Yukihiro "Matz" Matsumoto f8883178c5 mruby-task: prevent segfault when sleep is called from C function; fix #6642
when sleep() was called from within a C function (such as module.new's block
evaluation), the task scheduler would segfault while attempting to resume the
task. this occurred because C functions don't execute bytecode and thus their
callinfo has no valid program counter (pc). when the task tried to resume
execution, mrb_vm_exec() received a null pc, causing a segmentation fault.

the fix adds two safeguards in task.c:

1. C function boundary detection: before suspending a task for sleep, check
   if we're inside a C function by examining the cci (c call info) field.
   if cci > 0, fall back to blocking sleep via HAL instead of attempting
   cooperative context switch. this preserves sleep functionality without
   raising exceptions, though it blocks other tasks during the sleep period.

2. proc fallback in execute_task(): use the task's stored proc if the
   current callinfo's proc is null, ensuring mrb_vm_exec() always receives
   a valid proc pointer.

this approach prioritizes functionality over strict cooperative multitasking
semantics - tasks can still sleep inside C functions, but the sleep becomes
blocking. the alternative would be raising an exception like fiber does, but
that would break existing code unexpectedly.

Co-authored-by: Claude <noreply@anthropic.com>
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The mruby programming language

mruby

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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 3.x. Also, its syntax is Ruby 3.x compatible except for pattern matching.

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 3.4.0 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 or rvm.

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.

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

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.

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Automated archival mirror of github.com/mruby/mruby
Readme MIT 44 MiB
Languages
C 69.9%
Ruby 23.9%
Yacc 4.7%
C++ 1.4%