fuse_lowlevel.c

Linux下fuse用户文件系统的的源代码

/*
    FUSE: Filesystem in Userspace
    Copyright (C) 2001-2006  Miklos Szeredi <[e-mail]>

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

#include "fuse_lowlevel.h"
#include "fuse_kernel.h"
#include "fuse_opt.h"
#include "fuse_i.h"
#include "fuse_misc.h"
#include "fuse_common_compat.h"
#include "fuse_lowlevel_compat.h"

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <errno.h>

#define PARAM(inarg) (((char *)(inarg)) + sizeof(*(inarg)))
#define OFFSET_MAX 0x7fffffffffffffffLL

struct fuse_ll;

struct fuse_req {
    struct fuse_ll *f;
    uint64_t unique;
    int ctr;
    pthread_mutex_t lock;
    struct fuse_ctx ctx;
    struct fuse_chan *ch;
    int interrupted;
    union {
        struct {
            uint64_t unique;
        } i;
        struct {
            fuse_interrupt_func_t func;
            void *data;
        } ni;
    } u;
    struct fuse_req *next;
    struct fuse_req *prev;
};

struct fuse_ll {
    int debug;
    int allow_root;
    struct fuse_lowlevel_ops op;
    int got_init;
    void *userdata;
    uid_t owner;
    struct fuse_conn_info conn;
    struct fuse_req list;
    struct fuse_req interrupts;
    pthread_mutex_t lock;
    int got_destroy;
};

static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr)
{
    attr->ino       = stbuf->st_ino;
    attr->mode      = stbuf->st_mode;
    attr->nlink     = stbuf->st_nlink;
    attr->uid       = stbuf->st_uid;
    attr->gid       = stbuf->st_gid;
    attr->rdev      = stbuf->st_rdev;
    attr->size      = stbuf->st_size;
    attr->blocks    = stbuf->st_blocks;
    attr->atime     = stbuf->st_atime;
    attr->mtime     = stbuf->st_mtime;
    attr->ctime     = stbuf->st_ctime;
#ifdef FUSE_STAT_HAS_NANOSEC
    attr->atimensec = ST_ATIM(stbuf).tv_nsec;
    attr->mtimensec = ST_MTIM(stbuf).tv_nsec;
    attr->ctimensec = ST_CTIM(stbuf).tv_nsec;
#endif
}

static void convert_attr(const struct fuse_setattr_in *attr, struct stat *stbuf)
{
    stbuf->st_mode         = attr->mode;
    stbuf->st_uid          = attr->uid;
    stbuf->st_gid          = attr->gid;
    stbuf->st_size         = attr->size;
    stbuf->st_atime        = attr->atime;
    stbuf->st_mtime        = attr->mtime;
#ifdef FUSE_STAT_HAS_NANOSEC
    ST_ATIM(stbuf).tv_nsec = attr->atimensec;
    ST_MTIM(stbuf).tv_nsec = attr->mtimensec;
#endif
}

static  size_t iov_length(const struct iovec *iov, size_t count)
{
    size_t seg;
    size_t ret = 0;

    for (seg = 0; seg < count; seg++)
        ret += iov[seg].iov_len;
    return ret;
}

static void list_init_req(struct fuse_req *req)
{
    req->next = req;
    req->prev = req;
}

static void list_del_req(struct fuse_req *req)
{
    struct fuse_req *prev = req->prev;
    struct fuse_req *next = req->next;
    prev->next = next;
    next->prev = prev;
}

static void list_add_req(struct fuse_req *req, struct fuse_req *next)
{
    struct fuse_req *prev = next->prev;
    req->next = next;
    req->prev = prev;
    prev->next = req;
    next->prev = req;
}

static void destroy_req(fuse_req_t req)
{
    pthread_mutex_destroy(&req->lock);
    free(req);
}

static void free_req(fuse_req_t req)
{
    int ctr;
    struct fuse_ll *f = req->f;

    pthread_mutex_lock(&req->lock);
    req->u.ni.func = NULL;
    req->u.ni.data = NULL;
    pthread_mutex_unlock(&req->lock);

    pthread_mutex_lock(&f->lock);
    list_del_req(req);
    ctr = --req->ctr;
    pthread_mutex_unlock(&f->lock);
    if (!ctr)
        destroy_req(req);
}

static int send_reply(fuse_req_t req, int error, const void *arg,
                      size_t argsize)
{
    struct fuse_out_header out;
    struct iovec iov[2];
    size_t count;
    int res;

