fuse.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

  Implementation of the high-level FUSE API on top of the low-level
  API.

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB
*/


/* For pthread_rwlock_t */
#define _GNU_SOURCE

#include "config.h"
#include "fuse_i.h"
#include "fuse_lowlevel.h"
#include "fuse_opt.h"
#include "fuse_misc.h"
#include "fuse_kernel.h"

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdbool.h>
#include <unistd.h>
#include <time.h>
#include <fcntl.h>
#include <limits.h>
#include <errno.h>
#include <signal.h>
#include <dlfcn.h>
#include <assert.h>
#include <poll.h>
#include <sys/param.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/file.h>

#define FUSE_NODE_SLAB 1

#ifndef MAP_ANONYMOUS
#undef FUSE_NODE_SLAB
#endif

#ifndef RENAME_EXCHANGE
#define RENAME_EXCHANGE         (1 << 1)        /* Exchange source and dest */
#endif

#define FUSE_DEFAULT_INTR_SIGNAL SIGUSR1

#define FUSE_UNKNOWN_INO 0xffffffff
#define OFFSET_MAX 0x7fffffffffffffffLL

#define NODE_TABLE_MIN_SIZE 8192

struct fuse_fs {
        struct fuse_operations op;
        struct fuse_module *m;
        void *user_data;
        int debug;
};

struct fusemod_so {
        void *handle;
        int ctr;
};

struct lock_queue_element {
        struct lock_queue_element *next;
        pthread_cond_t cond;
        fuse_ino_t nodeid1;
        const char *name1;
        char **path1;
        struct node **wnode1;
        fuse_ino_t nodeid2;
        const char *name2;
        char **path2;
        struct node **wnode2;
        int err;
        bool first_locked : 1;
        bool second_locked : 1;
        bool done : 1;
};

struct node_table {
        struct node **array;
        size_t use;
        size_t size;
        size_t split;
};

#define container_of(ptr, type, member) ({                              \
                        const typeof( ((type *)0)->member ) *__mptr = (ptr); \
                        (type *)( (char *)__mptr - offsetof(type,member) );})

#define list_entry(ptr, type, member)           \
        container_of(ptr, type, member)

struct list_head {
        struct list_head *next;
        struct list_head *prev;
};

struct node_slab {
        struct list_head list;  /* must be the first member */
        struct list_head freelist;
        int used;
};

struct fuse {
        struct fuse_session *se;
        struct node_table name_table;
        struct node_table id_table;
        struct list_head lru_table;
        fuse_ino_t ctr;
        unsigned int generation;
        unsigned int hidectr;
        pthread_mutex_t lock;
        struct fuse_config conf;
        int intr_installed;
        struct fuse_fs *fs;
        struct lock_queue_element *lockq;
        int pagesize;
        struct list_head partial_slabs;
        struct list_head full_slabs;
        pthread_t prune_thread;
};

struct lock {
        int type;
        off_t start;
        off_t end;
        pid_t pid;
        uint64_t owner;
        struct lock *next;
};

struct node {
        struct node *name_next;
        struct node *id_next;
        fuse_ino_t nodeid;
        unsigned int generation;
        int refctr;
        struct node *parent;
        char *name;
        uint64_t nlookup;
        int open_count;
        struct timespec stat_updated;
        struct timespec mtime;
        off_t size;
        struct lock *locks;
        unsigned int is_hidden : 1;
        unsigned int cache_valid : 1;
        int treelock;
        char inline_name[32];
};

#define TREELOCK_WRITE -1
#define TREELOCK_WAIT_OFFSET INT_MIN

struct node_lru {
        struct node node;
        struct list_head lru;
        struct timespec forget_time;
};

struct fuse_direntry {
        struct stat stat;
        char *name;
        struct fuse_direntry *next;
};

struct fuse_dh {
        pthread_mutex_t lock;
        struct fuse *fuse;
        fuse_req_t req;
        char *contents;
        struct fuse_direntry *first;
        struct fuse_direntry **last;
        unsigned len;
        unsigned size;
        unsigned needlen;
        int filled;
        uint64_t fh;
        int error;
        fuse_ino_t nodeid;
};

struct fuse_context_i {
        struct fuse_context ctx;
        fuse_req_t req;
};

/* Defined by FUSE_REGISTER_MODULE() in lib/modules/subdir.c and iconv.c.  */
extern fuse_module_factory_t fuse_module_subdir_factory;
#ifdef HAVE_ICONV
extern fuse_module_factory_t fuse_module_iconv_factory;
#endif

static pthread_key_t fuse_context_key;
static pthread_mutex_t fuse_context_lock = PTHREAD_MUTEX_INITIALIZER;
static int fuse_context_ref;
static struct fuse_module *fuse_modules = NULL;

static int fuse_register_module(const char *name,
                                fuse_module_factory_t factory,
                                struct fusemod_so *so)
{
        struct fuse_module *mod;

        mod = calloc(1, sizeof(struct fuse_module));
        if (!mod) {
                fprintf(stderr, "fuse: failed to allocate module\n");
                return -1;
        }
        mod->name = strdup(name);
        if (!mod->name) {
                fprintf(stderr, "fuse: failed to allocate module name\n");
                free(mod);
                return -1;
        }
        mod->factory = factory;
        mod->ctr = 0;
        mod->so = so;
        if (mod->so)
                mod->so->ctr++;
        mod->next = fuse_modules;
        fuse_modules = mod;

        return 0;
}

static void fuse_unregister_module(struct fuse_module *m)
{
        struct fuse_module **mp;
        for (mp = &fuse_modules; *mp; mp = &(*mp)->next) {
                if (*mp == m) {
                        *mp = (*mp)->next;
                        break;
                }
        }
        free(m->name);
        free(m);
}

static int fuse_load_so_module(const char *module)
{
        int ret = -1;
        char *tmp;
        struct fusemod_so *so;
        fuse_module_factory_t factory;

        tmp = malloc(strlen(module) + 64);
        if (!tmp) {
                fprintf(stderr, "fuse: memory allocation failed\n");
                return -1;
        }
        sprintf(tmp, "libfusemod_%s.so", module);
        so = calloc(1, sizeof(struct fusemod_so));
        if (!so) {
                fprintf(stderr, "fuse: failed to allocate module so\n");
                goto out;
        }

        so->handle = dlopen(tmp, RTLD_NOW);
        if (so->handle == NULL) {
                fprintf(stderr, "fuse: dlopen(%s) failed: %s\n",
                        tmp, dlerror());
                goto out_free_so;
        }

        sprintf(tmp, "fuse_module_%s_factory", module);
        *(void**)(&factory) = dlsym(so->handle, tmp);
        if (factory == NULL) {
                fprintf(stderr, "fuse: symbol <%s> not found in module: %s\n",
                        tmp, dlerror());
                goto out_dlclose;
        }
        ret = fuse_register_module(module, factory, so);
        if (ret)
                goto out_dlclose;

out:
        free(tmp);
        return ret;

out_dlclose:
        dlclose(so->handle);
out_free_so:
        free(so);
        goto out;
}

static struct fuse_module *fuse_find_module(const char *module)
{
        struct fuse_module *m;
        for (m = fuse_modules; m; m = m->next) {
                if (strcmp(module, m->name) == 0) {
                        m->ctr++;
                        break;
                }
        }
        return m;
}

static struct fuse_module *fuse_get_module(const char *module)
{
        struct fuse_module *m;

