| /* |
| FUSE: Filesystem in Userspace |
| Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu> |
| Copyright (C) 2017 Nikolaus Rath <Nikolaus@rath.org> |
| Copyright (C) 2018 Valve, Inc |
| |
| This program can be distributed under the terms of the GNU GPL. |
| See the file COPYING. |
| */ |
| |
| /** @file |
| * |
| * This is a "high-performance" version of passthrough_ll.c. While |
| * passthrough_ll.c is designed to be as simple as possible, this |
| * example intended to be as efficient and correct as possible. |
| * |
| * passthrough_hp.cc mirrors a specified "source" directory under a |
| * specified the mountpoint with as much fidelity and performance as |
| * possible. |
| * |
| * If --nocache is specified, the source directory may be changed |
| * directly even while mounted and the filesystem will continue |
| * to work correctly. |
| * |
| * Without --nocache, the source directory is assumed to be modified |
| * only through the passthrough filesystem. This enables much better |
| * performance, but if changes are made directly to the source, they |
| * may not be immediately visible under the mountpoint and further |
| * access to the mountpoint may result in incorrect behavior, |
| * including data-loss. |
| * |
| * On its own, this filesystem fulfills no practical purpose. It is |
| * intended as a template upon which additional functionality can be |
| * built. |
| * |
| * Unless --nocache is specified, is only possible to write to files |
| * for which the mounting user has read permissions. This is because |
| * the writeback cache requires the kernel to be able to issue read |
| * requests for all files (which the passthrough filesystem cannot |
| * satisfy if it can't read the file in the underlying filesystem). |
| * |
| * ## Source code ## |
| * \include passthrough_hp.cc |
| */ |
| |
| #define FUSE_USE_VERSION 35 |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #ifndef _GNU_SOURCE |
| #define _GNU_SOURCE |
| #endif |
| |
| // C includes |
| #include <dirent.h> |
| #include <err.h> |
| #include <errno.h> |
| #include <ftw.h> |
| #include <fuse_lowlevel.h> |
| #include <inttypes.h> |
| #include <string.h> |
| #include <sys/file.h> |
| #include <sys/resource.h> |
| #include <sys/xattr.h> |
| #include <time.h> |
| #include <unistd.h> |
| #include <pthread.h> |
| |
| // C++ includes |
| #include <cstddef> |
| #include <cstdio> |
| #include <cstdlib> |
| #include <list> |
| #include "cxxopts.hpp" |
| #include <mutex> |
| #include <fstream> |
| #include <thread> |
| #include <iomanip> |
| |
| using namespace std; |
| |
| /* We are re-using pointers to our `struct sfs_inode` and `struct |
| sfs_dirp` elements as inodes and file handles. This means that we |
| must be able to store pointer a pointer in both a fuse_ino_t |
| variable and a uint64_t variable (used for file handles). */ |
| static_assert(sizeof(fuse_ino_t) >= sizeof(void*), |
| "void* must fit into fuse_ino_t"); |
| static_assert(sizeof(fuse_ino_t) >= sizeof(uint64_t), |
| "fuse_ino_t must be at least 64 bits"); |
| |
| |
| /* Forward declarations */ |
| struct Inode; |
| static Inode& get_inode(fuse_ino_t ino); |
| static void forget_one(fuse_ino_t ino, uint64_t n); |
| |
| // Uniquely identifies a file in the source directory tree. This could |
| // be simplified to just ino_t since we require the source directory |
| // not to contain any mountpoints. This hasn't been done yet in case |
| // we need to reconsider this constraint (but relaxing this would have |
| // the drawback that we can no longer re-use inode numbers, and thus |
| // readdir() would need to do a full lookup() in order to report the |
| // right inode number). |
| typedef std::pair<ino_t, dev_t> SrcId; |
| |
| // Define a hash function for SrcId |
| namespace std { |
| template<> |
| struct hash<SrcId> { |
| size_t operator()(const SrcId& id) const { |
| return hash<ino_t>{}(id.first) ^ hash<dev_t>{}(id.second); |
| } |
| }; |
| } |
| |
| // Maps files in the source directory tree to inodes |
| typedef std::unordered_map<SrcId, Inode> InodeMap; |
| |
| struct Inode { |
| int fd {-1}; |
| bool is_symlink {false}; |
| dev_t src_dev {0}; |
| ino_t src_ino {0}; |
| uint64_t nlookup {0}; |
| std::mutex m; |
| |
| // Delete copy constructor and assignments. We could implement |
| // move if we need it. |
| Inode() = default; |
| Inode(const Inode&) = delete; |
| Inode(Inode&& inode) = delete; |
