/************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2012 */ /* See the file NOTICE for conditions of use and distribution. */ #ifdef STAND_ALONE #include #include #include #endif /* This source file contains "default" system-dependent functions which provide functionality (or lack of it) in cases where the OS-specific os.c file has not. Some of them are tailored by macros defined in os.h files. */ #ifndef OS_RESTARTING_SIGNAL /************************************************* * Set up restarting signal * *************************************************/ /* This function has the same functionality as the ANSI C signal() function, except that it arranges that, if the signal happens during a system call, the system call gets restarted. (Also, it doesn't return a result.) Different versions of Unix have different defaults, and different ways of setting up a restarting signal handler. If the functionality is not available, the signal should be set to be ignored. This function is used only for catching SIGUSR1. */ void os_restarting_signal(int sig, void (*handler)(int)) { /* Many systems have the SA_RESTART sigaction for specifying that a signal should restart system calls. These include SunOS5, AIX, BSDI, IRIX, FreeBSD, OSF1, Linux and HP-UX 10 (but *not* HP-UX 9). */ #ifdef SA_RESTART struct sigaction act; act.sa_handler = handler; sigemptyset(&(act.sa_mask)); act.sa_flags = SA_RESTART; sigaction(sig, &act, NULL); #ifdef STAND_ALONE printf("Used SA_RESTART\n"); #endif /* SunOS4 and Ultrix default to non-interruptable signals, with SV_INTERRUPT for making them interruptable. This seems to be a dying fashion. */ #elif defined SV_INTERRUPT signal(sig, handler); #ifdef STAND_ALONE printf("Used default signal()\n"); #endif /* If neither SA_RESTART nor SV_INTERRUPT is available we don't know how to set up a restarting signal, so simply suppress the facility. */ #else signal(sig, SIG_IGN); #ifdef STAND_ALONE printf("Used SIG_IGN\n"); #endif #endif } #endif /* OS_RESTARTING_SIGNAL */ #ifndef OS_NON_RESTARTING_SIGNAL /************************************************* * Set up non-restarting signal * *************************************************/ /* This function has the same functionality as the ANSI C signal() function, except that it arranges that, if the signal happens during a system call, the system call gets interrupted. (Also, it doesn't return a result.) Different versions of Unix have different defaults, and different ways of setting up a non-restarting signal handler. For systems for which we don't know what to do, just use the normal signal() function and hope for the best. */ void os_non_restarting_signal(int sig, void (*handler)(int)) { /* Many systems have the SA_RESTART sigaction for specifying that a signal should restart system calls. These include SunOS5, AIX, BSDI, IRIX, FreeBSD, OSF1, Linux and HP-UX 10 (but *not* HP-UX 9). */ #ifdef SA_RESTART struct sigaction act; act.sa_handler = handler; sigemptyset(&(act.sa_mask)); act.sa_flags = 0; sigaction(sig, &act, NULL); #ifdef STAND_ALONE printf("Used sigaction() with flags = 0\n"); #endif /* SunOS4 and Ultrix default to non-interruptable signals, with SV_INTERRUPT for making them interruptable. This seems to be a dying fashion. */ #elif defined SV_INTERRUPT struct sigvec sv; sv.sv_handler = handler; sv.sv_flags = SV_INTERRUPT; sv.sv_mask = -1; sigvec(sig, &sv, NULL); #ifdef STAND_ALONE printf("Used sigvec() with flags = SV_INTERRUPT\n"); #endif /* If neither SA_RESTART nor SV_INTERRUPT is available we don't know how to set up a restarting signal, so just use the standard signal() function. */ #else signal(sig, handler); #ifdef STAND_ALONE printf("Used default signal()\n"); #endif #endif } #endif /* OS_NON_RESTARTING_SIGNAL */ #ifdef STRERROR_FROM_ERRLIST /************************************************* * Provide strerror() for non-ANSI libraries * *************************************************/ /* Some old-fashioned systems still around (e.g. SunOS4) don't have strerror() in their libraries, but can provide the same facility by this simple alternative function. */ char * strerror(int n) { if (n < 0 || n >= sys_nerr) return "unknown error