This patch fixs a critical segmentation fault in `io_gets` function caused by an uninitialized limit variable.
This bug may specifically heppen when:
- MicroRuby with task scheduler, which I'm implementing, enabled
## Root Cause Analysis
When `io_gets` is called without arguments (argc=0), the local variable `limit` remains uninitialized on the stack.
I guess that this uninitialized memory often contains leftover heap addresses from previous stack frames.
### The problematic flow:
1. `mrb_get_args(mrb, "|o?i?", &rs, &rs_given, &limit, &limit_given)` with 0 arguments
2. `limit_given = FALSE` but limit contains garbage heap address
3. Looks like later processing truncates this address, creating invalid pointer 0xffff0000
4. This value gets pushed onto VM stack during string operations
5. Garbage collector attempts to mark 0xffff0000 as valid object pointer
6. SIGSEGV in mrb_gc_mark() at gc.c:748
```
Program received signal SIGSEGV, Segmentation fault.
0x00005c8bebffa95c in mrb_gc_mark (mrb=0x5c8bec2836c8 <heap_pool+728>, obj=0xffff0000)
at .../gc.c:748
748 if (!is_white(obj)) return;
#1 mark_context_stack (mrb=0x5c8bec2836c8 <heap_pool+728>, c=0x5c8bec2b4a50 <heap_pool+202336>)
at .../gc.c:555
555 mrb_gc_mark(mrb, mrb_basic_ptr(v));
```
## Solution
I couldn't figure out the exact mechanism of the issue. Anyway, initializing the limit variable to zero could prevent invalid garbage stack memory:
```c
mrb_int limit = 0; // Explicit initialization
```
## Files Changed
- mrbgems/picoruby-mruby/lib/mruby/mrbgems/mruby-io/src/io.c
In the Windows-specific code path for IO.popen, the variable 'p'
is a struct, not a pointer. The code was using 'p->klass' to
access a member, which is incorrect and causes a build failure
on Windows. This has been corrected to use the 'klass' argument
directly.
Co-authored-by: Gemini <gemini@google.com>
Implements File.join in C for better performance, replacing the Ruby
implementation with direct C string manipulation and array processing.
Uses mruby's built-in recursion detection (MRB_RECURSIVE_UNARY_P) for
cleaner and more reliable recursive array handling.
Co-authored-by: Claude <noreply@anthropic.com>
Implements File.path in C for better performance, replacing the Ruby
implementation that used kind_of? check with direct C type validation.
Co-authored-by: Claude <noreply@anthropic.com>
Implement C version of File.extname for better performance:
- Direct C string processing instead of Ruby basename + rindex
- Efficient path parsing with single pass through string
- Proper handling of edge cases (dotfiles, trailing slashes, etc.)
- Maintains full compatibility with Ruby implementation
Performance improvement:
- Eliminates Ruby method call overhead for basename/rindex
- Direct C string operations vs Ruby string methods
- Faster path processing for file extension extraction
Co-authored-by: Claude <noreply@anthropic.com>
Moved IO#ungetbyte from Ruby to C implementation to eliminate
boundary crossing overhead and avoid temporary string allocations.
Added io_unget_data helper function to handle raw data operations
efficiently.
Co-authored-by: Claude <noreply@anthropic.com>
Moved IO#<< from Ruby to C implementation to reduce boundary
crossing overhead. Maintains full compatibility with automatic
to_s conversion and proper return value for method chaining.
Co-authored-by: Claude <noreply@anthropic.com>
Moved IO#print from Ruby to C implementation to reduce boundary
crossing overhead. Maintains full compatibility with automatic
to_s conversion for all arguments.
Co-authored-by: Claude <noreply@anthropic.com>
Moved IO#puts from Ruby to C implementation to reduce boundary
crossing overhead. Maintains full compatibility including array
recursion and newline handling.
Co-authored-by: Claude <noreply@anthropic.com>
Extract buffer adjustment logic from io_write into reusable helper
function io_prepare_write. This prepares for implementing io_puts
in C while maintaining consistency in write operations.
Co-authored-by: Claude <noreply@anthropic.com>
This commit refactors the `io_s_popen` function to improve readability
and maintainability. The function has been broken down into smaller,
more manageable functions, and the platform-specific code has been
separated.
Co-authored-by: Gemini <gemini@google.com>
The previous implementation of fd_write had a bug that caused it to
repeatedly write the entire string instead of the remaining portion.
