sdcard.c revision 6fd921ae03a0fa17acfe118753ecd76d25f02e10
1/* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#include <stdio.h> 18#include <stdlib.h> 19#include <string.h> 20#include <unistd.h> 21#include <errno.h> 22#include <fcntl.h> 23#include <sys/mount.h> 24#include <sys/stat.h> 25#include <sys/statfs.h> 26#include <sys/uio.h> 27#include <dirent.h> 28#include <ctype.h> 29 30#include <private/android_filesystem_config.h> 31 32#include "fuse.h" 33 34/* README 35 * 36 * What is this? 37 * 38 * sdcard is a program that uses FUSE to emulate FAT-on-sdcard style 39 * directory permissions (all files are given fixed owner, group, and 40 * permissions at creation, owner, group, and permissions are not 41 * changeable, symlinks and hardlinks are not createable, etc. 42 * 43 * usage: sdcard <path> <uid> <gid> 44 * 45 * It must be run as root, but will change to uid/gid as soon as it 46 * mounts a filesystem on /storage/sdcard. It will refuse to run if uid or 47 * gid are zero. 48 * 49 * 50 * Things I believe to be true: 51 * 52 * - ops that return a fuse_entry (LOOKUP, MKNOD, MKDIR, LINK, SYMLINK, 53 * CREAT) must bump that node's refcount 54 * - don't forget that FORGET can forget multiple references (req->nlookup) 55 * - if an op that returns a fuse_entry fails writing the reply to the 56 * kernel, you must rollback the refcount to reflect the reference the 57 * kernel did not actually acquire 58 * 59 */ 60 61#define FUSE_TRACE 0 62 63#if FUSE_TRACE 64#define TRACE(x...) fprintf(stderr,x) 65#else 66#define TRACE(x...) do {} while (0) 67#endif 68 69#define ERROR(x...) fprintf(stderr,x) 70 71#define FUSE_UNKNOWN_INO 0xffffffff 72 73#define MOUNT_POINT "/storage/sdcard0" 74 75/* Maximum number of bytes to write in one request. */ 76#define MAX_WRITE (256 * 1024) 77 78/* Maximum number of bytes to read in one request. */ 79#define MAX_READ (128 * 1024) 80 81/* Largest possible request. 82 * The request size is bounded by the maximum size of a FUSE_WRITE request because it has 83 * the largest possible data payload. */ 84#define MAX_REQUEST_SIZE (sizeof(struct fuse_in_header) + sizeof(struct fuse_write_in) + MAX_WRITE) 85 86struct handle { 87 struct node *node; 88 int fd; 89}; 90 91struct dirhandle { 92 struct node *node; 93 DIR *d; 94}; 95 96struct node { 97 __u64 nid; 98 __u64 gen; 99 100 struct node *next; /* per-dir sibling list */ 101 struct node *child; /* first contained file by this dir */ 102 struct node *all; /* global node list */ 103 struct node *parent; /* containing directory */ 104 105 __u32 refcount; 106 __u32 namelen; 107 108 char *name; 109 /* If non-null, this is the real name of the file in the underlying storage. 110 * This may differ from the field "name" only by case. 111 * strlen(actual_name) will always equal strlen(name), so it is safe to use 112 * namelen for both fields. 113 */ 114 char *actual_name; 115}; 116 117struct fuse { 118 __u64 next_generation; 119 __u64 next_node_id; 120 121 int fd; 122 123 struct node *all; 124 125 struct node root; 126 char rootpath[1024]; 127}; 128 129#define PATH_BUFFER_SIZE 1024 130 131#define NO_CASE_SENSITIVE_MATCH 0 132#define CASE_SENSITIVE_MATCH 1 133 134/* 135 * Get the real-life absolute path to a node. 136 * node: start at this node 137 * buf: storage for returned string 138 * name: append this string to path if set 139 */ 140char *do_node_get_path(struct node *node, char *buf, const char *name, int match_case_insensitive) 141{ 142 struct node *in_node = node; 143 const char *in_name = name; 144 char *out = buf + PATH_BUFFER_SIZE - 1; 145 