CVS commit: src/sys/kern

["Kamil Rytarowski" <kamil%netbsd.org@localhost>]

Module Name:    src
Committed By:   kamil
Date:           Tue Apr 30 20:50:30 UTC 2019

Modified Files:
        src/sys/kern: sys_ptrace_common.c

Log Message:
Return EIO for empty memory transfer from ptrace(2)

Certain operations of PT_READ/PT_WRITE and PIOD_READ/PIOD_WRITE can result
in 0 byte transfer and the ptrace(2) call still returned success.

GDB had a special handling of this case for PT_IO checking piod_len != 0,
but in LLDB this corner case caused infinite loop and breakage. The LLDB
case has been enhanced.

Unfortunately the status of operation of PT_READ/PT_WRITE is not
distinguishable between successful operation and empty opeartion. This
renders this call into a questionable one.

Change the behavior and return error with EIO in scenarios of
truncated/empty byte transfers by PT_READ/PT_WRITE and empty byte transfers
from PT_IO.

No code changed is needed in GDB and LLDB.


To generate a diff of this commit:
cvs rdiff -u -r1.48 -r1.49 src/sys/kern/sys_ptrace_common.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.