/* xnanosleep.c -- a more convenient interface to nanosleep Copyright (C) 2002-2007, 2009-2020 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 3 of the License, 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, see . */ /* Mostly written (for sleep.c) by Paul Eggert. Factored out (creating this file) by Jim Meyering. */ #include #include "xnanosleep.h" #include #include #include #include #include /* Sleep until the time (call it WAKE_UP_TIME) specified as SECONDS seconds after the time this function is called. SECONDS must be non-negative. If SECONDS is so large that it is not representable as a 'struct timespec', then use the maximum value for that interval. Return -1 on failure (setting errno), 0 on success. */ int xnanosleep (double seconds) { #if HAVE_PAUSE if (1.0 + TYPE_MAXIMUM (time_t) <= seconds) { do pause (); while (errno == EINTR); /* pause failed (!); fall back on repeated nanosleep calls. */ } #endif struct timespec ts_sleep = dtotimespec (seconds); for (;;) { /* Linux-2.6.8.1's nanosleep returns -1, but doesn't set errno when resumed after being suspended. Earlier versions would set errno to EINTR. nanosleep from linux-2.6.10, as well as implementations by (all?) other vendors, doesn't return -1 in that case; either it continues sleeping (if time remains) or it returns zero (if the wake-up time has passed). Gnulib's replacement nanosleep sometimes does not update TS_SLEEP, and it is possible some kernels have a similar bug. However, this merely causes xnanosleep to sleep longer than necessary, which is not a correctness bug. */ errno = 0; if (nanosleep (&ts_sleep, &ts_sleep) == 0) break; if (errno != EINTR && errno != 0) return -1; } return 0; }