int len; 146 out[0] = 0; 147 148 if (name) { 149 len = strlen(name); 150 goto start; 151 } 152 153 while (node) { 154 name = (node->actual_name ? node->actual_name : node->name); 155 len = node->namelen; 156 node = node->parent; 157 start: 158 if ((len + 1) > (out - buf)) 159 return 0; 160 out -= len; 161 memcpy(out, name, len); 162 /* avoid double slash at beginning of path */ 163 if (out[0] != '/') { 164 out --; 165 out[0] = '/'; 166 } 167 } 168 169 /* If we are searching for a file within node (rather than computing node's path) 170 * and fail, then we need to look for a case insensitive match. 171 */ 172 if (in_name && match_case_insensitive && access(out, F_OK) != 0) { 173 char *path, buffer[PATH_BUFFER_SIZE]; 174 DIR* dir; 175 struct dirent* entry; 176 path = do_node_get_path(in_node, buffer, NULL, NO_CASE_SENSITIVE_MATCH); 177 dir = opendir(path); 178 if (!dir) { 179 ERROR("opendir %s failed: %s", path, strerror(errno)); 180 return out; 181 } 182 183 while ((entry = readdir(dir))) { 184 if (!strcasecmp(entry->d_name, in_name)) { 185 /* we have a match - replace the name */ 186 len = strlen(in_name); 187 memcpy(buf + PATH_BUFFER_SIZE - len - 1, entry->d_name, len); 188 break; 189 } 190 } 191 closedir(dir); 192 } 193 194 return out; 195} 196 197char *node_get_path(struct node *node, char *buf, const char *name) 198{ 199 /* We look for case insensitive matches by default */ 200 return do_node_get_path(node, buf, name, CASE_SENSITIVE_MATCH); 201} 202 203void attr_from_stat(struct fuse_attr *attr, struct stat *s) 204{ 205 attr->ino = s->st_ino; 206 attr->size = s->st_size; 207 attr->blocks = s->st_blocks; 208 attr->atime = s->st_atime; 209 attr->mtime = s->st_mtime; 210 attr->ctime = s->st_ctime; 211 attr->atimensec = s->st_atime_nsec; 212 attr->mtimensec = s->st_mtime_nsec; 213 attr->ctimensec = s->st_ctime_nsec; 214 attr->mode = s->st_mode; 215 attr->nlink = s->st_nlink; 216 217 /* force permissions to something reasonable: 218 * world readable 219 * writable by the sdcard group 220 */ 221 if (attr->mode & 0100) { 222 attr->mode = (attr->mode & (~0777)) | 0775; 223 } else { 224 attr->mode = (attr->mode & (~0777)) | 0664; 225 } 226 227 /* all files owned by root.sdcard */ 228 attr->uid = 0; 229 attr->gid = AID_SDCARD_RW; 230} 231 232int node_get_attr(struct node *node, struct fuse_attr *attr) 233{ 234 int res; 235 struct stat s; 236 char *path, buffer[PATH_BUFFER_SIZE]; 237 238 path = node_get_path(node, buffer, 0); 239 res = lstat(path, &s); 240 if (res < 0) { 241 ERROR("lstat('%s') errno %d\n", path, errno); 242 return -1; 243 } 244 245 attr_from_stat(attr, &s); 246 attr->ino = node->nid; 247 248 return 0; 249} 250 251static void add_node_to_parent(struct node *node, struct node *parent) { 252 node->parent = parent; 253 node->next = parent->child; 254 parent->child = node; 255 parent->refcount++; 256} 257 258/* Check to see if our parent directory already has a file with a name 259 * that differs only by case. If we find one, store it in the actual_name 260 * field so node_get_path will map it to this file in the underlying storage. 