1 /**

     2  * test/demos/daemon.c

     3  * Copyright (C) 2008 Markus Broeker

     4  */

     5 

     6 #include <stdio.h>

     7 #include <stdlib.h>

     8 #include <string.h>

     9 #include <time.h>

    10 

    11 #include <fcntl.h>

    12 #include <unistd.h>

    13 #include <sys/stat.h>

    14 #include <sys/types.h>

    15 #include <signal.h>

    16 

    17 #define      MAXLEN 80

    18 #define    TIME_OUT 60

    19 #define  INPUT_FILE "/proc/meminfo"

    20 #define OUTPUT_FILE "/tmp/meminfo.log"

    21 #define   LOCK_FILE "/tmp/.daemon.lock"

    22 

    23 void check (int fd, char *buffer)

    24 {

    25     char response[1024];

    26     char time_stamp[40];

    27     int len;

    28 

    29     time_t t;

    30 

    31     t = time (NULL);

    32     strftime (time_stamp, sizeof (time_stamp), "%a %d %T", localtime (&t));

    33     len = snprintf (response, sizeof (response), "%s %s", time_stamp, buffer);

    34 

    35     write (fd, response, len);

    36 }

    37 

    38 void sigproc ()

    39 {

    40     if (unlink (LOCK_FILE) == 0)

    41         exit (EXIT_SUCCESS);

    42     exit (EXIT_FAILURE);

    43 }

    44 

    45 void sanity_check (int argc, char **argv)

    46 {

    47     struct stat st;

    48     int fd;

    49 

    50     if (argc == 2) {

    51         if (!strcmp (argv[1], "-h")) {

    52             printf ("Usage: %s [-f|]\n", argv[0]);

    53             printf ("Report bugs to mbroeker@largo.homelinux.org\n");

    54             exit (EXIT_SUCCESS);

    55         } else if (!strcmp (argv[1], "-f")) {

    56             if (unlink (LOCK_FILE) != 0)

    57                 exit (EXIT_FAILURE);

    58         } else {

    59             fprintf (stderr, "Unknown Option %s\n", argv[1]);

    60             exit (EXIT_FAILURE);

    61         }

    62     }

    63 

    64     if (stat (LOCK_FILE, &st) < 0) {

    65         fd = open (LOCK_FILE, O_WRONLY | O_CREAT, 0);

    66         close (fd);

    67     } else {

    68         fprintf (stderr, "%s is already running\n", argv[0]);

    69         exit (EXIT_FAILURE);

    70     }

    71 

    72     fprintf (stderr, "%s monitors %s every %d seconds into %s\n", argv[0], INPUT_FILE, TIME_OUT, OUTPUT_FILE);

    73 }

    74 

    75 int main (int argc, char **argv)

    76 {

    77     FILE *fin;

    78     static char buffer[MAXLEN];

    79     int fd;

    80 

    81     sanity_check (argc, argv);

    82 

    83     daemon (0, 0);

    84     signal (SIGTERM, sigproc);

    85 

    86     for (;;) {

    87         if ((fd = open (OUTPUT_FILE, O_WRONLY | O_CREAT, 0644)) < 0)

    88             return EXIT_FAILURE;

    89 

    90         if ((fin = fopen (INPUT_FILE, "r")) == NULL)

    91             return EXIT_FAILURE;

    92 

    93         while (fgets (buffer, sizeof (buffer), fin))

    94             check (fd, buffer);

    95 

    96         fclose (fin);

    97         close (fd);

    98 

    99         sleep (TIME_OUT);

   100     }

   101 

   102     return EXIT_SUCCESS;

   103 }