On Tue, 26 Jan 2021 12:14:02 +0900 Takashi Yano wrote: > Hi GDB maintainer, > > In GDB, debugged process cannot continue execution after break > if it reads stdin. > > With the following steps, cat is terminated with error. > > 1) Install coreutils-debuginfo package. > 2) Run "gdb cat" in console (command prompt), not in mintty. > 3) Enter "start" in gdb. > 4) Enter "cont" in gdb. > > This results in: > /usr/bin/cat: -: Input/output error > > Both gdb-9.2-1 and gdb-10.1-1(TEST) have this problem. > > I looked into this problem and found the cause is that the pgid > setting for /usr/bin/cat is lost after break. The following patch > for GDB source resolves the issue. In the following section, > winpid is passed to getpgid() rather than cygwin pid. Also, winpid > is passed to other POSIX system calls such as kill() elsewhere. > > --- inflow.c.orig 2020-05-24 06:10:29.000000000 +0900 > +++ inflow.c 2021-01-23 17:48:27.963609500 +0900 > @@ -364,11 +364,11 @@ > #ifdef HAVE_TERMIOS_H > /* If we can't tell the inferior's actual process group, > then restore whatever was the foreground pgrp the last > time the inferior was running. See also comments > describing terminal_state::process_group. */ > -#ifdef HAVE_GETPGID > +#if defined (HAVE_GETPGID) && !defined (__CYGWIN__) > result = tcsetpgrp (0, getpgid (inf->pid)); > #else > result = tcsetpgrp (0, tinfo->process_group); > #endif > if (result == -1) > > > I hope the GDB maintainer will check it out. > > Addresses: https://cygwin.com/pipermail/cygwin-patches/2021q1/011018.html
I have noticed that cygwin gdb essentially has the problem regarding terminal process group. Cygwin gdb uses CreateProcessW() to execute debugging process rather than exec(). If the debugging process is a cygwin process, cygwin pid is assigned, however, if the debugging process is a non cygwin process, cygwin pid is not assigned. Therefore, there is no appropriate process group ID to set. I wonder what is the right thing under that situation. Any idea? -- Takashi Yano <takashi.y...@nifty.ne.jp> -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple