1 /*
2 * This sample code shows how to use Libevent to read from a named pipe.
3 * XXX This code could make better use of the Libevent interfaces.
4 *
5 * XXX This does not work on Windows; ignore everything inside the _WIN32 block.
6 *
7 * On UNIX, compile with:
8 * cc -I/usr/local/include -o event-read-fifo event-read-fifo.c \
9 * -L/usr/local/lib -levent
10 */
11
12 #include <event2/event-config.h>
13
14 #include <sys/types.h>
15 #include <sys/stat.h>
16 #ifndef _WIN32
17 #include <sys/queue.h>
18 #include <unistd.h>
19 #include <sys/time.h>
20 #include <signal.h>
21 #else
22 #include <winsock2.h>
23 #include <windows.h>
24 #endif
25 #include <fcntl.h>
26 #include <stdlib.h>
27 #include <stdio.h>
28 #include <string.h>
29 #include <errno.h>
30
31 #include <event2/event.h>
32
33 static void
fifo_read(evutil_socket_t fd,short event,void * arg)34 fifo_read(evutil_socket_t fd, short event, void *arg)
35 {
36 char buf[255];
37 int len;
38 struct event *ev = arg;
39 #ifdef _WIN32
40 DWORD dwBytesRead;
41 #endif
42
43 fprintf(stderr, "fifo_read called with fd: %d, event: %d, arg: %p\n",
44 (int)fd, event, arg);
45 #ifdef _WIN32
46 len = ReadFile((HANDLE)fd, buf, sizeof(buf) - 1, &dwBytesRead, NULL);
47
48 /* Check for end of file. */
49 if (len && dwBytesRead == 0) {
50 fprintf(stderr, "End Of File");
51 event_del(ev);
52 return;
53 }
54
55 buf[dwBytesRead] = '\0';
56 #else
57 len = read(fd, buf, sizeof(buf) - 1);
58
59 if (len <= 0) {
60 if (len == -1)
61 perror("read");
62 else if (len == 0)
63 fprintf(stderr, "Connection closed\n");
64 event_del(ev);
65 event_base_loopbreak(event_get_base(ev));
66 return;
67 }
68
69 buf[len] = '\0';
70 #endif
71 fprintf(stdout, "Read: %s\n", buf);
72 }
73
74 /* On Unix, cleanup event.fifo if SIGINT is received. */
75 #ifndef _WIN32
76 static void
signal_cb(evutil_socket_t fd,short event,void * arg)77 signal_cb(evutil_socket_t fd, short event, void *arg)
78 {
79 struct event_base *base = arg;
80 event_base_loopbreak(base);
81 }
82 #endif
83
84 int
main(int argc,char ** argv)85 main(int argc, char **argv)
86 {
87 struct event *evfifo;
88 struct event_base* base;
89 #ifdef _WIN32
90 HANDLE socket;
91 /* Open a file. */
92 socket = CreateFileA("test.txt", /* open File */
93 GENERIC_READ, /* open for reading */
94 0, /* do not share */
95 NULL, /* no security */
96 OPEN_EXISTING, /* existing file only */
97 FILE_ATTRIBUTE_NORMAL, /* normal file */
98 NULL); /* no attr. template */
99
100 if (socket == INVALID_HANDLE_VALUE)
101 return 1;
102
103 #else
104 struct event *signal_int;
105 struct stat st;
106 const char *fifo = "event.fifo";
107 int socket;
108
109 if (lstat(fifo, &st) == 0) {
110 if ((st.st_mode & S_IFMT) == S_IFREG) {
111 errno = EEXIST;
112 perror("lstat");
113 exit(1);
114 }
115 }
116
117 unlink(fifo);
118 if (mkfifo(fifo, 0600) == -1) {
119 perror("mkfifo");
120 exit(1);
121 }
122
123 socket = open(fifo, O_RDONLY | O_NONBLOCK, 0);
124
125 if (socket == -1) {
126 perror("open");
127 exit(1);
128 }
129
130 fprintf(stderr, "Write data to %s\n", fifo);
131 #endif
132 /* Initialize the event library */
133 base = event_base_new();
134
135 /* Initialize one event */
136 #ifdef _WIN32
137 evfifo = event_new(base, (evutil_socket_t)socket, EV_READ|EV_PERSIST, fifo_read,
138 event_self_cbarg());
139 #else
140 /* catch SIGINT so that event.fifo can be cleaned up */
141 signal_int = evsignal_new(base, SIGINT, signal_cb, base);
142 event_add(signal_int, NULL);
143
144 evfifo = event_new(base, socket, EV_READ|EV_PERSIST, fifo_read,
145 event_self_cbarg());
146 #endif
147
148 /* Add it to the active events, without a timeout */
149 event_add(evfifo, NULL);
150
151 event_base_dispatch(base);
152 event_base_free(base);
153 #ifdef _WIN32
154 CloseHandle(socket);
155 #else
156 close(socket);
157 unlink(fifo);
158 #endif
159 libevent_global_shutdown();
160 return (0);
161 }
162
163