fuse_lowlevel.c

UNIX/LINUX下面的用户文件系统

static void do_flush(fuse_req_t req, fuse_ino_t nodeid,
                     struct fuse_flush_in *arg)
{
    struct fuse_file_info fi;

    memset(&fi, 0, sizeof(fi));
    fi.fh = arg->fh;
    fi.fh_old = fi.fh;

    if (req->f->op.flush)
        req->f->op.flush(req, nodeid, &fi);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_release(fuse_req_t req, fuse_ino_t nodeid,
                       struct fuse_release_in *arg)
{
    struct fuse_file_info fi;

    memset(&fi, 0, sizeof(fi));
    fi.flags = arg->flags;
    fi.fh = arg->fh;
    fi.fh_old = fi.fh;

    if (req->f->op.release)
        req->f->op.release(req, nodeid, &fi);
    else
        fuse_reply_err(req, 0);
}

static void do_fsync(fuse_req_t req, fuse_ino_t nodeid,
                     struct fuse_fsync_in *inarg)
{
    struct fuse_file_info fi;

    memset(&fi, 0, sizeof(fi));
    fi.fh = inarg->fh;
    fi.fh_old = fi.fh;

    if (req->f->op.fsync)
        req->f->op.fsync(req, nodeid, inarg->fsync_flags & 1, &fi);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_opendir(fuse_req_t req, fuse_ino_t nodeid,
                       struct fuse_open_in *arg)
{
    struct fuse_file_info fi;

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

    if (req->f->op.opendir)
        req->f->op.opendir(req, nodeid, &fi);
    else
        fuse_reply_open(req, &fi);
}

static void do_readdir(fuse_req_t req, fuse_ino_t nodeid,
                       struct fuse_read_in *arg)
{
    struct fuse_file_info fi;

    memset(&fi, 0, sizeof(fi));
    fi.fh = arg->fh;
    fi.fh_old = fi.fh;

    if (req->f->op.readdir)
        req->f->op.readdir(req, nodeid, arg->size, arg->offset, &fi);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_releasedir(fuse_req_t req, fuse_ino_t nodeid,
                          struct fuse_release_in *arg)
{
    struct fuse_file_info fi;

    memset(&fi, 0, sizeof(fi));
    fi.flags = arg->flags;
    fi.fh = arg->fh;
    fi.fh_old = fi.fh;

    if (req->f->op.releasedir)
        req->f->op.releasedir(req, nodeid, &fi);
    else
        fuse_reply_err(req, 0);
}

static void do_fsyncdir(fuse_req_t req, fuse_ino_t nodeid,
                        struct fuse_fsync_in *inarg)
{
    struct fuse_file_info fi;

    memset(&fi, 0, sizeof(fi));
    fi.fh = inarg->fh;
    fi.fh_old = fi.fh;

    if (req->f->op.fsyncdir)
        req->f->op.fsyncdir(req, nodeid, inarg->fsync_flags & 1, &fi);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_statfs(fuse_req_t req)
{
    if (req->f->op.statfs)
        req->f->op.statfs(req);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_setxattr(fuse_req_t req, fuse_ino_t nodeid,
                        struct fuse_setxattr_in *arg)
{
    char *name = PARAM(arg);
    char *value = name + strlen(name) + 1;

    if (req->f->op.setxattr)
            req->f->op.setxattr(req, nodeid, name, value, arg->size,
                                       arg->flags);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_getxattr(fuse_req_t req, fuse_ino_t nodeid,
                        struct fuse_getxattr_in *arg)
{
    if (req->f->op.getxattr)
        req->f->op.getxattr(req, nodeid, PARAM(arg), arg->size);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_listxattr(fuse_req_t req, fuse_ino_t nodeid,
                         struct fuse_getxattr_in *arg)
{
    if (req->f->op.listxattr)
        req->f->op.listxattr(req, nodeid, arg->size);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_removexattr(fuse_req_t req, fuse_ino_t nodeid, char *name)
{
    if (req->f->op.removexattr)
        req->f->op.removexattr(req, nodeid, name);
    else
        fuse_reply_err(req, ENOSYS);
}

