lib/fuse.c

/*
    FUSE: Filesystem in Userspace
    Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>

    This program can be distributed under the terms of the GNU LGPL.
    See the file COPYING.LIB
*/


/* For pthread_rwlock_t */
#define _GNU_SOURCE

#include "fuse_i.h"
#include "fuse_lowlevel.h"
#include "fuse_compat.h"

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <errno.h>
#include <assert.h>
#include <stdint.h>
#include <pthread.h>
#include <sys/param.h>
#include <sys/uio.h>

/* FUSE flags: */

/** Enable debuging output */
#define FUSE_DEBUG       (1 << 1)

/** If a file is removed but it's still open, don't hide the file but
    remove it immediately */
#define FUSE_HARD_REMOVE (1 << 2)

/** Use st_ino field in getattr instead of generating inode numbers  */
#define FUSE_USE_INO     (1 << 3)

/** Make a best effort to fill in inode number in a readdir **/
#define FUSE_READDIR_INO (1 << 5)

/** Ignore file mode supplied by the filesystem, and create one based
    on the 'umask' option */
#define FUSE_SET_MODE (1 << 6)

/** Ignore st_uid supplied by the filesystem and set it based on the
    'uid' option*/
#define FUSE_SET_UID (1 << 7)

/** Ignore st_gid supplied by the filesystem and set it based on the
    'gid' option*/
#define FUSE_SET_GID (1 << 8)

/** Bypass the page cache for read and write operations  */
#define FUSE_DIRECT_IO (1 << 9)

/** If the FUSE_KERNEL_CACHE flag is given, then cached data will not
    be flushed on open */
#define FUSE_KERNEL_CACHE (1 << 10)

#define FUSE_MAX_PATH 4096

struct fuse {
    struct fuse_session *se;
    int flags;
    struct fuse_operations op;
    int compat;
    struct node **name_table;
    size_t name_table_size;
    struct node **id_table;
    size_t id_table_size;
    fuse_ino_t ctr;
    unsigned int generation;
    unsigned int hidectr;
    pthread_mutex_t lock;
    pthread_rwlock_t tree_lock;
    void *user_data;
    uid_t uid;
    gid_t gid;
    mode_t umask;
    double entry_timeout;
    double attr_timeout;
};

struct node {
    struct node *name_next;
    struct node *id_next;
    fuse_ino_t nodeid;
    unsigned int generation;
    int refctr;
    fuse_ino_t parent;
    char *name;
    uint64_t nlookup;
    int open_count;
    int is_hidden;
};

struct fuse_dirhandle {
    pthread_mutex_t lock;
    struct fuse *fuse;
    char *contents;
    int allocated;
    unsigned len;
    unsigned needlen;
    int filled;
    unsigned long fh;
    int error;
    fuse_ino_t nodeid;
};

static struct fuse_context *(*fuse_getcontext)(void) = NULL;

#ifndef USE_UCLIBC
#define mutex_init(mut) pthread_mutex_init(mut, NULL)
#else
static void mutex_init(pthread_mutex_t *mut)
{
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);
    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
    pthread_mutex_init(mut, &attr);
    pthread_mutexattr_destroy(&attr);
}
#endif

static struct node *get_node_nocheck(struct fuse *f, fuse_ino_t nodeid)
{
    size_t hash = nodeid % f->id_table_size;
    struct node *node;

    for (node = f->id_table[hash]; node != NULL; node = node->id_next)
        if (node->nodeid == nodeid)
            return node;

    return NULL;
}

static struct node *get_node(struct fuse *f, fuse_ino_t nodeid)
{
    struct node *node = get_node_nocheck(f, nodeid);
    if (!node) {
        fprintf(stderr, "fuse internal error: node %lu not found\n",
                nodeid);
        abort();
    }
    return node;
}

static void free_node(struct node *node)
{
    free(node->name);
    free(node);
}

static void unhash_id(struct fuse *f, struct node *node)
{
    size_t hash = node->nodeid % f->id_table_size;
    struct node **nodep = &f->id_table[hash];

    for (; *nodep != NULL; nodep = &(*nodep)->id_next)
        if (*nodep == node) {
            *nodep = node->id_next;
            return;
        }
}

static void hash_id(struct fuse *f, struct node *node)
{
    size_t hash = node->nodeid % f->id_table_size;
    node->id_next = f->id_table[hash];
    f->id_table[hash] = node;
}

static unsigned int name_hash(struct fuse *f, fuse_ino_t parent, const char *name)
{
    unsigned int hash = *name;

    if (hash)
        for (name += 1; *name != '\0'; name++)
            hash = (hash << 5) - hash + *name;

    return (hash + parent) % f->name_table_size;
}

static void unref_node(struct fuse *f, struct node *node);

static void unhash_name(struct fuse *f, struct node *node)
{
    if (node->name) {
        size_t hash = name_hash(f, node->parent, node->name);
        struct node **nodep = &f->name_table[hash];

        for (; *nodep != NULL; nodep = &(*nodep)->name_next)
            if (*nodep == node) {
                *nodep = node->name_next;
                node->name_next = NULL;
                unref_node(f, get_node(f, node->parent));
                free(node->name);
                node->name = NULL;
                node->parent = 0;
                return;
            }
        fprintf(stderr, "fuse internal error: unable to unhash node: %lu\n",
                node->nodeid);
        abort();
    }
}

static int hash_name(struct fuse *f, struct node *node, fuse_ino_t parent,
                     const char *name)
{
    size_t hash = name_hash(f, parent, name);
    node->name = strdup(name);
    if (node->name == NULL)
        return -1;

    get_node(f, parent)->refctr ++;
    node->parent = parent;
    node->name_next = f->name_table[hash];
    f->name_table[hash] = node;
    return 0;
}

static void delete_node(struct fuse *f, struct node *node)
{
    if (f->flags & FUSE_DEBUG) {
        printf("delete: %lu\n", node->nodeid);
        fflush(stdout);
    }
    assert(!node->name);
    unhash_id(f, node);
    free_node(node);
}

static void unref_node(struct fuse *f, struct node *node)
{
    assert(node->refctr > 0);
    node->refctr --;
    if (!node->refctr)
        delete_node(f, node);
}