261 */ 262static void node_find_actual_name(struct node *node) 263{ 264 char *path, buffer[PATH_BUFFER_SIZE]; 265 const char *node_name = node->name; 266 DIR* dir; 267 struct dirent* entry; 268 269 if (!node->parent) return; 270 271 path = node_get_path(node->parent, buffer, 0); 272 dir = opendir(path); 273 if (!dir) { 274 ERROR("opendir %s failed: %s", path, strerror(errno)); 275 return; 276 } 277 278 while ((entry = readdir(dir))) { 279 const char *test_name = entry->d_name; 280 if (strcmp(test_name, node_name) && !strcasecmp(test_name, node_name)) { 281 /* we have a match - differs but only by case */ 282 node->actual_name = strdup(test_name); 283 if (!node->actual_name) { 284 ERROR("strdup failed - out of memory\n"); 285 exit(1); 286 } 287 break; 288 } 289 } 290 closedir(dir); 291} 292 293struct node *node_create(struct node *parent, const char *name, __u64 nid, __u64 gen) 294{ 295 struct node *node; 296 int namelen = strlen(name); 297 298 node = calloc(1, sizeof(struct node)); 299 if (node == 0) { 300 return 0; 301 } 302 node->name = malloc(namelen + 1); 303 if (node->name == 0) { 304 free(node); 305 return 0; 306 } 307 308 node->nid = nid; 309 node->gen = gen; 310 add_node_to_parent(node, parent); 311 memcpy(node->name, name, namelen + 1); 312 node->namelen = namelen; 313 node_find_actual_name(node); 314 return node; 315} 316 317static char *rename_node(struct node *node, const char *name) 318{ 319 node->namelen = strlen(name); 320 char *newname = realloc(node->name, node->namelen + 1); 321 if (newname == 0) 322 return 0; 323 node->name = newname; 324 memcpy(node->name, name, node->namelen + 1); 325 node_find_actual_name(node); 326 return node->name; 327} 328 329void fuse_init(struct fuse *fuse, int fd, const char *path) 330{ 331 fuse->fd = fd; 332 fuse->next_node_id = 2; 333 fuse->next_generation = 0; 334 335 fuse->all = &fuse->root; 336 337 memset(&fuse->root, 0, sizeof(fuse->root)); 338 fuse->root.nid = FUSE_ROOT_ID; /* 1 */ 339 fuse->root.refcount = 2; 340 rename_node(&fuse->root, path); 341} 342 343static inline void *id_to_ptr(__u64 nid) 344{ 345 return (void *) (uintptr_t) nid; 346} 347 348static inline __u64 ptr_to_id(void *ptr) 349{ 350 return (__u64) (uintptr_t) ptr; 351} 352 353 354struct node *lookup_by_inode(struct fuse *fuse, __u64 nid) 355{ 356 if (nid == FUSE_ROOT_ID) { 357 return &fuse->root; 358 } else { 359 return id_to_ptr(nid); 360 } 361} 362 363struct node *lookup_child_by_name(struct node *node, const char *name) 364{ 365 for (node = node->child; node; node = node->next) { 366 if (!strcmp(name, node->name)) { 367 return node; 368 } 369 } 370 return 0; 371} 372 373struct node *lookup_child_by_inode(struct node *node, __u64 nid) 374{ 375 for (node = node->child; node; node = node->next) { 376 if (node->nid == nid) { 377 return node; 378 } 379 } 380 return 0; 381} 382 383static void dec_refcount(struct node *node) { 384 if (node->refcount > 0) { 385 node->refcount--; 386 TRACE("dec_refcount %p(%s) -> %d\n", node, node->name, node->refcount); 387 } else { 388 ERROR("Zero refcnt %p\n", node); 389 } 390 } 391 392static struct node *remove_child(struct node *parent, __u64 nid) 393{ 394 struct node *prev = 0; 395 struct node *node; 396 397 for (node = parent->child; node; node = node->next) { 398 if (node->nid == nid) { 399 if (prev) { 400 prev->next = node->next; 401 } else { 402 parent->child = node->next; 403 } 404 node->next = 0; 405 node->parent = 0; 406 dec_refcount(parent); 407 return node; 408 } 409 prev = node; 410 } 411 return 0; 412} 413 414struct node *node_lookup(struct fuse *fuse, struct node *parent, const char *name, 415 struct fuse_attr *attr) 416{ 417 int res; 418 struct stat s; 419 char *path, buffer[PATH_BUFFER_SIZE]; 420 struct node *node; 421 422 path = node_get_path(parent, buffer, name); 423 /* XXX error? */ 424 425 res = lstat(path, &s); 426 if (res < 0) 427 return 0; 428 429 node = lookup_child_by_name(parent, name); 430 if (!node) { 431 node = node_create(parent, name, fuse->next_node_id++, fuse->next_generation++); 432 if (!node) 433 return 0; 434 node->nid = ptr_to_id(node); 435 node->all = fuse->all; 436 fuse->all = node; 437 } 438 439 attr_from_stat(attr, &s); 440 attr->ino = node->nid; 441 442 return node; 443} 444 445void node_release(struct node *node) 446{ 447 TRACE("RELEASE %p (%s) rc=%d\n", node, node->name, node->refcount); 448 dec_refcount(node); 449 if (node->refcount == 0) { 450 if (node->parent->child == node) { 451 node->parent->child = node->parent->child->next; 452 } else { 453 struct node *node2; 454 455 node2 = node->parent->child; 456 while (node2->next != node) 457 node2 = node2->next; 458 node2->next = node->next; 459 } 460 461 TRACE("DESTROY %p (%s)\n", node, node->name); 462 463 node_release(node->parent); 464 465 node->parent = 0; 466 node->next = 0; 467 468 /* TODO: remove debugging - poison memory */ 469 memset(node->name, 0xef, node->namelen); 470 free(node->name); 471 free(node->actual_name); 472 memset(node, 0xfc, sizeof(*node)); 473 free(node); 474 } 475} 476 477void fuse_status(struct fuse *fuse, __u64 unique, int err) 478{ 479 struct fuse_out_header hdr; 480 hdr.len = sizeof(hdr); 481 hdr.error = err; 482 hdr.unique = unique; 483 if (err) { 484// ERROR("*** %d ***\n", err); 485 } 486 write(fuse->fd, &hdr, sizeof(hdr)); 487} 488 489void fuse_reply(struct fuse *fuse, __u64 unique, void *data, int len) 490{ 491 struct fuse_out_header hdr; 492 struct iovec vec[2]; 493 int res; 494 495 hdr.len = len + sizeof(hdr); 496 hdr.error = 0; 497 hdr.unique = unique; 498 499 vec[0].iov_base = &hdr; 500 vec[0].iov_len = sizeof(hdr); 501 vec[1].iov_base = data; 502 vec[1].iov_len = len; 503 504 res = writev(fuse->fd, vec, 2); 505 if (res < 0) { 506 ERROR("*** REPLY FAILED *** %d\n", errno); 507 } 508} 509 510void lookup_entry(struct fuse *fuse, struct node *node, 511 const char *name, __u64 unique) 512{ 513 struct fuse_entry_out out; 514 515 memset(&out, 0, sizeof(out)); 516 517 node = node_lookup(fuse, node, name, &out.attr); 518 if (!node) { 519 fuse_status(fuse, unique, -ENOENT); 520 return; 521 } 522 523 node->refcount++; 524// fprintf(stderr,"ACQUIRE %p (%s) rc=%d\n", node, node->name, node->refcount); 525 out.nodeid = node->nid; 526 out.generation = node->gen; 527 out.entry_valid = 10; 528 out.attr_valid = 10; 529 530 fuse_reply(fuse, unique, &out, sizeof(out)); 531} 532 533void handle_fuse_request(struct fuse *fuse, 534 const struct fuse_in_header *hdr, const void *data, size_t data_len) 535{ 536 struct node *node; 537 538 if (hdr->nodeid) { 539 node = lookup_by_inode(fuse, hdr->nodeid); 540 if (!node) { 541 fuse_status(fuse, hdr->unique, -ENOENT); 542 return; 543 } 544 } else { 545 node = 0; 546 } 547 548 switch (hdr->opcode) { 549 case FUSE_LOOKUP: { /* bytez[] -> entry_out */ 550 const char* name = data; 551 TRACE("LOOKUP %llx %s\n", hdr->nodeid, name); 552 lookup_entry(fuse, node, name, hdr->unique); 553 return; 554 } 555 556 case FUSE_FORGET: { 557 const struct fuse_forget_in *req = data; 558 __u64 n = req->nlookup; 559 TRACE("FORGET %llx (%s) #%lld\n", hdr->nodeid, node->name, n); 560 /* no reply */ 561 while (n--) 562 node_release(node); 563 return; 564 } 565 566 case FUSE_GETATTR: { /* getattr_in -> attr_out */ 567 const struct fuse_getattr_in *req = data; 568 struct fuse_attr_out out; 569 570 TRACE("GETATTR flags=%x fh=%llx\n", req->getattr_flags, req->fh); 571 572 memset(&out, 0, sizeof(out)); 573 node_get_attr(node, &out.attr); 574 out.attr_valid = 10; 575 576 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 577 return; 578 } 579 580 case FUSE_SETATTR: { /* setattr_in -> attr_out */ 581 const struct fuse_setattr_in *req = data; 582 struct fuse_attr_out out; 583 char *path, buffer[PATH_BUFFER_SIZE]; 584 int res = 0; 585 struct timespec times[2]; 586 587 TRACE("SETATTR fh=%llx id=%llx valid=%x\n", 588 req->fh, hdr->nodeid, req->valid); 589 590 /* XXX: incomplete implementation on purpose. chmod/chown 591 * should NEVER be implemented.