        pthread_mutex_lock(&fuse_context_lock);
        m = fuse_find_module(module);
        if (!m) {
                int err = fuse_load_so_module(module);
                if (!err)
                        m = fuse_find_module(module);
        }
        pthread_mutex_unlock(&fuse_context_lock);
        return m;
}

static void fuse_put_module(struct fuse_module *m)
{
        pthread_mutex_lock(&fuse_context_lock);
        if (m->so)
                assert(m->ctr > 0);
        /* Builtin modules may already have m->ctr == 0 */
        if (m->ctr > 0)
                m->ctr--;
        if (!m->ctr && m->so) {
                struct fusemod_so *so = m->so;
                assert(so->ctr > 0);
                so->ctr--;
                if (!so->ctr) {
                        struct fuse_module **mp;
                        for (mp = &fuse_modules; *mp;) {
                                if ((*mp)->so == so)
                                        fuse_unregister_module(*mp);
                                else
                                        mp = &(*mp)->next;
                        }
                        dlclose(so->handle);
                        free(so);
                }
        } else if (!m->ctr) {
                fuse_unregister_module(m);
        }
        pthread_mutex_unlock(&fuse_context_lock);
}

static void init_list_head(struct list_head *list)
{
        list->next = list;
        list->prev = list;
}

static int list_empty(const struct list_head *head)
{
        return head->next == head;
}

static void list_add(struct list_head *new, struct list_head *prev,
                     struct list_head *next)
{
        next->prev = new;
        new->next = next;
        new->prev = prev;
        prev->next = new;
}

static inline void list_add_head(struct list_head *new, struct list_head *head)
{
        list_add(new, head, head->next);
}

static inline void list_add_tail(struct list_head *new, struct list_head *head)
{
        list_add(new, head->prev, head);
}

static inline void list_del(struct list_head *entry)
{
        struct list_head *prev = entry->prev;
        struct list_head *next = entry->next;

        next->prev = prev;
        prev->next = next;
}

static inline int lru_enabled(struct fuse *f)
{
        return f->conf.remember > 0;
}

static struct node_lru *node_lru(struct node *node)
{
        return (struct node_lru *) node;
}

static size_t get_node_size(struct fuse *f)
{
        if (lru_enabled(f))
                return sizeof(struct node_lru);
        else
                return sizeof(struct node);
}

#ifdef FUSE_NODE_SLAB
static struct node_slab *list_to_slab(struct list_head *head)
{
        return (struct node_slab *) head;
}

static struct node_slab *node_to_slab(struct fuse *f, struct node *node)
{
        return (struct node_slab *) (((uintptr_t) node) & ~((uintptr_t) f->pagesize - 1));
}

static int alloc_slab(struct fuse *f)
{
        void *mem;
        struct node_slab *slab;
        char *start;
        size_t num;
        size_t i;
        size_t node_size = get_node_size(f);

        mem = mmap(NULL, f->pagesize, PROT_READ | PROT_WRITE,
                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

        if (mem == MAP_FAILED)
                return -1;

        slab = mem;
        init_list_head(&slab->freelist);
        slab->used = 0;
        num = (f->pagesize - sizeof(struct node_slab)) / node_size;

        start = (char *) mem + f->pagesize - num * node_size;
        for (i = 0; i < num; i++) {
                struct list_head *n;

                n = (struct list_head *) (start + i * node_size);
                list_add_tail(n, &slab->freelist);
        }
        list_add_tail(&slab->list, &f->partial_slabs);

        return 0;
}

static struct node *alloc_node(struct fuse *f)
{
        struct node_slab *slab;
        struct list_head *node;

        if (list_empty(&f->partial_slabs)) {
                int res = alloc_slab(f);
                if (res != 0)
                        return NULL;
        }
        slab = list_to_slab(f->partial_slabs.next);
        slab->used++;
        node = slab->freelist.next;
        list_del(node);
        if (list_empty(&slab->freelist)) {
                list_del(&slab->list);
                list_add_tail(&slab->list, &f->full_slabs);
        }
        memset(node, 0, sizeof(struct node));

        return (struct node *) node;
}

static void free_slab(struct fuse *f, struct node_slab *slab)
{
        int res;

        list_del(&slab->list);
        res = munmap(slab, f->pagesize);
        if (res == -1)
                fprintf(stderr, "fuse warning: munmap(%p) failed\n", slab);
}

static void free_node_mem(struct fuse *f, struct node *node)
{
        struct node_slab *slab = node_to_slab(f, node);
        struct list_head *n = (struct list_head *) node;

        slab->used--;
        if (slab->used) {
                if (list_empty(&slab->freelist)) {
                        list_del(&slab->list);
                        list_add_tail(&slab->list, &f->partial_slabs);
                }
                list_add_head(n, &slab->freelist);
        } else {
                free_slab(f, slab);
        }
}
#else
static struct node *alloc_node(struct fuse *f)
{
        return (struct node *) calloc(1, get_node_size(f));
}

static void free_node_mem(struct fuse *f, struct node *node)
{
        (void) f;
        free(node);
}
#endif

static size_t id_hash(struct fuse *f, fuse_ino_t ino)
{
        uint64_t hash = ((uint32_t) ino * 2654435761U) % f->id_table.size;
        uint64_t oldhash = hash % (f->id_table.size / 2);

        if (oldhash >= f->id_table.split)
                return oldhash;
        else
                return hash;
}

static struct node *get_node_nocheck(struct fuse *f, fuse_ino_t nodeid)
{
        size_t hash = id_hash(f, nodeid);
        struct node *node;

        for (node = f->id_table.array[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 %llu not found\n",
                        (unsigned long long) nodeid);
                abort();
        }
        return node;
}

static void curr_time(struct timespec *now);
static double diff_timespec(const struct timespec *t1,
                           const struct timespec *t2);

static void remove_node_lru(struct node *node)
{
        struct node_lru *lnode = node_lru(node);
        list_del(&lnode->lru);
        init_list_head(&lnode->lru);
}

static void set_forget_time(struct fuse *f, struct node *node)
{
        struct node_lru *lnode = node_lru(node);

        list_del(&lnode->lru);
        list_add_tail(&lnode->lru, &f->lru_table);
        curr_time(&lnode->forget_time);
}

static void free_node(struct fuse *f, struct node *node)
{
        if (node->name != node->inline_name)
                free(node->name);
        free_node_mem(f, node);
}

static void node_table_reduce(struct node_table *t)
{
        size_t newsize = t->size / 2;
        void *newarray;

        if (newsize < NODE_TABLE_MIN_SIZE)
                return;

        newarray = realloc(t->array, sizeof(struct node *) * newsize);
        if (newarray != NULL)
                t->array = newarray;

        t->size = newsize;
        t->split = t->size / 2;
}

static void remerge_id(struct fuse *f)
{
        struct node_table *t = &f->id_table;
        int iter;

        if (t->split == 0)
                node_table_reduce(t);

        for (iter = 8; t->split > 0 && iter; iter--) {
                struct node **upper;

                t->split--;
                upper = &t->array[t->split + t->size / 2];
                if (*upper) {
                        struct node **nodep;

                        for (nodep = &t->array[t->split]; *nodep;
                             nodep = &(*nodep)->id_next);

                        *nodep = *upper;
                        *upper = NULL;
                        break;
                }
        }
}

static void unhash_id(struct fuse *f, struct node *node)
{
        struct node **nodep = &f->id_table.array[id_hash(f, node->nodeid)];

        for (; *nodep != NULL; nodep = &(*nodep)->id_next)
                if (*nodep == node) {
                        *nodep = node->id_next;
                        f->id_table.use--;