static fuse_ino_t next_id(struct fuse *f)
{
    do {
        f->ctr++;
        if (!f->ctr)
            f->generation ++;
    } while (f->ctr == 0 || get_node_nocheck(f, f->ctr) != NULL);
    return f->ctr;
}

static struct node *lookup_node(struct fuse *f, fuse_ino_t parent,
                                const char *name)
{
    size_t hash = name_hash(f, parent, name);
    struct node *node;

    for (node = f->name_table[hash]; node != NULL; node = node->name_next)
        if (node->parent == parent && strcmp(node->name, name) == 0)
            return node;

    return NULL;
}

static struct node *find_node(struct fuse *f, fuse_ino_t parent,
                              const char *name)
{
    struct node *node;

    pthread_mutex_lock(&f->lock);
    node = lookup_node(f, parent, name);
    if (node == NULL) {
        node = (struct node *) calloc(1, sizeof(struct node));
        if (node == NULL)
            goto out_err;

        node->refctr = 1;
        node->nodeid = next_id(f);
        node->open_count = 0;
        node->is_hidden = 0;
        node->generation = f->generation;
        if (hash_name(f, node, parent, name) == -1) {
            free(node);
            node = NULL;
            goto out_err;
        }
        hash_id(f, node);
    }
    node->nlookup ++;
 out_err:
    pthread_mutex_unlock(&f->lock);
    return node;
}

static char *add_name(char *buf, char *s, const char *name)
{
    size_t len = strlen(name);
    s -= len;
    if (s <= buf) {
        fprintf(stderr, "fuse: path too long: ...%s\n", s + len);
        return NULL;
    }
    strncpy(s, name, len);
    s--;
    *s = '/';

    return s;
}

static char *get_path_name(struct fuse *f, fuse_ino_t nodeid, const char *name)
{
    char buf[FUSE_MAX_PATH];
    char *s = buf + FUSE_MAX_PATH - 1;
    struct node *node;

    *s = '\0';

    if (name != NULL) {
        s = add_name(buf, s, name);
        if (s == NULL)
            return NULL;
    }

    pthread_mutex_lock(&f->lock);
    for (node = get_node(f, nodeid); node && node->nodeid != FUSE_ROOT_ID;
         node = get_node(f, node->parent)) {
        if (node->name == NULL) {
            s = NULL;
            break;
        }

        s = add_name(buf, s, node->name);
        if (s == NULL)
            break;
    }
    pthread_mutex_unlock(&f->lock);

    if (node == NULL || s == NULL)
        return NULL;
    else if (*s == '\0')
        return strdup("/");
    else
        return strdup(s);
}

static char *get_path(struct fuse *f, fuse_ino_t nodeid)
{
    return get_path_name(f, nodeid, NULL);
}

static void forget_node(struct fuse *f, fuse_ino_t nodeid, uint64_t nlookup)
{
    struct node *node;
    if (nodeid == FUSE_ROOT_ID)
        return;
    pthread_mutex_lock(&f->lock);
    node = get_node(f, nodeid);
    assert(node->nlookup >= nlookup);
    node->nlookup -= nlookup;
    if (!node->nlookup) {
        unhash_name(f, node);
        unref_node(f, node);
    }
    pthread_mutex_unlock(&f->lock);
}

static void remove_node(struct fuse *f, fuse_ino_t dir, const char *name)
{
    struct node *node;

    pthread_mutex_lock(&f->lock);
    node = lookup_node(f, dir, name);
    if (node != NULL)
        unhash_name(f, node);
    pthread_mutex_unlock(&f->lock);
}

static int rename_node(struct fuse *f, fuse_ino_t olddir, const char *oldname,
                        fuse_ino_t newdir, const char *newname, int hide)
{
    struct node *node;
    struct node *newnode;
    int err = 0;

    pthread_mutex_lock(&f->lock);
    node  = lookup_node(f, olddir, oldname);
    newnode  = lookup_node(f, newdir, newname);
    if (node == NULL)
        goto out;

    if (newnode != NULL) {
        if (hide) {
            fprintf(stderr, "fuse: hidden file got created during hiding\n");
            err = -EBUSY;
            goto out;
        }
        unhash_name(f, newnode);
    }

    unhash_name(f, node);
    if (hash_name(f, node, newdir, newname) == -1) {
        err = -ENOMEM;
        goto out;
    }

    if (hide)
        node->is_hidden = 1;

 out:
    pthread_mutex_unlock(&f->lock);
    return err;
}

static void set_stat(struct fuse *f, fuse_ino_t nodeid, struct stat *stbuf)
{
    if (!(f->flags & FUSE_USE_INO))
        stbuf->st_ino = nodeid;
    if (f->flags & FUSE_SET_MODE)
        stbuf->st_mode = (stbuf->st_mode & S_IFMT) | (0777 & ~f->umask);
    if (f->flags & FUSE_SET_UID)
        stbuf->st_uid = f->uid;
    if (f->flags & FUSE_SET_GID)
        stbuf->st_gid = f->gid;
}

static int is_open(struct fuse *f, fuse_ino_t dir, const char *name)
{
    struct node *node;
    int isopen = 0;
    pthread_mutex_lock(&f->lock);
    node = lookup_node(f, dir, name);
    if (node && node->open_count > 0)
        isopen = 1;
    pthread_mutex_unlock(&f->lock);
    return isopen;
}

static char *hidden_name(struct fuse *f, fuse_ino_t dir, const char *oldname,
                        char *newname, size_t bufsize)
{
    struct stat buf;
    struct node *node;
    struct node *newnode;
    char *newpath;
    int res;
    int failctr = 10;

    if (!f->op.getattr)
        return NULL;

    do {
        pthread_mutex_lock(&f->lock);
        node = lookup_node(f, dir, oldname);
        if (node == NULL) {
            pthread_mutex_unlock(&f->lock);
            return NULL;
        }
        do {
            f->hidectr ++;
            snprintf(newname, bufsize, ".fuse_hidden%08x%08x",
                     (unsigned int) node->nodeid, f->hidectr);
            newnode = lookup_node(f, dir, newname);
        } while(newnode);
        pthread_mutex_unlock(&f->lock);

        newpath = get_path_name(f, dir, newname);
        if (!newpath)
            break;