| Inode& operator=(Inode&& inode) = delete; |
| Inode& operator=(const Inode&) = delete; |
| |
| ~Inode() { |
| if(fd > 0) |
| close(fd); |
| } |
| }; |
| |
| struct Fs { |
| // Must be acquired *after* any Inode.m locks. |
| std::mutex mutex; |
| InodeMap inodes; // protected by mutex |
| Inode root; |
| double timeout; |
| bool debug; |
| std::string source; |
| size_t blocksize; |
| dev_t src_dev; |
| bool nosplice; |
| bool nocache; |
| }; |
| static Fs fs{}; |
| |
| |
| #define FUSE_BUF_COPY_FLAGS \ |
| (fs.nosplice ? \ |
| FUSE_BUF_NO_SPLICE : \ |
| static_cast<fuse_buf_copy_flags>(0)) |
| |
| |
| static Inode& get_inode(fuse_ino_t ino) { |
| if (ino == FUSE_ROOT_ID) |
| return fs.root; |
| |
| Inode* inode = reinterpret_cast<Inode*>(ino); |
| if(inode->fd == -1) { |
| cerr << "INTERNAL ERROR: Unknown inode " << ino << endl; |
| abort(); |
| } |
| return *inode; |
| } |
| |
| |
| static int get_fs_fd(fuse_ino_t ino) { |
| int fd = get_inode(ino).fd; |
| return fd; |
| } |
| |
| |
| static void sfs_init(void *userdata, fuse_conn_info *conn) { |
| (void)userdata; |
| if (conn->capable & FUSE_CAP_EXPORT_SUPPORT) |
| conn->want |= FUSE_CAP_EXPORT_SUPPORT; |
| |
| if (fs.timeout && conn->capable & FUSE_CAP_WRITEBACK_CACHE) |
| conn->want |= FUSE_CAP_WRITEBACK_CACHE; |
| |
| if (conn->capable & FUSE_CAP_FLOCK_LOCKS) |
| conn->want |= FUSE_CAP_FLOCK_LOCKS; |
| |
| // Use splicing if supported. Since we are using writeback caching |
| // and readahead, individual requests should have a decent size so |
| // that splicing between fd's is well worth it. |
| if (conn->capable & FUSE_CAP_SPLICE_WRITE && !fs.nosplice) |
| conn->want |= FUSE_CAP_SPLICE_WRITE; |
| if (conn->capable & FUSE_CAP_SPLICE_READ && !fs.nosplice) |
| conn->want |= FUSE_CAP_SPLICE_READ; |
| } |
| |
| |
| static void sfs_getattr(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) { |
| (void)fi; |
| Inode& inode = get_inode(ino); |
| struct stat attr; |
| auto res = fstatat(inode.fd, "", &attr, |
| AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); |
| if (res == -1) { |
| fuse_reply_err(req, errno); |
| return; |
| } |
| fuse_reply_attr(req, &attr, fs.timeout); |
| } |
| |
| |
| #ifdef HAVE_UTIMENSAT |
| static int utimensat_empty_nofollow(Inode& inode, |
| const struct timespec *tv) { |
| if (inode.is_symlink) { |
| /* Does not work on current kernels, but may in the future: |
| https://marc.info/?l=linux-kernel&m=154158217810354&w=2 */ |
| auto res = utimensat(inode.fd, "", tv, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); |
| if (res == -1 && errno == EINVAL) { |
| /* Sorry, no race free way to set times on symlink. */ |
| errno = EPERM; |
| } |
| return res; |
| } |
| |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", inode.fd); |
| |
| return utimensat(AT_FDCWD, procname, tv, 0); |
| } |
| #endif |
| |
| |
| static void do_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, |
| int valid, struct fuse_file_info* fi) { |
| Inode& inode = get_inode(ino); |
| int ifd = inode.fd; |
| int res; |
| |
| if (valid & FUSE_SET_ATTR_MODE) { |
| if (fi) { |
| res = fchmod(fi->fh, attr->st_mode); |
| } else { |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", ifd); |
| res = chmod(procname, attr->st_mode); |
| } |
| if (res == -1) |
| goto out_err; |
| } |
| if (valid & (FUSE_SET_ATTR_UID | FUSE_SET_ATTR_GID)) { |
| uid_t uid = (valid & FUSE_SET_ATTR_UID) ? attr->st_uid : static_cast<uid_t>(-1); |
| gid_t gid = (valid & FUSE_SET_ATTR_GID) ? attr->st_gid : static_cast<gid_t>(-1); |
| |
| res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); |
| if (res == -1) |
| goto out_err; |
| } |
| if (valid & FUSE_SET_ATTR_SIZE) { |
| if (fi) { |
| res = ftruncate(fi->fh, attr->st_size); |
| } else { |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", ifd); |
| res = truncate(procname, attr->st_size); |
| } |
| if (res == -1) |
| goto out_err; |
| } |
| if (valid & (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) { |
| struct timespec tv[2]; |
| |
| tv[0].tv_sec = 0; |
| tv[1].tv_sec = 0; |
| tv[0].tv_nsec = UTIME_OMIT; |
| tv[1].tv_nsec = UTIME_OMIT; |
| |
| if (valid & FUSE_SET_ATTR_ATIME_NOW) |
| tv[0].tv_nsec = UTIME_NOW; |
| else if (valid & FUSE_SET_ATTR_ATIME) |
| tv[0] = attr->st_atim; |
| |
| if (valid & FUSE_SET_ATTR_MTIME_NOW) |
| tv[1].tv_nsec = UTIME_NOW; |
| else if (valid & FUSE_SET_ATTR_MTIME) |
| tv[1] = attr->st_mtim; |
| |
| if (fi) |
| res = futimens(fi->fh, tv); |
