exit on select return -1 but errno == 0?

running under gdb, server exits(1) after a bit Breakpoint 15, main (argc=2, argv=0xbfe26764) at radiusd.c:600 600 if (errno == EINTR) { (gdb) p errno $9 = 0 (gdb) p status $10 = -1 (gdb) Debian GNU/Linux dpkg -l libc6 Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed |/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad) ||/ Name Version Description +++-=========================-=========================-================================================================== ii libc6 2.3.5-6 GNU C Library: Shared libraries and Timezone data