        res = f->op.getattr(newpath, &buf);
        if (res != 0)
            break;
        free(newpath);
        newpath = NULL;
    } while(--failctr);

    return newpath;
}

static int hide_node(struct fuse *f, const char *oldpath, fuse_ino_t dir,
                     const char *oldname)
{
    char newname[64];
    char *newpath;
    int err = -EBUSY;

    if (f->op.rename && f->op.unlink) {
        newpath = hidden_name(f, dir, oldname, newname, sizeof(newname));
        if (newpath) {
            int res = f->op.rename(oldpath, newpath);
            if (res == 0)
                err = rename_node(f, dir, oldname, dir, newname, 1);
            free(newpath);
        }
    }
    return err;
}

static int lookup_path(struct fuse *f, fuse_ino_t nodeid, const char *name,
                       const char *path, struct fuse_entry_param *e)
{
    int res;

    memset(e, 0, sizeof(struct fuse_entry_param));
    res = f->op.getattr(path, &e->attr);
    if (res == 0) {
        struct node *node;

        node = find_node(f, nodeid, name);
        if (node == NULL)
            res = -ENOMEM;
        else {
            e->ino = node->nodeid;
            e->generation = node->generation;
            e->entry_timeout = f->entry_timeout;
            e->attr_timeout = f->attr_timeout;
            set_stat(f, e->ino, &e->attr);
            if (f->flags & FUSE_DEBUG) {
                printf("   NODEID: %lu\n", (unsigned long) e->ino);
                fflush(stdout);
            }
        }
    }
    return res;
}

static struct fuse *req_fuse(fuse_req_t req)
{
    return (struct fuse *) fuse_req_userdata(req);
}

static struct fuse *req_fuse_prepare(fuse_req_t req)
{
    struct fuse_context *c = fuse_get_context();
    const struct fuse_ctx *ctx = fuse_req_ctx(req);
    c->fuse = req_fuse(req);
    c->uid = ctx->uid;
    c->gid = ctx->gid;
    c->pid = ctx->pid;
    c->private_data = c->fuse->user_data;

    return c->fuse;
}

static inline void reply_err(fuse_req_t req, int err)
{
    /* fuse_reply_err() uses non-negated errno values */
    fuse_reply_err(req, -err);
}

static void reply_entry(fuse_req_t req, const struct fuse_entry_param *e,
                        int err)
{
    if (!err) {
        if (fuse_reply_entry(req, e) == -ENOENT)
            forget_node(req_fuse(req), e->ino, 1);
    } else
        reply_err(req, err);
}

static void fuse_data_init(void *data)
{
    struct fuse *f = (struct fuse *) data;

    if (f->op.init)
        f->user_data = f->op.init();
}

static void fuse_data_destroy(void *data)
{
    struct fuse *f = (struct fuse *) data;

    if (f->op.destroy)
        f->op.destroy(f->user_data);
}

static void fuse_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("LOOKUP %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.getattr)
            err = lookup_path(f, parent, name, path, &e);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

static void fuse_forget(fuse_req_t req, fuse_ino_t ino, unsigned long nlookup)
{
    struct fuse *f = req_fuse(req);
    if (f->flags & FUSE_DEBUG) {
        printf("FORGET %lu/%lu\n", ino, nlookup);
        fflush(stdout);
    }
    forget_node(f, ino, nlookup);
    fuse_reply_none(req);
}

static void fuse_getattr(fuse_req_t req, fuse_ino_t ino)
{
    struct fuse *f = req_fuse_prepare(req);
    struct stat buf;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.getattr)
            err = f->op.getattr(path, &buf);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    if (!err) {
        set_stat(f, ino, &buf);
        fuse_reply_attr(req, &buf, f->attr_timeout);
    } else
        reply_err(req, err);
}

static int do_chmod(struct fuse *f, const char *path, struct stat *attr)
{
    int err;

    err = -ENOSYS;
    if (f->op.chmod)
        err = f->op.chmod(path, attr->st_mode);

    return err;
}

static int do_chown(struct fuse *f, const char *path, struct stat *attr,
                    int valid)
{
    int err;
    uid_t uid = (valid & FUSE_SET_ATTR_UID) ? attr->st_uid : (uid_t) -1;
    gid_t gid = (valid & FUSE_SET_ATTR_GID) ? attr->st_gid : (gid_t) -1;

    err = -ENOSYS;
    if (f->op.chown)
        err = f->op.chown(path, uid, gid);

    return err;
}

static int do_truncate(struct fuse *f, const char *path, struct stat *attr)
{
    int err;

    err = -ENOSYS;
    if (f->op.truncate)
        err = f->op.truncate(path, attr->st_size);

    return err;
}

static int do_utime(struct fuse *f, const char *path, struct stat *attr)
{
    int err;
    struct utimbuf buf;
    buf.actime = attr->st_atime;
    buf.modtime = attr->st_mtime;
    err = -ENOSYS;
    if (f->op.utime)
        err = f->op.utime(path, &buf);

    return err;
}

static void fuse_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
                         int valid)
{
    struct fuse *f = req_fuse_prepare(req);
    struct stat buf;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.getattr) {
            err = 0;
            if (!err && (valid & FUSE_SET_ATTR_MODE))
                err = do_chmod(f, path, attr);
            if (!err && (valid & (FUSE_SET_ATTR_UID | FUSE_SET_ATTR_GID)))
                err = do_chown(f, path, attr, valid);
            if (!err && (valid & FUSE_SET_ATTR_SIZE))
                err = do_truncate(f, path, attr);
            if (!err && (valid & (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) == (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME))
                err = do_utime(f, path, attr);
            if (!err)
                err = f->op.getattr(path, &buf);
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    if (!err) {
        set_stat(f, ino, &buf);
        fuse_reply_attr(req, &buf, f->attr_timeout);
    } else
        reply_err(req, err);
}

static void fuse_access(fuse_req_t req, fuse_ino_t ino, int mask)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.access)
            err = f->op.access(path, mask);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static void fuse_readlink(fuse_req_t req, fuse_ino_t ino)
{
    struct fuse *f = req_fuse_prepare(req);
    char linkname[PATH_MAX + 1];
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.readlink)
            err = f->op.readlink(path, linkname, sizeof(linkname));
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    if (!err) {
        linkname[PATH_MAX] = '\0';
        fuse_reply_readlink(req, linkname);
    } else
        reply_err(req, err);
}

