kqueue/kqdir.c

   1 /*
   2  * Compile with:
   3  * gcc kqdir.c -o kqdir -Wall -W -Wextra -ansi -pedantic
   4  *
   5  * The following program will monitor up to MAX_ENTRIES files
   6  * (in a directory supplied by the user), and will report any
   7  * delete, write or attributes' change operation.
   8 */
   9
  10 #include <dirent.h>
  11 #include <fcntl.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <string.h>    /* for strerror () */
  15 #include <unistd.h>
  16 #include <sys/event.h>
  17
  18 #define MAX_ENTRIES 256
  19
  20 /* Function prototypes */
  21 void diep(const char *s);
  22
  23 int main(int argc, char *argv[])
  24 {
  25     struct kevent evlist[MAX_ENTRIES];    /* events we want to monitor */
  26     struct kevent chlist[MAX_ENTRIES];    /* events that were triggered */
  27     struct dirent *pdent;
  28     DIR *pdir;
  29     char fullpath[256];
  30     int fdlist[MAX_ENTRIES], cnt, i, error, kq, nev;
  31
  32     /* Check argument count */
  33     if (argc != 2) {
  34         fprintf(stderr, "Usage: %s directory\n", argv[0]);
  35         exit(EXIT_FAILURE);
  36     }
  37
  38     /* Create a new kernel event queue */
  39     if ((kq = kqueue()) == -1)
  40         diep("kqueue()");
  41
  42     /*
  43      * Open directory named by argv[1], associate a directory stream
  44      * with it and return a pointer to it.
  45      */
  46     if ((pdir = opendir(argv[1])) == NULL)
  47         diep("opendir()");
  48
  49     /* Skip . and .. entries */
  50     cnt = 0;
  51     while((pdent = readdir(pdir)) != NULL && cnt++ < 2)
  52         ;    /* VOID */
  53
  54     /*
  55      * Get all directory entries and for each one of them,
  56      * initialise a kevent structure.
  57     */
  58     cnt = 0;
  59     while((pdent = readdir(pdir)) != NULL) {
  60         /*
  61          * Check whether we have exceeded the max number of
  62          * entries that we can monitor.
  63          */
  64         if (cnt > MAX_ENTRIES - 1) {
  65             fprintf(stderr, "Max number of entries exceeded\n");
  66             goto CLEANUP_AND_EXIT;
  67         }
  68
  69         /*
  70          * Check path length
  71          * don't forget +1 for the '\0'
  72          */
  73         if (strlen(argv[1] + strlen(pdent->d_name) + 2) > 256) {
  74             fprintf(stderr,"Max path length exceeded\n");
  75             goto CLEANUP_AND_EXIT;
  76         }
  77         strcpy(fullpath, argv[1]);
  78         strcat(fullpath, "/");
  79         strcat(fullpath, pdent->d_name);
  80
  81         /* Open directory entry */
  82         if ((fdlist[cnt] = open(fullpath, O_RDONLY)) == -1) {
  83             perror("open()");
  84             goto CLEANUP_AND_EXIT;
  85         }
  86
  87         /* Initialise kevent structure */
  88         EV_SET(&chlist[cnt], fdlist[cnt], EVFILT_VNODE,
  89                EV_ADD | EV_ENABLE | EV_ONESHOT,
  90                NOTE_DELETE | NOTE_EXTEND | NOTE_WRITE | NOTE_ATTRIB,
  91                0, 0);
  92
  93         cnt++;
  94     }
  95
  96     /* Loop forever */
  97     for (;;) {
  98         nev = kevent(kq, chlist, cnt, evlist, cnt, NULL);
  99         if (nev == -1)
 100             perror("kevent()");
 101
 102         else if (nev > 0) {
 103             for (i = 0; i < nev; i++) {
 104                 if (evlist[i].flags & EV_ERROR) {
 105                     fprintf(stderr, "EV_ERROR: %s\n", strerror(evlist[i].data));
 106                     goto CLEANUP_AND_EXIT;
 107                 }
 108
 109                 if (evlist[i].fflags & NOTE_DELETE)
 110                     printf("fd: %d Deleted\n", evlist[i].ident);
 111
 112                 else if (evlist[i].fflags & NOTE_EXTEND
 113                          || evlist[i].fflags & NOTE_WRITE)
 114                     printf("fd: %d Modified\n", evlist[i].ident);
 115
 116                 else if (evlist[i].fflags & NOTE_ATTRIB)
 117                     printf("fd: %d Attributes modified\n", evlist[i].ident);
 118             }
 119         }
 120     }
 121
 122     /* Clean up file descriptors, directory stream,  kqueue */
 123  CLEANUP_AND_EXIT:;
 124     error = EXIT_SUCCESS;
 125     for (i = 0; i < cnt; i++)
 126         if (close(fdlist[i]) == -1) {
 127             error = EXIT_FAILURE;
 128             perror("close");
 129         }
 130
 131     if ((closedir(pdir) == -1) || (close(kq) == -1)) {
 132         error = EXIT_FAILURE;
 133         perror("close");
 134     }
 135
 136     return error;
 137 }
 138
 139 void diep(const char *s)
 140 {
 141     perror(s);
 142     exit(EXIT_FAILURE);
 143 }