                        if(f->id_table.use < f->id_table.size / 4)
                                remerge_id(f);
                        return;
                }
}

static int node_table_resize(struct node_table *t)
{
        size_t newsize = t->size * 2;
        void *newarray;

        newarray = realloc(t->array, sizeof(struct node *) * newsize);
        if (newarray == NULL)
                return -1;

        t->array = newarray;
        memset(t->array + t->size, 0, t->size * sizeof(struct node *));
        t->size = newsize;
        t->split = 0;

        return 0;
}

static void rehash_id(struct fuse *f)
{
        struct node_table *t = &f->id_table;
        struct node **nodep;
        struct node **next;
        size_t hash;

        if (t->split == t->size / 2)
                return;

        hash = t->split;
        t->split++;
        for (nodep = &t->array[hash]; *nodep != NULL; nodep = next) {
                struct node *node = *nodep;
                size_t newhash = id_hash(f, node->nodeid);

                if (newhash != hash) {
                        next = nodep;
                        *nodep = node->id_next;
                        node->id_next = t->array[newhash];
                        t->array[newhash] = node;
                } else {
                        next = &node->id_next;
                }
        }
        if (t->split == t->size / 2)
                node_table_resize(t);
}

static void hash_id(struct fuse *f, struct node *node)
{
        size_t hash = id_hash(f, node->nodeid);
        node->id_next = f->id_table.array[hash];
        f->id_table.array[hash] = node;
        f->id_table.use++;

        if (f->id_table.use >= f->id_table.size / 2)
                rehash_id(f);
}

static size_t name_hash(struct fuse *f, fuse_ino_t parent,
                        const char *name)
{
        uint64_t hash = parent;
        uint64_t oldhash;

        for (; *name; name++)
                hash = hash * 31 + (unsigned char) *name;

        hash %= f->name_table.size;
        oldhash = hash % (f->name_table.size / 2);
        if (oldhash >= f->name_table.split)
                return oldhash;
        else
                return hash;
}

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

static void remerge_name(struct fuse *f)
{
        struct node_table *t = &f->name_table;
        int iter;

        if (t->split == 0)
                node_table_reduce(t);

        for (iter = 8; t->split > 0 && iter; iter--) {
                struct node **upper;

                t->split--;
                upper = &t->array[t->split + t->size / 2];
                if (*upper) {
                        struct node **nodep;

                        for (nodep = &t->array[t->split]; *nodep;
                             nodep = &(*nodep)->name_next);

                        *nodep = *upper;
                        *upper = NULL;
                        break;
                }
        }
}

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

                for (; *nodep != NULL; nodep = &(*nodep)->name_next)
                        if (*nodep == node) {
                                *nodep = node->name_next;
                                node->name_next = NULL;
                                unref_node(f, node->parent);
                                if (node->name != node->inline_name)
                                        free(node->name);
                                node->name = NULL;
                                node->parent = NULL;
                                f->name_table.use--;

                                if (f->name_table.use < f->name_table.size / 4)
                                        remerge_name(f);
                                return;
                        }
                fprintf(stderr,
                        "fuse internal error: unable to unhash node: %llu\n",
                        (unsigned long long) node->nodeid);
                abort();
        }
}

static void rehash_name(struct fuse *f)
{
        struct node_table *t = &f->name_table;
        struct node **nodep;
        struct node **next;
        size_t hash;

        if (t->split == t->size / 2)
                return;

        hash = t->split;
        t->split++;
        for (nodep = &t->array[hash]; *nodep != NULL; nodep = next) {
                struct node *node = *nodep;
                size_t newhash = name_hash(f, node->parent->nodeid, node->name);

                if (newhash != hash) {
                        next = nodep;
                        *nodep = node->name_next;
                        node->name_next = t->array[newhash];
                        t->array[newhash] = node;
                } else {
                        next = &node->name_next;
                }
        }
        if (t->split == t->size / 2)
                node_table_resize(t);
}

static int hash_name(struct fuse *f, struct node *node, fuse_ino_t parentid,
                     const char *name)
{
        size_t hash = name_hash(f, parentid, name);
        struct node *parent = get_node(f, parentid);
        if (strlen(name) < sizeof(node->inline_name)) {
                strcpy(node->inline_name, name);
                node->name = node->inline_name;
        } else {
                node->name = strdup(name);
                if (node->name == NULL)
                        return -1;
        }

        parent->refctr ++;
        node->parent = parent;
        node->name_next = f->name_table.array[hash];
        f->name_table.array[hash] = node;
        f->name_table.use++;

        if (f->name_table.use >= f->name_table.size / 2)
                rehash_name(f);

        return 0;
}

static void delete_node(struct fuse *f, struct node *node)
{
        if (f->conf.debug)
                fprintf(stderr, "DELETE: %llu\n",
                        (unsigned long long) node->nodeid);

        assert(node->treelock == 0);
        unhash_name(f, node);
        if (lru_enabled(f))
                remove_node_lru(node);
        unhash_id(f, node);
        free_node(f, 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 = (f->ctr + 1) & 0xffffffff;
                if (!f->ctr)
                        f->generation ++;
        } while (f->ctr == 0 || f->ctr == FUSE_UNKNOWN_INO ||
                 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.array[hash]; node != NULL; node = node->name_next)
                if (node->parent->nodeid == parent &&
                    strcmp(node->name, name) == 0)
                        return node;

        return NULL;
}

static void inc_nlookup(struct node *node)
{
        if (!node->nlookup)
                node->refctr++;
        node->nlookup++;
}

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

        pthread_mutex_lock(&f->lock);
        if (!name)
                node = get_node(f, parent);
        else
                node = lookup_node(f, parent, name);
        if (node == NULL) {
                node = alloc_node(f);
                if (node == NULL)
                        goto out_err;

                node->nodeid = next_id(f);
                node->generation = f->generation;
                if (f->conf.remember)
                        inc_nlookup(node);

                if (hash_name(f, node, parent, name) == -1) {
                        free_node(f, node);
                        node = NULL;
                        goto out_err;
                }
                hash_id(f, node);
                if (lru_enabled(f)) {
                        struct node_lru *lnode = node_lru(node);
                        init_list_head(&lnode->lru);
                }
        } else if (lru_enabled(f) && node->nlookup == 1) {
                remove_node_lru(node);
        }
        inc_nlookup(node);
out_err:
        pthread_mutex_unlock(&f->lock);
        return node;
}

static int lookup_path_in_cache(struct fuse *f,
                const char *path, fuse_ino_t *inop)
{
        char *tmp = strdup(path);
        if (!tmp)
                return -ENOMEM;

        pthread_mutex_lock(&f->lock);
        fuse_ino_t ino = FUSE_ROOT_ID;

        int err = 0;
        char *save_ptr;
        char *path_element = strtok_r(tmp, "/", &save_ptr);
        while (path_element != NULL) {
                struct node *node = lookup_node(f, ino, path_element);
                if (node == NULL) {
                        err = -ENOENT;
                        break;
                }
                ino = node->nodeid;
                path_element = strtok_r(NULL, "/", &save_ptr);
        }
        pthread_mutex_unlock(&f->lock);
        free(tmp);

        if (!err)
                *inop = ino;
        return err;
}

static char *add_name(char **buf, unsigned *bufsize, char *s, const char *name)
{
        size_t len = strlen(name);

        if (s - len <= *buf) {
                unsigned pathlen = *bufsize - (s - *buf);
                unsigned newbufsize = *bufsize;
                char *newbuf;

                while (newbufsize < pathlen + len + 1) {
                        if (newbufsize >= 0x80000000)
                                newbufsize = 0xffffffff;
                        else
                                newbufsize *= 2;
                }

                newbuf = realloc(*buf, newbufsize);
                if (newbuf == NULL)
                        return NULL;