static void fuse_mknod(fuse_req_t req, fuse_ino_t parent, const char *name,
                       mode_t mode, dev_t rdev)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("MKNOD %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.mknod && f->op.getattr) {
            err = f->op.mknod(path, mode, rdev);
            if (!err)
                err = lookup_path(f, parent, name, path, &e);
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

static void fuse_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name,
                       mode_t mode)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("MKDIR %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.mkdir && f->op.getattr) {
            err = f->op.mkdir(path, mode);
            if (!err)
                err = lookup_path(f, parent, name, path, &e);
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

static void fuse_unlink(fuse_req_t req, fuse_ino_t parent, const char *name)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_wrlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("UNLINK %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.unlink) {
            if (!(f->flags & FUSE_HARD_REMOVE) && is_open(f, parent, name))
                err = hide_node(f, path, parent, name);
            else {
                err = f->op.unlink(path);
                if (!err)
                    remove_node(f, parent, name);
            }
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static void fuse_rmdir(fuse_req_t req, fuse_ino_t parent, const char *name)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_wrlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("RMDIR %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.rmdir) {
            err = f->op.rmdir(path);
            if (!err)
                remove_node(f, parent, name);
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static void fuse_symlink(fuse_req_t req, const char *linkname,
                         fuse_ino_t parent, const char *name)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("SYMLINK %s\n", path);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.symlink && f->op.getattr) {
            err = f->op.symlink(linkname, path);
            if (!err)
                err = lookup_path(f, parent, name, path, &e);
        }
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

static void fuse_rename(fuse_req_t req, fuse_ino_t olddir, const char *oldname,
                        fuse_ino_t newdir, const char *newname)
{
    struct fuse *f = req_fuse_prepare(req);
    char *oldpath;
    char *newpath;
    int err;

    err = -ENOENT;
    pthread_rwlock_wrlock(&f->tree_lock);
    oldpath = get_path_name(f, olddir, oldname);
    if (oldpath != NULL) {
        newpath = get_path_name(f, newdir, newname);
        if (newpath != NULL) {
            if (f->flags & FUSE_DEBUG) {
                printf("RENAME %s -> %s\n", oldpath, newpath);
                fflush(stdout);
            }
            err = -ENOSYS;
            if (f->op.rename) {
                err = 0;
                if (!(f->flags & FUSE_HARD_REMOVE) &&
                    is_open(f, newdir, newname))
                    err = hide_node(f, newpath, newdir, newname);
                if (!err) {
                    err = f->op.rename(oldpath, newpath);
                    if (!err)
                        err = rename_node(f, olddir, oldname, newdir, newname, 0);
                }
            }
            free(newpath);
        }
        free(oldpath);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static void fuse_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t newparent,
                      const char *newname)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *oldpath;
    char *newpath;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    oldpath = get_path(f, ino);
    if (oldpath != NULL) {
        newpath =  get_path_name(f, newparent, newname);
        if (newpath != NULL) {
            if (f->flags & FUSE_DEBUG) {
                printf("LINK %s\n", newpath);
                fflush(stdout);
            }
            err = -ENOSYS;
            if (f->op.link && f->op.getattr) {
                err = f->op.link(oldpath, newpath);
                if (!err)
                    err = lookup_path(f, newparent, newname, newpath, &e);
            }
            free(newpath);
        }
        free(oldpath);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_entry(req, &e, err);
}

static void fuse_create(fuse_req_t req, fuse_ino_t parent, const char *name,
                        mode_t mode, struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_entry_param e;
    char *path;
    int opened = 0;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path_name(f, parent, name);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.create && f->op.getattr) {
            int oerr = f->op.create(path, mode, fi);
            if (!oerr)
                opened = 1;
            
            if (f->flags & FUSE_DEBUG) {
                if (opened)
                    printf("CREATE[%lu] flags: 0x%x %s\n", fi->fh, fi->flags, path);
                else
                    printf("LOOKUP(CREATE) %s\n", path);
                fflush(stdout);
            }

            err = lookup_path(f, parent, name, path, &e);
            if (err) {
                if (f->op.release && opened)
                    f->op.release(path, fi);
            } else if (opened != (S_ISREG(e.attr.st_mode) != 0)) {
                err = oerr ? oerr : -EIO;
                if (f->op.release && opened)
                    f->op.release(path, fi);
                forget_node(f, e.ino, 1);
            }
        }
    }

    if (!err) {
        if (f->flags & FUSE_DIRECT_IO)
            fi->direct_io = 1;
        if (f->flags & FUSE_KERNEL_CACHE)
            fi->keep_cache = 1;

        pthread_mutex_lock(&f->lock);
        if (fuse_reply_create(req, &e, fi) == -ENOENT) {
            /* The open syscall was interrupted, so it must be cancelled */
            if(f->op.release && opened)
                f->op.release(path, fi);
            forget_node(f, e.ino, 1);
        } else {
            struct node *node = get_node(f, e.ino);
            node->open_count ++;
        }
        pthread_mutex_unlock(&f->lock);
    } else
        reply_err(req, err);

    if (path)
        free(path);
    pthread_rwlock_unlock(&f->tree_lock);
}

static void fuse_open(fuse_req_t req, fuse_ino_t ino,
                      struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path = NULL;
    int err = 0;

    pthread_rwlock_rdlock(&f->tree_lock);
    if (f->op.open) {
        err = -ENOENT;
        path = get_path(f, ino);
        if (path != NULL) {
            if (!f->compat)
                err = f->op.open(path, fi);
            else
                err = ((struct fuse_operations_compat2 *) &f->op)->open(path, fi->flags);
        }
    }
    if (!err) {
        if (f->flags & FUSE_DEBUG) {
            printf("OPEN[%lu] flags: 0x%x\n", fi->fh, fi->flags);
            fflush(stdout);
        }

        if (f->flags & FUSE_DIRECT_IO)
            fi->direct_io = 1;
        if (f->flags & FUSE_KERNEL_CACHE)
            fi->keep_cache = 1;

