Bug #18880: IO#sysread on Windows does not validate arguments

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x64-mingw-ucrt]
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN

[javanthropus (Jeremy Bopp)]

When passing an invalid number of bytes to read, such as -1 , to IO#sysread on Linux, an ArgumentError is raised. On Windows Errno::EINVAL is raised instead.

r, w = IO.pipe
r.sysread(-1)

This raises ArgumentError on non-Windows and Errno::EINVAL on Windows.

[javanthropus (Jeremy Bopp)]

I'm interested in submitting a patch for this, but which behavior is considered correct?

[nobu (Nobuyoshi Nakada)]

The ArgumentError is correct.
Even on Windows, sysread(-2) raises an ArgumentError too.

At rounding up len in io.c:io_setstrbuf(), negative values are not considered.

[javanthropus (Jeremy Bopp)]

I submitted PR https://github.com/ruby/ruby/pull/6354 with a simple fix. I don't have a Windows system to test with though, so I couldn't verify that it works.

[javanthropus (Jeremy Bopp)]

• Status changed from Open to Closed

Applied in changeset git|684353fc03afd6e7c887b65bd18f0b3aeb98101c.

---

[Win32] Negative length IO#sysread

Raise ArgumentError in IO#sysread on Windows when given a negative
length.

Fixes [Bug #18880]