kqdir.c

   1 #include <dirent.h>
   2 #include <fcntl.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>    /* for strerror () */
   6 #include <unistd.h>
   7 #include <sys/event.h>
   8
   9 #define MAX_ENTRIES 256
  10
  11 /* function prototypes */
  12 void diep(const char *s);
  13
  14 int main(int argc, char *argv[])
  15 {
  16     struct kevent evlist[MAX_ENTRIES];    /* events we want to monitor */
  17     struct kevent chlist[MAX_ENTRIES];    /* events that were triggered */
  18     struct dirent *pdent;
  19     DIR *pdir;
  20     char fullpath[256];
  21     int fdlist[MAX_ENTRIES], cnt, i, kq, nev;
  22
  23     /* check argument count */
  24     if (argc != 2) {
  25         fprintf(stderr, "Usage: %s directory\n", argv[0]);
  26         exit(EXIT_FAILURE);
  27     }
  28
  29     /* create a new kernel event queue */
  30     if ((kq = kqueue()) == -1)
  31         diep("kqueue");
  32
  33     /* open directory named by argv[1], associate a directory stream
  34        with it and return a pointer to it
  35      */
  36     if ((pdir = opendir(argv[1])) == NULL)
  37         diep("opendir");
  38
  39     /* skip . and .. entries */
  40     cnt = 0;
  41     while((pdent = readdir(pdir)) != NULL && cnt++ < 2)
  42         ;
  43
  44     /* get all directory entries and for each one of them,
  45        initialise a kevent structure
  46     */
  47     cnt = 0;
  48     while((pdent = readdir(pdir)) != NULL) {
  49         /* check whether we have exceeded the max number of
  50            entries that we can monitor
  51          */
  52         if (cnt > MAX_ENTRIES - 1) {
  53             fprintf(stderr, "Max number of entries exceeded\n");
  54             goto CLEANUP_AND_EXIT;
  55         }
  56
  57         /* check path length */
  58         if (strlen(argv[1] + strlen(pdent->d_name) + 1) > 256) {
  59             fprintf(stderr,"Max path length exceeded\n");
  60             goto CLEANUP_AND_EXIT;
  61         }
  62         strcpy(fullpath, argv[1]);
  63         strcat(fullpath, "/");
  64         strcat(fullpath, pdent->d_name);
  65
  66         /* open directory entry */
  67         if ((fdlist[cnt] = open(fullpath, O_RDONLY)) == -1) {
  68             perror("open");
  69             goto CLEANUP_AND_EXIT;
  70         }
  71
  72         /* initialise kevent structure */
  73         EV_SET(&chlist[cnt], fdlist[cnt], EVFILT_VNODE,
  74                EV_ADD | EV_ENABLE | EV_ONESHOT,
  75                NOTE_DELETE | NOTE_EXTEND | NOTE_WRITE | NOTE_ATTRIB,
  76                0, 0);
  77
  78         cnt++;
  79     }
  80
  81     /* loop forever */
  82     for (;;) {
  83         nev = kevent(kq, chlist, cnt, evlist, cnt, NULL);
  84         if (nev == -1)
  85             perror("kevent");
  86
  87         else if (nev > 0) {
  88             for (i = 0; i < nev; i++) {
  89                 if (evlist[i].flags & EV_ERROR) {
  90                     fprintf(stderr, "EV_ERROR: %s\n", strerror(evlist[i].data));
  91                     goto CLEANUP_AND_EXIT;
  92                 }
  93
  94                 if (evlist[i].fflags & NOTE_DELETE) {
  95                     printf("fd: %d Deleted\n", evlist[i].ident);
  96                 }
  97                 else if (evlist[i].fflags & NOTE_EXTEND ||
  98                     evlist[i].fflags & NOTE_WRITE) {
  99                     printf("fd: %d Modified\n", evlist[i].ident);
 100                 }
 101                 else if (evlist[i].fflags & NOTE_ATTRIB) {
 102                     printf("fd: %d Attributes modified\n", evlist[i].ident);
 103                 }
 104             }
 105         }
 106     }
 107
 108     /* close open file descriptors, directory stream and kqueue */
 109 CLEANUP_AND_EXIT:;
 110     for (i = 0; i < cnt; i++)
 111         close(fdlist[i]);
 112     closedir(pdir);
 113     close(kq);
 114
 115     return EXIT_SUCCESS;
 116 }
 117
 118 void diep(const char *s)
 119 {
 120     perror(s);
 121     exit(EXIT_FAILURE);
 122 }
 123