        pthread_mutex_lock(&f->lock);
        if (fuse_reply_open(req, fi) == -ENOENT) {
            /* The open syscall was interrupted, so it must be cancelled */
            if(f->op.release && path != NULL) {
                if (!f->compat)
                    f->op.release(path, fi);
                else
                    ((struct fuse_operations_compat2 *) &f->op)->release(path, fi->flags);
            }
        } else {
            struct node *node = get_node(f, ino);
            node->open_count ++;
        }
        pthread_mutex_unlock(&f->lock);
    } else
        reply_err(req, err);

    if (path)
        free(path);
    pthread_rwlock_unlock(&f->tree_lock);
}

static void fuse_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
                      struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    char *buf;
    int res;

    buf = (char *) malloc(size);
    if (buf == NULL) {
        reply_err(req, -ENOMEM);
        return;
    }

    res = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("READ[%lu] %u bytes from %llu\n", fi->fh, size, off);
            fflush(stdout);
        }

        res = -ENOSYS;
        if (f->op.read)
            res = f->op.read(path, buf, size, off, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);

    if (res >= 0) {
        if (f->flags & FUSE_DEBUG) {
            printf("   READ[%lu] %u bytes\n", fi->fh, res);
            fflush(stdout);
        }
        fuse_reply_buf(req, buf, res);
    } else
        reply_err(req, res);

    free(buf);
}

static void fuse_write(fuse_req_t req, fuse_ino_t ino, const char *buf,
                       size_t size, off_t off, struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int res;

    res = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("WRITE%s[%lu] %u bytes to %llu\n",
                   fi->writepage ? "PAGE" : "", fi->fh, size, off);
            fflush(stdout);
        }

        res = -ENOSYS;
        if (f->op.write)
            res = f->op.write(path, buf, size, off, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);

    if (res >= 0)
        fuse_reply_write(req, res);
    else
        reply_err(req, res);
}

static void fuse_flush(fuse_req_t req, fuse_ino_t ino,
                       struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("FLUSH[%lu]\n", fi->fh);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.flush)
            err = f->op.flush(path, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static void fuse_release(fuse_req_t req, fuse_ino_t ino,
                         struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    struct node *node;
    int unlink_hidden;

    pthread_mutex_lock(&f->lock);
    node = get_node(f, ino);
    assert(node->open_count > 0);
    --node->open_count;
    unlink_hidden = (node->is_hidden && !node->open_count);
    pthread_mutex_unlock(&f->lock);

    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (f->flags & FUSE_DEBUG) {
        printf("RELEASE[%lu] flags: 0x%x\n", fi->fh, fi->flags);
        fflush(stdout);
    }
    if (f->op.release) {
        if (!f->compat)
            f->op.release(path ? path : "-", fi);
        else if (path)
            ((struct fuse_operations_compat2 *) &f->op)->release(path, fi->flags);
    }

    if(unlink_hidden && path)
        f->op.unlink(path);

    if (path)
        free(path);
    pthread_rwlock_unlock(&f->tree_lock);

    reply_err(req, 0);
}

static void fuse_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
                       struct fuse_file_info *fi)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        if (f->flags & FUSE_DEBUG) {
            printf("FSYNC[%lu]\n", fi->fh);
            fflush(stdout);
        }
        err = -ENOSYS;
        if (f->op.fsync)
            err = f->op.fsync(path, datasync, fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static struct fuse_dirhandle *get_dirhandle(const struct fuse_file_info *llfi,
                                            struct fuse_file_info *fi)
{
    struct fuse_dirhandle *dh = (struct fuse_dirhandle *) llfi->fh;
    memset(fi, 0, sizeof(struct fuse_file_info));
    fi->fh = dh->fh;
    return dh;
}

static void fuse_opendir(fuse_req_t req, fuse_ino_t ino,
                       struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_dirhandle *dh;

    dh = (struct fuse_dirhandle *) malloc(sizeof(struct fuse_dirhandle));
    if (dh == NULL) {
        reply_err(req, -ENOMEM);
        return;
    }
    memset(dh, 0, sizeof(struct fuse_dirhandle));
    dh->fuse = f;
    dh->contents = NULL;
    dh->len = 0;
    dh->filled = 0;
    dh->nodeid = ino;
    mutex_init(&dh->lock);

    llfi->fh = (unsigned long) dh;

    if (f->op.opendir) {
        struct fuse_file_info fi;
        char *path;
        int err;

        memset(&fi, 0, sizeof(fi));
        fi.flags = llfi->flags;

        err = -ENOENT;
        pthread_rwlock_rdlock(&f->tree_lock);
        path = get_path(f, ino);
        if (path != NULL) {
            err = f->op.opendir(path, &fi);
            dh->fh = fi.fh;
        }
        if (!err) {
            pthread_mutex_lock(&f->lock);
            if (fuse_reply_open(req, llfi) == -ENOENT) {
                /* The opendir syscall was interrupted, so it must be
                   cancelled */
                if(f->op.releasedir)
                    f->op.releasedir(path, &fi);
                pthread_mutex_destroy(&dh->lock);
                free(dh);
            }
            pthread_mutex_unlock(&f->lock);
        } else {
            reply_err(req, err);
            free(dh);
        }
        free(path);
        pthread_rwlock_unlock(&f->tree_lock);
    } else
        fuse_reply_open(req, llfi);
}

static int fill_dir_common(struct fuse_dirhandle *dh, const char *name,
                           const struct stat *statp, off_t off)
{
    struct stat stbuf;
    unsigned namelen = strlen(name);
    unsigned entsize;
    unsigned newlen;
    char *newptr;

    if (statp)
        stbuf = *statp;
    else {
        memset(&stbuf, 0, sizeof(stbuf));
        stbuf.st_ino = (ino_t) -1;
    }

    if (!(dh->fuse->flags & FUSE_USE_INO)) {
        stbuf.st_ino = (ino_t) -1;
        if (dh->fuse->flags & FUSE_READDIR_INO) {
            struct node *node;
            pthread_mutex_lock(&dh->fuse->lock);
            node = lookup_node(dh->fuse, dh->nodeid, name);
            if (node)
                stbuf.st_ino  = (ino_t) node->nodeid;
            pthread_mutex_unlock(&dh->fuse->lock);
        }
    }