| else { |
| #ifdef HAVE_UTIMENSAT |
| res = utimensat_empty_nofollow(inode, tv); |
| #else |
| res = -1; |
| errno = EOPNOTSUPP; |
| #endif |
| } |
| if (res == -1) |
| goto out_err; |
| } |
| return sfs_getattr(req, ino, fi); |
| |
| out_err: |
| fuse_reply_err(req, errno); |
| } |
| |
| |
| static void sfs_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, |
| int valid, fuse_file_info *fi) { |
| (void) ino; |
| do_setattr(req, ino, attr, valid, fi); |
| } |
| |
| |
| static int do_lookup(fuse_ino_t parent, const char *name, |
| fuse_entry_param *e) { |
| if (fs.debug) |
| cerr << "DEBUG: lookup(): name=" << name |
| << ", parent=" << parent << endl; |
| memset(e, 0, sizeof(*e)); |
| e->attr_timeout = fs.timeout; |
| e->entry_timeout = fs.timeout; |
| |
| auto newfd = openat(get_fs_fd(parent), name, O_PATH | O_NOFOLLOW); |
| if (newfd == -1) |
| return errno; |
| |
| auto res = fstatat(newfd, "", &e->attr, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); |
| if (res == -1) { |
| auto saveerr = errno; |
| close(newfd); |
| if (fs.debug) |
| cerr << "DEBUG: lookup(): fstatat failed" << endl; |
| return saveerr; |
| } |
| |
| if (e->attr.st_dev != fs.src_dev) { |
| cerr << "WARNING: Mountpoints in the source directory tree will be hidden." << endl; |
| return ENOTSUP; |
| } else if (e->attr.st_ino == FUSE_ROOT_ID) { |
| cerr << "ERROR: Source directory tree must not include inode " |
| << FUSE_ROOT_ID << endl; |
| return EIO; |
| } |
| |
| SrcId id {e->attr.st_ino, e->attr.st_dev}; |
| unique_lock<mutex> fs_lock {fs.mutex}; |
| Inode* inode_p; |
| try { |
| inode_p = &fs.inodes[id]; |
| } catch (std::bad_alloc&) { |
| return ENOMEM; |
| } |
| e->ino = reinterpret_cast<fuse_ino_t>(inode_p); |
| Inode& inode {*inode_p}; |
| |
| if(inode.fd != -1) { // found existing inode |
| fs_lock.unlock(); |
| if (fs.debug) |
| cerr << "DEBUG: lookup(): inode " << e->attr.st_ino |
| << " (userspace) already known." << endl; |
| lock_guard<mutex> g {inode.m}; |
| inode.nlookup++; |
| close(newfd); |
| } else { // no existing inode |
| /* This is just here to make Helgrind happy. It violates the |
| lock ordering requirement (inode.m must be acquired before |
| fs.mutex), but this is of no consequence because at this |
| point no other thread has access to the inode mutex */ |
| lock_guard<mutex> g {inode.m}; |
| inode.src_ino = e->attr.st_ino; |
| inode.src_dev = e->attr.st_dev; |
| inode.is_symlink = S_ISLNK(e->attr.st_mode); |
| inode.nlookup = 1; |
| inode.fd = newfd; |
| fs_lock.unlock(); |
| |
| if (fs.debug) |
| cerr << "DEBUG: lookup(): created userspace inode " << e->attr.st_ino |
| << endl; |
| } |
| |
| return 0; |
| } |
| |
| |
| static void sfs_lookup(fuse_req_t req, fuse_ino_t parent, const char *name) { |
| fuse_entry_param e {}; |
| auto err = do_lookup(parent, name, &e); |
| if (err == ENOENT) { |
| e.attr_timeout = fs.timeout; |
| e.entry_timeout = fs.timeout; |
| e.ino = e.attr.st_ino = 0; |
| fuse_reply_entry(req, &e); |
| } else if (err) { |
| if (err == ENFILE || err == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, err); |
| } else { |
| fuse_reply_entry(req, &e); |
| } |
| } |
| |
| |
| static void mknod_symlink(fuse_req_t req, fuse_ino_t parent, |
| const char *name, mode_t mode, dev_t rdev, |
| const char *link) { |
| int res; |
| Inode& inode_p = get_inode(parent); |
| auto saverr = ENOMEM; |
| |
| if (S_ISDIR(mode)) |
| res = mkdirat(inode_p.fd, name, mode); |
| else if (S_ISLNK(mode)) |
| res = symlinkat(link, inode_p.fd, name); |
| else |
| res = mknodat(inode_p.fd, name, mode, rdev); |
| saverr = errno; |
| if (res == -1) |
| goto out; |
| |
| fuse_entry_param e; |
| saverr = do_lookup(parent, name, &e); |
| if (saverr) |
| goto out; |
| |
| fuse_reply_entry(req, &e); |
| return; |
| |
| out: |
| if (saverr == ENFILE || saverr == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, saverr); |
| } |
| |
| |
| static void sfs_mknod(fuse_req_t req, fuse_ino_t parent, const char *name, |
| mode_t mode, dev_t rdev) { |
| mknod_symlink(req, parent, name, mode, rdev, nullptr); |
| } |
| |
| |
| static void sfs_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name, |
| mode_t mode) { |
| mknod_symlink(req, parent, name, S_IFDIR | mode, 0, nullptr); |
| } |
| |
| |
| static void sfs_symlink(fuse_req_t req, const char *link, fuse_ino_t parent, |
| const char *name) { |
| mknod_symlink(req, parent, name, S_IFLNK, 0, link); |