                *buf = newbuf;
                s = newbuf + newbufsize - pathlen;
                memmove(s, newbuf + *bufsize - pathlen, pathlen);
                *bufsize = newbufsize;
        }
        s -= len;
        strncpy(s, name, len);
        s--;
        *s = '/';

        return s;
}

static void unlock_path(struct fuse *f, fuse_ino_t nodeid, struct node *wnode,
                        struct node *end)
{
        struct node *node;

        if (wnode) {
                assert(wnode->treelock == TREELOCK_WRITE);
                wnode->treelock = 0;
        }

        for (node = get_node(f, nodeid);
             node != end && node->nodeid != FUSE_ROOT_ID; node = node->parent) {
                assert(node->treelock != 0);
                assert(node->treelock != TREELOCK_WAIT_OFFSET);
                assert(node->treelock != TREELOCK_WRITE);
                node->treelock--;
                if (node->treelock == TREELOCK_WAIT_OFFSET)
                        node->treelock = 0;
        }
}

static int try_get_path(struct fuse *f, fuse_ino_t nodeid, const char *name,
                        char **path, struct node **wnodep, bool need_lock)
{
        unsigned bufsize = 256;
        char *buf;
        char *s;
        struct node *node;
        struct node *wnode = NULL;
        int err;

        *path = NULL;

        err = -ENOMEM;
        buf = malloc(bufsize);
        if (buf == NULL)
                goto out_err;

        s = buf + bufsize - 1;
        *s = '\0';

        if (name != NULL) {
                s = add_name(&buf, &bufsize, s, name);
                err = -ENOMEM;
                if (s == NULL)
                        goto out_free;
        }

        if (wnodep) {
                assert(need_lock);
                wnode = lookup_node(f, nodeid, name);
                if (wnode) {
                        if (wnode->treelock != 0) {
                                if (wnode->treelock > 0)
                                        wnode->treelock += TREELOCK_WAIT_OFFSET;
                                err = -EAGAIN;
                                goto out_free;
                        }
                        wnode->treelock = TREELOCK_WRITE;
                }
        }

        for (node = get_node(f, nodeid); node->nodeid != FUSE_ROOT_ID;
             node = node->parent) {
                err = -ENOENT;
                if (node->name == NULL || node->parent == NULL)
                        goto out_unlock;

                err = -ENOMEM;
                s = add_name(&buf, &bufsize, s, node->name);
                if (s == NULL)
                        goto out_unlock;

                if (need_lock) {
                        err = -EAGAIN;
                        if (node->treelock < 0)
                                goto out_unlock;

                        node->treelock++;
                }
        }

        if (s[0])
                memmove(buf, s, bufsize - (s - buf));
        else
                strcpy(buf, "/");

        *path = buf;
        if (wnodep)
                *wnodep = wnode;

        return 0;

 out_unlock:
        if (need_lock)
                unlock_path(f, nodeid, wnode, node);
 out_free:
        free(buf);

 out_err:
        return err;
}

static void queue_element_unlock(struct fuse *f, struct lock_queue_element *qe)
{
        struct node *wnode;

        if (qe->first_locked) {
                wnode = qe->wnode1 ? *qe->wnode1 : NULL;
                unlock_path(f, qe->nodeid1, wnode, NULL);
                qe->first_locked = false;
        }
        if (qe->second_locked) {
                wnode = qe->wnode2 ? *qe->wnode2 : NULL;
                unlock_path(f, qe->nodeid2, wnode, NULL);
                qe->second_locked = false;
        }
}

static void queue_element_wakeup(struct fuse *f, struct lock_queue_element *qe)
{
        int err;
        bool first = (qe == f->lockq);

        if (!qe->path1) {
                /* Just waiting for it to be unlocked */
                if (get_node(f, qe->nodeid1)->treelock == 0)
                        pthread_cond_signal(&qe->cond);

                return;
        }

        if (!qe->first_locked) {
                err = try_get_path(f, qe->nodeid1, qe->name1, qe->path1,
                                   qe->wnode1, true);
                if (!err)
                        qe->first_locked = true;
                else if (err != -EAGAIN)
                        goto err_unlock;
        }
        if (!qe->second_locked && qe->path2) {
                err = try_get_path(f, qe->nodeid2, qe->name2, qe->path2,
                                   qe->wnode2, true);
                if (!err)
                        qe->second_locked = true;
                else if (err != -EAGAIN)
                        goto err_unlock;
        }

        if (qe->first_locked && (qe->second_locked || !qe->path2)) {
                err = 0;
                goto done;
        }

        /*
         * Only let the first element be partially locked otherwise there could
         * be a deadlock.
         *
         * But do allow the first element to be partially locked to prevent
         * starvation.
         */
        if (!first)
                queue_element_unlock(f, qe);

        /* keep trying */
        return;

err_unlock:
        queue_element_unlock(f, qe);
done:
        qe->err = err;
        qe->done = true;
        pthread_cond_signal(&qe->cond);
}

static void wake_up_queued(struct fuse *f)
{
        struct lock_queue_element *qe;

        for (qe = f->lockq; qe != NULL; qe = qe->next)
                queue_element_wakeup(f, qe);
}

static void debug_path(struct fuse *f, const char *msg, fuse_ino_t nodeid,
                       const char *name, bool wr)
{
        if (f->conf.debug) {
                struct node *wnode = NULL;

                if (wr)
                        wnode = lookup_node(f, nodeid, name);

                if (wnode) {
                        fprintf(stderr, "%s %llu (w)\n",
                                msg, (unsigned long long) wnode->nodeid);
                } else {
                        fprintf(stderr, "%s %llu\n",
                                msg, (unsigned long long) nodeid);
                }
        }
}

static void queue_path(struct fuse *f, struct lock_queue_element *qe)
{
        struct lock_queue_element **qp;

        qe->done = false;
        qe->first_locked = false;
        qe->second_locked = false;
        pthread_cond_init(&qe->cond, NULL);
        qe->next = NULL;
        for (qp = &f->lockq; *qp != NULL; qp = &(*qp)->next);
        *qp = qe;
}

static void dequeue_path(struct fuse *f, struct lock_queue_element *qe)
{
        struct lock_queue_element **qp;

        pthread_cond_destroy(&qe->cond);
        for (qp = &f->lockq; *qp != qe; qp = &(*qp)->next);
        *qp = qe->next;
}

static int wait_path(struct fuse *f, struct lock_queue_element *qe)
{
        queue_path(f, qe);

        do {
                pthread_cond_wait(&qe->cond, &f->lock);
        } while (!qe->done);

        dequeue_path(f, qe);

        return qe->err;
}

static int get_path_common(struct fuse *f, fuse_ino_t nodeid, const char *name,
                           char **path, struct node **wnode)
{
        int err;

        pthread_mutex_lock(&f->lock);
        err = try_get_path(f, nodeid, name, path, wnode, true);
        if (err == -EAGAIN) {
                struct lock_queue_element qe = {
                        .nodeid1 = nodeid,
                        .name1 = name,
                        .path1 = path,
                        .wnode1 = wnode,
                };
                debug_path(f, "QUEUE PATH", nodeid, name, !!wnode);
                err = wait_path(f, &qe);
                debug_path(f, "DEQUEUE PATH", nodeid, name, !!wnode);
        }
        pthread_mutex_unlock(&f->lock);

        return err;
}

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

static int get_path_nullok(struct fuse *f, fuse_ino_t nodeid, char **path)
{
        int err = 0;

        if (f->conf.nullpath_ok) {
                *path = NULL;
        } else {
                err = get_path_common(f, nodeid, NULL, path, NULL);
                if (err == -ENOENT)
                        err = 0;
        }

        return err;
}

static int get_path_name(struct fuse *f, fuse_ino_t nodeid, const char *name,
                         char **path)
{
        return get_path_common(f, nodeid, name, path, NULL);
}

static int get_path_wrlock(struct fuse *f, fuse_ino_t nodeid, const char *name,
                           char **path, struct node **wnode)
{
        return get_path_common(f, nodeid, name, path, wnode);
}