    entsize = fuse_dirent_size(namelen);
    newlen = dh->len + entsize;

    if (off) {
        dh->filled = 0;
        if (newlen > dh->needlen)
            return 1;
    }

    newptr = (char *) realloc(dh->contents, newlen);
    if (!newptr) {
        dh->error = -ENOMEM;
        return 1;
    }
    dh->contents = newptr;
    fuse_add_dirent(dh->contents + dh->len, name, &stbuf, off ? off : newlen);
    dh->len = newlen;
    return 0;
}

static int fill_dir(void *buf, const char *name, const struct stat *stbuf,
                    off_t off)
{
    return fill_dir_common((struct fuse_dirhandle *) buf, name, stbuf, off);
}

static int fill_dir_old(struct fuse_dirhandle *dh, const char *name, int type,
                        ino_t ino)
{
    struct stat stbuf;

    memset(&stbuf, 0, sizeof(stbuf));
    stbuf.st_mode = type << 12;
    stbuf.st_ino = ino;

    fill_dir_common(dh, name, &stbuf, 0);
    return dh->error;
}

static int readdir_fill(struct fuse *f, fuse_ino_t ino, size_t size,
                        off_t off, struct fuse_dirhandle *dh,
                        struct fuse_file_info *fi)
{
    int err = -ENOENT;
    char *path;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        dh->len = 0;
        dh->error = 0;
        dh->needlen = size;
        dh->filled = 1;
        err = -ENOSYS;
        if (f->op.readdir)
            err = f->op.readdir(path, dh, fill_dir, off, fi);
        else if (f->op.getdir)
            err = f->op.getdir(path, dh, fill_dir_old);
        if (!err)
            err = dh->error;
        if (err)
            dh->filled = 0;
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    return err;
}

static void fuse_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
                         off_t off, struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_file_info fi;
    struct fuse_dirhandle *dh = get_dirhandle(llfi, &fi);

    pthread_mutex_lock(&dh->lock);
    /* According to SUS, directory contents need to be refreshed on
       rewinddir() */
    if (!off)
        dh->filled = 0;

    if (!dh->filled) {
        int err = readdir_fill(f, ino, size, off, dh, &fi);
        if (err) {
            reply_err(req, err);
            goto out;
        }
    }
    if (dh->filled) {
        if (off < dh->len) {
            if (off + size > dh->len)
                size = dh->len - off;
        } else
            size = 0;
    } else {
        size = dh->len;
        off = 0;
    }
    fuse_reply_buf(req, dh->contents + off, size);
 out:
    pthread_mutex_unlock(&dh->lock);
}

static void fuse_releasedir(fuse_req_t req, fuse_ino_t ino,
                            struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_file_info fi;
    struct fuse_dirhandle *dh = get_dirhandle(llfi, &fi);
    if (f->op.releasedir) {
        char *path;

        pthread_rwlock_rdlock(&f->tree_lock);
        path = get_path(f, ino);
        f->op.releasedir(path ? path : "-", &fi);
        free(path);
        pthread_rwlock_unlock(&f->tree_lock);
    }
    pthread_mutex_lock(&dh->lock);
    pthread_mutex_unlock(&dh->lock);
    pthread_mutex_destroy(&dh->lock);
    free(dh->contents);
    free(dh);
    reply_err(req, 0);
}

static void fuse_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync,
                          struct fuse_file_info *llfi)
{
    struct fuse *f = req_fuse_prepare(req);
    struct fuse_file_info fi;
    char *path;
    int err;

    get_dirhandle(llfi, &fi);

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.fsyncdir)
            err = f->op.fsyncdir(path, datasync, &fi);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static int default_statfs(struct statfs *buf)
{
    buf->f_namelen = 255;
    buf->f_bsize = 512;
    return 0;
}

static void convert_statfs_compat(struct fuse_statfs_compat1 *compatbuf,
                                  struct statfs *stbuf)
{
    stbuf->f_bsize   = compatbuf->block_size;
    stbuf->f_blocks  = compatbuf->blocks;
    stbuf->f_bfree   = compatbuf->blocks_free;
    stbuf->f_bavail  = compatbuf->blocks_free;
    stbuf->f_files   = compatbuf->files;
    stbuf->f_ffree   = compatbuf->files_free;
    stbuf->f_namelen = compatbuf->namelen;
}

static void fuse_statfs(fuse_req_t req)
{
    struct fuse *f = req_fuse_prepare(req);
    struct statfs buf;
    int err;

    memset(&buf, 0, sizeof(struct statfs));
    if (f->op.statfs) {
        if (!f->compat || f->compat > 11)
            err = f->op.statfs("/", &buf);
        else {
            struct fuse_statfs_compat1 compatbuf;
            memset(&compatbuf, 0, sizeof(struct fuse_statfs_compat1));
            err = ((struct fuse_operations_compat1 *) &f->op)->statfs(&compatbuf);
            if (!err)
                convert_statfs_compat(&compatbuf, &buf);
        }
    }
    else
        err = default_statfs(&buf);

    if (!err)
        fuse_reply_statfs(req, &buf);
    else
        reply_err(req, err);
}

static void fuse_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
                          const char *value, size_t size, int flags)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.setxattr)
            err = f->op.setxattr(path, name, value, size, flags);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static int common_getxattr(struct fuse *f, fuse_ino_t ino, const char *name,
                           char *value, size_t size)
{
    int err;
    char *path;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.getxattr)
            err = f->op.getxattr(path, name, value, size);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    return err;
}

static void fuse_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
                        size_t size)
{
    struct fuse *f = req_fuse_prepare(req);
    int res;

    if (size) {
        char *value = (char *) malloc(size);
        if (value == NULL) {
            reply_err(req, -ENOMEM);
            return;
        }
        res = common_getxattr(f, ino, name, value, size);
        if (res > 0)
            fuse_reply_buf(req, value, res);
        else
            reply_err(req, res);
        free(value);
    } else {
        res = common_getxattr(f, ino, name, NULL, 0);
        if (res >= 0)
            fuse_reply_xattr(req, res);
        else
            reply_err(req, res);
    }
}