*/ 592 593 path = node_get_path(node, buffer, 0); 594 if (req->valid & FATTR_SIZE) 595 res = truncate(path, req->size); 596 if (res) 597 goto getout; 598 599 /* Handle changing atime and mtime. If FATTR_ATIME_and FATTR_ATIME_NOW 600 * are both set, then set it to the current time. Else, set it to the 601 * time specified in the request. Same goes for mtime. Use utimensat(2) 602 * as it allows ATIME and MTIME to be changed independently, and has 603 * nanosecond resolution which fuse also has. 604 */ 605 if (req->valid & (FATTR_ATIME | FATTR_MTIME)) { 606 times[0].tv_nsec = UTIME_OMIT; 607 times[1].tv_nsec = UTIME_OMIT; 608 if (req->valid & FATTR_ATIME) { 609 if (req->valid & FATTR_ATIME_NOW) { 610 times[0].tv_nsec = UTIME_NOW; 611 } else { 612 times[0].tv_sec = req->atime; 613 times[0].tv_nsec = req->atimensec; 614 } 615 } 616 if (req->valid & FATTR_MTIME) { 617 if (req->valid & FATTR_MTIME_NOW) { 618 times[1].tv_nsec = UTIME_NOW; 619 } else { 620 times[1].tv_sec = req->mtime; 621 times[1].tv_nsec = req->mtimensec; 622 } 623 } 624 TRACE("Calling utimensat on %s with atime %ld, mtime=%ld\n", path, times[0].tv_sec, times[1].tv_sec); 625 res = utimensat(-1, path, times, 0); 626 } 627 628 getout: 629 memset(&out, 0, sizeof(out)); 630 node_get_attr(node, &out.attr); 631 out.attr_valid = 10; 632 633 if (res) 634 fuse_status(fuse, hdr->unique, -errno); 635 else 636 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 637 return; 638 } 639 640// case FUSE_READLINK: 641// case FUSE_SYMLINK: 642 case FUSE_MKNOD: { /* mknod_in, bytez[] -> entry_out */ 643 const struct fuse_mknod_in *req = data; 644 const char *name = ((const char*) data) + sizeof(*req); 645 char *path, buffer[PATH_BUFFER_SIZE]; 646 int res; 647 648 TRACE("MKNOD %s @ %llx\n", name, hdr->nodeid); 649 path = node_get_path(node, buffer, name); 650 651 __u32 mode = (req->mode & (~0777)) | 0664; 652 res = mknod(path, mode, req->rdev); /* XXX perm?*/ 653 if (res < 0) { 654 fuse_status(fuse, hdr->unique, -errno); 655 } else { 656 lookup_entry(fuse, node, name, hdr->unique); 657 } 658 return; 659 } 660 661 case FUSE_MKDIR: { /* mkdir_in, bytez[] -> entry_out */ 662 const struct fuse_mkdir_in *req = data; 663 const char *name = ((const char*) data) + sizeof(*req); 664 struct fuse_entry_out out; 665 char *path, buffer[PATH_BUFFER_SIZE]; 666 int res; 667 668 TRACE("MKDIR %s @ %llx 0%o\n", name, hdr->nodeid, req->mode); 669 path = node_get_path(node, buffer, name); 670 671 __u32 mode = (req->mode & (~0777)) | 0775; 672 res = mkdir(path, mode); 673 if (res < 0) { 674 fuse_status(fuse, hdr->unique, -errno); 675 } else { 676 lookup_entry(fuse, node, name, hdr->unique); 677 } 678 return; 679 } 680 681 case FUSE_UNLINK: { /* bytez[] -> */ 682 const char* name = data; 683 char *path, buffer[PATH_BUFFER_SIZE]; 684 int res; 685 TRACE("UNLINK %s @ %llx\n", name, hdr->nodeid); 686 path = node_get_path(node, buffer, name); 687 res = unlink(path); 688 fuse_status(fuse, hdr->unique, res ? -errno : 0); 689 return; 690 } 691 692 case FUSE_RMDIR: { /* bytez[] -> */ 693 const char* name = data; 694 char *path, buffer[PATH_BUFFER_SIZE]; 695 int res; 696 TRACE("RMDIR %s @ %llx\n", name, hdr->nodeid); 697 path = node_get_path(node, buffer, name); 