    if (error <= -1000 || error > 0) {
        fprintf(stderr, "fuse: bad error value: %i\n",  error);
        error = -ERANGE;
    }

    out.unique = req->unique;
    out.error = error;
    count = 1;
    iov[0].iov_base = &out;
    iov[0].iov_len = sizeof(struct fuse_out_header);
    if (argsize && !error) {
        count++;
        iov[1].iov_base = (void *) arg;
        iov[1].iov_len = argsize;
    }
    out.len = iov_length(iov, count);

    if (req->f->debug) {
        printf("   unique: %llu, error: %i (%s), outsize: %i\n",
               out.unique, out.error, strerror(-out.error), out.len);
        fflush(stdout);
    }
    res = fuse_chan_send(req->ch, iov, count);
    free_req(req);

    return res;
}

size_t fuse_dirent_size(size_t namelen)
{
    return FUSE_DIRENT_ALIGN(FUSE_NAME_OFFSET + namelen);
}

char *fuse_add_dirent(char *buf, const char *name, const struct stat *stbuf,
                      off_t off)
{
    unsigned namelen = strlen(name);
    unsigned entlen = FUSE_NAME_OFFSET + namelen;
    unsigned entsize = fuse_dirent_size(namelen);
    unsigned padlen = entsize - entlen;
    struct fuse_dirent *dirent = (struct fuse_dirent *) buf;

    dirent->ino = stbuf->st_ino;
    dirent->off = off;
    dirent->namelen = namelen;
    dirent->type = (stbuf->st_mode & 0170000) >> 12;
    strncpy(dirent->name, name, namelen);
    if (padlen)
        memset(buf + entlen, 0, padlen);

    return buf + entsize;
}

size_t fuse_add_direntry(fuse_req_t req, char *buf, size_t bufsize,
                         const char *name, const struct stat *stbuf, off_t off)
{
    size_t entsize;

    (void) req;
    entsize = fuse_dirent_size(strlen(name));
    if (entsize <= bufsize && buf)
        fuse_add_dirent(buf, name, stbuf, off);
    return entsize;
}

static void convert_statfs(const struct statvfs *stbuf,
                           struct fuse_kstatfs *kstatfs)
{
    kstatfs->bsize	= stbuf->f_bsize;
    kstatfs->frsize	= stbuf->f_frsize;
    kstatfs->blocks	= stbuf->f_blocks;
    kstatfs->bfree	= stbuf->f_bfree;
    kstatfs->bavail	= stbuf->f_bavail;
    kstatfs->files	= stbuf->f_files;
    kstatfs->ffree	= stbuf->f_ffree;
    kstatfs->namelen	= stbuf->f_namemax;
}

static int send_reply_ok(fuse_req_t req, const void *arg, size_t argsize)
{
    return send_reply(req, 0, arg, argsize);
}

int fuse_reply_err(fuse_req_t req, int err)
{
    return send_reply(req, -err, NULL, 0);
}

void fuse_reply_none(fuse_req_t req)
{
    fuse_chan_send(req->ch, NULL, 0);
    free_req(req);
}

static unsigned long calc_timeout_sec(double t)
{
    if (t > (double) ULONG_MAX)
        return ULONG_MAX;
    else if (t < 0.0)
        return 0;
    else
        return (unsigned long) t;
}

static unsigned int calc_timeout_nsec(double t)
{
    double f = t - (double) calc_timeout_sec(t);
    if (f < 0.0)
        return 0;
    else if (f >= 0.999999999)
        return 999999999;
    else
        return (unsigned int) (f * 1.0e9);
}

static void fill_entry(struct fuse_entry_out *arg,
                       const struct fuse_entry_param *e)
{
    arg->nodeid = e->ino;
    arg->generation = e->generation;
    arg->entry_valid = calc_timeout_sec(e->entry_timeout);
    arg->entry_valid_nsec = calc_timeout_nsec(e->entry_timeout);
    arg->attr_valid = calc_timeout_sec(e->attr_timeout);
    arg->attr_valid_nsec = calc_timeout_nsec(e->attr_timeout);
    convert_stat(&e->attr, &arg->attr);
}

static void fill_open(struct fuse_open_out *arg,
                      const struct fuse_file_info *f)
{
    arg->fh = f->fh;
    if (f->direct_io)
        arg->open_flags |= FOPEN_DIRECT_IO;
    if (f->keep_cache)
        arg->open_flags |= FOPEN_KEEP_CACHE;
}

int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
{
    struct fuse_entry_out arg;

