ref: 354d513a481471aed9458886ec942aa9c8bd1dc9
dir: /libc/time.c/
#include <u.h> #include <libc.h> /* * After a fork with fd's copied, both fd's are pointing to * the same Chan structure. Since the offset is kept in the Chan * structure, the seek's and read's in the two processes can * compete at moving the offset around. Hence the unusual loop * in the middle of this routine. */ static long oldtime(long *tp) { char b[20]; static int f = -1; int i, retries; long t; memset(b, 0, sizeof(b)); for(retries = 0; retries < 100; retries++){ if(f < 0) f = open("/dev/time", OREAD|OCEXEC); if(f < 0) break; if(seek(f, 0, 0) < 0 || (i = read(f, b, sizeof(b))) < 0){ close(f); f = -1; } else { if(i != 0) break; } } t = atol(b); if(tp) *tp = t; return t; } long time(long *tp) { vlong t; t = nsec()/((vlong)1000000000); if(t == 0) t = oldtime(0); if(tp != nil) *tp = t; return t; }