698 res = rmdir(path); 699 fuse_status(fuse, hdr->unique, res ? -errno : 0); 700 return; 701 } 702 703 case FUSE_RENAME: { /* rename_in, oldname, newname -> */ 704 const struct fuse_rename_in *req = data; 705 const char *oldname = ((const char*) data) + sizeof(*req); 706 const char *newname = oldname + strlen(oldname) + 1; 707 char *oldpath, oldbuffer[PATH_BUFFER_SIZE]; 708 char *newpath, newbuffer[PATH_BUFFER_SIZE]; 709 struct node *target; 710 struct node *newparent; 711 int res; 712 713 TRACE("RENAME %s->%s @ %llx\n", oldname, newname, hdr->nodeid); 714 715 target = lookup_child_by_name(node, oldname); 716 if (!target) { 717 fuse_status(fuse, hdr->unique, -ENOENT); 718 return; 719 } 720 oldpath = node_get_path(node, oldbuffer, oldname); 721 722 newparent = lookup_by_inode(fuse, req->newdir); 723 if (!newparent) { 724 fuse_status(fuse, hdr->unique, -ENOENT); 725 return; 726 } 727 if (newparent == node) { 728 /* Special case for renaming a file where destination 729 * is same path differing only by case. 730 * In this case we don't want to look for a case insensitive match. 731 * This allows commands like "mv foo FOO" to work as expected. 732 */ 733 newpath = do_node_get_path(newparent, newbuffer, newname, NO_CASE_SENSITIVE_MATCH); 734 } else { 735 newpath = node_get_path(newparent, newbuffer, newname); 736 } 737 738 if (!remove_child(node, target->nid)) { 739 ERROR("RENAME remove_child not found"); 740 fuse_status(fuse, hdr->unique, -ENOENT); 741 return; 742 } 743 if (!rename_node(target, newname)) { 744 fuse_status(fuse, hdr->unique, -ENOMEM); 745 return; 746 } 747 add_node_to_parent(target, newparent); 748 749 res = rename(oldpath, newpath); 750 TRACE("RENAME result %d\n", res); 751 752 fuse_status(fuse, hdr->unique, res ? -errno : 0); 753 return; 754 } 755 756// case FUSE_LINK: 757 case FUSE_OPEN: { /* open_in -> open_out */ 758 const struct fuse_open_in *req = data; 759 struct fuse_open_out out; 760 char *path, buffer[PATH_BUFFER_SIZE]; 761 struct handle *h; 762 763 h = malloc(sizeof(*h)); 764 if (!h) { 765 fuse_status(fuse, hdr->unique, -ENOMEM); 766 return; 767 } 768 769 path = node_get_path(node, buffer, 0); 770 TRACE("OPEN %llx '%s' 0%o fh=%p\n", hdr->nodeid, path, req->flags, h); 771 h->fd = open(path, req->flags); 772 if (h->fd < 0) { 773 ERROR("ERROR\n"); 774 fuse_status(fuse, hdr->unique, -errno); 775 free(h); 776 return; 777 } 778 out.fh = ptr_to_id(h); 779 out.open_flags = 0; 780 out.padding = 0; 781 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 782 return; 783 } 784 785 case FUSE_READ: { /* read_in -> byte[] */ 786 char buffer[MAX_READ]; 787 const struct fuse_read_in *req = data; 788 struct handle *h = id_to_ptr(req->fh); 789 int res; 790 TRACE("READ %p(%d) %u@%llu\n", h, h->fd, req->size, req->offset); 791 if (req->size > sizeof(buffer)) { 792 fuse_status(fuse, hdr->unique, -EINVAL); 793 return; 794 } 795 res = pread64(h->fd, buffer, req->size, req->offset); 796 if (res < 0) { 797 fuse_status(fuse, hdr->unique, -errno); 798 return; 799 } 800 fuse_reply(fuse, hdr->unique, buffer, res); 801 return; 802 } 803 804 case FUSE_WRITE: { /* write_in, byte[write_in.size] -> write_out */ 805 const struct fuse_write_in *req = data; 806 const void* buffer = (const __u8*)data + sizeof(*req); 807 struct fuse_write_out out; 808 struct handle *h = id_to_ptr(req->fh); 809 int res; 810 TRACE("WRITE %p(%d) %u@%llu\n", h, h->fd, req->size, req->offset); 811 res = pwrite64(h->fd, buffer, req->size, req->offset); 812 if (res < 0) { 813 fuse_status(fuse, hdr->unique, -errno); 814 return; 