| } |
| |
| |
| static int linkat_empty_nofollow(Inode& inode, int dfd, const char *name) { |
| if (inode.is_symlink) { |
| auto res = linkat(inode.fd, "", dfd, name, AT_EMPTY_PATH); |
| if (res == -1 && (errno == ENOENT || errno == EINVAL)) { |
| /* Sorry, no race free way to hard-link a symlink. */ |
| errno = EOPNOTSUPP; |
| } |
| return res; |
| } |
| |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", inode.fd); |
| return linkat(AT_FDCWD, procname, dfd, name, AT_SYMLINK_FOLLOW); |
| } |
| |
| |
| static void sfs_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, |
| const char *name) { |
| Inode& inode = get_inode(ino); |
| Inode& inode_p = get_inode(parent); |
| fuse_entry_param e {}; |
| |
| e.attr_timeout = fs.timeout; |
| e.entry_timeout = fs.timeout; |
| |
| auto res = linkat_empty_nofollow(inode, inode_p.fd, name); |
| if (res == -1) { |
| fuse_reply_err(req, errno); |
| return; |
| } |
| |
| res = fstatat(inode.fd, "", &e.attr, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); |
| if (res == -1) { |
| fuse_reply_err(req, errno); |
| return; |
| } |
| e.ino = reinterpret_cast<fuse_ino_t>(&inode); |
| { |
| lock_guard<mutex> g {inode.m}; |
| inode.nlookup++; |
| } |
| |
| fuse_reply_entry(req, &e); |
| return; |
| } |
| |
| |
| static void sfs_rmdir(fuse_req_t req, fuse_ino_t parent, const char *name) { |
| Inode& inode_p = get_inode(parent); |
| lock_guard<mutex> g {inode_p.m}; |
| auto res = unlinkat(inode_p.fd, name, AT_REMOVEDIR); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| static void sfs_rename(fuse_req_t req, fuse_ino_t parent, const char *name, |
| fuse_ino_t newparent, const char *newname, |
| unsigned int flags) { |
| Inode& inode_p = get_inode(parent); |
| Inode& inode_np = get_inode(newparent); |
| if (flags) { |
| fuse_reply_err(req, EINVAL); |
| return; |
| } |
| |
| auto res = renameat(inode_p.fd, name, inode_np.fd, newname); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| static void sfs_unlink(fuse_req_t req, fuse_ino_t parent, const char *name) { |
| Inode& inode_p = get_inode(parent); |
| auto res = unlinkat(inode_p.fd, name, 0); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| static void forget_one(fuse_ino_t ino, uint64_t n) { |
| Inode& inode = get_inode(ino); |
| unique_lock<mutex> l {inode.m}; |
| |
| if(n > inode.nlookup) { |
| cerr << "INTERNAL ERROR: Negative lookup count for inode " |
| << inode.src_ino << endl; |
| abort(); |
| } |
| inode.nlookup -= n; |
| if (!inode.nlookup) { |
| if (fs.debug) |
| cerr << "DEBUG: forget: cleaning up inode " << inode.src_ino << endl; |
| { |
| lock_guard<mutex> g_fs {fs.mutex}; |
| l.unlock(); |
| fs.inodes.erase({inode.src_ino, inode.src_dev}); |
| } |
| } else if (fs.debug) |
| cerr << "DEBUG: forget: inode " << inode.src_ino |
| << " lookup count now " << inode.nlookup << endl; |
| } |
| |
| static void sfs_forget(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup) { |
| forget_one(ino, nlookup); |
| fuse_reply_none(req); |
| } |
| |
| |
| static void sfs_forget_multi(fuse_req_t req, size_t count, |
| fuse_forget_data *forgets) { |
| for (int i = 0; i < count; i++) |
| forget_one(forgets[i].ino, forgets[i].nlookup); |
| fuse_reply_none(req); |
| } |
| |
| |
| static void sfs_readlink(fuse_req_t req, fuse_ino_t ino) { |
| Inode& inode = get_inode(ino); |
| char buf[PATH_MAX + 1]; |
| auto res = readlinkat(inode.fd, "", buf, sizeof(buf)); |
| if (res == -1) |
| fuse_reply_err(req, errno); |
| else if (res == sizeof(buf)) |
| fuse_reply_err(req, ENAMETOOLONG); |
| else { |
| buf[res] = '\0'; |
| fuse_reply_readlink(req, buf); |
| } |
| } |
| |
| |
| struct DirHandle { |
| DIR *dp {nullptr}; |
| off_t offset; |
| |
| DirHandle() = default; |
| DirHandle(const DirHandle&) = delete; |
| DirHandle& operator=(const DirHandle&) = delete; |
| |
| ~DirHandle() { |
| if(dp) |
| closedir(dp); |
| } |
| }; |
| |
| |
| static DirHandle *get_dir_handle(fuse_file_info *fi) { |
| return reinterpret_cast<DirHandle*>(fi->fh); |
| } |
| |
| |
| static void sfs_opendir(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) { |
| Inode& inode = get_inode(ino); |
| auto d = new (nothrow) DirHandle; |
| if (d == nullptr) { |
| fuse_reply_err(req, ENOMEM); |
| return; |
| } |
| |
| // Make Helgrind happy - it can't know that there's an implicit |
| // synchronization due to the fact that other threads cannot |
| // access d until we've called fuse_reply_*. |
