1 files changed, 278 insertions, 0 deletions
diff --git a/draft/fuse-examples/fsel.c b/draft/fuse-examples/fsel.c
new file mode 100644
index 0000000..9cf0221
--- /dev/null
+++ b/draft/fuse-examples/fsel.c
@@ -0,0 +1,278 @@
+/*
+  FUSE fsel: FUSE select example
+  Copyright (C) 2008       SUSE Linux Products GmbH
+  Copyright (C) 2008       Tejun Heo <teheo@suse.de>
+
+  This program can be distributed under the terms of the GNU GPL.
+  See the file COPYING.
+
+  gcc -Wall fsel.c `pkg-config fuse --cflags --libs` -o fsel
+*/
+
+#define FUSE_USE_VERSION 29
+
+#include <fuse.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <time.h>
+#include <pthread.h>
+#include <poll.h>
+
+/*
+ * fsel_open_mask is used to limit the number of opens to 1 per file.
+ * This is to use file index (0-F) as fh as poll support requires
+ * unique fh per open file.  Lifting this would require proper open
+ * file management.
+ */
+static unsigned fsel_open_mask;
+static const char fsel_hex_map[] = "0123456789ABCDEF";
+static struct fuse *fsel_fuse;	/* needed for poll notification */
+
+#define FSEL_CNT_MAX	10	/* each file can store upto 10 chars */
+#define FSEL_FILES	16
+
+static pthread_mutex_t fsel_mutex;	/* protects notify_mask and cnt array */
+static unsigned fsel_poll_notify_mask;	/* poll notification scheduled? */
+static struct fuse_pollhandle *fsel_poll_handle[FSEL_FILES]; /* poll notify handles */
+static unsigned fsel_cnt[FSEL_FILES];	/* nbytes stored in each file */
+
+static int fsel_path_index(const char *path)
+{
+	char ch = path[1];
+
+	if (strlen(path) != 2 || path[0] != '/' || !isxdigit(ch) || islower(ch))
+		return -1;
+	return ch <= '9' ? ch - '0' : ch - 'A' + 10;
+}
+
+static int fsel_getattr(const char *path, struct stat *stbuf)
+{
+	int idx;
+
+	memset(stbuf, 0, sizeof(struct stat));
+
+	if (strcmp(path, "/") == 0) {
+		stbuf->st_mode = S_IFDIR | 0555;
+		stbuf->st_nlink = 2;
+		return 0;
+	}
+
+	idx = fsel_path_index(path);
+	if (idx < 0)
+		return -ENOENT;
+
+	stbuf->st_mode = S_IFREG | 0444;
+	stbuf->st_nlink = 1;
+	stbuf->st_size = fsel_cnt[idx];
+	return 0;
+}
+
+static int fsel_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+			off_t offset, struct fuse_file_info *fi)
+{
+	char name[2] = { };
+	int i;
+
+	(void) offset;
+	(void) fi;
+
+	if (strcmp(path, "/") != 0)
+		return -ENOENT;
+
+	for (i = 0; i < FSEL_FILES; i++) {
+		name[0] = fsel_hex_map[i];
+		filler(buf, name, NULL, 0);
+	}
+
+	return 0;
+}
+
+static int fsel_open(const char *path, struct fuse_file_info *fi)
+{
+	int idx = fsel_path_index(path);
+
+	if (idx < 0)
+		return -ENOENT;
+	if ((fi->flags & 3) != O_RDONLY)
+		return -EACCES;
+	if (fsel_open_mask & (1 << idx))
+		return -EBUSY;
+	fsel_open_mask |= (1 << idx);
+
+	/*
+	 * fsel files are nonseekable somewhat pipe-like files which
+	 * gets filled up periodically by producer thread and consumed
+	 * on read.  Tell FUSE as such.
