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Diffstat (limited to 'lib/nanosleep.c')
| -rw-r--r-- | lib/nanosleep.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/lib/nanosleep.c b/lib/nanosleep.c new file mode 100644 index 0000000..89c5512 --- /dev/null +++ b/lib/nanosleep.c @@ -0,0 +1,192 @@ +/* Provide a replacement for the POSIX nanosleep function. + + Copyright (C) 1999, 2000, 2002, 2004, 2005, 2006, 2007 Free + Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* written by Jim Meyering */ + +#include <config.h> + +#include <time.h> + +#include "timespec.h" + +#include <stdbool.h> +#include <stdio.h> +#include <sys/types.h> +#if HAVE_SYS_SELECT_H +# include <sys/select.h> +#endif +#include <signal.h> + +#include <sys/time.h> +#include <errno.h> + +#include <unistd.h> + +#undef nanosleep + +enum { BILLION = 1000 * 1000 * 1000 }; + +#if HAVE_BUG_BIG_NANOSLEEP + +void +getnow (struct timespec *t) +{ +# if defined CLOCK_MONOTONIC && HAVE_CLOCK_GETTIME + if (clock_gettime (CLOCK_MONOTONIC, t) == 0) + return; +# endif + gettime (t); +} + +int +rpl_nanosleep (const struct timespec *requested_delay, + struct timespec *remaining_delay) +{ + /* nanosleep mishandles large sleeps due to internal overflow + problems, so check that the proper amount of time has actually + elapsed. */ + + struct timespec delay = *requested_delay; + struct timespec t0; + getnow (&t0); + + for (;;) + { + int r = nanosleep (&delay, remaining_delay); + if (r == 0) + { + time_t secs_sofar; + struct timespec now; + getnow (&now); + + secs_sofar = now.tv_sec - t0.tv_sec; + if (requested_delay->tv_sec < secs_sofar) + return 0; + delay.tv_sec = requested_delay->tv_sec - secs_sofar; + delay.tv_nsec = requested_delay->tv_nsec - (now.tv_nsec - t0.tv_nsec); + if (delay.tv_nsec < 0) + { + if (delay.tv_sec == 0) + return 0; + delay.tv_nsec += BILLION; + delay.tv_sec--; + } + else if (BILLION <= delay.tv_nsec) + { + delay.tv_nsec -= BILLION; + delay.tv_sec++; + } + } + } +} + +#else + +/* Some systems (MSDOS) don't have SIGCONT. + Using SIGTERM here turns the signal-handling code below + into a no-op on such systems. */ +# ifndef SIGCONT +# define SIGCONT SIGTERM +# endif + +# if ! HAVE_SIGINTERRUPT +# define siginterrupt(sig, flag) /* empty */ +# endif + +static sig_atomic_t volatile suspended; + +/* Handle SIGCONT. */ + +static void +sighandler (int sig) +{ + suspended = 1; +} + +/* Suspend execution for at least *TS_DELAY seconds. */ + +static void +my_usleep (const struct timespec *ts_delay) +{ + struct timeval tv_delay; + tv_delay.tv_sec = ts_delay->tv_sec; + tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000; + if (tv_delay.tv_usec == 1000000) + { + time_t t1 = tv_delay.tv_sec + 1; + if (t1 < tv_delay.tv_sec) + tv_delay.tv_usec = 1000000 - 1; /* close enough */ + else + { + tv_delay.tv_sec = t1; + tv_delay.tv_usec = 0; + } + } + select (0, NULL, NULL, NULL, &tv_delay); +} + +/* Suspend execution for at least *REQUESTED_DELAY seconds. The + *REMAINING_DELAY part isn't implemented yet. */ + +int +rpl_nanosleep (const struct timespec *requested_delay, + struct timespec *remaining_delay) +{ + static bool initialized; + + /* set up sig handler */ + if (! initialized) + { +# ifdef SA_NOCLDSTOP + struct sigaction oldact, newact; + newact.sa_handler = sighandler; + sigemptyset (&newact.sa_mask); + newact.sa_flags = 0; + + sigaction (SIGCONT, NULL, &oldact); + if (oldact.sa_handler != SIG_IGN) + sigaction (SIGCONT, &newact, NULL); +# else + if (signal (SIGCONT, SIG_IGN) != SIG_IGN) + { + signal (SIGCONT, sighandler); + siginterrupt (SIGCONT, 1); + } +# endif + initialized = true; + } + + suspended = 0; + + my_usleep (requested_delay); + + if (suspended) + { + /* Calculate time remaining. */ + /* FIXME: the code in sleep doesn't use this, so there's no + rush to implement it. */ + + errno = EINTR; + } + + /* FIXME: Restore sig handler? */ + + return suspended; +} +#endif |