IO::Memory.write_bytes IO::ByteFormat::BigEndian triggers Invalid memory access

[636f7374]

Summary

• I accidentally triggered this problem while modifying the code.
• Reproducible.

Sample

• Code

damage_slice = "\xd1\x8c\x81\x80\x00\x01\x00\x02".to_slice
damage_io = IO::Memory.new damage_slice
ttl = damage_io.read_bytes UInt32, IO::ByteFormat::BigEndian
damage_io.write_bytes ttl, IO::ByteFormat::BigEndian

• Verbose

Output
Invalid memory access (signal 10) at address 0x10c8ccbd0
[0x10c7967e6] *Exception::CallStack::print_backtrace:(Int32 | Nil) +118
[0x10c763eee] __crystal_sigfault_handler +318
[0x7fff70cb75fd] _sigtramp +29

exit status: 10

System Information

$ crystal -v
Crystal 0.36.1 (2021-02-02)

LLVM: 11.0.1
Default target: x86_64-apple-macosx

-

$ uname -a
Darwin iMac.local 19.6.0 Darwin Kernel Version 19.6.0: Mon Aug 31 22:12:52 PDT 2020; root:xnu-6153.141.2~1/RELEASE_X86_64 x86_64

[oprypin]

I think this is #10362

[636f7374]

@oprypin Okay :)

[oprypin]

Yes, it is. On master it produces Unhandled exception: Read-only stream (IO::Error).
This will not be "fixed" but the error has been made explicit. You are trying to write to a buffer that's based on read-only memory.
I recommend closing this.

[straight-shoota]

Duplicate of #10362