| lock_guard<mutex> g {inode.m}; |
| |
| auto fd = openat(inode.fd, ".", O_RDONLY); |
| if (fd == -1) |
| goto out_errno; |
| |
| // On success, dir stream takes ownership of fd, so we |
| // do not have to close it. |
| d->dp = fdopendir(fd); |
| if(d->dp == nullptr) |
| goto out_errno; |
| |
| d->offset = 0; |
| |
| fi->fh = reinterpret_cast<uint64_t>(d); |
| if(fs.timeout) { |
| fi->keep_cache = 1; |
| fi->cache_readdir = 1; |
| } |
| fuse_reply_open(req, fi); |
| return; |
| |
| out_errno: |
| auto error = errno; |
| delete d; |
| if (error == ENFILE || error == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, error); |
| } |
| |
| |
| static bool is_dot_or_dotdot(const char *name) { |
| return name[0] == '.' && |
| (name[1] == '\0' || (name[1] == '.' && name[2] == '\0')); |
| } |
| |
| |
| static void do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size, |
| off_t offset, fuse_file_info *fi, int plus) { |
| auto d = get_dir_handle(fi); |
| Inode& inode = get_inode(ino); |
| lock_guard<mutex> g {inode.m}; |
| char *p; |
| auto rem = size; |
| int err = 0, count = 0; |
| |
| if (fs.debug) |
| cerr << "DEBUG: readdir(): started with offset " |
| << offset << endl; |
| |
| auto buf = new (nothrow) char[size]; |
| if (!buf) { |
| fuse_reply_err(req, ENOMEM); |
| return; |
| } |
| p = buf; |
| |
| if (offset != d->offset) { |
| if (fs.debug) |
| cerr << "DEBUG: readdir(): seeking to " << offset << endl; |
| seekdir(d->dp, offset); |
| d->offset = offset; |
| } |
| |
| while (1) { |
| struct dirent *entry; |
| errno = 0; |
| entry = readdir(d->dp); |
| if (!entry) { |
| if(errno) { |
| err = errno; |
| if (fs.debug) |
| warn("DEBUG: readdir(): readdir failed with"); |
| goto error; |
| } |
| break; // End of stream |
| } |
| d->offset = entry->d_off; |
| if (is_dot_or_dotdot(entry->d_name)) |
| continue; |
| |
| fuse_entry_param e{}; |
| size_t entsize; |
| if(plus) { |
| err = do_lookup(ino, entry->d_name, &e); |
| if (err) |
| goto error; |
| entsize = fuse_add_direntry_plus(req, p, rem, entry->d_name, &e, entry->d_off); |
| |
| if (entsize > rem) { |
| if (fs.debug) |
| cerr << "DEBUG: readdir(): buffer full, returning data. " << endl; |
| forget_one(e.ino, 1); |
| break; |
| } |
| } else { |
| e.attr.st_ino = entry->d_ino; |
| e.attr.st_mode = entry->d_type << 12; |
| entsize = fuse_add_direntry(req, p, rem, entry->d_name, &e.attr, entry->d_off); |
| |
| if (entsize > rem) { |
| if (fs.debug) |
| cerr << "DEBUG: readdir(): buffer full, returning data. " << endl; |
| break; |
| } |
| } |
| |
| p += entsize; |
| rem -= entsize; |
| count++; |
| if (fs.debug) { |
| cerr << "DEBUG: readdir(): added to buffer: " << entry->d_name |
| << ", ino " << e.attr.st_ino << ", offset " << entry->d_off << endl; |
| } |
| } |
| err = 0; |
| error: |
| |
| // If there's an error, we can only signal it if we haven't stored |
| // any entries yet - otherwise we'd end up with wrong lookup |
| // counts for the entries that are already in the buffer. So we |
| // return what we've collected until that point. |
| if (err && rem == size) { |
| if (err == ENFILE || err == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, err); |
| } else { |
| if (fs.debug) |
| cerr << "DEBUG: readdir(): returning " << count |
| << " entries, curr offset " << d->offset << endl; |
| fuse_reply_buf(req, buf, size - rem); |
| } |
| delete[] buf; |
| return; |
| } |
| |
| |
| static void sfs_readdir(fuse_req_t req, fuse_ino_t ino, size_t size, |
| off_t offset, fuse_file_info *fi) { |
| // operation logging is done in readdir to reduce code duplication |
| do_readdir(req, ino, size, offset, fi, 0); |
| } |
| |
| |
| static void sfs_readdirplus(fuse_req_t req, fuse_ino_t ino, size_t size, |
| off_t offset, fuse_file_info *fi) { |
| // operation logging is done in readdir to reduce code duplication |
| do_readdir(req, ino, size, offset, fi, 1); |
| } |
| |
| |
| static void sfs_releasedir(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) { |
| (void) ino; |
| auto d = get_dir_handle(fi); |
| delete d; |
| fuse_reply_err(req, 0); |
| } |
| |
| |
| static void sfs_create(fuse_req_t req, fuse_ino_t parent, const char *name, |
| mode_t mode, fuse_file_info *fi) { |
| Inode& inode_p = get_inode(parent); |
| |
| auto fd = openat(inode_p.fd, name, |
| (fi->flags | O_CREAT) & ~O_NOFOLLOW, mode); |
| if (fd == -1) { |
| auto err = errno; |