static void do_init(fuse_req_t req, struct fuse_init_in *arg)
{
    struct fuse_init_out outarg;
    struct fuse_ll *f = req->f;
    size_t bufsize = fuse_chan_bufsize(req->ch);

    if (f->debug) {
        printf("INIT: %u.%u\n", arg->major, arg->minor);
        fflush(stdout);
    }
    f->got_init = 1;
    if (f->op.init)
        f->op.init(f->userdata);

    f->major = FUSE_KERNEL_VERSION;
    f->minor = arg->minor;

    if (bufsize < FUSE_MIN_READ_BUFFER) {
        fprintf(stderr, "fuse: warning: buffer size too small: %i\n", bufsize);
        bufsize = FUSE_MIN_READ_BUFFER;
    }

    memset(&outarg, 0, sizeof(outarg));
    outarg.major = f->major;
    outarg.minor = FUSE_KERNEL_MINOR_VERSION;
    outarg.max_write = bufsize - 4096;

    if (f->debug) {
        printf("   INIT: %u.%u\n", outarg.major, outarg.minor);
        fflush(stdout);
    }

    send_reply_ok(req, &outarg, arg->minor < 5 ? 8 : sizeof(outarg));
}

void *fuse_req_userdata(fuse_req_t req)
{
    return req->f->userdata;
}

const struct fuse_ctx *fuse_req_ctx(fuse_req_t req)
{
    return &req->ctx;
}

static void fuse_ll_process(void *data, const char *buf, size_t len,
                     struct fuse_chan *ch)
{
    struct fuse_ll *f = (struct fuse_ll *) data;
    struct fuse_in_header *in = (struct fuse_in_header *) buf;
    const void *inarg = buf + sizeof(struct fuse_in_header);
    struct fuse_req *req;

    if (f->debug) {
        printf("unique: %llu, opcode: %s (%i), nodeid: %lu, insize: %i\n",
               in->unique, opname((enum fuse_opcode) in->opcode), in->opcode,
               (unsigned long) in->nodeid, len);
        fflush(stdout);
    }

    req = (struct fuse_req *) malloc(sizeof(struct fuse_req));
    if (req == NULL) {
        fprintf(stderr, "fuse: failed to allocate request\n");
        return;
    }

    req->f = f;
    req->unique = in->unique;
    req->ctx.uid = in->uid;
    req->ctx.gid = in->gid;
    req->ctx.pid = in->pid;
    req->ch = ch;

    if (!f->got_init && in->opcode != FUSE_INIT)
        fuse_reply_err(req, EIO);
    else if (f->allow_root && in->uid != f->owner && in->uid != 0 &&
             in->opcode != FUSE_INIT && in->opcode != FUSE_READ &&
             in->opcode != FUSE_WRITE && in->opcode != FUSE_FSYNC &&
             in->opcode != FUSE_RELEASE && in->opcode != FUSE_READDIR &&
             in->opcode != FUSE_FSYNCDIR && in->opcode != FUSE_RELEASEDIR) {
        fuse_reply_err(req, EACCES);
    } else switch (in->opcode) {
    case FUSE_INIT:
        do_init(req, (struct fuse_init_in *) inarg);
        break;

    case FUSE_LOOKUP:
        do_lookup(req, in->nodeid, (char *) inarg);
        break;

    case FUSE_FORGET:
        do_forget(req, in->nodeid, (struct fuse_forget_in *) inarg);
        break;

    case FUSE_GETATTR:
        do_getattr(req, in->nodeid);
        break;

    case FUSE_SETATTR:
        do_setattr(req, in->nodeid, (struct fuse_setattr_in *) inarg);
        break;