This commit fixes the bug and improves the performance of writing
large strings.
Co-authored-by: Gemini <gemini@google.com>
Replace XML-style markup tags in comments with markdown equivalents:
- <code>...</code> to `...` (inline code)
- <tt>...</tt> to `...` (teletype/monospace)
- <i>...</i> to *...* (italics/emphasis)
- +...+ to `...` (parameter/variable references)
Updated 80+ files across core source, headers, mrbgems, and libraries
to use consistent markdown formatting in documentation comments.
Handled edge cases including special characters like <=> operators.
Co-authored-by: Atlassian Rovo Dev
Added complete call-seq documentation for the entire mruby-io gem across
both Ruby and C implementations:
## Ruby Methods (mrblib/) - 50 methods documented:
### Kernel Module (kernel.rb):
- Backtick operator: shell command execution with output capture
- open: unified file/subprocess opening with pipe support
- p: debug output with inspect formatting and multiple argument handling
- print/puts/printf: output methods with proper formatting and separators
- gets/readline/readlines: input methods with various line handling options
### File Constants (file_constants.rb):
- FNM_* constants: file name matching flags for glob and fnmatch operations
with detailed explanations of case sensitivity, escaping, and pattern behavior
### IO Class (io.rb):
Class methods:
- IO.open: creates IO objects with automatic resource management
- IO.popen: subprocess communication with pipe handling
- IO.pipe: creates connected pipe endpoints for IPC
- IO.read: convenience method for reading entire files
Instance methods:
- Stream positioning: pos=, rewind, tell with proper seeking behavior
- Iteration: each, each_byte, each_char with enumerator support
- Output: puts, print, printf with formatting and newline handling
- Utility: hash, <<, ungetbyte with proper stream manipulation
- Global streams: STDIN/STDOUT/STDERR and $stdin/$stdout/$stderr
### File Class (file.rb):
Instance methods:
- Constructor: handles both file paths and file descriptors
- Timestamps: atime, ctime, mtime with proper Time object conversion
- Inspection: inspect method for debugging file objects
Class methods:
- Path utilities: join with cross-platform separator handling
- File iteration: foreach with block and enumerator support
- FileTest delegation: complete set of file type and existence checks
(directory?, exist?, file?, pipe?, size, socket?, symlink?, zero?)
- Path manipulation: extname for extension extraction, path for conversion
## C Methods (src/) - 25 methods documented:
### Core IO Operations (io.c):
- File descriptor management: fileno with proper error handling
- Stream state: closed?, eof?, sync/sync= for buffering control
- Process management: pid for pipe process tracking
- Resource management: close_on_exec?/close_on_exec= for FD_CLOEXEC handling
### Reading Operations:
- Character reading: getc, readchar with EOF handling differences
- Byte reading: getbyte, readbyte with integer conversion
- Buffer reading: read with length and output buffer support
- Stream manipulation: ungetc for character pushback
### System Operations:
- IO multiplexing: IO.select for monitoring multiple streams
- Constructor: IO.new for creating IO objects from file descriptors
- Stream flushing: flush for forcing output to OS
Co-authored-by: Atlassian Rovo Dev
The reason for this is to fix the following problems
- Even on non-Windows, drive letter recognition was still being handled.
- On Windows, paths starting with a slash were not expanded correctly.
- On Windows, relative paths containing drive letters behaved differently than in CRuby.
Due to reimplementation, the internal methods `File._concat_path`, `File._gethome` and `File._getwd` methods have been removed.
The purpose is as follows:
- Stop using `mrb_locale_from_utf8()`.
- Because there is no corresponding `mrb_utf8_from_locale()`.
- Because on Windows, for example, if the code page is 932 (CP932, likely ShiftJIS), it cannot be distinguished from the second byte 0x5c (\), and returns wrong results.
- Stop using `dirname(3)`.
- Because leading consecutive slashes are not truncated.
For example, if `/////a/b` is given, CRuby returns `/a`, but mruby so far returns `/////a`.
- Because the `path` argument cannot be passed in an immutable form.
- Stop using `_splitpath()` in the Windows implementation.
- Because there is no support for UNC paths with up to 32767 characters.
ref. https://learn.microsoft.com/ja-jp/dotnet/standard/io/file-path-formats#unc-paths
- Because modifying the result of paths terminated by a directory separator.
Previously, for example, `C:/` would return `C:.` instead of `C:/`, and `a/b/` would return `a/b` instead of `a`.
dearblue