kqueue/kqdir.c

   1 /* compile with:
   2    gcc kqdir.c -o kqdir -Wall -W -Wextra -ansi -pedantic
   3
   4    The following program will monitor up to MAX_ENTRIES files
   5    (in a directory supplied by the user), and will report any
   6    delete, write or attributes' change operation.
   7 */
   8
   9 #include <dirent.h>
  10 #include <fcntl.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>    /* for strerror () */
  14 #include <unistd.h>
  15 #include <sys/event.h>
  16
  17 #define MAX_ENTRIES 256
  18
  19 /* function prototypes */
  20 void diep(const char *s);
  21
  22 int main(int argc, char *argv[])
  23 {
  24     struct kevent evlist[MAX_ENTRIES];    /* events we want to monitor */
  25     struct kevent chlist[MAX_ENTRIES];    /* events that were triggered */
  26     struct dirent *pdent;
  27     DIR *pdir;
  28     char fullpath[256];
  29     int fdlist[MAX_ENTRIES], cnt, i, kq, nev;
  30
  31     /* check argument count */
  32     if (argc != 2) {
  33         fprintf(stderr, "Usage: %s directory\n", argv[0]);
  34         exit(EXIT_FAILURE);
  35     }
  36
  37     /* create a new kernel event queue */
  38     if ((kq = kqueue()) == -1)
  39         diep("kqueue");
  40
  41     /* open directory named by argv[1], associate a directory stream
  42        with it and return a pointer to it
  43      */
  44     if ((pdir = opendir(argv[1])) == NULL)
  45         diep("opendir");
  46
  47     /* skip . and .. entries */
  48     cnt = 0;
  49     while((pdent = readdir(pdir)) != NULL && cnt++ < 2)
  50         ;
  51
  52     /* get all directory entries and for each one of them,
  53        initialise a kevent structure
  54     */
  55     cnt = 0;
  56     while((pdent = readdir(pdir)) != NULL) {
  57         /* check whether we have exceeded the max number of
  58            entries that we can monitor
  59          */
  60         if (cnt > MAX_ENTRIES - 1) {
  61             fprintf(stderr, "Max number of entries exceeded\n");
  62             goto CLEANUP_AND_EXIT;
  63         }
  64
  65         /* check path length
  66            don't forget +1 for the '\0'
  67          */
  68         if (strlen(argv[1] + strlen(pdent->d_name) + 2) > 256) {
  69             fprintf(stderr,"Max path length exceeded\n");
  70             goto CLEANUP_AND_EXIT;
  71         }
  72         strcpy(fullpath, argv[1]);
  73         strcat(fullpath, "/");
  74         strcat(fullpath, pdent->d_name);
  75
  76         /* open directory entry */
  77         if ((fdlist[cnt] = open(fullpath, O_RDONLY)) == -1) {
  78             perror("open");
  79             goto CLEANUP_AND_EXIT;
  80         }
  81
  82         /* initialise kevent structure */
  83         EV_SET(&chlist[cnt], fdlist[cnt], EVFILT_VNODE,
  84                EV_ADD | EV_ENABLE | EV_ONESHOT,
  85                NOTE_DELETE | NOTE_EXTEND | NOTE_WRITE | NOTE_ATTRIB,
  86                0, 0);
  87
  88         cnt++;
  89     }
  90
  91     /* loop forever */
  92     for (;;) {
  93         nev = kevent(kq, chlist, cnt, evlist, cnt, NULL);
  94         if (nev == -1)
  95             perror("kevent");
  96
  97         else if (nev > 0) {
  98             for (i = 0; i < nev; i++) {
  99                 if (evlist[i].flags & EV_ERROR) {
 100                     fprintf(stderr, "EV_ERROR: %s\n", strerror(evlist[i].data));
 101                     goto CLEANUP_AND_EXIT;
 102                 }
 103
 104                 if (evlist[i].fflags & NOTE_DELETE)
 105                     printf("fd: %d Deleted\n", evlist[i].ident);
 106
 107                 else if (evlist[i].fflags & NOTE_EXTEND
 108                          || evlist[i].fflags & NOTE_WRITE)
 109                     printf("fd: %d Modified\n", evlist[i].ident);
 110
 111                 else if (evlist[i].fflags & NOTE_ATTRIB)
 112                     printf("fd: %d Attributes modified\n", evlist[i].ident);
 113             }
 114         }
 115     }
 116
 117     /* close open file descriptors, directory stream and kqueue */
 118 CLEANUP_AND_EXIT:;
 119     for (i = 0; i < cnt; i++)
 120         close(fdlist[i]);
 121     closedir(pdir);
 122     close(kq);
 123
 124     return EXIT_SUCCESS;
 125 }
 126
 127 void diep(const char *s)
 128 {
 129     perror(s);
 130     exit(EXIT_FAILURE);
 131 }
 132