    case FUSE_READLINK:
        do_readlink(req, in->nodeid);
        break;

    case FUSE_MKNOD:
        do_mknod(req, in->nodeid, (struct fuse_mknod_in *) inarg);
        break;

    case FUSE_MKDIR:
        do_mkdir(req, in->nodeid, (struct fuse_mkdir_in *) inarg);
        break;

    case FUSE_UNLINK:
        do_unlink(req, in->nodeid, (char *) inarg);
        break;

    case FUSE_RMDIR:
        do_rmdir(req, in->nodeid, (char *) inarg);
        break;

    case FUSE_SYMLINK:
        do_symlink(req, in->nodeid, (char *) inarg,
                   ((char *) inarg) + strlen((char *) inarg) + 1);
        break;

    case FUSE_RENAME:
        do_rename(req, in->nodeid, (struct fuse_rename_in *) inarg);
        break;

    case FUSE_LINK:
        do_link(req, in->nodeid, (struct fuse_link_in *) inarg);
        break;

    case FUSE_OPEN:
        do_open(req, in->nodeid, (struct fuse_open_in *) inarg);
        break;

    case FUSE_FLUSH:
        do_flush(req, in->nodeid, (struct fuse_flush_in *) inarg);
        break;

    case FUSE_RELEASE:
        do_release(req, in->nodeid, (struct fuse_release_in *) inarg);
        break;

    case FUSE_READ:
        do_read(req, in->nodeid, (struct fuse_read_in *) inarg);
        break;

    case FUSE_WRITE:
        do_write(req, in->nodeid, (struct fuse_write_in *) inarg);
        break;

    case FUSE_STATFS:
        do_statfs(req);
        break;

    case FUSE_FSYNC:
        do_fsync(req, in->nodeid, (struct fuse_fsync_in *) inarg);
        break;

    case FUSE_SETXATTR:
        do_setxattr(req, in->nodeid, (struct fuse_setxattr_in *) inarg);
        break;

    case FUSE_GETXATTR:
        do_getxattr(req, in->nodeid, (struct fuse_getxattr_in *) inarg);
        break;

    case FUSE_LISTXATTR:
        do_listxattr(req, in->nodeid, (struct fuse_getxattr_in *) inarg);
        break;

    case FUSE_REMOVEXATTR:
        do_removexattr(req, in->nodeid, (char *) inarg);
        break;

    case FUSE_OPENDIR:
        do_opendir(req, in->nodeid, (struct fuse_open_in *) inarg);
        break;

    case FUSE_READDIR:
        do_readdir(req, in->nodeid, (struct fuse_read_in *) inarg);
        break;

    case FUSE_RELEASEDIR:
        do_releasedir(req, in->nodeid, (struct fuse_release_in *) inarg);
        break;

    case FUSE_FSYNCDIR:
        do_fsyncdir(req, in->nodeid, (struct fuse_fsync_in *) inarg);
        break;

    case FUSE_ACCESS:
        do_access(req, in->nodeid, (struct fuse_access_in *) inarg);
        break;

    case FUSE_CREATE:
        do_create(req, in->nodeid, (struct fuse_open_in *) inarg);
        break;

    default:
        fuse_reply_err(req, ENOSYS);
    }
}

enum {
    KEY_HELP,
    KEY_VERSION,
};

static struct fuse_opt fuse_ll_opts[] = {
    { "debug", offsetof(struct fuse_ll, debug), 1 },
    { "-d", offsetof(struct fuse_ll, debug), 1 },
    { "allow_root", offsetof(struct fuse_ll, allow_root), 1 },
    FUSE_OPT_KEY("-h", KEY_HELP),
    FUSE_OPT_KEY("--help", KEY_HELP),
    FUSE_OPT_KEY("-V", KEY_VERSION),
    FUSE_OPT_KEY("--version", KEY_VERSION),
    FUSE_OPT_END
};