static int common_listxattr(struct fuse *f, fuse_ino_t ino, char *list,
                            size_t size)
{
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.listxattr)
            err = f->op.listxattr(path, list, size);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    return err;
}

static void fuse_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
{
    struct fuse *f = req_fuse_prepare(req);
    int res;

    if (size) {
        char *list = (char *) malloc(size);
        if (list == NULL) {
            reply_err(req, -ENOMEM);
            return;
        }
        res = common_listxattr(f, ino, list, size);
        if (res > 0)
            fuse_reply_buf(req, list, res);
        else
            reply_err(req, res);
        free(list);
    } else {
        res = common_listxattr(f, ino, NULL, 0);
        if (res >= 0)
            fuse_reply_xattr(req, res);
        else
            reply_err(req, res);
    }
}

static void fuse_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
{
    struct fuse *f = req_fuse_prepare(req);
    char *path;
    int err;

    err = -ENOENT;
    pthread_rwlock_rdlock(&f->tree_lock);
    path = get_path(f, ino);
    if (path != NULL) {
        err = -ENOSYS;
        if (f->op.removexattr)
            err = f->op.removexattr(path, name);
        free(path);
    }
    pthread_rwlock_unlock(&f->tree_lock);
    reply_err(req, err);
}

static struct fuse_lowlevel_ops fuse_path_ops = {
    .init = fuse_data_init,
    .destroy = fuse_data_destroy,
    .lookup = fuse_lookup,
    .forget = fuse_forget,
    .getattr = fuse_getattr,
    .setattr = fuse_setattr,
    .access = fuse_access,
    .readlink = fuse_readlink,
    .mknod = fuse_mknod,
    .mkdir = fuse_mkdir,
    .unlink = fuse_unlink,
    .rmdir = fuse_rmdir,
    .symlink = fuse_symlink,
    .rename = fuse_rename,
    .link = fuse_link,
    .create = fuse_create,
    .open = fuse_open,
    .read = fuse_read,
    .write = fuse_write,
    .flush = fuse_flush,
    .release = fuse_release,
    .fsync = fuse_fsync,
    .opendir = fuse_opendir,
    .readdir = fuse_readdir,
    .releasedir = fuse_releasedir,
    .fsyncdir = fuse_fsyncdir,
    .statfs = fuse_statfs,
    .setxattr = fuse_setxattr,
    .getxattr = fuse_getxattr,
    .listxattr = fuse_listxattr,
    .removexattr = fuse_removexattr,
};

static void free_cmd(struct fuse_cmd *cmd)
{
    free(cmd->buf);
    free(cmd);
}

void fuse_process_cmd(struct fuse *f, struct fuse_cmd *cmd)
{
    fuse_session_process(f->se, cmd->buf, cmd->buflen, cmd->ch);
}

int fuse_exited(struct fuse *f)
{
    return fuse_session_exited(f->se);
}

struct fuse_session *fuse_get_session(struct fuse *f)
{
    return f->se;
}

static struct fuse_cmd *fuse_alloc_cmd(size_t bufsize)
{
    struct fuse_cmd *cmd = (struct fuse_cmd *) malloc(sizeof(*cmd));
    if (cmd == NULL) {
        fprintf(stderr, "fuse: failed to allocate cmd\n");
        return NULL;
    }
    cmd->buf = (char *) malloc(bufsize);
    if (cmd->buf == NULL) {
        fprintf(stderr, "fuse: failed to allocate read buffer\n");
        free(cmd);
        return NULL;
    }
    return cmd;
}

struct fuse_cmd *fuse_read_cmd(struct fuse *f)
{
    struct fuse_chan *ch = fuse_session_next_chan(f->se, NULL);
    size_t bufsize = fuse_chan_bufsize(ch);
    struct fuse_cmd *cmd = fuse_alloc_cmd(bufsize);
    if (cmd != NULL) {
        int res = fuse_chan_receive(ch, cmd->buf, bufsize);
        if (res <= 0) {
            free_cmd(cmd);
            return NULL;
        }
        cmd->buflen = res;
        cmd->ch = ch;
    }
    return cmd;
}

int fuse_loop(struct fuse *f)
{
    if (f)
        return fuse_session_loop(f->se);
    else
        return -1;
}

int fuse_invalidate(struct fuse *f, const char *path)
{
    (void) f;
    (void) path;
    return -EINVAL;
}

void fuse_exit(struct fuse *f)
{
    fuse_session_exit(f->se);
}

struct fuse_context *fuse_get_context()
{
    static struct fuse_context context;
    if (fuse_getcontext)
        return fuse_getcontext();
    else
        return &context;
}

void fuse_set_getcontext_func(struct fuse_context *(*func)(void))
{
    fuse_getcontext = func;
}

static int begins_with(const char *s, const char *beg)
{
    if (strncmp(s, beg, strlen(beg)) == 0)
        return 1;
    else
        return 0;
}

int fuse_is_lib_option(const char *opt)
{
    if (fuse_lowlevel_is_lib_option(opt) ||
        strcmp(opt, "debug") == 0 ||
        strcmp(opt, "hard_remove") == 0 ||
        strcmp(opt, "use_ino") == 0 ||
        strcmp(opt, "allow_root") == 0 ||
        strcmp(opt, "readdir_ino") == 0 ||
        strcmp(opt, "direct_io") == 0 ||
        strcmp(opt, "kernel_cache") == 0 ||
        begins_with(opt, "umask=") ||
        begins_with(opt, "uid=") ||
        begins_with(opt, "gid=") ||
        begins_with(opt, "entry_timeout=") ||
        begins_with(opt, "attr_timeout="))
        return 1;
    else
        return 0;
}

static int parse_lib_opts(struct fuse *f, const char *opts, char **llopts)
{
    if (opts) {
        char *xopts = strdup(opts);
        char *s = xopts;
        char *opt;
        char *d = xopts;

        if (xopts == NULL) {
            fprintf(stderr, "fuse: memory allocation failed\n");
            return -1;
        }