number"; return sys_errlist[n]; } #endif /* STRERROR_FROM_ERRLIST */ #ifndef OS_STRSIGNAL /************************************************* * Provide strsignal() for systems without * *************************************************/ /* Some systems have strsignal() to turn signal numbers into names; others may have other means of doing this. This function is used for those systems that have nothing. It provides a basic translation for the common standard signal numbers. I've been extra cautious with the ifdef's here. Probably more than is necessary... */ const char * os_strsignal(const int n) { switch (n) { #ifdef SIGHUP case SIGHUP: return "hangup"; #endif #ifdef SIGINT case SIGINT: return "interrupt"; #endif #ifdef SIGQUIT case SIGQUIT: return "quit"; #endif #ifdef SIGILL case SIGILL: return "illegal instruction"; #endif #ifdef SIGTRAP case SIGTRAP: return "trace trap"; #endif #ifdef SIGABRT case SIGABRT: return "abort"; #endif #ifdef SIGEMT case SIGEMT: return "EMT instruction"; #endif #ifdef SIGFPE case SIGFPE: return "arithmetic exception"; #endif #ifdef SIGKILL case SIGKILL: return "killed"; #endif #ifdef SIGBUS case SIGBUS: return "bus error"; #endif #ifdef SIGSEGV case SIGSEGV: return "segmentation fault"; #endif #ifdef SIGSYS case SIGSYS: return "bad system call"; #endif #ifdef SIGPIPE case SIGPIPE: return "broken pipe"; #endif #ifdef SIGALRM case SIGALRM: return "alarm"; #endif #ifdef SIGTERM case SIGTERM: return "terminated"; #endif #ifdef SIGUSR1 case SIGUSR1: return "user signal 1"; #endif #ifdef SIGUSR2 case SIGUSR2: return "user signal 2"; #endif #ifdef SIGCHLD case SIGCHLD: return "child stop or exit"; #endif #ifdef SIGPWR case SIGPWR: return "power fail/restart"; #endif #ifdef SIGURG case SIGURG: return "urgent condition on I/O channel"; #endif #ifdef SIGSTOP case SIGSTOP: return "stop"; #endif #ifdef SIGTSTP case SIGTSTP: return "stop from tty"; #endif #ifdef SIGXCPU case SIGXCPU: return "exceeded CPU limit"; #endif #ifdef SIGXFSZ case SIGXFSZ: return "exceeded file size limit"; #endif default: return "unrecognized signal number"; } } #endif /* OS_STRSIGNAL */ #ifndef OS_STREXIT /************************************************* * Provide strexit() for systems without * *************************************************/ /* Actually, I don't know of any system that has a strexit() function to turn exit codes into text, but this function is implemented this way so that if any OS does have such a thing, it could be used instead of this build-in one. */ const char * os_strexit(const int n) { switch (n) { /* On systems without sysexits.h we can assume only those exit codes that are given a default value in exim.h. */ #ifndef NO_SYSEXITS case EX_USAGE: return "(could mean usage or syntax error)"; case EX_DATAERR: return "(could mean error in input data)"; case EX_NOINPUT: return "(could mean input data missing)"; case EX_NOUSER: return "(could mean user nonexistent)"; case EX_NOHOST: return "(could mean host nonexistent)"; case EX_SOFTWARE: return "(could mean internal software error)"; case EX_OSERR: return "(could mean internal operating system error)"; case EX_OSFILE: return "(could mean system file missing)"; case EX_IOERR: return "(could mean input/output error)"; case EX_PROTOCOL: return "(could mean protocol error)"; case EX_NOPERM: return "(could mean permission denied)"; #endif case EX_EXECFAILED: return "(could mean unable to exec or command does not exist)"; case EX_UNAVAILABLE: return "(could mean service or program unavailable)"; case EX_CANTCREAT: return "(could mean can't create output file)"; case EX_TEMPFAIL: return "(could mean temporary error)"; case EX_CONFIG: return "(could mean configuration error)"; default: return ""; } } #endif /* OS_STREXIT */ /*********************************************************** * Load average function * ***********************************************************/ /* Although every Unix seems to have a different way of getting the load average, a number of them have things in common. Some common variants are provided below, but if an OS has unique requirements it can be handled in a specific os.c file. What is required is a function called os_getloadavg