static void fuse_ll_version(void)
{
    fprintf(stderr, "using FUSE kernel interface version %i.%i\n",
            FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
}

static int fuse_ll_opt_proc(void *data, const char *arg, int key,
                            struct fuse_args *outargs)
{
    (void) data; (void) outargs;

    switch (key) {
    case KEY_HELP:
        break;

    case KEY_VERSION:
        fuse_ll_version();
        break;

    default:
        fprintf(stderr, "fuse: unknown option `%s'\n", arg);
    }

    return -1;
}

int fuse_lowlevel_is_lib_option(const char *opt)
{
    return fuse_opt_match(fuse_ll_opts, opt);
}

static void fuse_ll_destroy(void *data)
{
    struct fuse_ll *f = (struct fuse_ll *) data;

    if (f->op.destroy)
        f->op.destroy(f->userdata);

    free(f);
}

struct fuse_session *fuse_lowlevel_new(struct fuse_args *args,
                                       const struct fuse_lowlevel_ops *op,
                                       size_t op_size, void *userdata)
{
    struct fuse_ll *f;
    struct fuse_session *se;
    struct fuse_session_ops sop = {
        .process = fuse_ll_process,
        .destroy = fuse_ll_destroy,
    };

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

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

    if (fuse_opt_parse(args, f, fuse_ll_opts, fuse_ll_opt_proc) == -1)
        goto out_free;

    memcpy(&f->op, op, op_size);
    f->owner = getuid();
    f->userdata = userdata;

    se = fuse_session_new(&sop, f);
    if (!se)
        goto out_free;

    return se;

 out_free:
    free(f);
 out:
    return NULL;
}

#ifndef __FreeBSD__

#include "fuse_lowlevel_compat.h"

static void fill_open_compat(struct fuse_open_out *arg,
                      const struct fuse_file_info_compat *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;
}

static void convert_statfs_compat(const struct statfs *compatbuf,
                                  struct statvfs *buf)
{
    buf->f_bsize	= compatbuf->f_bsize;
    buf->f_blocks	= compatbuf->f_blocks;
    buf->f_bfree	= compatbuf->f_bfree;
    buf->f_bavail	= compatbuf->f_bavail;
    buf->f_files	= compatbuf->f_files;
    buf->f_ffree	= compatbuf->f_ffree;
    buf->f_namemax	= compatbuf->f_namelen;
}

int fuse_reply_open_compat(fuse_req_t req,
                           const struct fuse_file_info_compat *f)
{
    struct fuse_open_out arg;

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

int fuse_reply_statfs_compat(fuse_req_t req, const struct statfs *stbuf)
{
    struct statvfs newbuf;

    memset(&newbuf, 0, sizeof(newbuf));
    convert_statfs_compat(stbuf, &newbuf);

    return fuse_reply_statfs(req, &newbuf);
}

struct fuse_session *fuse_lowlevel_new_compat(const char *opts,
                                              const struct fuse_lowlevel_ops *op,
                                              size_t op_size, void *userdata)
{
    struct fuse_session *se;
    struct fuse_args args = FUSE_ARGS_INIT(0, NULL);

    if (opts &&
        (fuse_opt_add_arg(&args, "") == -1 ||
         fuse_opt_add_arg(&args, "-o") == -1 ||
         fuse_opt_add_arg(&args, opts) == -1)) {
        fuse_opt_free_args(&args);
        return NULL;
    }
    se = fuse_lowlevel_new(&args, op, op_size, userdata);
    fuse_opt_free_args(&args);

    return se;
}

__asm__(".symver fuse_reply_statfs_compat,fuse_reply_statfs@FUSE_2.4");
__asm__(".symver fuse_reply_open_compat,fuse_reply_open@FUSE_2.4");
__asm__(".symver fuse_lowlevel_new_compat,fuse_lowlevel_new@FUSE_2.4");

#endif /* __FreeBSD__ */