| if (err == ENFILE || err == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, err); |
| return; |
| } |
| |
| fi->fh = fd; |
| fuse_entry_param e; |
| auto err = do_lookup(parent, name, &e); |
| if (err) { |
| if (err == ENFILE || err == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, err); |
| } else |
| fuse_reply_create(req, &e, fi); |
| } |
| |
| |
| static void sfs_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync, |
| fuse_file_info *fi) { |
| (void) ino; |
| int res; |
| int fd = dirfd(get_dir_handle(fi)->dp); |
| if (datasync) |
| res = fdatasync(fd); |
| else |
| res = fsync(fd); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| static void sfs_open(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) { |
| Inode& inode = get_inode(ino); |
| |
| /* With writeback cache, kernel may send read requests even |
| when userspace opened write-only */ |
| if (fs.timeout && (fi->flags & O_ACCMODE) == O_WRONLY) { |
| fi->flags &= ~O_ACCMODE; |
| fi->flags |= O_RDWR; |
| } |
| |
| /* With writeback cache, O_APPEND is handled by the kernel. This |
| breaks atomicity (since the file may change in the underlying |
| filesystem, so that the kernel's idea of the end of the file |
| isn't accurate anymore). However, no process should modify the |
| file in the underlying filesystem once it has been read, so |
| this is not a problem. */ |
| if (fs.timeout && fi->flags & O_APPEND) |
| fi->flags &= ~O_APPEND; |
| |
| /* Unfortunately we cannot use inode.fd, because this was opened |
| with O_PATH (so it doesn't allow read/write access). */ |
| char buf[64]; |
| sprintf(buf, "/proc/self/fd/%i", inode.fd); |
| auto fd = open(buf, fi->flags & ~O_NOFOLLOW); |
| if (fd == -1) { |
| auto err = errno; |
| if (err == ENFILE || err == EMFILE) |
| cerr << "ERROR: Reached maximum number of file descriptors." << endl; |
| fuse_reply_err(req, err); |
| return; |
| } |
| |
| fi->keep_cache = (fs.timeout != 0); |
| fi->fh = fd; |
| fuse_reply_open(req, fi); |
| } |
| |
| |
| static void sfs_release(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) { |
| (void) ino; |
| close(fi->fh); |
| fuse_reply_err(req, 0); |
| } |
| |
| |
| static void sfs_flush(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) { |
| (void) ino; |
| auto res = close(dup(fi->fh)); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| static void sfs_fsync(fuse_req_t req, fuse_ino_t ino, int datasync, |
| fuse_file_info *fi) { |
| (void) ino; |
| int res; |
| if (datasync) |
| res = fdatasync(fi->fh); |
| else |
| res = fsync(fi->fh); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| static void do_read(fuse_req_t req, size_t size, off_t off, fuse_file_info *fi) { |
| |
| fuse_bufvec buf = FUSE_BUFVEC_INIT(size); |
| buf.buf[0].flags = static_cast<fuse_buf_flags>( |
| FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK); |
| buf.buf[0].fd = fi->fh; |
| buf.buf[0].pos = off; |
| |
| fuse_reply_data(req, &buf, FUSE_BUF_COPY_FLAGS); |
| } |
| |
| static void sfs_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t off, |
| fuse_file_info *fi) { |
| (void) ino; |
| do_read(req, size, off, fi); |
| } |
| |
| |
| static void do_write_buf(fuse_req_t req, size_t size, off_t off, |
| fuse_bufvec *in_buf, fuse_file_info *fi) { |
| fuse_bufvec out_buf = FUSE_BUFVEC_INIT(size); |
| out_buf.buf[0].flags = static_cast<fuse_buf_flags>( |
| FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK); |
| out_buf.buf[0].fd = fi->fh; |
| out_buf.buf[0].pos = off; |
| |
| auto res = fuse_buf_copy(&out_buf, in_buf, FUSE_BUF_COPY_FLAGS); |
| if (res < 0) |
| fuse_reply_err(req, -res); |
| else |
| fuse_reply_write(req, (size_t)res); |
| } |
| |
| |
| static void sfs_write_buf(fuse_req_t req, fuse_ino_t ino, fuse_bufvec *in_buf, |
| off_t off, fuse_file_info *fi) { |
| (void) ino; |
| auto size {fuse_buf_size(in_buf)}; |
| do_write_buf(req, size, off, in_buf, fi); |
| } |
| |
| |
| static void sfs_statfs(fuse_req_t req, fuse_ino_t ino) { |
| struct statvfs stbuf; |
| |
| auto res = fstatvfs(get_fs_fd(ino), &stbuf); |
| if (res == -1) |
| fuse_reply_err(req, errno); |
| else |
| fuse_reply_statfs(req, &stbuf); |
| } |
| |
| |
| #ifdef HAVE_POSIX_FALLOCATE |
| static void sfs_fallocate(fuse_req_t req, fuse_ino_t ino, int mode, |
| off_t offset, off_t length, fuse_file_info *fi) { |
| (void) ino; |
| if (mode) { |
| fuse_reply_err(req, EOPNOTSUPP); |
| return; |
| } |
| |
| auto err = posix_fallocate(fi->fh, offset, length); |
