FBSD 5.5 and software timers

Michael Scheidell scheidell at secnap.net
Tue Jul 25 19:27:55 UTC 2006

Found it!  library libc_r

Given POC:

int main( int argc, char **argv )
char execs1[256] = "/bin/date +A%Y%m%d%H%M.%S";
char execs2[256] = "/bin/date +B%Y%m%d%H%M.%S";
int a;

  while ( 1) {

    system( execs1 );
     usleep( 500*1000);
    system( execs2 );

  return 0;
}  /* main */

compile with:
cc -g  -c nanotest.c
cc -g  -o nanotest nanotest.o

everything works as expected.

time forward, back, doesn't matter (date prints out wallclock, 
nanosleep() sleeps 500*1000*1000us  (.5 seconds)

this breaks it:
cc -g  -c nanotest.c
cc -g  -o nanotest nanotest.o -lc_r

setting clock back 'hangs' during usleep (500*1000)
didn't hang on 5.4.
I will be writing up a bug report shortly.

Michael Scheidell, CTO
SECNAP Network Security / www.secnap.com
scheidell at secnap.net  / 1+561-999-5000, x 1131

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