815 } 816 out.size = res; 817 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 818 return; 819 } 820 821 case FUSE_STATFS: { /* getattr_in -> attr_out */ 822 struct statfs stat; 823 struct fuse_statfs_out out; 824 int res; 825 826 TRACE("STATFS\n"); 827 828 if (statfs(fuse->root.name, &stat)) { 829 fuse_status(fuse, hdr->unique, -errno); 830 return; 831 } 832 833 memset(&out, 0, sizeof(out)); 834 out.st.blocks = stat.f_blocks; 835 out.st.bfree = stat.f_bfree; 836 out.st.bavail = stat.f_bavail; 837 out.st.files = stat.f_files; 838 out.st.ffree = stat.f_ffree; 839 out.st.bsize = stat.f_bsize; 840 out.st.namelen = stat.f_namelen; 841 out.st.frsize = stat.f_frsize; 842 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 843 return; 844 } 845 846 case FUSE_RELEASE: { /* release_in -> */ 847 const struct fuse_release_in *req = data; 848 struct handle *h = id_to_ptr(req->fh); 849 TRACE("RELEASE %p(%d)\n", h, h->fd); 850 close(h->fd); 851 free(h); 852 fuse_status(fuse, hdr->unique, 0); 853 return; 854 } 855 856 case FUSE_FSYNC: { 857 const struct fuse_fsync_in *req = data; 858 int is_data_sync = req->fsync_flags & 1; 859 struct handle *h = id_to_ptr(req->fh); 860 int res; 861 TRACE("FSYNC %p(%d) is_data_sync=%d\n", h, h->fd, is_data_sync); 862 res = is_data_sync ? fdatasync(h->fd) : fsync(h->fd); 863 if (res < 0) { 864 fuse_status(fuse, hdr->unique, -errno); 865 return; 866 } 867 fuse_status(fuse, hdr->unique, 0); 868 return; 869 } 870 871// case FUSE_SETXATTR: 872// case FUSE_GETXATTR: 873// case FUSE_LISTXATTR: 874// case FUSE_REMOVEXATTR: 875 case FUSE_FLUSH: { 876 fuse_status(fuse, hdr->unique, 0); 877 return; 878 } 879 880 case FUSE_OPENDIR: { /* open_in -> open_out */ 881 const struct fuse_open_in *req = data; 882 struct fuse_open_out out; 883 char *path, buffer[PATH_BUFFER_SIZE]; 884 struct dirhandle *h; 885 886 h = malloc(sizeof(*h)); 887 if (!h) { 888 fuse_status(fuse, hdr->unique, -ENOMEM); 889 return; 890 } 891 892 path = node_get_path(node, buffer, 0); 893 TRACE("OPENDIR %llx '%s'\n", hdr->nodeid, path); 894 h->d = opendir(path); 895 if (h->d == 0) { 896 ERROR("ERROR\n"); 897 fuse_status(fuse, hdr->unique, -errno); 898 free(h); 899 return; 900 } 901 out.fh = ptr_to_id(h); 902 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 903 return; 904 } 905 906 case FUSE_READDIR: { 907 const struct fuse_read_in *req = data; 908 char buffer[8192]; 909 struct fuse_dirent *fde = (struct fuse_dirent*) buffer; 910 struct dirent *de; 911 struct dirhandle *h = id_to_ptr(req->fh); 912 TRACE("READDIR %p\n", h); 913 if (req->offset == 0) { 914 /* rewinddir() might have been called above us, so rewind here too */ 915 TRACE("calling rewinddir()\n"); 916 rewinddir(h->d); 917 } 918 de = readdir(h->d); 919 if (!de) { 920 fuse_status(fuse, hdr->unique, 0); 921 return; 922 } 923 fde->ino = FUSE_UNKNOWN_INO; 924 /* increment the offset so we can detect when rewinddir() seeks back to the beginning */ 925 fde->off = req->offset + 1; 926 fde->type = de->d_type; 927 fde->namelen = strlen(de->d_name); 928 memcpy(fde->name, de->d_name, fde->namelen + 1); 929 fuse_reply(fuse, hdr->unique, fde, 930 FUSE_DIRENT_ALIGN(sizeof(struct fuse_dirent) + fde->namelen)); 931 return; 932 } 933 934 case FUSE_RELEASEDIR: { /* release_in -> */ 935 const struct fuse_release_in *req = data; 936 struct dirhandle *h = id_to_ptr(req->fh); 937 TRACE("RELEASEDIR %p\n",h); 938 closedir(h->d); 939 free(h); 940 fuse_status(fuse, hdr->unique, 0); 941 return; 942 } 943 944// case FUSE_FSYNCDIR: 945 case FUSE_INIT: { /* init_in -> init_out */ 946 const struct fuse_init_in *req = data; 947 struct fuse_init_out out; 948 949 TRACE("INIT ver=%d.