The tool supports two formats of a compatibility report: HTML (default) and XML. To generate XML report you should specify -xml additional option.

The report consists of:

  • Test Info - The library name and compared version numbers. Environment info: GCC version and CPU type.
  • Test Results - Verdict on compatibility. Number of header files, shared libraries, symbols and data types checked by the tool.
  • Problem Summary - Classification of compatibility problems.
  • Added Symbols - The list of added symbols.
  • Removed Symbols - The list of removed symbols.
  • Problems with Data Types - The list of compatibility problems caused by changes in data types (divided by the severity level: High, Medium and Low). List of affected symbols.
  • Problems with Symbols - The list of compatibility problems caused by changes in symbol parameters or attributes (divided by the severity level).
  • Problems with Constants - The list of changed constants (#defines).
  • Other Changes in Data Types - The list of compatible changes in data types.
  • Other Changes in Symbols - The list of compatible changes in symbols.

Verdict on Compatibility

If the tool detects problems with high or medium level of severity or at least one removed symbol then the compatibility verdict is incompatible (otherwise compatible). Low-severity problems can be considered as warnings and don't affect the compatibility verdict unless the -strict option is specified.

Error Codes

Code Meaning
0 Compatible. The tool has run without any errors.
1 Incompatible. The tool has run without any errors.
2 Common error code (undifferentiated).
3 A system command is not found.
4 Cannot access input files.
5 Cannot compile header files.
6 Headers have been compiled with minor errors.
7 Invalid input ABI dump.
8 Unsupported version of input ABI dump.
9 Cannot find a module.
10 Empty intersection between headers and shared objects.
11 Empty set of symbols in headers.

FAQ

  • What is an ABI and how does it differ from an API?

An Application Binary Interface (ABI) is the set of supported run-time interfaces provided by a software component or set of components for applications to use, whereas an Application Programming Interface (API) is the set of build-time interfaces. The ABI may be defined by the formula: ABI = API + compiler ABI.

  • Why does this tool need both shared libraries and header files to check ABI compliance?

Without header files it is impossible to determine public symbols in ABI and data type definitions. Without shared libraries it is impossible to determine exported symbols in the ABI of the target library and also impossible to detect added/removed symbols.

Similar Tools

  1. icheck - C interface ABI/API checker.
  2. BCS - The Symbian binary compatibility suite.
  3. shlib-compat - ABI compatibility checker that uses DWARF debug info.
  4. qbic - A tool to check for binary incompatibilities in Qt4 Toolkit.
  5. libabigail - A C++ library for ABI analysis.
  6. chkshlib, cmpdylib, cmpshlib - Tools to compare binary symbols.

Bugs

Please post bug reports, feature requests and questions to the issue tracker.

Developers

The tool is developed by Andrey Ponomarenko.

Articles

Here is the list of articles about shared libraries and binary compatibility:

  1. "Binary Compatibility Issues With C++", KDE TechBase
  2. "Binary Compatibility Examples", KDE TechBase
  3. "Automated Verification of Shared Libraries for Backward Binary Compatibility", A. Ponomarenko and V. Rubanov, VALID 2010
  4. "Backward compatibility of software interfaces: Steps towards automatic verification", A. Ponomarenko and V. Rubanov, Programming and Computer Software 2012
  5. "Itanium C++ ABI", linux-foundation.org
  6. "ABI Compatibility", Josh Faust
  7. "ABI : stability check", Les RPM de Remi - Blog
  8. "Calling conventions for different C++ compilers and operating systems", Agner Fog
  9. "Calling conventions on the x86 platform", Andreas Jonsson
  10. "Some thoughts on binary compatibility", Thiago Macieira
  11. "Binary Compatibility of C++ shared libraries on GNU/Linux", Pavel Shved, Denis Silakov
  12. "Library Interface Versioning in Solaris and Linux", David J. Brown and Karl Runge
  13. "Steps to Version Your Shared Library", hp.com
  14. "Binary-compatible C++ Interfaces", Chad Austin
  15. "ABI Policy and Guidelines", gnu.org
  16. "Binary Compatibility", gnu.org
  17. "Stability of the C++ ABI: Evolution of a Programing Language", Stephen Clamage
  18. "When binary compatibility breaks", Debian Library Packaging guide
  19. "Library Code Policy", KDE TechBase
  20. "How To Write Shared Libraries", Ulrich Drepper
  21. "Program Library HOWTO", linux.org
  22. "Writing shared libraries", Mike Hearn
  23. "Shared libraries in Linux: growing pains or fundamental problem?", Sergey Ayukov
  24. "Fragile Binary Interface Problem", Steven Newton
  25. "The amazing world of library incompatibility", oocities.org
  26. "ABI compatibility in C++", elpauer.org
  27. "The impact of C++ templates on library ABI", Michał Górny
  28. "ABI compliance checker Notes", sourceware.org
  29. "Preserving Compatibility", symbian.org
  30. "Architectures and ABIs detailed", Thiago Macieira's blog
  31. "Interface Versioning in C++", ACCU
  32. "Generic ABI Standard", "ELF and ABI Standards", freestandards.org
  33. Processor ABI standards: Intel386, AMD64, ARM, PowerPC, S/390, Itanium, MIPS, SPARC, PA-RISK, M32R
  34. Binary compatibility for library developers, Video, Thiago Macieira
  35. ACC for abi breaks, Dimitri Ledkov
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