started own cowfs implementation

2007-07-31 15:23:23 +00:00
parent ebd9ef27c3
commit f8afabcac3
4 changed files with 488 additions and 29 deletions
@@ -0,0 +1,413 @@
+/*
+ * Copyright (C) 2007 Martin Willi
+ * Hochschule fuer Technik Rapperswil
+ * Copyright (C) 2001-2007 Miklos Szeredi
+ *
+ * Based on example shipped with FUSE.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+
+#define FUSE_USE_VERSION 26
+
+#include <fuse.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <pthread.h>
+
+#include "cowfs.h"
+
+#include <library.h>
+#include <debug.h>
+
+typedef struct private_cowfs_t private_cowfs_t;
+
+struct private_cowfs_t {
+	/** public cowfs interface */
+	cowfs_t public;
+	/** fuse channel to mountpoint */
+	struct fuse_chan *chan;
+	/** fuse handle */
+	struct fuse *fuse;
+	/** mountpoint of cowfs FUSE */
+	char *mount;
+	/** read only master filesystem */
+	char *master;
+	/** copy on write overlay to master */
+	char *host;
+	/** optional scenario COW overlay */
+	char *scenario;
+	/** thread processing FUSE */
+	pthread_t thread;
+};
+
+
+static int cowfs_getattr(const char *path, struct stat *stbuf)
+{
+    int res;
+
+    res = lstat(path, stbuf);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_access(const char *path, int mask)
+{
+    int res;
+
+    res = access(path, mask);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_readlink(const char *path, char *buf, size_t size)
+{
+    int res;
+
+    res = readlink(path, buf, size - 1);
+    if (res == -1)
+        return -errno;
+
+    buf[res] = '\0';
+    return 0;
+}
+
+
+static int cowfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+                       off_t offset, struct fuse_file_info *fi)
+{
+    DIR *dp;
+    struct dirent *de;
+
+    (void) offset;
+    (void) fi;
+
+    dp = opendir(path);
+    if (dp == NULL)
+        return -errno;
+
+    while ((de = readdir(dp)) != NULL) {
+        struct stat st;
+        memset(&st, 0, sizeof(st));
+        st.st_ino = de->d_ino;
+        st.st_mode = de->d_type << 12;
+        if (filler(buf, de->d_name, &st, 0))
+            break;
+    }
+
+    closedir(dp);
+    return 0;
+}
+
+static int cowfs_mknod(const char *path, mode_t mode, dev_t rdev)
+{
+    int res;
+
+    res = mknod(path, mode, rdev);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_mkdir(const char *path, mode_t mode)
+{
+    int res;
+
+    res = mkdir(path, mode);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_unlink(const char *path)
+{
+    int res;
+
+    res = unlink(path);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_rmdir(const char *path)
+{
+    int res;
+
+    res = rmdir(path);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_symlink(const char *from, const char *to)
+{
+    int res;
+
+    res = symlink(from, to);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_rename(const char *from, const char *to)
+{
+    int res;
+
+    res = rename(from, to);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_link(const char *from, const char *to)
+{
+    int res;
+
+    res = link(from, to);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_chmod(const char *path, mode_t mode)
+{
+    int res;
+
+    res = chmod(path, mode);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_chown(const char *path, uid_t uid, gid_t gid)
+{
+    int res;
+
+    res = lchown(path, uid, gid);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_truncate(const char *path, off_t size)
+{
+    int res;
+
+    res = truncate(path, size);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_utimens(const char *path, const struct timespec ts[2])
+{
+    int res;
+    struct timeval tv[2];
+
+    tv[0].tv_sec = ts[0].tv_sec;
+    tv[0].tv_usec = ts[0].tv_nsec / 1000;
+    tv[1].tv_sec = ts[1].tv_sec;
+    tv[1].tv_usec = ts[1].tv_nsec / 1000;
+