#if defined(__FreeBSD__)
#define CHECK_DIR_LOOP
#endif

#if defined(CHECK_DIR_LOOP)
static int check_dir_loop(struct fuse *f,
                          fuse_ino_t nodeid1, const char *name1,
                          fuse_ino_t nodeid2, const char *name2)
{
        struct node *node, *node1, *node2;
        fuse_ino_t id1, id2;

        node1 = lookup_node(f, nodeid1, name1);
        id1 = node1 ? node1->nodeid : nodeid1;

        node2 = lookup_node(f, nodeid2, name2);
        id2 = node2 ? node2->nodeid : nodeid2;

        for (node = get_node(f, id2); node->nodeid != FUSE_ROOT_ID;
             node = node->parent) {
                if (node->name == NULL || node->parent == NULL)
                        break;

                if (node->nodeid != id2 && node->nodeid == id1)
                        return -EINVAL;
        }

        if (node2)
        {
                for (node = get_node(f, id1); node->nodeid != FUSE_ROOT_ID;
                     node = node->parent) {
                        if (node->name == NULL || node->parent == NULL)
                                break;

                        if (node->nodeid != id1 && node->nodeid == id2)
                                return -ENOTEMPTY;
                }
        }

        return 0;
}
#endif

static int try_get_path2(struct fuse *f, fuse_ino_t nodeid1, const char *name1,
                         fuse_ino_t nodeid2, const char *name2,
                         char **path1, char **path2,
                         struct node **wnode1, struct node **wnode2)
{
        int err;

        /* FIXME: locking two paths needs deadlock checking */
        err = try_get_path(f, nodeid1, name1, path1, wnode1, true);
        if (!err) {
                err = try_get_path(f, nodeid2, name2, path2, wnode2, true);
                if (err) {
                        struct node *wn1 = wnode1 ? *wnode1 : NULL;

                        unlock_path(f, nodeid1, wn1, NULL);
                        free(*path1);
                }
        }
        return err;
}

static int get_path2(struct fuse *f, fuse_ino_t nodeid1, const char *name1,
                     fuse_ino_t nodeid2, const char *name2,
                     char **path1, char **path2,
                     struct node **wnode1, struct node **wnode2)
{
        int err;

        pthread_mutex_lock(&f->lock);

#if defined(CHECK_DIR_LOOP)
        if (name1)
        {
                // called during rename; perform dir loop check
                err = check_dir_loop(f, nodeid1, name1, nodeid2, name2);
                if (err)
                        goto out_unlock;
        }
#endif

        err = try_get_path2(f, nodeid1, name1, nodeid2, name2,
                            path1, path2, wnode1, wnode2);
        if (err == -EAGAIN) {
                struct lock_queue_element qe = {
                        .nodeid1 = nodeid1,
                        .name1 = name1,
                        .path1 = path1,
                        .wnode1 = wnode1,
                        .nodeid2 = nodeid2,
                        .name2 = name2,
                        .path2 = path2,
                        .wnode2 = wnode2,
                };

                debug_path(f, "QUEUE PATH1", nodeid1, name1, !!wnode1);
                debug_path(f, "      PATH2", nodeid2, name2, !!wnode2);
                err = wait_path(f, &qe);
                debug_path(f, "DEQUEUE PATH1", nodeid1, name1, !!wnode1);
                debug_path(f, "        PATH2", nodeid2, name2, !!wnode2);
        }

#if defined(CHECK_DIR_LOOP)
out_unlock:
#endif
        pthread_mutex_unlock(&f->lock);

        return err;
}

static void free_path_wrlock(struct fuse *f, fuse_ino_t nodeid,
                             struct node *wnode, char *path)
{
        pthread_mutex_lock(&f->lock);
        unlock_path(f, nodeid, wnode, NULL);
        if (f->lockq)
                wake_up_queued(f);
        pthread_mutex_unlock(&f->lock);
        free(path);
}

static void free_path(struct fuse *f, fuse_ino_t nodeid, char *path)
{
        if (path)
                free_path_wrlock(f, nodeid, NULL, path);
}

static void free_path2(struct fuse *f, fuse_ino_t nodeid1, fuse_ino_t nodeid2,
                       struct node *wnode1, struct node *wnode2,
                       char *path1, char *path2)
{
        pthread_mutex_lock(&f->lock);
        unlock_path(f, nodeid1, wnode1, NULL);
        unlock_path(f, nodeid2, wnode2, NULL);
        wake_up_queued(f);
        pthread_mutex_unlock(&f->lock);
        free(path1);
        free(path2);
}

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);

        /*
         * Node may still be locked due to interrupt idiocy in open,
         * create and opendir
         */
        while (node->nlookup == nlookup && node->treelock) {
                struct lock_queue_element qe = {
                        .nodeid1 = nodeid,
                };

                debug_path(f, "QUEUE PATH (forget)", nodeid, NULL, false);
                queue_path(f, &qe);

                do {
                        pthread_cond_wait(&qe.cond, &f->lock);
                } while (node->nlookup == nlookup && node->treelock);

                dequeue_path(f, &qe);
                debug_path(f, "DEQUEUE_PATH (forget)", nodeid, NULL, false);
        }

        assert(node->nlookup >= nlookup);
        node->nlookup -= nlookup;
        if (!node->nlookup) {
                unref_node(f, node);
        } else if (lru_enabled(f) && node->nlookup == 1) {
                set_forget_time(f, node);
        }
        pthread_mutex_unlock(&f->lock);
}

static void unlink_node(struct fuse *f, struct node *node)
{
        if (f->conf.remember) {
                assert(node->nlookup > 1);
                node->nlookup--;
        }
        unhash_name(f, node);
}

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)
                unlink_node(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;
                }
                unlink_node(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 int exchange_node(struct fuse *f, fuse_ino_t olddir, const char *oldname,
                         fuse_ino_t newdir, const char *newname)
{
        struct node *oldnode;
        struct node *newnode;
        int err;

        pthread_mutex_lock(&f->lock);
        oldnode  = lookup_node(f, olddir, oldname);
        newnode  = lookup_node(f, newdir, newname);

        if (oldnode)
                unhash_name(f, oldnode);
        if (newnode)
                unhash_name(f, newnode);

        err = -ENOMEM;
        if (oldnode) {
                if (hash_name(f, oldnode, newdir, newname) == -1)
                        goto out;
        }
        if (newnode) {
                if (hash_name(f, newnode, olddir, oldname) == -1)
                        goto out;
        }
        err = 0;
out:
        pthread_mutex_unlock(&f->lock);
        return err;
}

static void set_stat(struct fuse *f, fuse_ino_t nodeid, struct stat *stbuf)
{
        if (!f->conf.use_ino)
                stbuf->st_ino = nodeid;
        if (f->conf.set_mode)
                stbuf->st_mode = (stbuf->st_mode & S_IFMT) |
                                 (0777 & ~f->conf.umask);
        if (f->conf.set_uid)
                stbuf->st_uid = f->conf.uid;
        if (f->conf.set_gid)
                stbuf->st_gid = f->conf.gid;
}

