src/OS/os.c-Linux

   1 /* $Cambridge: exim/src/OS/os.c-Linux,v 1.2 2005/04/06 14:09:17 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1997 - 2001 */
   8 /* See the file NOTICE for conditions of use and distribution. */
   9
  10 /* Linux-specific code. This is concatenated onto the generic
  11 src/os.c file. */
  12
  13
  14 /*************************************************
  15 *              Load average computation          *
  16 *************************************************/
  17
  18 /*Linux has an apparently unique way of getting the load average, so we provide
  19 a unique function here, and define OS_LOAD_AVERAGE to stop src/os.c trying to
  20 provide the function. However, when compiling os.c for utilities, we may not
  21 want this at all, so check that it isn't set first. */
  22
  23 #if !defined(OS_LOAD_AVERAGE) && defined(__linux__)
  24 #define OS_LOAD_AVERAGE
  25
  26 /* Linux has 2 ways of returning load average:
  27
  28   (1) Do a read on /proc/loadavg
  29   (2) Use the sysinfo library function and syscall
  30
  31 The latter is simpler but in Linux 2.0 - 2.2 (and probably later releases) is
  32 exceptionally slow - 10-50ms per call is not unusual and about 100x slow the
  33 first method. This cripples high performance mail servers by increasing CPU
  34 utilisation by 3-5x.
  35
  36 In Exim's very early days, it used the 1st method. Later, it switched to the
  37 2nd method. Now it tries the 1st method and falls back to the 2nd if /proc is
  38 unavailable. */
  39
  40 #include <sys/sysinfo.h>
  41
  42 static int
  43 linux_slow_getloadavg(void)
  44 {
  45 struct sysinfo s;
  46 double avg;
  47 if (sysinfo(&s) < 0) return -1;
  48 avg = (double) (s.loads[0]) / (1<<SI_LOAD_SHIFT);
  49 return (int)(avg * 1000.0);
  50 }
  51
  52 int
  53 os_getloadavg(void)
  54 {
  55 char buffer[40];
  56 double avg;
  57 int count;
  58 int fd = open ("/proc/loadavg", O_RDONLY);
  59 if (fd == -1) return linux_slow_getloadavg();
  60 count = read (fd, buffer, sizeof(buffer));
  61 (void)close (fd);
  62 if (count <= 0) return linux_slow_getloadavg();
  63 count = sscanf (buffer, "%lf", &avg);
  64 if (count < 1) return linux_slow_getloadavg();
  65 return (int)(avg * 1000.0);
  66 }
  67 #endif  /* OS_LOAD_AVERAGE */
  68
  69
  70
  71
  72
  73 /*************************************************
  74 *         Finding interface addresses            *
  75 *************************************************/
  76
  77 /* This function is not required for utilities; we cut it out if
  78 FIND_RUNNING_INTERFACES is already defined. */
  79
  80 #ifndef FIND_RUNNING_INTERFACES
  81
  82 /* This code, contributed by Jason Gunthorpe, appears to be the current
  83 way of finding IPv6 interfaces in Linux. It first calls the common function in
  84 order to find IPv4 interfaces, then grobbles around to find the others. Jason
  85 said, "This is so horrible, don't look. Slightly ripped from net-tools
  86 ifconfig." It gets called by virtue of os_find_running_interfaces being defined
  87 as a macro for os_find_running_interfaces_linux in the os.h-Linux file. */
  88
  89 ip_address_item *
  90 os_find_running_interfaces_linux(void)
  91 {
  92 ip_address_item *yield = NULL;
  93
  94 #if HAVE_IPV6
  95 ip_address_item *last = NULL;
  96 ip_address_item  *next;
  97 char addr6p[8][5];
  98 unsigned int plen, scope, dad_status, if_idx;
  99 char devname[20];
 100 FILE *f;
 101 #endif
 102
 103 yield = os_common_find_running_interfaces();
 104
 105 #if HAVE_IPV6
 106
 107 /* Open the /proc file; give up if we can't. */
 108
 109 if ((f = fopen("/proc/net/if_inet6", "r")) == NULL) return yield;
 110
 111 /* Pick out the data from within the file, and add it on to the chain */
 112
 113 last = yield;
 114 if (last != NULL) while (last->next != NULL) last = last->next;
 115
 116 while (fscanf(f, "%4s%4s%4s%4s%4s%4s%4s%4s %02x %02x %02x %02x %20s\n",
 117              addr6p[0], addr6p[1], addr6p[2], addr6p[3],
 118              addr6p[4], addr6p[5], addr6p[6], addr6p[7],
 119              &if_idx, &plen, &scope, &dad_status, devname) != EOF)
 120   {
 121   struct sockaddr_in6 addr;
 122
 123   /* This data has to survive for ever, so use malloc. */
 124
 125   next = store_malloc(sizeof(ip_address_item));
 126   next->next = NULL;
 127   next->port = 0;
 128   sprintf(CS next->address, "%s:%s:%s:%s:%s:%s:%s:%s",
 129          addr6p[0], addr6p[1], addr6p[2], addr6p[3],
 130          addr6p[4], addr6p[5], addr6p[6], addr6p[7]);
 131
 132   /* Normalize the representation */
 133
 134   inet_pton(AF_INET6, CS next->address, &addr.sin6_addr);
 135   inet_ntop(AF_INET6, &addr.sin6_addr, CS next->address, sizeof(next->address));
 136
 137   if (yield == NULL) yield = last = next; else
 138     {
 139     last->next = next;
 140     last = next;
 141     }
 142
 143   DEBUG(D_interface)
 144     debug_printf("Actual local interface address is %s (%s)\n", last->address,
 145       devname);
 146   }
 147 fclose(f);
 148 #endif  /* HAVE_IPV6 */
 149
 150 return yield;
 151 }
 152
 153 #endif  /* FIND_RUNNING_INTERFACES */
 154
 155 /* End of os.c-Linux */