+    res = utimes(path, tv);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static int cowfs_open(const char *path, struct fuse_file_info *fi)
+{
+    int res;
+
+    res = open(path, fi->flags);
+    if (res == -1)
+        return -errno;
+
+    close(res);
+    return 0;
+}
+
+static int cowfs_read(const char *path, char *buf, size_t size, off_t offset,
+                    struct fuse_file_info *fi)
+{
+    int fd;
+    int res;
+
+    (void) fi;
+    fd = open(path, O_RDONLY);
+    if (fd == -1)
+        return -errno;
+
+    res = pread(fd, buf, size, offset);
+    if (res == -1)
+        res = -errno;
+
+    close(fd);
+    return res;
+}
+
+static int cowfs_write(const char *path, const char *buf, size_t size,
+                     off_t offset, struct fuse_file_info *fi)
+{
+    int fd;
+    int res;
+
+    (void) fi;
+    fd = open(path, O_WRONLY);
+    if (fd == -1)
+        return -errno;
+
+    res = pwrite(fd, buf, size, offset);
+    if (res == -1)
+        res = -errno;
+
+    close(fd);
+    return res;
+}
+
+static int cowfs_statfs(const char *path, struct statvfs *stbuf)
+{
+    int res;
+
+    res = statvfs(path, stbuf);
+    if (res == -1)
+        return -errno;
+
+    return 0;
+}
+
+static void *cowfs_init(struct fuse_conn_info *conn)
+{
+	struct fuse_context *ctx;
+	
+	ctx = fuse_get_context();
+	
+	return ctx->private_data;
+}
+
+static struct fuse_operations cowfs_operations = {
+    .getattr	= cowfs_getattr,
+    .access		= cowfs_access,
+    .readlink	= cowfs_readlink,
+    .readdir	= cowfs_readdir,
+    .mknod		= cowfs_mknod,
+    .mkdir		= cowfs_mkdir,
+    .symlink	= cowfs_symlink,
+    .unlink		= cowfs_unlink,
+    .rmdir		= cowfs_rmdir,
+    .rename		= cowfs_rename,
+    .link		= cowfs_link,
+    .chmod		= cowfs_chmod,
+    .chown		= cowfs_chown,
+    .truncate	= cowfs_truncate,
+    .utimens	= cowfs_utimens,
+    .open		= cowfs_open,
+    .read		= cowfs_read,
+    .write		= cowfs_write,
+    .statfs		= cowfs_statfs,
+    .init		= cowfs_init,
+};
+
+/**
+ * Implementation of cowfs_t.set_scenario.
+ */
+static void set_scenario(private_cowfs_t *this, char *path)
+{
+	free(this->scenario);
+	this->scenario = path ? strdup(path) : NULL;
+}
+
+/**
+ * stop, umount and destroy a cowfs FUSE filesystem
+ */
+static void destroy(private_cowfs_t *this)
+{
+	fuse_exit(this->fuse);
+	pthread_join(this->thread, NULL);
+	fuse_unmount(this->mount, this->chan);
+	fuse_destroy(this->fuse);
+	free(this->mount);
+	free(this->master);
+	free(this->host);
+	free(this->scenario);
+	free(this);
+}
+
+/**
+ * creates a new cowfs fuse instance
+ */
+cowfs_t *cowfs_create(char *master, char *host, char *mount)
+{
+	struct fuse_args args = {0, NULL, 0};
+	private_cowfs_t *this = malloc_thing(private_cowfs_t);
+	
+	this->public.set_scenario = (void(*)(cowfs_t*, char *path))set_scenario;
+	this->public.destroy = (void(*)(cowfs_t*))destroy;
+	
+    this->chan = fuse_mount(mount, &args);
+    if (this->chan == NULL)
+    {
+    	DBG1("mounting cowfs FUSE on '%s' failed", mount);
+    	free(this);
+    	return NULL;
+    }
+    
+    this->fuse = fuse_new(this->chan, &args, &cowfs_operations,
+    					  sizeof(cowfs_operations), this);
+    if (this->fuse == NULL)
+    {
+    	DBG1("creating cowfs FUSE handle failed");
+    	fuse_unmount(mount, this->chan);
+    	free(this);
+    	return NULL;
+    }
+    
+    this->mount = strdup(mount);
+    this->master = strdup(master);
+    this->host = strdup(host);
+	this->scenario = NULL;
+	
+	if (pthread_create(&this->thread, NULL, (void*)fuse_loop_mt, this->fuse) != 0)
+	{
+    	DBG1("creating thread to handle FUSE failed");
+    	fuse_unmount(mount, this->chan);
+    	free(this->mount);
+    	free(this->master);
+    	free(this->host);
+    	free(this);
+    	return NULL;
+	}
+    
+    return &this->public;
+}
+