%d maxread=%d flags=%x\n", 950 req->major, req->minor, req->max_readahead, req->flags); 951 952 out.major = FUSE_KERNEL_VERSION; 953 out.minor = FUSE_KERNEL_MINOR_VERSION; 954 out.max_readahead = req->max_readahead; 955 out.flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES; 956 out.max_background = 32; 957 out.congestion_threshold = 32; 958 out.max_write = MAX_WRITE; 959 960 fuse_reply(fuse, hdr->unique, &out, sizeof(out)); 961 return; 962 } 963 964 default: { 965 ERROR("NOTIMPL op=%d uniq=%llx nid=%llx\n", 966 hdr->opcode, hdr->unique, hdr->nodeid); 967 fuse_status(fuse, hdr->unique, -ENOSYS); 968 break; 969 } 970 } 971} 972 973void handle_fuse_requests(struct fuse *fuse) 974{ 975 __u8 req[MAX_REQUEST_SIZE]; 976 977 for (;;) { 978 ssize_t len = read(fuse->fd, req, sizeof(req)); 979 if (len < 0) { 980 if (errno == EINTR) 981 continue; 982 ERROR("handle_fuse_requests: errno=%d\n", errno); 983 return; 984 } 985 986 if ((size_t)len < sizeof(struct fuse_in_header)) { 987 ERROR("request too short: len=%zu\n", (size_t)len); 988 return; 989 } 990 991 const struct fuse_in_header *hdr = (void*)req; 992 if (hdr->len != (size_t)len) { 993 ERROR("malformed header: len=%zu, hdr->len=%u\n", (size_t)len, hdr->len); 994 return; 995 } 996 997 const void *data = req + sizeof(struct fuse_in_header); 998 size_t data_len = len - sizeof(struct fuse_in_header); 999 handle_fuse_request(fuse, hdr, data, data_len); 1000 } 1001} 1002 1003static int usage() 1004{ 1005 ERROR("usage: sdcard <path> <uid> <gid>\n\n"); 1006 return 1; 1007} 1008 1009static int run(const char* path, uid_t uid, gid_t gid) 1010{ 1011 int fd; 1012 char opts[256]; 1013 int res; 1014 struct fuse fuse; 1015 1016 /* cleanup from previous instance, if necessary */ 1017 umount2(MOUNT_POINT, 2); 1018 1019 fd = open("/dev/fuse", O_RDWR); 1020 if (fd < 0){ 1021 ERROR("cannot open fuse device (error %d)\n", errno); 1022 return -1; 1023 } 1024 1025 snprintf(opts, sizeof(opts), 1026 "fd=%i,rootmode=40000,default_permissions,allow_other,user_id=%d,group_id=%d", 1027 fd, uid, gid); 1028 1029 res = mount("/dev/fuse", MOUNT_POINT, "fuse", MS_NOSUID | MS_NODEV, opts); 1030 if (res < 0) { 1031 ERROR("cannot mount fuse filesystem (error %d)\n", errno); 1032 goto error; 1033 } 1034 1035 res = setgid(gid); 1036 if (res < 0) { 1037 ERROR("cannot setgid (error %d)\n", errno); 1038 goto error; 1039 } 1040 1041 res = setuid(uid); 1042 if (res < 0) { 1043 ERROR("cannot setuid (error %d)\n", errno); 1044 goto error; 1045 } 1046 1047 fuse_init(&fuse, fd, path); 1048 1049 umask(0); 1050 handle_fuse_requests(&fuse); 1051 1052 /* we do not attempt to umount the file system here because we are no longer 1053 * running as the root user */ 1054 res = 0; 1055 1056error: 1057 close(fd); 1058 return res; 1059} 1060 1061int main(int argc, char **argv) 1062{ 1063 int fd; 1064 int res; 1065 const char *path = NULL; 1066 uid_t uid = 0; 1067 gid_t gid = 0; 1068 int i; 1069 1070 for (i = 1; i < argc; i++) { 1071 char* arg = argv[i]; 1072 if (!path) 1073 path = arg; 1074 else if (!uid) 1075 uid = strtoul(arg, 0, 10); 1076 else if (!gid) 1077 gid = strtoul(arg, 0, 10); 1078 else { 1079 ERROR("too many arguments\n"); 1080 return usage(); 1081 } 1082 } 1083 1084 if (!path) { 1085 ERROR("no path specified\n"); 1086 return usage(); 1087 } 1088 if (!uid || !gid) { 1089 ERROR("uid and gid must be nonzero\n"); 1090 return usage(); 1091 } 1092 1093 res = run(path, uid, gid); 1094 return res < 0 ? 1 : 0; 1095} 1096