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

static void fuse_intr_sighandler(int sig)
{
        (void) sig;
        /* Nothing to do */
}

struct fuse_intr_data {
        pthread_t id;
        pthread_cond_t cond;
        int finished;
};

static void fuse_interrupt(fuse_req_t req, void *d_)
{
        struct fuse_intr_data *d = d_;
        struct fuse *f = req_fuse(req);

        if (d->id == pthread_self())
                return;

        pthread_mutex_lock(&f->lock);
        while (!d->finished) {
                struct timeval now;
                struct timespec timeout;

                pthread_kill(d->id, f->conf.intr_signal);
                gettimeofday(&now, NULL);
                timeout.tv_sec = now.tv_sec + 1;
                timeout.tv_nsec = now.tv_usec * 1000;
                pthread_cond_timedwait(&d->cond, &f->lock, &timeout);
        }
        pthread_mutex_unlock(&f->lock);
}

static void fuse_do_finish_interrupt(struct fuse *f, fuse_req_t req,
                                     struct fuse_intr_data *d)
{
        pthread_mutex_lock(&f->lock);
        d->finished = 1;
        pthread_cond_broadcast(&d->cond);
        pthread_mutex_unlock(&f->lock);
        fuse_req_interrupt_func(req, NULL, NULL);
        pthread_cond_destroy(&d->cond);
}

static void fuse_do_prepare_interrupt(fuse_req_t req, struct fuse_intr_data *d)
{
        d->id = pthread_self();
        pthread_cond_init(&d->cond, NULL);
        d->finished = 0;
        fuse_req_interrupt_func(req, fuse_interrupt, d);
}

static inline void fuse_finish_interrupt(struct fuse *f, fuse_req_t req,
                                         struct fuse_intr_data *d)
{
        if (f->conf.intr)
                fuse_do_finish_interrupt(f, req, d);
}

static inline void fuse_prepare_interrupt(struct fuse *f, fuse_req_t req,
                                          struct fuse_intr_data *d)
{
        if (f->conf.intr)
                fuse_do_prepare_interrupt(req, d);
}

static const char* file_info_string(struct fuse_file_info *fi,
                              char* buf, size_t len)
{
        if(fi == NULL)
                return "NULL";
        snprintf(buf, len, "%llu", (unsigned long long) fi->fh);
        return buf;
}

int fuse_fs_getattr(struct fuse_fs *fs, const char *path, struct stat *buf,
                    struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.getattr) {
                if (fs->debug) {
                        char buf[10];
                        fprintf(stderr, "getattr[%s] %s\n",
                                file_info_string(fi, buf, sizeof(buf)),
                                path);
                }
                return fs->op.getattr(path, buf, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_rename(struct fuse_fs *fs, const char *oldpath,
                   const char *newpath, unsigned int flags)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.rename) {
                if (fs->debug)
                        fprintf(stderr, "rename %s %s 0x%x\n", oldpath, newpath,
                                flags);

                return fs->op.rename(oldpath, newpath, flags);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_unlink(struct fuse_fs *fs, const char *path)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.unlink) {
                if (fs->debug)
                        fprintf(stderr, "unlink %s\n", path);

                return fs->op.unlink(path);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_rmdir(struct fuse_fs *fs, const char *path)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.rmdir) {
                if (fs->debug)
                        fprintf(stderr, "rmdir %s\n", path);

                return fs->op.rmdir(path);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_symlink(struct fuse_fs *fs, const char *linkname, const char *path)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.symlink) {
                if (fs->debug)
                        fprintf(stderr, "symlink %s %s\n", linkname, path);

                return fs->op.symlink(linkname, path);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_link(struct fuse_fs *fs, const char *oldpath, const char *newpath)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.link) {
                if (fs->debug)
                        fprintf(stderr, "link %s %s\n", oldpath, newpath);

                return fs->op.link(oldpath, newpath);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_release(struct fuse_fs *fs,  const char *path,
                    struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.release) {
                if (fs->debug)
                        fprintf(stderr, "release%s[%llu] flags: 0x%x\n",
                                fi->flush ? "+flush" : "",
                                (unsigned long long) fi->fh, fi->flags);

                return fs->op.release(path, fi);
        } else {
                return 0;
        }
}

int fuse_fs_opendir(struct fuse_fs *fs, const char *path,
                    struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.opendir) {
                int err;

                if (fs->debug)
                        fprintf(stderr, "opendir flags: 0x%x %s\n", fi->flags,
                                path);

                err = fs->op.opendir(path, fi);

                if (fs->debug && !err)
                        fprintf(stderr, "   opendir[%llu] flags: 0x%x %s\n",
                                (unsigned long long) fi->fh, fi->flags, path);

                return err;
        } else {
                return 0;
        }
}

int fuse_fs_open(struct fuse_fs *fs, const char *path,
                 struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.open) {
                int err;

                if (fs->debug)
                        fprintf(stderr, "open flags: 0x%x %s\n", fi->flags,
                                path);

                err = fs->op.open(path, fi);

                if (fs->debug && !err)
                        fprintf(stderr, "   open[%llu] flags: 0x%x %s\n",
                                (unsigned long long) fi->fh, fi->flags, path);

                return err;
        } else {
                return 0;
        }
}

static void fuse_free_buf(struct fuse_bufvec *buf)
{
        if (buf != NULL) {
                size_t i;

                for (i = 0; i < buf->count; i++)
                        if (!(buf->buf[0].flags & FUSE_BUF_IS_FD))
                                free(buf->buf[i].mem);
                free(buf);
        }
}

int fuse_fs_read_buf(struct fuse_fs *fs, const char *path,
                     struct fuse_bufvec **bufp, size_t size, off_t off,
                     struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.read || fs->op.read_buf) {
                int res;

                if (fs->debug)
                        fprintf(stderr,
                                "read[%llu] %zu bytes from %llu flags: 0x%x\n",
                                (unsigned long long) fi->fh,
                                size, (unsigned long long) off, fi->flags);

                if (fs->op.read_buf) {
                        res = fs->op.read_buf(path, bufp, size, off, fi);
                } else {
                        struct fuse_bufvec *buf;
                        void *mem;

                        buf = malloc(sizeof(struct fuse_bufvec));
                        if (buf == NULL)
                                return -ENOMEM;

                        mem = malloc(size);
                        if (mem == NULL) {
                                free(buf);
                                return -ENOMEM;
                        }
                        *buf = FUSE_BUFVEC_INIT(size);
                        buf->buf[0].mem = mem;
                        *bufp = buf;

                        res = fs->op.read(path, mem, size, off, fi);
                        if (res >= 0)
                                buf->buf[0].size = res;
                }

                if (fs->debug && res >= 0)
                        fprintf(stderr, "   read[%llu] %zu bytes from %llu\n",
                                (unsigned long long) fi->fh,
                                fuse_buf_size(*bufp),
                                (unsigned long long) off);
                if (res >= 0 && fuse_buf_size(*bufp) > size)
                        fprintf(stderr, "fuse: read too many bytes\n");

                if (res < 0)
                        return res;

                return 0;
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_read(struct fuse_fs *fs, const char *path, char *mem, size_t size,
                 off_t off, struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.read || fs->op.read_buf) {
                int res;

                if (fs->debug)
                        fprintf(stderr,
                                "read[%llu] %zu bytes from %llu flags: 0x%x\n",
                                (unsigned long long) fi->fh,
                                size, (unsigned long long) off, fi->flags);

                if (fs->op.read_buf) {
                        struct fuse_bufvec *buf = NULL;