    /* before ABI 7.4 e->ino == 0 was invalid, only ENOENT meant
       negative entry */
    if (!e->ino && req->f->conn.proto_minor < 4)
        return fuse_reply_err(req, ENOENT);

    memset(&arg, 0, sizeof(arg));
    fill_entry(&arg, e);
    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
                      const struct fuse_file_info *f)
{
    struct {
        struct fuse_entry_out e;
        struct fuse_open_out o;
    } arg;

    memset(&arg, 0, sizeof(arg));
    fill_entry(&arg.e, e);
    fill_open(&arg.o, f);
    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_attr(fuse_req_t req, const struct stat *attr,
                    double attr_timeout)
{
    struct fuse_attr_out arg;

    memset(&arg, 0, sizeof(arg));
    arg.attr_valid = calc_timeout_sec(attr_timeout);
    arg.attr_valid_nsec = calc_timeout_nsec(attr_timeout);
    convert_stat(attr, &arg.attr);

    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_readlink(fuse_req_t req, const char *linkname)
{
    return send_reply_ok(req, linkname, strlen(linkname));
}

int fuse_reply_open(fuse_req_t req, const struct fuse_file_info *f)
{
    struct fuse_open_out arg;

    memset(&arg, 0, sizeof(arg));
    fill_open(&arg, f);
    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_write(fuse_req_t req, size_t count)
{
    struct fuse_write_out arg;

    memset(&arg, 0, sizeof(arg));
    arg.size = count;

    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_buf(fuse_req_t req, const char *buf, size_t size)
{
    return send_reply_ok(req, buf, size);
}

int fuse_reply_statfs(fuse_req_t req, const struct statvfs *stbuf)
{
    struct fuse_statfs_out arg;
    size_t size = req->f->conn.proto_minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(arg);

    memset(&arg, 0, sizeof(arg));
    convert_statfs(stbuf, &arg.st);

    return send_reply_ok(req, &arg, size);
}

int fuse_reply_xattr(fuse_req_t req, size_t count)
{
    struct fuse_getxattr_out arg;

    memset(&arg, 0, sizeof(arg));
    arg.size = count;

    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_lock(fuse_req_t req, struct flock *lock)
{
    struct fuse_lk_out arg;

    memset(&arg, 0, sizeof(arg));
    arg.lk.type = lock->l_type;
    if (lock->l_type != F_UNLCK) {
        arg.lk.start = lock->l_start;
        if (lock->l_len == 0)
            arg.lk.end = OFFSET_MAX;
        else
            arg.lk.end = lock->l_start + lock->l_len - 1;
    }
    arg.lk.pid = lock->l_pid;
    return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_bmap(fuse_req_t req, uint64_t idx)
{
    struct fuse_bmap_out arg;

    memset(&arg, 0, sizeof(arg));
    arg.block = idx;

    return send_reply_ok(req, &arg, sizeof(arg));
}

static void do_lookup(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
{
    char *name = (char *) inarg;

    if (req->f->op.lookup)
        req->f->op.lookup(req, nodeid, name);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_forget(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
{
    struct fuse_forget_in *arg = (struct fuse_forget_in *) inarg;

    if (req->f->op.forget)
        req->f->op.forget(req, nodeid, arg->nlookup);
}

static void do_getattr(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
{
    (void) inarg;

    if (req->f->op.getattr)
        req->f->op.getattr(req, nodeid, NULL);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_setattr(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
{
    struct fuse_setattr_in *arg = (struct fuse_setattr_in *) inarg;

    if (req->f->op.setattr) {
        struct fuse_file_info *fi = NULL;
        struct fuse_file_info fi_store;
        struct stat stbuf;
        memset(&stbuf, 0, sizeof(stbuf));
        convert_attr(arg, &stbuf);
        if (arg->valid & FATTR_FH) {
            arg->valid &= ~FATTR_FH;
            memset(&fi_store, 0, sizeof(fi_store));
            fi = &fi_store;
            fi->fh = arg->fh;
            fi->fh_old = fi->fh;
        }
        req->f->op.setattr(req, nodeid, &stbuf, arg->valid, fi);
    } else
        fuse_reply_err(req, ENOSYS);
}

static void do_access(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
{
    struct fuse_access_in *arg = (struct fuse_access_in *) inarg;

    if (req->f->op.access)
        req->f->op.access(req, nodeid, arg->mask);
    else