098b713c7
Denys Vlasenko
2017-01-11
Subject
ash: commented-out possible fix for 7694
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shell/ash.c+79 -4
| @@ -3579,6 +3579,72 @@ static struct job *curjob; //lots | |
| /* number of presumed living untracked jobs */ | |
| static int jobless; //4 | |
| + | #if 0 |
| + | /* Bash has a feature: it restores termios after a successful wait for |
| + | * a foreground job which had at least one stopped or sigkilled member. |
| + | * The probable rationale is that SIGSTOP and SIGKILL can preclude task from |
| + | * properly restoring tty state. Should we do this too? |
| + | * A reproducer: ^Z an interactive python: |
| + | * |
| + | * # python |
| + | * Python 2.7.12 (...) |
| + | * >>> ^Z |
| + | * { python leaves tty in -icanon -echo state. We do survive that... } |
| + | * [1]+ Stopped python |
| + | * { ...however, next program (python #2) does not survive it well: } |
| + | * # python |
| + | * Python 2.7.12 (...) |
| + | * >>> Traceback (most recent call last): |
| + | * { above, I typed "qwerty<CR>", but -echo state is still in effect } |
| + | * File "<stdin>", line 1, in <module> |
| + | * NameError: name 'qwerty' is not defined |
| + | * |
| + | * The implementation below is modeled on bash code and seems to work. |
| + | * However, I'm not sure we should do this. For one: what if I'd fg |
| + | * the stopped python instead? It'll be confused by "restored" tty state. |
| + | */ |
| + | static struct termios shell_tty_info; |
| + | static void |
| + | get_tty_state(void) |
| + | { |
| + | if (rootshell && ttyfd >= 0) |
| + | tcgetattr(ttyfd, &shell_tty_info); |
| + | } |
| + | static void |
| + | set_tty_state(void) |
| + | { |
| + | /* if (rootshell) - caller ensures this */ |
| + | if (ttyfd >= 0) |
| + | tcsetattr(ttyfd, TCSADRAIN, &shell_tty_info); |
| + | } |
| + | static int |
| + | job_signal_status(struct job *jp) |
| + | { |
| + | int status; |
| + | unsigned i; |
| + | struct procstat *ps = jp->ps; |
| + | for (i = 0; i < jp->nprocs; i++) { |
| + | status = ps[i].ps_status; |
| + | if (WIFSIGNALED(status) || WIFSTOPPED(status)) |
| + | return status; |
| + | } |
| + | return 0; |
| + | } |
| + | static void |
| + | restore_tty_if_stopped_or_signaled(struct job *jp) |
| + | { |
| + | //TODO: check what happens if we come from waitforjob() in expbackq() |
| + | if (rootshell) { |
| + | int s = job_signal_status(jp); |
| + | if (s) /* WIFSIGNALED(s) || WIFSTOPPED(s) */ |
| + | set_tty_state(); |
| + | } |
| + | } |
| + | #else |
| + | # define get_tty_state() ((void)0) |
| + | # define restore_tty_if_stopped_or_signaled(jp) ((void)0) |
| + | #endif |
| + | |
| static void | |
| set_curjob(struct job *jp, unsigned mode) | |
| { | |
| @@ -3910,8 +3976,10 @@ restartjob(struct job *jp, int mode) | |
| goto out; | |
| jp->state = JOBRUNNING; | |
| pgid = jp->ps[0].ps_pid; | |
| - | if (mode == FORK_FG) |
| + | if (mode == FORK_FG) { |
| + | get_tty_state(); |
| xtcsetpgrp(ttyfd, pgid); | |
| + | } |
| killpg(pgid, SIGCONT); | |
| ps = jp->ps; | |
| i = jp->nprocs; | |
| @@ -4445,7 +4513,7 @@ makejob(/*union node *node,*/ int nprocs) | |
| memset(jp, 0, sizeof(*jp)); | |
| #if JOBS | |
| /* jp->jobctl is a bitfield. | |
| - | * "jp->jobctl |= jobctl" likely to give awful code */ |
| + | * "jp->jobctl |= doing_jobctl" likely to give awful code */ |
| if (doing_jobctl) | |
| jp->jobctl = 1; | |
| #endif | |
| @@ -5040,6 +5108,8 @@ waitforjob(struct job *jp) | |
| #if JOBS | |
| if (jp->jobctl) { | |
| xtcsetpgrp(ttyfd, rootpid); | |
| + | restore_tty_if_stopped_or_signaled(jp); |
| + | |
| /* | |
| * This is truly gross. | |
| * If we're doing job control, then we did a TIOCSPGRP which | |
| @@ -8852,13 +8922,15 @@ static int | |
| evalsubshell(union node *n, int flags) | |
| { | |
| struct job *jp; | |
| - | int backgnd = (n->type == NBACKGND); |
| + | int backgnd = (n->type == NBACKGND); /* FORK_BG(1) if yes, else FORK_FG(0) */ |
| int status; | |
| expredir(n->nredir.redirect); | |
| if (!backgnd && (flags & EV_EXIT) && !may_have_traps) | |
| goto nofork; | |
| INT_OFF; | |
| + | if (backgnd == FORK_FG) |
| + | get_tty_state(); |
| jp = makejob(/*n,*/ 1); | |
| if (forkshell(jp, n, backgnd) == 0) { | |
| /* child */ | |
| @@ -8873,7 +8945,7 @@ evalsubshell(union node *n, int flags) | |
| } | |
| /* parent */ | |
| status = 0; | |
| - | if (!backgnd) |
| + | if (backgnd == FORK_FG) |
| status = waitforjob(jp); | |
| INT_ON; | |
| return status; | |
| @@ -8965,6 +9037,8 @@ evalpipe(union node *n, int flags) | |
| pipelen++; | |
| flags |= EV_EXIT; | |
| INT_OFF; | |
| + | if (n->npipe.pipe_backgnd == 0) |
| + | get_tty_state(); |
| jp = makejob(/*n,*/ pipelen); | |
| prevfd = -1; | |
| for (lp = n->npipe.cmdlist; lp; lp = lp->next) { | |
| @@ -9647,6 +9721,7 @@ evalcommand(union node *cmd, int flags) | |
| if (!(flags & EV_EXIT) || may_have_traps) { | |
| /* No, forking off a child is necessary */ | |
| INT_OFF; | |
| + | get_tty_state(); |
| jp = makejob(/*cmd,*/ 1); | |
| if (forkshell(jp, cmd, FORK_FG) != 0) { | |
| /* parent */ | |