kqueue/kqdir.c

   1 /* compile with:
   2    gcc kqdir.c -o kqdir -Wall -W -Wextra -ansi -pedantic */
   3
   4 #include <dirent.h>
   5 #include <fcntl.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>    /* for strerror () */
   9 #include <unistd.h>
  10 #include <sys/event.h>
  11
  12 #define MAX_ENTRIES 256
  13
  14 /* function prototypes */
  15 void diep(const char *s);
  16
  17 int main(int argc, char *argv[])
  18 {
  19     struct kevent evlist[MAX_ENTRIES];    /* events we want to monitor */
  20     struct kevent chlist[MAX_ENTRIES];    /* events that were triggered */
  21     struct dirent *pdent;
  22     DIR *pdir;
  23     char fullpath[256];
  24     int fdlist[MAX_ENTRIES], cnt, i, kq, nev;
  25
  26     /* check argument count */
  27     if (argc != 2) {
  28         fprintf(stderr, "Usage: %s directory\n", argv[0]);
  29         exit(EXIT_FAILURE);
  30     }
  31
  32     /* create a new kernel event queue */
  33     if ((kq = kqueue()) == -1)
  34         diep("kqueue");
  35
  36     /* open directory named by argv[1], associate a directory stream
  37        with it and return a pointer to it
  38      */
  39     if ((pdir = opendir(argv[1])) == NULL)
  40         diep("opendir");
  41
  42     /* skip . and .. entries */
  43     cnt = 0;
  44     while((pdent = readdir(pdir)) != NULL && cnt++ < 2)
  45         ;
  46
  47     /* get all directory entries and for each one of them,
  48        initialise a kevent structure
  49     */
  50     cnt = 0;
  51     while((pdent = readdir(pdir)) != NULL) {
  52         /* check whether we have exceeded the max number of
  53            entries that we can monitor
  54          */
  55         if (cnt > MAX_ENTRIES - 1) {
  56             fprintf(stderr, "Max number of entries exceeded\n");
  57             goto CLEANUP_AND_EXIT;
  58         }
  59
  60         /* check path length */
  61         if (strlen(argv[1] + strlen(pdent->d_name) + 1) > 256) {
  62             fprintf(stderr,"Max path length exceeded\n");
  63             goto CLEANUP_AND_EXIT;
  64         }
  65         strcpy(fullpath, argv[1]);
  66         strcat(fullpath, "/");
  67         strcat(fullpath, pdent->d_name);
  68
  69         /* open directory entry */
  70         if ((fdlist[cnt] = open(fullpath, O_RDONLY)) == -1) {
  71             perror("open");
  72             goto CLEANUP_AND_EXIT;
  73         }
  74
  75         /* initialise kevent structure */
  76         EV_SET(&chlist[cnt], fdlist[cnt], EVFILT_VNODE,
  77                EV_ADD | EV_ENABLE | EV_ONESHOT,
  78                NOTE_DELETE | NOTE_EXTEND | NOTE_WRITE | NOTE_ATTRIB,
  79                0, 0);
  80
  81         cnt++;
  82     }
  83
  84     /* loop forever */
  85     for (;;) {
  86         nev = kevent(kq, chlist, cnt, evlist, cnt, NULL);
  87         if (nev == -1)
  88             perror("kevent");
  89
  90         else if (nev > 0) {
  91             for (i = 0; i < nev; i++) {
  92                 if (evlist[i].flags & EV_ERROR) {
  93                     fprintf(stderr, "EV_ERROR: %s\n", strerror(evlist[i].data));
  94                     goto CLEANUP_AND_EXIT;
  95                 }
  96
  97                 if (evlist[i].fflags & NOTE_DELETE) {
  98                     printf("fd: %d Deleted\n", evlist[i].ident);
  99                 }
 100                 else if (evlist[i].fflags & NOTE_EXTEND ||
 101                     evlist[i].fflags & NOTE_WRITE) {
 102                     printf("fd: %d Modified\n", evlist[i].ident);
 103                 }
 104                 else if (evlist[i].fflags & NOTE_ATTRIB) {
 105                     printf("fd: %d Attributes modified\n", evlist[i].ident);
 106                 }
 107             }
 108         }
 109     }
 110
 111     /* close open file descriptors, directory stream and kqueue */
 112 CLEANUP_AND_EXIT:;
 113     for (i = 0; i < cnt; i++)
 114         close(fdlist[i]);
 115     closedir(pdir);
 116     close(kq);
 117
 118     return EXIT_SUCCESS;
 119 }
 120
 121 void diep(const char *s)
 122 {
 123     perror(s);
 124     exit(EXIT_FAILURE);
 125 }
 126