/************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1997 - 2018 */ /* SPDX-License-Identifier: GPL-2.0-or-later */ /* See the file NOTICE for conditions of use and distribution. */ /* Linux-specific code. This is concatenated onto the generic src/os.c file. */ /************************************************* * Load average computation * *************************************************/ /*Linux has an apparently unique way of getting the load average, so we provide a unique function here, and define OS_LOAD_AVERAGE to stop src/os.c trying to provide the function. However, when compiling os.c for utilities, we may not want this at all, so check that it isn't set first. */ #if !defined(OS_LOAD_AVERAGE) && defined(__linux__) #define OS_LOAD_AVERAGE /* Linux has 2 ways of returning load average: (1) Do a read on /proc/loadavg (2) Use the sysinfo library function and syscall The latter is simpler but in Linux 2.0 - 2.2 (and probably later releases) is exceptionally slow - 10-50ms per call is not unusual and about 100x slow the first method. This cripples high performance mail servers by increasing CPU utilisation by 3-5x. In Exim's very early days, it used the 1st method. Later, it switched to the 2nd method. Now it tries the 1st method and falls back to the 2nd if /proc is unavailable. */ #include <sys/sysinfo.h> static int linux_slow_getloadavg(void) { struct sysinfo s; double avg; if (sysinfo(&s) < 0) return -1; avg = (double) (s.loads[0]) / (1<<SI_LOAD_SHIFT); return (int)(avg * 1000.0); } int os_getloadavg(void) { char buffer[40]; double avg; int count; int fd = open ("/proc/loadavg", O_RDONLY); if (fd == -1) return linux_slow_getloadavg(); count = read (fd, buffer, sizeof(buffer)); (void)close (fd); if (count <= 0) return linux_slow_getloadavg(); count = sscanf (buffer, "%lf", &avg); if (count < 1) return linux_slow_getloadavg(); return (int)(avg * 1000.0); } #endif /* OS_LOAD_AVERAGE */ /************************************************* * Finding interface addresses * *************************************************/ /* This function is not required for utilities; we cut it out if FIND_RUNNING_INTERFACES is already defined. */ #ifndef FIND_RUNNING_INTERFACES /* This code, contributed by Jason Gunthorpe, appears to be the current way of finding IPv6 interfaces in Linux. It first calls the common function in order to find IPv4 interfaces, then grobbles around to find the others. Jason said, "This is so horrible, don't look. Slightly ripped from net-tools ifconfig." It gets called by virtue of os_find_running_interfaces being defined as a macro for os_find_running_interfaces_linux in the os.h-Linux file. */ ip_address_item * os_find_running_interfaces_linux(void) { ip_address_item *yield = NULL; #if HAVE_IPV6 ip_address_item *last = NULL; ip_address_item *next; char addr6p[8][5]; unsigned int plen, scope, dad_status, if_idx; char devname[20+1]; FILE *f; #endif yield = os_common_find_running_interfaces(); #if HAVE_IPV6 /* Open the /proc file; give up if we can't. */ if ((f = fopen("/proc/net/if_inet6", "r")) == NULL) return yield; /* Pick out the data from within the file, and add it on to the chain */ last = yield; if (last != NULL) while (last->next != NULL) last = last->next; while (fscanf(f, "%4s%4s%4s%4s%4s%4s%4s%4s %02x %02x %02x %02x %20s\n", addr6p[0], addr6p[1], addr6p[2], addr6p[3], addr6p[4], addr6p[5], addr6p[6], addr6p[7], &if_idx, &plen, &scope, &dad_status, devname) != EOF) { struct sockaddr_in6 addr; /* This data has to survive for ever, so use malloc. */ next = store_malloc(sizeof(ip_address_item)); next->next = NULL; next->port = 0; sprintf(CS next->address, "%s:%s:%s:%s:%s:%s:%s:%s", addr6p[0], addr6p[1], addr6p[2], addr6p[3], addr6p[4], addr6p[5], addr6p[6], addr6p[7]); /* Normalize the representation */ inet_pton(AF_INET6, CS next->address, &addr.sin6_addr); inet_ntop(AF_INET6, &addr.sin6_addr, CS next->address, sizeof(next->address)); 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, devname); } fclose(f); #endif /* HAVE_IPV6 */ return yield; } #endif /* FIND_RUNNING_INTERFACES */ /************* * Sendfile * *************/ #include <sys/sendfile.h> ssize_t os_sendfile(int out, int in, off_t * off, size_t cnt) { return sendfile(out, in, off, cnt); } /* End of os.c-Linux */