                        res = fs->op.read_buf(path, &buf, size, off, fi);
                        if (res == 0) {
                                struct fuse_bufvec dst = FUSE_BUFVEC_INIT(size);

                                dst.buf[0].mem = mem;
                                res = fuse_buf_copy(&dst, buf, 0);
                        }
                        fuse_free_buf(buf);
                } else {
                        res = fs->op.read(path, mem, size, off, fi);
                }

                if (fs->debug && res >= 0)
                        fprintf(stderr, "   read[%llu] %u bytes from %llu\n",
                                (unsigned long long) fi->fh,
                                res,
                                (unsigned long long) off);
                if (res >= 0 && res > (int) size)
                        fprintf(stderr, "fuse: read too many bytes\n");

                return res;
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_write_buf(struct fuse_fs *fs, const char *path,
                      struct fuse_bufvec *buf, off_t off,
                      struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.write_buf || fs->op.write) {
                int res;
                size_t size = fuse_buf_size(buf);

                assert(buf->idx == 0 && buf->off == 0);
                if (fs->debug)
                        fprintf(stderr,
                                "write%s[%llu] %zu bytes to %llu flags: 0x%x\n",
                                fi->writepage ? "page" : "",
                                (unsigned long long) fi->fh,
                                size,
                                (unsigned long long) off,
                                fi->flags);

                if (fs->op.write_buf) {
                        res = fs->op.write_buf(path, buf, off, fi);
                } else {
                        void *mem = NULL;
                        struct fuse_buf *flatbuf;
                        struct fuse_bufvec tmp = FUSE_BUFVEC_INIT(size);

                        if (buf->count == 1 &&
                            !(buf->buf[0].flags & FUSE_BUF_IS_FD)) {
                                flatbuf = &buf->buf[0];
                        } else {
                                res = -ENOMEM;
                                mem = malloc(size);
                                if (mem == NULL)
                                        goto out;

                                tmp.buf[0].mem = mem;
                                res = fuse_buf_copy(&tmp, buf, 0);
                                if (res <= 0)
                                        goto out_free;

                                tmp.buf[0].size = res;
                                flatbuf = &tmp.buf[0];
                        }

                        res = fs->op.write(path, flatbuf->mem, flatbuf->size,
                                           off, fi);
out_free:
                        free(mem);
                }
out:
                if (fs->debug && res >= 0)
                        fprintf(stderr, "   write%s[%llu] %u bytes to %llu\n",
                                fi->writepage ? "page" : "",
                                (unsigned long long) fi->fh, res,
                                (unsigned long long) off);
                if (res > (int) size)
                        fprintf(stderr, "fuse: wrote too many bytes\n");

                return res;
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_write(struct fuse_fs *fs, const char *path, const char *mem,
                  size_t size, off_t off, struct fuse_file_info *fi)
{
        struct fuse_bufvec bufv = FUSE_BUFVEC_INIT(size);

        bufv.buf[0].mem = (void *) mem;

        return fuse_fs_write_buf(fs, path, &bufv, off, fi);
}

int fuse_fs_fsync(struct fuse_fs *fs, const char *path, int datasync,
                  struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.fsync) {
                if (fs->debug)
                        fprintf(stderr, "fsync[%llu] datasync: %i\n",
                                (unsigned long long) fi->fh, datasync);

                return fs->op.fsync(path, datasync, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_fsyncdir(struct fuse_fs *fs, const char *path, int datasync,
                     struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.fsyncdir) {
                if (fs->debug)
                        fprintf(stderr, "fsyncdir[%llu] datasync: %i\n",
                                (unsigned long long) fi->fh, datasync);

                return fs->op.fsyncdir(path, datasync, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_flush(struct fuse_fs *fs, const char *path,
                  struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.flush) {
                if (fs->debug)
                        fprintf(stderr, "flush[%llu]\n",
                                (unsigned long long) fi->fh);

                return fs->op.flush(path, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_statfs(struct fuse_fs *fs, const char *path, struct statvfs *buf)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.statfs) {
                if (fs->debug)
                        fprintf(stderr, "statfs %s\n", path);

                return fs->op.statfs(path, buf);
        } else {
                buf->f_namemax = 255;
                buf->f_bsize = 512;
                return 0;
        }
}

int fuse_fs_releasedir(struct fuse_fs *fs, const char *path,
                       struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.releasedir) {
                if (fs->debug)
                        fprintf(stderr, "releasedir[%llu] flags: 0x%x\n",
                                (unsigned long long) fi->fh, fi->flags);

                return fs->op.releasedir(path, fi);
        } else {
                return 0;
        }
}

int fuse_fs_readdir(struct fuse_fs *fs, const char *path, void *buf,
                    fuse_fill_dir_t filler, off_t off,
                    struct fuse_file_info *fi,
                    enum fuse_readdir_flags flags)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.readdir) {
                if (fs->debug) {
                        fprintf(stderr, "readdir%s[%llu] from %llu\n",
                                (flags & FUSE_READDIR_PLUS) ? "plus" : "",
                                (unsigned long long) fi->fh,
                                (unsigned long long) off);
                }

                return fs->op.readdir(path, buf, filler, off, fi, flags);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_create(struct fuse_fs *fs, const char *path, mode_t mode,
                   struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.create) {
                int err;

                if (fs->debug)
                        fprintf(stderr,
                                "create flags: 0x%x %s 0%o umask=0%03o\n",
                                fi->flags, path, mode,
                                fuse_get_context()->umask);

                err = fs->op.create(path, mode, fi);

                if (fs->debug && !err)
                        fprintf(stderr, "   create[%llu] flags: 0x%x %s\n",
                                (unsigned long long) fi->fh, fi->flags, path);

                return err;
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_lock(struct fuse_fs *fs, const char *path,
                 struct fuse_file_info *fi, int cmd, struct flock *lock)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.lock) {
                if (fs->debug)
                        fprintf(stderr, "lock[%llu] %s %s start: %llu len: %llu pid: %llu\n",
                                (unsigned long long) fi->fh,
                                (cmd == F_GETLK ? "F_GETLK" :
                                 (cmd == F_SETLK ? "F_SETLK" :
                                  (cmd == F_SETLKW ? "F_SETLKW" : "???"))),
                                (lock->l_type == F_RDLCK ? "F_RDLCK" :
                                 (lock->l_type == F_WRLCK ? "F_WRLCK" :
                                  (lock->l_type == F_UNLCK ? "F_UNLCK" :
                                   "???"))),
                                (unsigned long long) lock->l_start,
                                (unsigned long long) lock->l_len,
                                (unsigned long long) lock->l_pid);

                return fs->op.lock(path, fi, cmd, lock);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_flock(struct fuse_fs *fs, const char *path,
                  struct fuse_file_info *fi, int op)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.flock) {
                if (fs->debug) {
                        int xop = op & ~LOCK_NB;