which takes no arguments and passes back the load average * 1000 as an int, or -1 if no data is available. */ /* ----------------------------------------------------------------------- */ /* If the OS has got a BSD getloadavg() function, life is very easy. */ #if !defined(OS_LOAD_AVERAGE) && defined(HAVE_BSD_GETLOADAVG) #define OS_LOAD_AVERAGE int os_getloadavg(void) { double avg; int loads = getloadavg (&avg, 1); if (loads != 1) return -1; return (int)(avg * 1000.0); } #endif /* ----------------------------------------------------------------------- */ /* ----------------------------------------------------------------------- */ /* Only SunOS5 has the kstat functions as far as I know, but put the code here as there is the -hal variant, and other systems might follow this road one day. */ #if !defined(OS_LOAD_AVERAGE) && defined(HAVE_KSTAT) #define OS_LOAD_AVERAGE #include int os_getloadavg(void) { int avg; kstat_ctl_t *kc; kstat_t *ksp; kstat_named_t *kn; if ((kc = kstat_open()) == NULL || (ksp = kstat_lookup(kc, LOAD_AVG_KSTAT_MODULE, 0, LOAD_AVG_KSTAT)) == NULL || kstat_read(kc, ksp, NULL) < 0 || (kn = kstat_data_lookup(ksp, LOAD_AVG_SYMBOL)) == NULL) return -1; avg = (int)(((double)(kn->LOAD_AVG_FIELD)/FSCALE) * 1000.0); kstat_close(kc); return avg; } #endif /* ----------------------------------------------------------------------- */ /* ----------------------------------------------------------------------- */ /* Handle OS where a kernel symbol has to be read from /dev/kmem */ #if !defined(OS_LOAD_AVERAGE) && defined(HAVE_DEV_KMEM) #define OS_LOAD_AVERAGE #include static int avg_kd = -1; static long avg_offset; int os_getloadavg(void) { LOAD_AVG_TYPE avg; if (avg_kd < 0) { struct nlist nl[2]; nl[0].n_name = LOAD_AVG_SYMBOL; nl[1].n_name = ""; nlist (KERNEL_PATH, nl); avg_offset = (long)nl[0].n_value; avg_kd = open ("/dev/kmem", 0); if (avg_kd < 0) return -1; (void) fcntl(avg_kd, F_SETFD, FD_CLOEXEC); } if (lseek (avg_kd, avg_offset, 0) == -1L || read (avg_kd, (char *)(&avg), sizeof (avg)) != sizeof(avg)) return -1; return (int)(((double)avg/FSCALE)*1000.0); } #endif /* ----------------------------------------------------------------------- */ /* ----------------------------------------------------------------------- */ /* If nothing is known about this OS, then the load average facility is not available. */ #ifndef OS_LOAD_AVERAGE int os_getloadavg(void) { return -1; } #endif /* ----------------------------------------------------------------------- */ #if !defined FIND_RUNNING_INTERFACES /************************************************* * Find all the running network interfaces * *************************************************/ /* Finding all the running interfaces is something that has os-dependent tweaks, even in the IPv4 case, and it gets worse for IPv6, which is why this code is now in the os-dependent source file. There is a common function which works on most OS (except IRIX) for IPv4 interfaces, and, with some variations controlled by macros, on at least one OS for IPv6 and IPv4 interfaces. On Linux with IPv6, the common function is used for the IPv4 interfaces and additional code used for IPv6. Consequently, the real function is called os_common_find_running_interfaces() so that it can be called from the Linux function. On non-Linux systems, the macro for os_find_running_interfaces just calls the common function; on Linux it calls the Linux function. This function finds the addresses of all the running interfaces on the machine. A chain of blocks containing the textual form of the addresses is returned. getifaddrs() provides a sane consistent way to query this on modern OSs, otherwise fall back to a maze of twisty ioctl() calls Arguments: none Returns: a chain of ip_address_items, each pointing to a textual version of an IP address, with the port field set to zero */ #ifndef NO_FIND_INTERFACES #ifdef HAVE_GETIFADDRS #include ip_address_item * os_common_find_running_interfaces(void) { struct ifaddrs *ifalist = NULL; ip_address_item *yield = NULL; ip_address_item *last = NULL; ip_address_item *next; if (getifaddrs(&ifalist) != 0) log_write(0, LOG_PANIC_DIE, "Unable to call getifaddrs: %d %s", errno, strerror(errno)); struct ifaddrs *ifa; for (ifa = ifalist; ifa != NULL; ifa = ifa->ifa_next) { if (ifa->ifa_addr->sa_family != AF_INET #if HAVE_IPV6 && ifa->ifa_addr->sa_family != AF_INET6 #endif /* HAVE_IPV6 */ ) continue; if ( !