| fuse_reply_err(req, err); |
| } |
| #endif |
| |
| static void sfs_flock(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi, |
| int op) { |
| (void) ino; |
| auto res = flock(fi->fh, op); |
| fuse_reply_err(req, res == -1 ? errno : 0); |
| } |
| |
| |
| #ifdef HAVE_SETXATTR |
| static void sfs_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name, |
| size_t size) { |
| char *value = nullptr; |
| Inode& inode = get_inode(ino); |
| ssize_t ret; |
| int saverr; |
| |
| if (inode.is_symlink) { |
| /* Sorry, no race free way to getxattr on symlink. */ |
| saverr = ENOTSUP; |
| goto out; |
| } |
| |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", inode.fd); |
| |
| if (size) { |
| value = new (nothrow) char[size]; |
| if (value == nullptr) { |
| saverr = ENOMEM; |
| goto out; |
| } |
| |
| ret = getxattr(procname, name, value, size); |
| if (ret == -1) |
| goto out_err; |
| saverr = 0; |
| if (ret == 0) |
| goto out; |
| |
| fuse_reply_buf(req, value, ret); |
| } else { |
| ret = getxattr(procname, name, nullptr, 0); |
| if (ret == -1) |
| goto out_err; |
| |
| fuse_reply_xattr(req, ret); |
| } |
| out_free: |
| delete[] value; |
| return; |
| |
| out_err: |
| saverr = errno; |
| out: |
| fuse_reply_err(req, saverr); |
| goto out_free; |
| } |
| |
| |
| static void sfs_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) { |
| char *value = nullptr; |
| Inode& inode = get_inode(ino); |
| ssize_t ret; |
| int saverr; |
| |
| if (inode.is_symlink) { |
| /* Sorry, no race free way to listxattr on symlink. */ |
| saverr = ENOTSUP; |
| goto out; |
| } |
| |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", inode.fd); |
| |
| if (size) { |
| value = new (nothrow) char[size]; |
| if (value == nullptr) { |
| saverr = ENOMEM; |
| goto out; |
| } |
| |
| ret = listxattr(procname, value, size); |
| if (ret == -1) |
| goto out_err; |
| saverr = 0; |
| if (ret == 0) |
| goto out; |
| |
| fuse_reply_buf(req, value, ret); |
| } else { |
| ret = listxattr(procname, nullptr, 0); |
| if (ret == -1) |
| goto out_err; |
| |
| fuse_reply_xattr(req, ret); |
| } |
| out_free: |
| delete[] value; |
| return; |
| out_err: |
| saverr = errno; |
| out: |
| fuse_reply_err(req, saverr); |
| goto out_free; |
| } |
| |
| |
| static void sfs_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name, |
| const char *value, size_t size, int flags) { |
| Inode& inode = get_inode(ino); |
| ssize_t ret; |
| int saverr; |
| |
| if (inode.is_symlink) { |
| /* Sorry, no race free way to setxattr on symlink. */ |
| saverr = ENOTSUP; |
| goto out; |
| } |
| |
| char procname[64]; |
| sprintf(procname, "/proc/self/fd/%i", inode.fd); |
| |
| ret = setxattr(procname, name, value, size, flags); |
| saverr = ret == -1 ? errno : 0; |
| |
| out: |
| fuse_reply_err(req, saverr); |
| } |
| |
| |
| static void sfs_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name) { |
| char procname[64]; |
| Inode& inode = get_inode(ino); |
| ssize_t ret; |
| int saverr; |
| |
| if (inode.is_symlink) { |
| /* Sorry, no race free way to setxattr on symlink. */ |
| saverr = ENOTSUP; |
| goto out; |
| } |
| |
| sprintf(procname, "/proc/self/fd/%i", inode.fd); |
| ret = removexattr(procname, name); |
| saverr = ret == -1 ? errno : 0; |
| |
| out: |
| fuse_reply_err(req, saverr); |
| } |
| #endif |
| |
| |
| static void assign_operations(fuse_lowlevel_ops &sfs_oper) { |
| sfs_oper.init = sfs_init; |
| sfs_oper.lookup = sfs_lookup; |
| sfs_oper.mkdir = sfs_mkdir; |
| sfs_oper.mknod = sfs_mknod; |
| sfs_oper.symlink = sfs_symlink; |
| sfs_oper.link = sfs_link; |
| sfs_oper.unlink = sfs_unlink; |
| sfs_oper.rmdir = sfs_rmdir; |
| sfs_oper.rename = sfs_rename; |
| sfs_oper.forget = sfs_forget; |
| sfs_oper.forget_multi = sfs_forget_multi; |
| sfs_oper.getattr = sfs_getattr; |
| sfs_oper.setattr = sfs_setattr; |
| sfs_oper.readlink = sfs_readlink; |
| sfs_oper.opendir = sfs_opendir; |
| sfs_oper.readdir = sfs_readdir; |
| sfs_oper.readdirplus = sfs_readdirplus; |
| sfs_oper.releasedir = sfs_releasedir; |
| sfs_oper.fsyncdir = sfs_fsyncdir; |
| sfs_oper.create = sfs_create; |
| sfs_oper.open = sfs_open; |
| sfs_oper.release = sfs_release; |
| sfs_oper.flush = sfs_flush; |
| sfs_oper.fsync = sfs_fsync; |
| sfs_oper.read = sfs_read; |
| sfs_oper.write_buf = sfs_write_buf; |
| sfs_oper.statfs = sfs_statfs; |
| #ifdef HAVE_POSIX_FALLOCATE |
| sfs_oper.fallocate = sfs_fallocate; |
| #endif |
| sfs_oper.flock = sfs_flock; |
