Correzioni estetiche al codice con maggiori controlli sugli errori.

[gapil.git] / sources / inotify_monitor.c

diff --git a/sources/inotify_monitor.c b/sources/inotify_monitor.c
index 92391cf39b5133c8ab49435f6c76a1878f0f8dee..e5e04d9aaf369543a59de9093971197fccb5b563 100644 (file)
--- a/sources/inotify_monitor.c
+++ b/sources/inotify_monitor.c
@@ -18,21 +18,25 @@
  */
 /*****************************************************************************
  *
- * File inotufy_monitor.c: 
+ * File inotify_monitor.c: 
  *
- * An example for shared memory use: monitor a directory status,
- * saving data in a shared memory segment
+ * An example of the inotify interface: use inotify to watch the
+ * status of a directory or a file
  *
  * Author: S. Piccardi Jul. 2007
  *
  *****************************************************************************/
 #include <sys/types.h>
-#include <sys/inotify.h>
-#include <stdlib.h>        /* C standard library */
-#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/inotify.h> /* Linux inotify interface */
+#include <sys/epoll.h>   /* Linux epoll interface */
+#include <stdlib.h>      /* C standard library */
+#include <unistd.h>      /* Unix standard library */
 #include <errno.h>       /* error definitions and routines */ 
 #include <stdio.h>       /* standard I/O library */
 #include <string.h>      /* string functions */
+#include <fcntl.h>       /* fcntl function */
+#include <sys/ioctl.h>   /* ioctl function */
 
 
 #include "macros.h"
@@ -43,17 +47,18 @@ void printevent(unsigned int mask);
 
 int main(int argc, char *argv[]) 
 {
-    int i, size;
-    int fd, wd;
-    char buffer[128*sizeof(struct inotify_event)];
+    int i, size, nread;
+    int fd, wd, epfd;
+    char buffer[1024 + sizeof(struct inotify_event)];
     unsigned int mask=0;
     struct inotify_event * event;
+    struct epoll_event epev;
     /*
      * Input section: decode command line parameters 
      * Use getopt function
      */
     opterr = 0;         /* don't want writing to stderr */
-    while ( (i = getopt(argc, argv, "hrwcda")) != -1) {
+    while ((i = getopt(argc, argv, "hrwcda")) != -1) {
        switch (i) {
        /* 
         * Handling options 
@@ -90,42 +95,77 @@ int main(int argc, char *argv[])
      *               Main code beginning
      * 
      * ***********************************************************/
-    /* There must be one argument */
-    if ((argc - optind) != 1) {  
+    if ((argc - optind) != 1) {           /* There must be one argument */
        printf("Wrong number of arguments %d\n", argc - optind);
         usage();
     }
-    /* initalialize inotify */
-    fd = inotify_init ();
-    if (fd < 0)
+    epfd = epoll_create(5);               /* initialize epoll */
+    if (epfd < 0) {
+        perror("Failing on epoll_create");
+       exit(-1);
+    }
+    fd = inotify_init();                  /* initialize inotify */
+    if (fd < 0) {
         perror("Failing on inotify_init");
-
-    /* add watch */
-    wd = inotify_add_watch(fd, argv[optind], mask);
-    if ( wd <= 0) {
+       exit(-1);
+    }
+    if (fcntl(fd, F_SETFL, O_NONBLOCK)) { /* no blocking I/O on inotify */
+       perror("Cannot set noblocking I/O on inotify fd");
+       exit(-1);
+    }
+    wd = inotify_add_watch(fd, argv[optind], mask);  /* add watch */
+    if (wd <= 0) {
        printf("Failing to add watched file %s, mask %i; %s\n", 
              argv[optind], mask, strerror(errno));
        exit(-1);
-    }    
+    }
+    epev.data.fd = fd;        /* add inotify fd to epoll */
+    epev.events = EPOLLIN;
+    if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &epev)) {
+        perror("Failing on epoll_ctl");
+       exit(-1);
+    }
     /* 
      * Main Loop: read events and print them
      */
     while (1) {
-       size = read(fd, buffer, sizeof(buffer));
+       if (epoll_wait(epfd, &epev, 1, -1) < 0) {
+           perror("error on epoll_wait");
+           exit(-1);
+       }
+       if (epev.data.fd != fd) 
+           printf("something wrong, epoll activity on %i instead of %i\n",
+                  epev.data.fd, fd);
        
-       event = (struct inotify_event *) buffer;
-        if (wd != event->wd) {
-           printf("Error, getting different watch descriptor, %i and %i\n",
-                  wd, event->wd); 
-           exit(1);
+       if (ioctl(fd, FIONREAD, &size)) {
+           perror("error on getting inotify event size");
+           exit(-1);
+       }
+       if (size > sizeof(buffer)) {
+           printf("Too many %i data to read, something wrong\n", size);
+           exit(-1);
+       }
+       i = 0;
+       while (i < size) {
+           nread = read(fd, buffer, size);
+           if (nread < 0) {
+               perror("error reading inotify data");
+               exit(1);
+           }
+           i += nread; 
+           event = (struct inotify_event *) buffer;
+           if (wd != event->wd) {
+               printf("Getting different watch descriptor, %i and %i\n",
+                      wd, event->wd); 
+           } else {
+               printf("Observed event on %s\n", argv[optind-1+event->wd]);
+               if (event->name != NULL)
+                   printf("On file %s\n", event->name);
+               printevent(event->mask);
+           }
        }
-       printf("Observed event on %s\n", argv[optind-1+event->wd]);
-       if (event->name != NULL)
-           printf("On file %s\n", event->name);
-       printevent(event->mask);
     }
     return 0;
-
 }
 /*
  * routine to print usage info and exit