(ifa->ifa_flags & IFF_UP) ) /* Only want 'UP' interfaces */ continue; /* Create a data block for the address, fill in the data, and put it on the chain. */ next = store_get(sizeof(ip_address_item)); next->next = NULL; next->port = 0; (void)host_ntoa(-1, ifa->ifa_addr, next->address, NULL); if (yield == NULL) yield = last = next; else { last->next = next; last = next; } DEBUG(D_interface) debug_printf("Actual local interface address is %s (%s)\n", last->address, ifa->ifa_name); } /* free the list of addresses, and return the chain of data blocks. */ freeifaddrs (ifalist); return yield; } #else /* HAVE_GETIFADDRS */ /* Problems: (1) Solaris 2 has the SIOGIFNUM call to get the number of interfaces, but other OS (including Solaris 1) appear not to. So just screw in a largeish fixed number, defined by MAX_INTERFACES. This is in the config.h file and can be changed in Local/Makefile. Unfortunately, the www addressing scheme means that some hosts have a very large number of virtual interfaces. Such hosts are recommended to set local_interfaces to avoid problems with this. (2) If the standard code is run on IRIX, it does not return any alias interfaces. There is special purpose code for that operating system, which uses the sysctl() function. The code is in OS/os.c-IRIX, and this code isn't used on that OS. (3) Some experimental/developing OS (e.g. GNU/Hurd) do not have any means of finding the interfaces. If NO_FIND_INTERFACES is set, a fudge-up is used instead. (4) Some operating systems set the IP address in what SIOCGIFCONF returns; others do not, and require SIOCGIFADDR to be called to get it. For most of the former, calling the latter does no harm, but it causes grief on Linux and BSD systems in the case of IP aliasing, so a means of cutting it out is provided. */ /* If there is IPv6 support, and SIOCGLIFCONF is defined, define macros to use these new, longer versions of the old IPv4 interfaces. Otherwise, define the macros to use the historical versions. */ #if HAVE_IPV6 && defined SIOCGLIFCONF #define V_ifconf lifconf #define V_ifreq lifreq #define V_GIFADDR SIOCGLIFADDR #define V_GIFCONF SIOCGLIFCONF #define V_GIFFLAGS SIOCGLIFFLAGS #define V_ifc_buf lifc_buf #define V_ifc_family lifc_family #define V_ifc_flags lifc_flags #define V_ifc_len lifc_len #define V_ifr_addr lifr_addr #define V_ifr_flags lifr_flags #define V_ifr_name lifr_name #define V_FAMILY_QUERY AF_UNSPEC #define V_family ss_family #else #define V_ifconf ifconf #define V_ifreq ifreq #define V_GIFADDR SIOCGIFADDR #define V_GIFCONF SIOCGIFCONF #define V_GIFFLAGS SIOCGIFFLAGS #define V_ifc_buf ifc_buf #define V_ifc_family ifc_family #define V_ifc_flags ifc_flags #define V_ifc_len ifc_len #define V_ifr_addr ifr_addr #define V_ifr_flags ifr_flags #define V_ifr_name ifr_name #define V_family sa_family #endif /* In all cases of IPv6 support, use an IPv6 socket. Otherwise (at least on Solaris 8) the call to read the flags doesn't work for IPv6 interfaces. If we find we can't actually make an IPv6 socket, the code will revert to trying an IPv4 socket. */ #if HAVE_IPV6 #define FAMILY AF_INET6 #else #define FAMILY AF_INET #endif /* OK, after all that preliminary stuff, here's the code. */ ip_address_item * os_common_find_running_interfaces(void) { struct V_ifconf ifc; struct V_ifreq ifreq; int vs; ip_address_item *yield = NULL; ip_address_item *last = NULL; ip_address_item *next; char *cp; char buf[MAX_INTERFACES*sizeof(struct V_ifreq)]; struct sockaddr *addrp; size_t len = 0; char addrbuf[512]; /* We have to create a socket in order to do ioctls on it to find out what we want to know. */ if ((vs = socket(FAMILY, SOCK_DGRAM, 0)) < 0) { #if HAVE_IPV6 DEBUG(D_interface) debug_printf("Unable to create IPv6 socket to find interface addresses:\n " "error %d %s\nTrying for an IPv4 socket\n", errno, strerror(errno)); vs = socket(AF_INET, SOCK_DGRAM, 0); if (vs < 0) #endif log_write(0, LOG_PANIC_DIE, "Unable to create IPv4 socket to find interface " "addresses: %d %s", errno, strerror(errno)); } /* Get the interface configuration. Some additional data is required when the new structures are in use. */ ifc.V_ifc_len = sizeof(buf); ifc.V_ifc_buf = buf; #ifdef V_FAMILY_QUERY ifc.V_ifc_family = V_FAMILY_QUERY; ifc.V_ifc_flags = 0; #endif if (ioctl(vs, V_GIFCONF, (char *)&ifc) < 0) log_write(0, LOG_PANIC_DIE, "Unable to get interface configuration: %d %s", errno, strerror(errno)); /* If the buffer is big enough, the ioctl sets the value of ifc.V_ifc_len to the amount actually used. If the buffer isn't big enough, at least on some operating systems, ifc.V_ifc_len still gets set to correspond to the total number of interfaces, even though they don't all fit in the buffer. */ if (ifc.V_ifc_len > sizeof(buf)) { ifc.V_ifc_len = sizeof(buf); DEBUG(D_interface) debug_printf("more than %d interfaces found: remainder not used\n" "(set MAX_INTERFACES in Local/Makefile and rebuild if you want more)\n", MAX_INTERFACES); } /* For each interface, check it is an IP interface, get its flags, and see if it is up; if not, skip. BSD systems differ from others in what SIOCGIFCONF returns. Other systems return a vector of ifreq structures whose size is as defined by the structure. BSD systems allow sockaddrs to be longer than their sizeof, which in turn makes the ifreq structures longer than their sizeof. The code below has its origins in amd and ifconfig; it uses the sa_len field of each sockaddr to determine each item's length. This is complicated by the fact that, at least on BSD systems, the data in the buffer is not guaranteed to be aligned. Thus, we must first copy the basic struct to some aligned memory before looking at the field in the fixed part to find its length, and then recopy the correct length. */ for (cp = buf; cp < buf + ifc.V_ifc_len; cp += len) { memcpy((char *)&ifreq, cp, sizeof(ifreq)); #ifndef HAVE_SA_LEN len = sizeof(struct V_ifreq); #else len = ((ifreq.ifr_addr.sa_len > sizeof(ifreq.ifr_addr))? ifreq.ifr_addr.sa_len : sizeof(ifreq.ifr_addr)) + sizeof(ifreq.V_ifr_name); if (len > sizeof(addrbuf)) log_write(0, LOG_PANIC_DIE, "Address for %s interface is absurdly long", ifreq.V_ifr_name); #endif /* If not an IP interface, skip */ if (ifreq.V_ifr_addr.V_family != AF_INET #if HAVE_IPV6 && ifreq.V_ifr_addr.V_family != AF_INET6 #endif ) continue; /* Get the interface flags, and if the interface is down, continue. Formerly, we treated the inability to get the flags as a panic-die error. However, it seems that on some OS (Solaris 9 being the case noted), it is possible to have an interface in this list for which this call fails because the interface hasn't been "plumbed" to any protocol (IPv4 or IPv6). Therefore, we now just treat this case as "down" as well. */ if (ioctl(vs, V_GIFFLAGS, (char *)&ifreq) < 0) { continue; /************* log_write(0, LOG_PANIC_DIE, "Unable to get flags for %s interface: %d %s", ifreq.V_ifr_name, errno, strerror(errno)); *************/ } if ((ifreq.V_ifr_flags & IFF_UP) == 0) continue; /* On some operating systems we have to get the IP address of the interface by another call. On others, it's already there, but we must copy the full length because we only copied the basic length above, and anyway, GIFFLAGS may have wrecked the data. */ #ifndef SIOCGIFCONF_GIVES_ADDR if (ioctl(vs, V_GIFADDR, (char *)&ifreq) < 0) log_write(0, LOG_PANIC_DIE, "Unable to get IP address for %s interface: " "%d %s", ifreq.V_ifr_name, errno, strerror(errno)); addrp = &ifreq.V_ifr_addr; #else memcpy(addrbuf, cp + offsetof(struct V_ifreq, V_ifr_addr), len - sizeof(ifreq.V_ifr_name)); addrp = (struct sockaddr *)addrbuf; #endif /* Create a data block for the address, fill in the data, and put it on the chain. */ next = store_get(sizeof(ip_address_item)); next->next = NULL; next->port = 0; (void)host_ntoa(-1, addrp, next->address, NULL); if (yield == NULL) yield = last = next; else { last->next = next; last = next; } DEBUG(D_interface) debug_printf("Actual local interface address is %s (%s)\n", last->address, ifreq.V_ifr_name); } /* Close the socket, and return the chain of data blocks. */ (void)close(vs); return yield; } #endif /* HAVE_GETIFADDRS */ #else /* NO_FIND_INTERFACES */ /* Some experimental or developing OS (e.g. GNU/Hurd) do not have the ioctls, and there is no other way to get a list of the (IP addresses of) local interfaces. We just return the loopback address(es). */ ip_address_item * os_common_find_running_interfaces(void) { ip_address_item *yield = store_get(sizeof(address_item)); yield->address = US"127.0.0.1"; yield->port = 0; yield->next = NULL; #if HAVE_IPV6 yield->next = store_get(sizeof(address_item)); yield->next->address = US"::1"; yield->next->port = 0; yield->next->next = NULL; #endif DEBUG(D_interface) debug_printf("Unable to find local interface addresses " "on this OS: returning loopback address(es)\n"); return yield; } #endif /* NO_FIND_INTERFACES */ #endif /* FIND_RUNNING_INTERFACES */ /* ----------------------------------------------------------------------- */ /*********************************************************** * DNS Resolver Base Finder * ***********************************************************/ /* We need to be able to set options for the system resolver(5), historically made available as _res. At least one OS (NetBSD) now no longer provides this directly, instead making you call a function per thread to get a handle. Other OSs handle thread-safe resolver differently, in ways which fail if the programmer creates their own structs. */ #if !defined(OS_GET_DNS_RESOLVER_RES) && !defined(COMPILE_UTILITY) #include /* confirmed that res_state is typedef'd as a struct* on BSD and Linux, will find out how unportable it is on other OSes, but most resolver implementations should be descended from ISC's bind. Linux and BSD do: define _res (*__res_state()) identically. We just can't rely on __foo functions. It's surprising that use of _res has been as portable as it has, for so long. So, since _res works everywhere, and everything can decode the struct, I'm going to gamble that res_state is a typedef everywhere and use that as the return type. */ res_state os_get_dns_resolver_res(void) { return &_res; } #endif /* OS_GET_DNS_RESOLVER_RES */ /* ----------------------------------------------------------------------- */ /*********************************************************** * Time-related functions * ***********************************************************/ /* At least Solaris, and probably others, don't have this */ #ifndef _BSD_SOURCE # include # include time_t timegm(struct tm * tm) { time_t ret; char *tz; tz = getenv("TZ"); setenv("TZ", "", 1); tzset(); ret = mktime(tm); if (tz) setenv("TZ", tz, 1); else unsetenv("TZ"); tzset(); return ret; } #endif /* ----------------------------------------------------------------------- */ /************************************************* ************************************************** * Stand-alone test program * ************************************************** *************************************************/ #ifdef STAND_ALONE #ifdef CLOCKS_PER_SEC #define REAL_CLOCK_TICK CLOCKS_PER_SEC #else #ifdef CLK_TCK #define REAL_CLOCK_TICK CLK_TCK #else #define REAL_CLOCK_TICK 1000000 /* SunOS4 */ #endif #endif int main(int argc, char **argv) { char buffer[128]; int fd = fileno(stdin); int rc; printf("Testing restarting signal; wait for handler message, then type a line\n"); strcpy(buffer, "*** default ***\n"); os_restarting_signal(SIGALRM, sigalrm_handler); alarm(2); if ((rc = read(fd, buffer, sizeof(buffer))) < 0) printf("No data read\n"); else { buffer[rc] = 0; printf("Read: %s", buffer); } alarm(0); printf("Testing non-restarting signal; should read no data after handler message\n"); strcpy(buffer, "*** default ***\n"); os_non_restarting_signal(SIGALRM, sigalrm_handler); alarm(2); if ((rc = read(fd, buffer, sizeof(buffer))) < 0) printf("No data read\n"); else { buffer[rc] = 0; printf("Read: %s", buffer); } alarm(0); printf("Testing load averages (last test - ^C to kill)\n"); for (;;) { int avg; clock_t used; clock_t before = clock(); avg = os_getloadavg(); used = clock() - before; printf("cpu time = %.2f ", (double)used/REAL_CLOCK_TICK); if (avg < 0) { printf("load average not available\n"); break; } printf("load average = %.2f\n", (double)avg/1000.0); sleep(2); } return 0; } #endif /* End of os.c */