wendy

watch files or directory and run commands on any event
git clone git://z3bra.org/wendy
Log | Files | Refs | README | LICENSE

wendy.c (5343B)


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/wait.h>

#include "arg.h"

/* definitions, defaults, bla bla blah */
#define EVENT_SIZE      (sizeof(struct inotify_event))

/* maximum number of event * queuing at the same time */
#define BUF_LEN         (512 * (EVENT_SIZE+16))

/* macro used to retrieve the path of the node triggering the event */
#define EVENT_PATH(e)   (e->len ? e->name : wd_path(e->wd))

/* environment variable names set by wendy to pass to the command */
#define ENV_PATH        "WENDY_INODE"
#define ENV_MASK        "WENDY_EVENT"

/* default value for the mask when -m is not specified */
#define DEFAULT_MASK    (IN_CLOSE_WRITE|IN_MODIFY)

/* timeout value used by default to queue the events */
#define DEFAULT_TIMEOUT 1

struct node_t {
	int wd;
	char path[PATH_MAX];
	struct node_t *next;
};

int verbose = 0, nb = 0;
struct node_t *head = NULL;

void
usage(char *name)
{
	fprintf(stderr, "usage: %s [-lq] [-m mask] [-f file] [-t timeout] "
	                "[cmd [args..]]\n", name);
	exit(1);
}

void
list_events()
{
	fprintf(stdout, "IN_ACCESS ........ %u\n"
			"IN_MODIFY ........ %u\n"
			"IN_ATTRIB ........ %u\n"
			"IN_CLOSE_WRITE ... %u\n"
			"IN_CLOSE_NOWRITE . %u\n"
			"IN_OPEN .......... %u\n"
			"IN_MOVED_FROM .... %u\n"
			"IN_MOVED_TO ...... %u\n"
			"IN_CREATE ........ %u\n"
			"IN_DELETE ........ %u\n"
			"IN_DELETE_SELF ... %u\n"
			"IN_MOVE_SELF ..... %u\n"
			"IN_ALL_EVENTS .... %u\n"
			"IN_UNMOUNT ....... %u\n",
			IN_ACCESS,
			IN_MODIFY,
			IN_ATTRIB,
			IN_CLOSE_WRITE,
			IN_CLOSE_NOWRITE,
			IN_OPEN,
			IN_MOVED_FROM,
			IN_MOVED_TO,
			IN_CREATE,
			IN_DELETE,
			IN_DELETE_SELF,
			IN_MOVE_SELF,
			IN_ALL_EVENTS,
			IN_UNMOUNT);
}

char *
read_filename(int fd)
{
	int i;
	char *fn = NULL, ch;

	fn = malloc(PATH_MAX);
	if (!fn)
		return NULL;

	for (i=0; read(fd, &ch, 1) > 0 && i < PATH_MAX; i++) {
		if (ch == 0 || ch == '\n') {
			*(fn + i + 1) = 0;
			return fn;
		} else {
			*(fn+i) = ch;
		}
	}

	return NULL;
}

struct node_t *
add_node(int wd, const char *path)
{
	struct node_t *n = NULL;

	n = malloc(sizeof(struct node_t));
	if (!n)
		return NULL;

	n->wd = wd;
	strncpy(n->path, path, PATH_MAX);
	n->next = head ? head : NULL;
	head = n;

	nb++;
	return n;
}

const char *
wd_path(int wd)
{
	struct node_t *n = head;

	while (n && n->wd != wd)
		n = n->next;

	return n ? n->path : "unknown";
}

int
watch_node(int fd, const char *path, uint32_t mask)
{
	int wd = -1;

	if (!path)
		return -1;

	/* add a watcher on the file */
	wd  = inotify_add_watch(fd, path, mask);
	if (wd < 0) {
		perror("inotify_add_watch");
		return wd;
	}

	add_node(wd, path);
	return wd;
}

int
main (int argc, char **argv)
{
	int  fd, len, i = 0, timeout = 0;
	uint32_t mask = DEFAULT_MASK;
	char buf[BUF_LEN], strmask[8];
	char *fn = NULL, *argv0 = NULL;
	char **cmd = NULL;
	struct inotify_event *ev;

	/* get file descriptor */
	fd = inotify_init();
	if (fd < 0)
		perror("inotify_init");


	ARGBEGIN{
	case 'm':
		mask = atoi(EARGF(usage(argv0)));
		break;
	case 'l':
		list_events();
		return 0;
		break; /* NOT REACHED */
	case 'v':
		verbose++;
		break;
	case 'f':
		watch_node(fd, EARGF(usage(argv0)), mask);
		break;
	case 't':
		timeout = atoi(EARGF(usage(argv0)));
		break;
	default:
		usage(argv0);
	}ARGEND;

	if (argc > 0)
		cmd = argv;

	/* test given arguments */
	if (!timeout)   { timeout = DEFAULT_TIMEOUT; }

	if (!nb) {
		while ((fn = read_filename(0)) != NULL)
			watch_node(fd, fn, mask);

		free(fn);
	}

	/* start looping */
	while (nb>0) {
		/* get every event raised, and queue them */
		len = read(fd, buf, BUF_LEN);
		if (!len || len < 0)
			perror("read");

		i = 0;

		/* treat all events queued */
		while (i < len) {

			/* get events one by one */
			ev = (struct inotify_event *) &buf[i];

			/*
			 * IN_IGNORED is triggered when a file watched
			 * doesn't exists anymore. In this case we
			 * delete the node we were watching, and try to
			 * watch the file again. If that fails, then the 'nb'
			 * variable will be decremented, so that wendy can terminate
			 * when there is no more files to watch.
			 */
			if (ev->mask & IN_IGNORED) {
				nb--;
				if (watch_node(fd, EVENT_PATH(ev), mask) < 0 && verbose)
					fprintf(stderr, "%s: watch removed\n", EVENT_PATH(ev));
			} else if (verbose) {
				printf("%u\t%s\n", ev->mask, EVENT_PATH(ev));
				fflush(stdout);
			}

			/*
			 * Do not do anything if no command given.  Also only
			 * execute the command if the file concerned by the
			 * event is the one we're watching, or if we're not
			 * looking for a specific file.
			 *
			 * If you don't undersand this sentence, don't worry.
			 * Me neither.  Just trust the if().
			 */
			if (cmd) {
				/*
				 * OMG a new event! raise an alert!
				 * We first add two variables to the environment
				 * and then run the command.
				 * Also, double-forking.
				 */
				snprintf(strmask, 8, "%d", ev->mask);
				setenv(ENV_MASK, strmask, 1);
				setenv(ENV_PATH, EVENT_PATH(ev), 1);
				if (!fork())
				if (!fork()) execvp(cmd[0], cmd);
				else exit(0);
				else wait(NULL);
			}

			/* jump to the next one */
			i += EVENT_SIZE + ev->len;
		}
		/* wait before queuing events */
		if (nb > 0)
			sleep(timeout);
	}

	return EXIT_SUCCESS;
}