| #ifdef HAVE_SETXATTR |
| sfs_oper.setxattr = sfs_setxattr; |
| sfs_oper.getxattr = sfs_getxattr; |
| sfs_oper.listxattr = sfs_listxattr; |
| sfs_oper.removexattr = sfs_removexattr; |
| #endif |
| } |
| |
| static void print_usage(char *prog_name) { |
| cout << "Usage: " << prog_name << " --help\n" |
| << " " << prog_name << " [options] <source> <mountpoint>\n"; |
| } |
| |
| static cxxopts::ParseResult parse_wrapper(cxxopts::Options& parser, int& argc, char**& argv) { |
| try { |
| return parser.parse(argc, argv); |
| } catch (cxxopts::option_not_exists_exception& exc) { |
| std::cout << argv[0] << ": " << exc.what() << std::endl; |
| print_usage(argv[0]); |
| exit(2); |
| } |
| } |
| |
| |
| static cxxopts::ParseResult parse_options(int argc, char **argv) { |
| cxxopts::Options opt_parser(argv[0]); |
| opt_parser.add_options() |
| ("debug", "Enable filesystem debug messages") |
| ("debug-fuse", "Enable libfuse debug messages") |
| ("help", "Print help") |
| ("nocache", "Disable all caching") |
| ("nosplice", "Do not use splice(2) to transfer data") |
| ("single", "Run single-threaded"); |
| |
| // FIXME: Find a better way to limit the try clause to just |
| // opt_parser.parse() (cf. https://github.com/jarro2783/cxxopts/issues/146) |
| auto options = parse_wrapper(opt_parser, argc, argv); |
| |
| if (options.count("help")) { |
| print_usage(argv[0]); |
| // Strip everything before the option list from the |
| // default help string. |
| auto help = opt_parser.help(); |
| std::cout << std::endl << "options:" |
| << help.substr(help.find("\n\n") + 1, string::npos); |
| exit(0); |
| |
| } else if (argc != 3) { |
| std::cout << argv[0] << ": invalid number of arguments\n"; |
| print_usage(argv[0]); |
| exit(2); |
| } |
| |
| fs.debug = options.count("debug") != 0; |
| fs.nosplice = options.count("nosplice") != 0; |
| fs.source = std::string {realpath(argv[1], NULL)}; |
| |
| return options; |
| } |
| |
| |
| static void maximize_fd_limit() { |
| struct rlimit lim {}; |
| auto res = getrlimit(RLIMIT_NOFILE, &lim); |
| if (res != 0) { |
| warn("WARNING: getrlimit() failed with"); |
| return; |
| } |
| lim.rlim_cur = lim.rlim_max; |
| res = setrlimit(RLIMIT_NOFILE, &lim); |
| if (res != 0) |
| warn("WARNING: setrlimit() failed with"); |
| } |
| |
| |
| int main(int argc, char *argv[]) { |
| |
| // Parse command line options |
| auto options {parse_options(argc, argv)}; |
| |
| // We need an fd for every dentry in our the filesystem that the |
| // kernel knows about. This is way more than most processes need, |
| // so try to get rid of any resource softlimit. |
| maximize_fd_limit(); |
| |
| // Initialize filesystem root |
| fs.root.fd = -1; |
| fs.root.nlookup = 9999; |
| fs.root.is_symlink = false; |
| fs.timeout = options.count("nocache") ? 0 : 86400.0; |
| |
| struct stat stat; |
| auto ret = lstat(fs.source.c_str(), &stat); |
| if (ret == -1) |
| err(1, "ERROR: failed to stat source (\"%s\")", fs.source.c_str()); |
| if (!S_ISDIR(stat.st_mode)) |
| errx(1, "ERROR: source is not a directory"); |
| fs.src_dev = stat.st_dev; |
| |
| fs.root.fd = open(fs.source.c_str(), O_PATH); |
| if (fs.root.fd == -1) |
| err(1, "ERROR: open(\"%s\", O_PATH)", fs.source.c_str()); |
| |
| // Initialize fuse |
| fuse_args args = FUSE_ARGS_INIT(0, nullptr); |
| if (fuse_opt_add_arg(&args, argv[0]) || |
| fuse_opt_add_arg(&args, "-o") || |
| fuse_opt_add_arg(&args, "default_permissions,fsname=hpps") || |
| (options.count("debug-fuse") && fuse_opt_add_arg(&args, "-odebug"))) |
| errx(3, "ERROR: Out of memory"); |
| |
| fuse_lowlevel_ops sfs_oper {}; |
| assign_operations(sfs_oper); |
| auto se = fuse_session_new(&args, &sfs_oper, sizeof(sfs_oper), &fs); |
| if (se == nullptr) |
| goto err_out1; |
| |
| if (fuse_set_signal_handlers(se) != 0) |
| goto err_out2; |
| |
| // Don't apply umask, use modes exactly as specified |
| umask(0); |
| |
| // Mount and run main loop |
| struct fuse_loop_config loop_config; |
| loop_config.clone_fd = 0; |
| loop_config.max_idle_threads = 10; |
| if (fuse_session_mount(se, argv[2]) != 0) |
| goto err_out3; |
| if (options.count("single")) |
| ret = fuse_session_loop(se); |
| else |
| ret = fuse_session_loop_mt(se, &loop_config); |
| |
| fuse_session_unmount(se); |
| |
| err_out3: |
| fuse_remove_signal_handlers(se); |
| err_out2: |
| fuse_session_destroy(se); |
| err_out1: |
| fuse_opt_free_args(&args); |
| |
| return ret ? 1 : 0; |
| } |
| |