Hi! Me and Ilya Arkhipov were investigating the cause of this bug: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=215572 In short, when FreeBSD ports options dialog is interrupted by Ctrl+C, there's chance of sporadic terminal corruption. They are not always reproducible and seem to be dependent on a machine, shell, terminal, tmux used, but are not tied to any specific configuration. The investigation led us to the following conclusion: - the corruption is caused by dialog4ports program (which handles ports options dialogs) not being able to restore terminal state on exit - dialog4ports does indeed try to restore terminal state, but the corresponding ioctl (TIOCSETAW) fails with EIO - examining kern/tty.c suggests that this happens likely because the make which is the session leader or something dies before dialog4ports - which led us to bmake as a culprit Here's the ktrace of the problem (the process hierarchy here is make -> sh -> dialog4ports) --- 78337 dialog4ports CALL sigaction(SIGTSTP,0x800a80228,0) 78337 dialog4ports RET sigaction 0 78337 dialog4ports CALL clock_gettime(0xd,0x7fffffffde08) 78337 dialog4ports RET clock_gettime 0 78337 dialog4ports CALL gettimeofday(0x7fffffffdc90,0) 78337 dialog4ports RET gettimeofday 0 78337 dialog4ports CALL poll(0x7fffffffdca0,0x2,0xffffffff) (make and sh receive SIGINT first) 78265 make RET wait4 RESTART 78335 sh RET wait4 -1 errno 4 Interrupted system call 78265 make PSIG SIGINT caught handler=0x402530 mask=0x0 code=SI_KERNEL 78335 sh PSIG SIGINT caught handler=0x41b950 mask=0x0 code=SI_KERNEL 78265 make CALL lstat(0x800ab9900,0x7fffffffd1f0) 78265 make NAMI "do-config" 78335 sh CALL sigreturn(0x7fffffffd280) 78335 sh RET sigreturn JUSTRETURN 78265 make RET lstat -1 errno 2 No such file or directory 78335 sh CALL wait4(0xffffffff,0x7fffffffd6ec,0,0) 78265 make CALL sigaction(SIGINT,0x7fffffffd250,0x7fffffffd230) 78265 make RET sigaction 0 78265 make CALL kill(0x131b9,SIGINT) 78265 make RET kill 0 78265 make CALL sigreturn(0x7fffffffd2d0) 78265 make RET sigreturn JUSTRETURN (make kills itself) 78265 make PSIG SIGINT SIG_DFL code=SI_USER (dialog4ports finally starts to process the signal) 78337 dialog4ports RET poll -1 errno 4 Interrupted system call 78337 dialog4ports PSIG SIGINT caught handler=0x800855e00 mask=0x0 code=SI_KERNEL 78337 dialog4ports CALL sigaction(SIGINT,0x7fffffffd7c0,0) 78337 dialog4ports RET sigaction 0 78337 dialog4ports CALL ioctl(0x1,TIOCGETA,0x7fffffffd770) 78337 dialog4ports RET ioctl 0 78337 dialog4ports CALL write(0x1,0x801676a00,0x17) 78337 dialog4ports GIO fd 1 wrote 23 bytes 78337 dialog4ports RET write 23/0x17 (this call should restore terminal state, but it fails) 78337 dialog4ports CALL ioctl(0x1,TIOCSETAW,0x80161604c) 78337 dialog4ports RET ioctl -1 errno 5 Input/output error 78337 dialog4ports CALL exit(0x1) --- Here's the ktrace of the case which didn't cause terminal corruption: --- 79506 dialog4ports CALL poll(0x7fffffffdc00,0x2,0xffffffff) 79506 dialog4ports RET poll -1 errno 4 Interrupted system call (dialog4ports is lucky enough to start processing the signal before make) 79506 dialog4ports PSIG SIGINT caught handler=0x800855e00 mask=0x0 code=SI_KERNEL 79506 dialog4ports CALL sigaction(SIGINT,0x7fffffffd720,0) 79506 dialog4ports RET sigaction 0 79506 dialog4ports CALL ioctl(0x1,TIOCGETA,0x7fffffffd6d0) 79506 dialog4ports RET ioctl 0 79506 dialog4ports CALL write(0x1,0x801676a00,0x17) 79506 dialog4ports GIO fd 1 wrote 23 bytes 79506 dialog4ports RET write 23/0x17 (and cleanup succeeds) 79506 dialog4ports CALL ioctl(0x1,TIOCSETAW,0x80161604c) 79506 dialog4ports RET ioctl 0 79506 dialog4ports CALL exit(0x1) 79433 make RET wait4 RESTART 79433 make PSIG SIGINT caught handler=0x402530 mask=0x0 code=SI_KERNEL 79433 make CALL lstat(0x800ab4980,0x7fffffffd140) 79433 make NAMI "do-config" 79433 make RET lstat -1 errno 2 No such file or directory 79433 make CALL sigaction(SIGINT,0x7fffffffd1a0,0x7fffffffd180) 79433 make RET sigaction 0 79433 make CALL kill(0x13649,SIGINT) 79433 make RET kill 0 79433 make CALL sigreturn(0x7fffffffd220) 79433 make RET sigreturn JUSTRETURN 79433 make PSIG SIGINT SIG_DFL code=SI_USER 79504 sh RET wait4 -1 errno 4 Interrupted system call 79504 sh PSIG SIGINT caught handler=0x41b950 mask=0x0 code=SI_KERNEL 79504 sh CALL sigreturn(0x7fffffffd1d0) 79504 sh RET sigreturn JUSTRETURN --- For reference, here's the program which demonstrates the tty layer behaviour which causes this: --- #include <stdio.h> #include <sys/ioctl.h> #include <sys/types.h> #include <signal.h> #include <termios.h> #include <unistd.h> #include <errno.h> #include <string.h> int main() { struct termios t; int ret; // save terminal state ret = ioctl(1, TIOCGETA, &t); fprintf(stderr, "ioctl(1, TIOCGETA) -> %d / %s\n", ret, strerror(errno)); pid_t p = fork(); if (p > 0) { // parent would die from SIGTERM early kill(getpid(), SIGTERM); } else if (p == 0) { // child tries to restore terminal state with some delay usleep(1000); // because parent is dead now, this will fail with EIO ret = ioctl(1, TIOCSETAW, &t); fprintf(stderr, "ioctl(1, TIOCSETAW) -> %d / %s\n", ret, strerror(errno)); } return 0; } --- Now to fix this, I suggest that instead of killing itself, make should signal all its childs carefully and wait() on them, only then die itself. Now after a quick glance at bmake sources it seems like the jobs control code https://svnweb.freebsd.org/base/head/contrib/bmake/job.c?revision=317239&view=markup#l2633 does the very same thing that I've just described, however bmake is run in compat mode by default, and CompatInterrupt does exactly what ktrace shows - it just kills itself. https://svnweb.freebsd.org/base/head/contrib/bmake/compat.c?revision=310304&view=markup#l180 So, to fix this problem it seems that CompatInterrupt should be improved as described above. Also wanted to ask kib_at_, ian_at_ (as recent committers to tty.c) it this behavior of tty layer is correct and if it could be improved. -- Dmitry Marakasov . 55B5 0596 FF1E 8D84 5F56 9510 D35A 80DD F9D2 F77D amdmi3_at_amdmi3.ru ..: jabber: amdmi3_at_jabber.ru http://amdmi3.ruReceived on Wed Jul 19 2017 - 11:00:21 UTC
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