diff options
| -rw-r--r-- | src/xz/mytime.c | 56 | ||||
| -rw-r--r-- | src/xz/mytime.h | 6 | ||||
| -rw-r--r-- | src/xz/private.h | 12 | ||||
| -rw-r--r-- | src/xz/signals.c | 17 |
4 files changed, 89 insertions, 2 deletions
diff --git a/src/xz/mytime.c b/src/xz/mytime.c index 7e8a0749..0b0e2be7 100644 --- a/src/xz/mytime.c +++ b/src/xz/mytime.c @@ -20,7 +20,12 @@ uint64_t opt_flush_timeout = 0; +#ifdef USE_SIGTSTP_HANDLER +static volatile uint64_t start_time; +#else static uint64_t start_time; +#endif + static uint64_t next_flush; @@ -48,10 +53,49 @@ mytime_now(void) } +#ifdef USE_SIGTSTP_HANDLER +extern void +mytime_sigtstp_handler(int sig lzma_attribute((__unused__))) +{ + // Measure how long the process stays in the stopped state and add + // that amount to start_time. This way the the progress indicator + // won't count the stopped time as elapsed time and the estimated + // remaining time won't be confused by the time spent in the + // stopped state. + // + // FIXME? Is raising SIGSTOP the correct thing to do? POSIX.1-2017 + // says that orphan processes shouldn't stop on SIGTSTP. So perhaps + // the most correct thing to do could be to revert to the default + // handler for SIGTSTP, unblock SIGTSTP, and then raise(SIGTSTP). + // It's quite a bit more complicated than just raising SIGSTOP though. + // + // The difference between raising SIGTSTP vs. SIGSTOP can be seen on + // the shell command line too by running "echo $?" after stopping + // a process but perhaps that doesn't matter. + const uint64_t t = mytime_now(); + raise(SIGSTOP); + start_time += mytime_now() - t; + return; +} +#endif + + extern void mytime_set_start_time(void) { +#ifdef USE_SIGTSTP_HANDLER + // Block the signals when accessing start_time so that we cannot + // end up with a garbage value. start_time is volatile but access + // to it isn't atomic at least on 32-bit systems. + signals_block(); +#endif + start_time = mytime_now(); + +#ifdef USE_SIGTSTP_HANDLER + signals_unblock(); +#endif + return; } @@ -59,7 +103,17 @@ mytime_set_start_time(void) extern uint64_t mytime_get_elapsed(void) { - return mytime_now() - start_time; +#ifdef USE_SIGTSTP_HANDLER + signals_block(); +#endif + + const uint64_t t = mytime_now() - start_time; + +#ifdef USE_SIGTSTP_HANDLER + signals_unblock(); +#endif + + return t; } diff --git a/src/xz/mytime.h b/src/xz/mytime.h index a7be2aa7..5a3c1e21 100644 --- a/src/xz/mytime.h +++ b/src/xz/mytime.h @@ -21,6 +21,12 @@ extern uint64_t opt_flush_timeout; +#ifdef USE_SIGTSTP_HANDLER +/// \brief Signal handler for SIGTSTP +extern void mytime_sigtstp_handler(int sig); +#endif + + /// \brief Store the time when (de)compression was started /// /// The start time is also stored as the time of the first flush. diff --git a/src/xz/private.h b/src/xz/private.h index 6414bdb5..a20dbc57 100644 --- a/src/xz/private.h +++ b/src/xz/private.h @@ -49,6 +49,18 @@ # define ENABLE_SANDBOX 1 #endif +// Handling SIGTSTP keeps time-keeping for progress indicator correct +// if xz is stopped. It requires use of clock_gettime() as that is +// async-signal safe in POSIX. Require also SIGALRM support since +// on systems where SIGALRM isn't available, progress indicator code +// polls the time and the SIGTSTP handling adds slight overhead to +// that code. Most (all?) systems that have SIGTSTP also have SIGALRM +// so this requirement won't exclude many systems. +#if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_CLOCK_MONOTONIC) \ + && defined(SIGTSTP) && defined(SIGALRM) +# define USE_SIGTSTP_HANDLER 1 +#endif + #include "main.h" #include "mytime.h" #include "coder.h" diff --git a/src/xz/signals.c b/src/xz/signals.c index 7aef463c..ff42a396 100644 --- a/src/xz/signals.c +++ b/src/xz/signals.c @@ -82,6 +82,11 @@ signals_init(void) sigaddset(&hooked_signals, message_progress_sigs[i]); #endif +#ifdef USE_SIGTSTP_HANDLER + // Add the SIGTSTP handler from mytime.c to hooked_signals. + sigaddset(&hooked_signals, SIGTSTP); +#endif + // Using "my_sa" because "sa" may conflict with a sockaddr variable // from system headers on Solaris. struct sigaction my_sa; @@ -96,10 +101,11 @@ signals_init(void) my_sa.sa_flags = 0; my_sa.sa_handler = &signal_handler; + struct sigaction old; + for (size_t i = 0; i < ARRAY_SIZE(sigs); ++i) { // If the parent process has left some signals ignored, // we don't unignore them. - struct sigaction old; if (sigaction(sigs[i], NULL, &old) == 0 && old.sa_handler == SIG_IGN) continue; @@ -109,6 +115,15 @@ signals_init(void) message_signal_handler(); } +#ifdef USE_SIGTSTP_HANDLER + if (!(sigaction(SIGTSTP, NULL, &old) == 0 + && old.sa_handler == SIG_IGN)) { + my_sa.sa_handler = &mytime_sigtstp_handler; + if (sigaction(SIGTSTP, &my_sa, NULL)) + message_signal_handler(); + } +#endif + signals_are_initialized = true; return; |