+	 */
+	fi->fh = idx;
+	fi->direct_io = 1;
+	fi->nonseekable = 1;
+
+	return 0;
+}
+
+static int fsel_release(const char *path, struct fuse_file_info *fi)
+{
+	int idx = fi->fh;
+
+	(void) path;
+
+	fsel_open_mask &= ~(1 << idx);
+	return 0;
+}
+
+static int fsel_read(const char *path, char *buf, size_t size, off_t offset,
+		     struct fuse_file_info *fi)
+{
+	int idx = fi->fh;
+
+	(void) path;
+	(void) offset;
+
+	pthread_mutex_lock(&fsel_mutex);
+	if (fsel_cnt[idx] < size)
+		size = fsel_cnt[idx];
+	printf("READ   %X transferred=%zu cnt=%u\n", idx, size, fsel_cnt[idx]);
+	fsel_cnt[idx] -= size;
+	pthread_mutex_unlock(&fsel_mutex);
+
+	memset(buf, fsel_hex_map[idx], size);
+	return size;
+}
+
+static int fsel_poll(const char *path, struct fuse_file_info *fi,
+		     struct fuse_pollhandle *ph, unsigned *reventsp)
+{
+	static unsigned polled_zero;
+	int idx = fi->fh;
+
+	(void) path;
+
+	/*
+	 * Poll notification requires pointer to struct fuse which
+	 * can't be obtained when using fuse_main().  As notification
+	 * happens only after poll is called, fill it here from
+	 * fuse_context.
+	 */
+	if (!fsel_fuse) {
+		struct fuse_context *cxt = fuse_get_context();
+		if (cxt)
+			fsel_fuse = cxt->fuse;
+	}
+
+	pthread_mutex_lock(&fsel_mutex);
+
+	if (ph != NULL) {
+		struct fuse_pollhandle *oldph = fsel_poll_handle[idx];
+
+		if (oldph)
+			fuse_pollhandle_destroy(oldph);
+
+		fsel_poll_notify_mask |= (1 << idx);
+		fsel_poll_handle[idx] = ph;
+	}
+
+	if (fsel_cnt[idx]) {
+		*reventsp |= POLLIN;
+		printf("POLL   %X cnt=%u polled_zero=%u\n",
+		       idx, fsel_cnt[idx], polled_zero);
+		polled_zero = 0;
+	} else
+		polled_zero++;
+
+	pthread_mutex_unlock(&fsel_mutex);
+	return 0;
+}
+
+static struct fuse_operations fsel_oper = {
+	.getattr	= fsel_getattr,
+	.readdir	= fsel_readdir,
+	.open		= fsel_open,
+	.release	= fsel_release,
+	.read		= fsel_read,
+	.poll		= fsel_poll,
+};
+
+static void *fsel_producer(void *data)
+{
+	const struct timespec interval = { 0, 250000000 };
+	unsigned idx = 0, nr = 1;
+
+	(void) data;
+
+	while (1) {
+		int i, t;
+
+		pthread_mutex_lock(&fsel_mutex);
+
+		/*
+		 * This is the main producer loop which is executed
+		 * ever 500ms.  On each iteration, it fills one byte
+		 * to 1, 2 or 4 files and sends poll notification if
+		 * requested.
+		 */
+		for (i = 0, t = idx; i < nr;
+		     i++, t = (t + FSEL_FILES / nr) % FSEL_FILES) {
+			if (fsel_cnt[t] == FSEL_CNT_MAX)
+				continue;
+
+			fsel_cnt[t]++;
+			if (fsel_fuse && (fsel_poll_notify_mask & (1 << t))) {
+				struct fuse_pollhandle *ph;
+
+				printf("NOTIFY %X\n", t);
+				ph = fsel_poll_handle[t];
+				fuse_notify_poll(ph);
+				fuse_pollhandle_destroy(ph);
+				fsel_poll_notify_mask &= ~(1 << t);
+				fsel_poll_handle[t] = NULL;
+			}
+		}
+
+		idx = (idx + 1) % FSEL_FILES;
+		if (idx == 0)
+			nr = (nr * 2) % 7;	/* cycle through 1, 2 and 4 */
+
+		pthread_mutex_unlock(&fsel_mutex);
+
+		nanosleep(&interval, NULL);
+	}
+
+	return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+	pthread_t producer;
+	pthread_attr_t attr;
+	int ret;
+
+	errno = pthread_mutex_init(&fsel_mutex, NULL);
+	if (errno) {
+		perror("pthread_mutex_init");
+		return 1;
+	}
+
+	errno = pthread_attr_init(&attr);
+	if (errno) {
+		perror("pthread_attr_init");
+		return 1;
+	}
+
+	errno = pthread_create(&producer, &attr, fsel_producer, NULL);
+	if (errno) {
+		perror("pthread_create");
+		return 1;
+	}
+
+	ret = fuse_main(argc, argv, &fsel_oper, NULL);
+
+	pthread_cancel(producer);
+	pthread_join(producer, NULL);
+
+	return ret;
+}