Bug 180146
| Summary: | /bin/sh: Early SIGWINCH can end process | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Grant Watson <grant_watson> |
| Component: | bin | Assignee: | Jilles Tjoelker <jilles> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | ||
| Priority: | Normal | ||
| Version: | 9.1-RELEASE | ||
| Hardware: | Any | ||
| OS: | Any | ||
Responsible Changed From-To: freebsd-bugs->jilles Over to maintainer. In PR bin/180146, you wrote: > There appears to be a race condition in /bin/sh where receiving > SIGWINCH too early will cause the process to end. Bugs ports/178194 > and ports/178651, which I filed, are occurrences of this bug. Although I cannot reproduce this bug using the termit reproducer, I can imagine libedit contains this kind of bug since it is of a low quality in general (see also http://www.freebsd.org/cgi/query-pr.cgi?pr=bin/169773 ). Perhaps the below patch will work around your issue (while delaying the response to a true SIGWINCH until <Enter> is pressed). commit 548c429eea82f483d56181115451f70146d9b948 Author: Jilles Tjoelker <jilles@stack.nl> Date: Sun Sep 1 18:22:24 2013 +0200 sh: Enable system call restart for the default SIGWINCH handler. This makes it apply later than it should but avoids libedit bugs. diff --git a/bin/sh/trap.c b/bin/sh/trap.c index 3fc8566..73e156b 100644 --- a/bin/sh/trap.c +++ b/bin/sh/trap.c @@ -260,6 +260,7 @@ setsignal(int signo) struct sigaction sa; char *t; + sa.sa_flags = 0; if ((t = trap[signo]) == NULL) action = S_DFL; else if (*t != '\0') @@ -297,6 +298,7 @@ setsignal(int signo) case SIGWINCH: if (rootshell && iflag) action = S_CATCH; + sa.sa_flags |= SA_RESTART; break; #endif } @@ -334,7 +336,6 @@ setsignal(int signo) } *t = action; sa.sa_handler = sigact; - sa.sa_flags = 0; sigemptyset(&sa.sa_mask); sigaction(signo, &sa, NULL); } -- Jilles Tjoelker Author: jilles Date: Tue Jan 14 22:56:25 2014 New Revision: 260654 URL: http://svnweb.freebsd.org/changeset/base/260654 Log: sh: Remove SIGWINCH handler and just check for resize before every read. The SIGWINCH handler triggers breakage in libedit which is hard to fix; see PR bin/169773. Also, window size changes while a program is in foreground (and it rather than sh will receive SIGWINCH) will now be picked up automatically. Downside: it is now certain that a resize is only processed after pressing <Enter>. If libedit is fixed, sh will most likely have to be changed also. PR: bin/180146 Modified: head/bin/sh/input.c head/bin/sh/trap.c head/bin/sh/trap.h Modified: head/bin/sh/input.c ============================================================================== --- head/bin/sh/input.c Tue Jan 14 22:46:23 2014 (r260653) +++ head/bin/sh/input.c Tue Jan 14 22:56:25 2014 (r260654) @@ -162,20 +162,16 @@ preadfd(void) int nr; parsenextc = parsefile->buf; -#ifndef NO_HISTORY - if (el != NULL && gotwinch) { - gotwinch = 0; - el_resize(el); - } -#endif retry: #ifndef NO_HISTORY if (parsefile->fd == 0 && el) { static const char *rl_cp; static int el_len; - if (rl_cp == NULL) + if (rl_cp == NULL) { + el_resize(el); rl_cp = el_gets(el, &el_len); + } if (rl_cp == NULL) nr = el_len == 0 ? 0 : -1; else { Modified: head/bin/sh/trap.c ============================================================================== --- head/bin/sh/trap.c Tue Jan 14 22:46:23 2014 (r260653) +++ head/bin/sh/trap.c Tue Jan 14 22:56:25 2014 (r260654) @@ -80,7 +80,6 @@ static char *volatile trap[NSIG]; /* tra static volatile sig_atomic_t gotsig[NSIG]; /* indicates specified signal received */ static int ignore_sigchld; /* Used while handling SIGCHLD traps. */ -volatile sig_atomic_t gotwinch; static int last_trapsig; static int exiting; /* exitshell() has been called */ @@ -293,12 +292,6 @@ setsignal(int signo) action = S_IGN; break; #endif -#ifndef NO_HISTORY - case SIGWINCH: - if (rootshell && iflag) - action = S_CATCH; - break; -#endif } } @@ -400,11 +393,6 @@ onsig(int signo) gotsig[signo] = 1; pendingsig = signo; } - -#ifndef NO_HISTORY - if (signo == SIGWINCH) - gotwinch = 1; -#endif } @@ -490,9 +478,6 @@ setinteractive(int on) setsignal(SIGINT); setsignal(SIGQUIT); setsignal(SIGTERM); -#ifndef NO_HISTORY - setsignal(SIGWINCH); -#endif is_interactive = on; } Modified: head/bin/sh/trap.h ============================================================================== --- head/bin/sh/trap.h Tue Jan 14 22:46:23 2014 (r260653) +++ head/bin/sh/trap.h Tue Jan 14 22:56:25 2014 (r260654) @@ -36,7 +36,6 @@ extern volatile sig_atomic_t pendingsig; extern volatile sig_atomic_t pendingsig_waitcmd; extern int in_dotrap; -extern volatile sig_atomic_t gotwinch; void clear_traps(void); int have_traps(void); _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org" State Changed From-To: open->patched I have applied a workaround for libedit breakage in 11-current in SVN r260654. This change was merged to stable/10 in SVN r262951. No MFC to older branches is planned. |
There appears to be a race condition in /bin/sh where receiving SIGWINCH too early will cause the process to end. Bugs ports/178194 and ports/178651, which I filed, are occurrences of this bug. How-To-Repeat: Way to Reproduce #1: Install termit and paste the following into ~/.config/termit/rc.lua: defaults = { showScrollbar = false, hideMenubar = true } setOptions(defaults) Then run "termit -e /bin/sh". Running "termit -e 'truss -o shlog.txt /bin/sh'" does not surpress the bug for me. Way to Reproduce #2: Install the awesome window manager, create a user whose shell is /bin/sh, and ensure that this user does not have a ~/.config/awesome/rc.lua file that would override the default configuration. Log in as this user. Left click the box in the upper-right corner of the screen to switch to a tiling layout. Press super+return (that is, windows+return) four or five times; each time an xterm should open. Many will close, but one or two may remain open. Running "truss xterm -e /bin/sh" does not surpress the bug for me, but running truss between xterm and sh does.