                        fprintf(stderr, "lock[%llu] %s%s\n",
                                (unsigned long long) fi->fh,
                                xop == LOCK_SH ? "LOCK_SH" :
                                (xop == LOCK_EX ? "LOCK_EX" :
                                 (xop == LOCK_UN ? "LOCK_UN" : "???")),
                                (op & LOCK_NB) ? "|LOCK_NB" : "");
                }
                return fs->op.flock(path, fi, op);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_chown(struct fuse_fs *fs, const char *path, uid_t uid,
                  gid_t gid, struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.chown) {
                if (fs->debug) {
                        char buf[10];
                        fprintf(stderr, "chown[%s] %s %lu %lu\n",
                                file_info_string(fi, buf, sizeof(buf)),
                                path, (unsigned long) uid, (unsigned long) gid);
                }
                return fs->op.chown(path, uid, gid, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_truncate(struct fuse_fs *fs, const char *path, off_t size,
                      struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.truncate) {
                if (fs->debug) {
                        char buf[10];
                        fprintf(stderr, "truncate[%s] %llu\n",
                                file_info_string(fi, buf, sizeof(buf)),
                                (unsigned long long) size);
                }
                return fs->op.truncate(path, size, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_utimens(struct fuse_fs *fs, const char *path,
                    const struct timespec tv[2], struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.utimens) {
                if (fs->debug) {
                        char buf[10];
                        fprintf(stderr, "utimens[%s] %s %li.%09lu %li.%09lu\n",
                                file_info_string(fi, buf, sizeof(buf)),
                                path, tv[0].tv_sec, tv[0].tv_nsec,
                                tv[1].tv_sec, tv[1].tv_nsec);
                }
                return fs->op.utimens(path, tv, fi);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_access(struct fuse_fs *fs, const char *path, int mask)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.access) {
                if (fs->debug)
                        fprintf(stderr, "access %s 0%o\n", path, mask);

                return fs->op.access(path, mask);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_readlink(struct fuse_fs *fs, const char *path, char *buf,
                     size_t len)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.readlink) {
                if (fs->debug)
                        fprintf(stderr, "readlink %s %lu\n", path,
                                (unsigned long) len);

                return fs->op.readlink(path, buf, len);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_mknod(struct fuse_fs *fs, const char *path, mode_t mode,
                  dev_t rdev)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.mknod) {
                if (fs->debug)
                        fprintf(stderr, "mknod %s 0%o 0x%llx umask=0%03o\n",
                                path, mode, (unsigned long long) rdev,
                                fuse_get_context()->umask);

                return fs->op.mknod(path, mode, rdev);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_mkdir(struct fuse_fs *fs, const char *path, mode_t mode)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.mkdir) {
                if (fs->debug)
                        fprintf(stderr, "mkdir %s 0%o umask=0%03o\n",
                                path, mode, fuse_get_context()->umask);

                return fs->op.mkdir(path, mode);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_setxattr(struct fuse_fs *fs, const char *path, const char *name,
                     const char *value, size_t size, int flags)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.setxattr) {
                if (fs->debug)
                        fprintf(stderr, "setxattr %s %s %lu 0x%x\n",
                                path, name, (unsigned long) size, flags);

                return fs->op.setxattr(path, name, value, size, flags);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_getxattr(struct fuse_fs *fs, const char *path, const char *name,
                     char *value, size_t size)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.getxattr) {
                if (fs->debug)
                        fprintf(stderr, "getxattr %s %s %lu\n",
                                path, name, (unsigned long) size);

                return fs->op.getxattr(path, name, value, size);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_listxattr(struct fuse_fs *fs, const char *path, char *list,
                      size_t size)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.listxattr) {
                if (fs->debug)
                        fprintf(stderr, "listxattr %s %lu\n",
                                path, (unsigned long) size);

                return fs->op.listxattr(path, list, size);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_bmap(struct fuse_fs *fs, const char *path, size_t blocksize,
                 uint64_t *idx)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.bmap) {
                if (fs->debug)
                        fprintf(stderr, "bmap %s blocksize: %lu index: %llu\n",
                                path, (unsigned long) blocksize,
                                (unsigned long long) *idx);

                return fs->op.bmap(path, blocksize, idx);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_removexattr(struct fuse_fs *fs, const char *path, const char *name)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.removexattr) {
                if (fs->debug)
                        fprintf(stderr, "removexattr %s %s\n", path, name);

                return fs->op.removexattr(path, name);
        } else {
                return -ENOSYS;
        }
}

int fuse_fs_ioctl(struct fuse_fs *fs, const char *path, int cmd, void *arg,
                  struct fuse_file_info *fi, unsigned int flags, void *data)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.ioctl) {
                if (fs->debug)
                        fprintf(stderr, "ioctl[%llu] 0x%x flags: 0x%x\n",
                                (unsigned long long) fi->fh, cmd, flags);

                return fs->op.ioctl(path, cmd, arg, fi, flags, data);
        } else
                return -ENOSYS;
}

int fuse_fs_poll(struct fuse_fs *fs, const char *path,
                 struct fuse_file_info *fi, struct fuse_pollhandle *ph,
                 unsigned *reventsp)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.poll) {
                int res;

                if (fs->debug)
                        fprintf(stderr, "poll[%llu] ph: %p, events 0x%x\n",
                                (unsigned long long) fi->fh, ph,
                                fi->poll_events);

                res = fs->op.poll(path, fi, ph, reventsp);

                if (fs->debug && !res)
                        fprintf(stderr, "   poll[%llu] revents: 0x%x\n",
                                (unsigned long long) fi->fh, *reventsp);

                return res;
        } else
                return -ENOSYS;
}

int fuse_fs_fallocate(struct fuse_fs *fs, const char *path, int mode,
                off_t offset, off_t length, struct fuse_file_info *fi)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.fallocate) {
                if (fs->debug)
                        fprintf(stderr, "fallocate %s mode %x, offset: %llu, length: %llu\n",
                                path,
                                mode,
                                (unsigned long long) offset,
                                (unsigned long long) length);

                return fs->op.fallocate(path, mode, offset, length, fi);
        } else
                return -ENOSYS;
}

ssize_t fuse_fs_copy_file_range(struct fuse_fs *fs, const char *path_in,
                                struct fuse_file_info *fi_in, off_t off_in,
                                const char *path_out,
                                struct fuse_file_info *fi_out, off_t off_out,
                                size_t len, int flags)
{
        fuse_get_context()->private_data = fs->user_data;
        if (fs->op.copy_file_range) {
                if (fs->debug)
                        fprintf(stderr, "copy_file_range from %s:%llu to "
                                        "%s:%llu, length: %llu\n",
                                path_in,
                                (unsigned long long) off_in,
                                path_out,
                                (unsigned long long) off_out,
                                (unsigned long long) len);

                return fs->op.copy_file_range(path_in, fi_in, off_in, path_out,
                                              fi_out, off_out, len, flags);
        } else
                return -ENOSYS;
}

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;

        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);

                res = try_get_path(f, dir, newname, &newpath, NULL, false);
                pthread_mutex_unlock(&f->lock);
                if (res)
                        break;

                memset(&buf, 0, sizeof(buf));
                res = fuse_fs_getattr(f->fs, newpath, &buf, NULL);
                if (res == -ENOENT)
                        break;
                free(newpath);
                newpath = NULL;
        } while(res == 0 && --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;

        newpath = hidden_name(f, dir, oldname, newname, sizeof(newname));
        if (newpath) {
                err = fuse_fs_rename(f->fs, oldpath, newpath, 0);
                if (!err)
                        err = rename_node(f, dir, oldname, dir, newname, 1);
                free(newpath);
        }
        return err;
}

static int mtime_eq(const struct stat *stbuf, const