fuse_lowlevel.c

FUSE文件系统开发工具,将内核层面的文件系统开发过程平移到应用层面上来。

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <[e-mail]>

  This program can be distributed under the terms of the GNU LGPLv2.
  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;
	attr->atimensec = ST_ATIM_NSEC(stbuf);
	attr->mtimensec = ST_MTIM_NSEC(stbuf);
	attr->ctimensec = ST_CTIM_NSEC(stbuf);
}

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;
	ST_ATIM_NSEC_SET(stbuf, attr->atimensec);
	ST_MTIM_NSEC_SET(stbuf, attr->mtimensec);
}

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_iov(fuse_req_t req, int error, struct iovec *iov,
			  int count)
{
	struct fuse_out_header out;
	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;
	iov[0].iov_base = &out;
	iov[0].iov_len = sizeof(struct fuse_out_header);
	out.len = iov_length(iov, count);

	if (req->f->debug)
		fprintf(stderr,
			"   unique: %llu, error: %i (%s), outsize: %i\n",
			(unsigned long long) out.unique, out.error,
			strerror(-out.error), out.len);
	res = fuse_chan_send(req->ch, iov, count);
	free_req(req);

	return res;
}

static int send_reply(fuse_req_t req, int error, const void *arg,
		      size_t argsize)
{
	struct iovec iov[2];
	int count = 1;
	if (argsize) {
		iov[1].iov_base = (void *) arg;
		iov[1].iov_len = argsize;
		count++;
	}
	return send_reply_iov(req, error, iov, count);
}

int fuse_reply_iov(fuse_req_t req, const struct iovec *iov, int count)
{
	int res;
	struct iovec *padded_iov;

	padded_iov = malloc((count + 1) * sizeof(struct iovec));
	if (padded_iov == NULL)
		return fuse_reply_err(req, -ENOMEM);

	memcpy(padded_iov + 1, iov, count * sizeof(struct iovec));
	count++;

	res = send_reply_iov(req, 0, padded_iov, count);
	free(padded_iov);

	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);
	else
		fuse_reply_none(req);
}

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;