        while((opt = strsep(&s, ","))) {
            if (fuse_lowlevel_is_lib_option(opt)) {
                size_t optlen = strlen(opt);
                if (strcmp(opt, "debug") == 0)
                    f->flags |= FUSE_DEBUG;
                memmove(d, opt, optlen);
                d += optlen;
                *d++ = ',';
            } else if (strcmp(opt, "hard_remove") == 0)
                f->flags |= FUSE_HARD_REMOVE;
            else if (strcmp(opt, "use_ino") == 0)
                f->flags |= FUSE_USE_INO;
            else if (strcmp(opt, "readdir_ino") == 0)
                f->flags |= FUSE_READDIR_INO;
            else if (strcmp(opt, "direct_io") == 0)
                f->flags |= FUSE_DIRECT_IO;
            else if (strcmp(opt, "kernel_cache") == 0)
                f->flags |= FUSE_KERNEL_CACHE;
            else if (sscanf(opt, "umask=%o", &f->umask) == 1)
                f->flags |= FUSE_SET_MODE;
            else if (sscanf(opt, "uid=%u", &f->uid) == 1)
                f->flags |= FUSE_SET_UID;
            else if(sscanf(opt, "gid=%u", &f->gid) == 1)
                f->flags |= FUSE_SET_GID;
            else if (sscanf(opt, "entry_timeout=%lf", &f->entry_timeout) == 1)
                /* nop */;
            else if (sscanf(opt, "attr_timeout=%lf", &f->attr_timeout) == 1)
                /* nop */;
            else
                fprintf(stderr, "fuse: warning: unknown option `%s'\n", opt);
        }
        if (d != xopts) {
            d[-1] = '\0';
            *llopts = xopts;
        }
        else
            free(xopts);
    }
    return 0;
}

struct fuse *fuse_new_common(int fd, const char *opts,
                             const struct fuse_operations *op,
                             size_t op_size, int compat)
{
    struct fuse_chan *ch;
    struct fuse *f;
    struct node *root;
    char *llopts = NULL;

    if (sizeof(struct fuse_operations) < op_size) {
        fprintf(stderr, "fuse: warning: library too old, some operations may not not work\n");
        op_size = sizeof(struct fuse_operations);
    }

    f = (struct fuse *) calloc(1, sizeof(struct fuse));
    if (f == NULL) {
        fprintf(stderr, "fuse: failed to allocate fuse object\n");
        goto out;
    }

    f->entry_timeout = 1.0;
    f->attr_timeout = 1.0;

    if (parse_lib_opts(f, opts, &llopts) == -1)
        goto out_free;

    f->se = fuse_lowlevel_new(llopts, &fuse_path_ops, sizeof(fuse_path_ops), f);
    free(llopts);
    if (f->se == NULL)
        goto out_free;
    
    ch = fuse_kern_chan_new(fd);
    if (ch == NULL)
        goto out_free_session;
    
    fuse_session_add_chan(f->se, ch);

    f->ctr = 0;
    f->generation = 0;
    /* FIXME: Dynamic hash table */
    f->name_table_size = 14057;
    f->name_table = (struct node **)
        calloc(1, sizeof(struct node *) * f->name_table_size);
    if (f->name_table == NULL) {
        fprintf(stderr, "fuse: memory allocation failed\n");
        goto out_free_session;
    }

    f->id_table_size = 14057;
    f->id_table = (struct node **)
        calloc(1, sizeof(struct node *) * f->id_table_size);
    if (f->id_table == NULL) {
        fprintf(stderr, "fuse: memory allocation failed\n");
        goto out_free_name_table;
    }

    mutex_init(&f->lock);
    memcpy(&f->op, op, op_size);
    f->compat = compat;

    root = (struct node *) calloc(1, sizeof(struct node));
    if (root == NULL) {
        fprintf(stderr, "fuse: memory allocation failed\n");
        goto out_free_id_table;
    }

    root->name = strdup("/");
    if (root->name == NULL) {
        fprintf(stderr, "fuse: memory allocation failed\n");
        goto out_free_root;
    }

    root->parent = 0;
    root->nodeid = FUSE_ROOT_ID;
    root->generation = 0;
    root->refctr = 1;
    root->nlookup = 1;
    hash_id(f, root);

    return f;

 out_free_root:
    free(root);
 out_free_id_table:
    free(f->id_table);
 out_free_name_table:
    free(f->name_table);
 out_free_session:
    fuse_session_destroy(f->se);
 out_free:
    free(f);
 out:
    return NULL;
}

struct fuse *fuse_new(int fd, const char *opts,
                      const struct fuse_operations *op, size_t op_size)
{
    return fuse_new_common(fd, opts, op, op_size, 0);
}

struct fuse *fuse_new_compat2(int fd, const char *opts,
                              const struct fuse_operations_compat2 *op)
{
    return fuse_new_common(fd, opts, (struct fuse_operations *) op,
                           sizeof(struct fuse_operations_compat2), 21);
}

struct fuse *fuse_new_compat1(int fd, int flags,
                              const struct fuse_operations_compat1 *op)
{
    const char *opts = NULL;
    if (flags & FUSE_DEBUG_COMPAT1)
        opts = "debug";
    return fuse_new_common(fd, opts, (struct fuse_operations *) op,
                           sizeof(struct fuse_operations_compat1), 11);
}

void fuse_destroy(struct fuse *f)
{
    size_t i;
    for (i = 0; i < f->id_table_size; i++) {
        struct node *node;

        for (node = f->id_table[i]; node != NULL; node = node->id_next) {
            if (node->is_hidden) {
                char *path = get_path(f, node->nodeid);
                if (path) {
                    f->op.unlink(path);
                    free(path);
                }
            }
        }
    }
    for (i = 0; i < f->id_table_size; i++) {
        struct node *node;
        struct node *next;

        for (node = f->id_table[i]; node != NULL; node = next) {
            next = node->id_next;
            free_node(node);
        }
    }
    free(f->id_table);
    free(f->name_table);
    pthread_mutex_destroy(&f->lock);
    fuse_session_destroy(f->se);
    free(f);
}

__asm__(".symver fuse_exited,__fuse_exited@");
__asm__(".symver fuse_process_cmd,__fuse_process_cmd@");
__asm__(".symver fuse_read_cmd,__fuse_read_cmd@");
__asm__(".symver fuse_set_getcontext_func,__fuse_set_getcontext_func@");
__asm__(".symver fuse_new_compat2,fuse_new@");