HASUMI Hitoshi
d95ebe4a23
This patch fixes a bug in the stack extension logic that could cause a HardFault on certain configurations when the stack is reallocated to a new address. ## Background When the mruby VM's stack runs out, stack_extend_alloc() calls mrb_realloc to grow it. If reallocation moves the block to a new address, envadjust() adjusts all ci->stack pointers to point into the new allocation. ## The bug The bug happened under the configuration below: - MRB_INT64 on MRB_32BIT (`sizeof(mrb_value) == 16` because MRB_NO_BOXING is now mandatory) - Allocator with 8-byte alignment (eg. PICORB_ALLOC_ALIGN=8 in PicoRuby for Raspi Pico) The delta was computed via mrb_value* pointer subtraction: ```c ptrdiff_t delta = newbase - oldbase; // units of sizeof(mrb_value) ``` If : - Old address: 0x2004c508 - New address: 0x2004c510 (8-byte difference) The pointer subtraction truncated: 8 / 16 = 0. envadjust() was misleaded as `delta == 0` and returned early without adjusting any ci->stack pointers. The stbase was updated to the new address, but all stack pointers still pointed 8 bytes before it. Every register access was shifted, reading garbage, ultimately causing a HardFault. ## The fix Byte-level char* calculation instead of mrb_value* calculation: ```c ptrdiff_t off = (char*)newbase - (char*)oldbase; // ... ci->stack = (mrb_value*)((char*)ci->stack + off); ``` This ensures the adjustment is exact regardless of sizeof(mrb_value) and allocator alignment.
mruby
Table of contents
- What is mruby
- How to get mruby
- mruby homepage
- Mailing list
- How to compile, test, and install (mruby and gems)
- Amalgamation (single-file build)
- Building documentation
- How to customize mruby (mrbgems)
- Index of Document
- License
- Note for License
- How to Contribute
- Star History
- Contributors
What is mruby
mruby is the lightweight implementation of the Ruby language complying to (part of) the ISO standard with more recent features provided by Ruby 4.x. Also, its syntax is Ruby 4.x compatible.
You can link and embed mruby within your application. The "mruby" interpreter program and the interactive "mirb" shell are provided as examples. You can also compile Ruby programs into compiled byte code using the "mrbc" compiler. All these tools are located in the "bin" directory. "mrbc" can also generate compiled byte code in a C source file. See the "mrbtest" program under the "test" directory for an example.
This achievement was sponsored by the Regional Innovation Creation R&D Programs of the Ministry of Economy, Trade and Industry of Japan.
How to get mruby
To get mruby, you can download the stable version 4.0.0 from the official mruby GitHub repository or clone the trunk of the mruby source tree with the "git clone" command. You can also install and compile mruby using ruby-install, ruby-build, rvm, conda or Homebrew.
The latest development version of mruby can be downloaded via the following URL: https://github.com/mruby/mruby/zipball/master
The trunk of the mruby source tree can be checked out with the following command:
$ git clone https://github.com/mruby/mruby.git
mruby homepage
The URL of the mruby homepage is: https://mruby.org.
Mailing list
We don't have a mailing list, but you can use GitHub issues.
How to compile, test, and install (mruby and gems)
For the simplest case, type
rake all test
See the compile.md file for the detail.
Amalgamation (single-file build)
mruby supports amalgamation, which combines all source files into a single
mruby.c and mruby.h for easy embedding (similar to SQLite).
rake amalgam
Output files are generated in build/host/amalgam/. To use:
gcc -I./build/host/amalgam your_app.c ./build/host/amalgam/mruby.c -o your_app -lm
Building documentation
There are two sets of documentation in mruby: the mruby API (generated by YARD) and C API (Doxygen and Graphviz)
To build both of them, simply go
rake doc
You can also view them in your browser
rake view_api
rake view_capi
How to customize mruby (mrbgems)
mruby contains a package manager called "mrbgems" that you can use to create extensions in C and/or Ruby. For a guide on how to use mrbgems, consult the mrbgems.md file, and for example code, refer to the examples/mrbgems/ folder.
Index of Document
- About the Limitations of mruby
- About Amalgamation (Single-File Build)
- C API Reference
- About the Compile
- About the Debugger with the
mrdbCommand - About GC Arena
- Getting Started with mruby
- About the mruby directory structure
- About Linking with
libmruby - About Memory Allocator Customization and Heap Regions
- About Build-time Configurations
- About the Build-time Library Manager
- ROM Method Tables for Memory-Efficient Method Registration
- About the Symbols
- Internal Implementation / About mruby Architecture
- Internal Implementation / About Value Boxing
- Internal Implementation / About mruby Virtual Machine Instructions
License
mruby is released under the MIT License.
Note for License
mruby has chosen a MIT License due to its permissive license allowing developers to target various environments such as embedded systems. However, the license requires the display of the copyright notice and license information in manuals for instance. Doing so for big projects can be complicated or troublesome. This is why mruby has decided to display "mruby developers" as the copyright name to make it simple conventionally. In the future, mruby might ask you to distribute your new code (that you will commit,) under the MIT License as a member of "mruby developers" but contributors will keep their copyright. (We did not intend for contributors to transfer or waive their copyrights, actual copyright holder name (contributors) will be listed in the AUTHORS file.)
Please ask us if you want to distribute your code under another license.
How to Contribute
To contribute to mruby, please refer to the contribution guidelines and send a pull request to the mruby GitHub repository. By contributing, you grant non-exclusive rights to your code under the MIT License.