sdcard.c revision ca1030ae42edfbeaedef5ea02a2c279bbb3b10cf 
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 /mnt/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 "/mnt/sdcard"
74
75struct handle {
76    struct node *node;
77    int fd;
78};
79
80struct dirhandle {
81    struct node *node;
82    DIR *d;
83};
84
85struct node {
86    __u64 nid;
87    __u64 gen;
88
89    struct node *next;          /* per-dir sibling list */
90    struct node *child;         /* first contained file by this dir */
91    struct node *all;           /* global node list */
92    struct node *parent;        /* containing directory */
93
94    __u32 refcount;
95    __u32 namelen;
96
97    char *name;
98    /* If non-null, this is the real name of the file in the underlying storage.
99     * This may differ from the field "name" only by case.
100     * strlen(actual_name) will always equal strlen(name), so it is safe to use
101     * namelen for both fields.
102     */
103    char *actual_name;
104};
105
106struct fuse {
107    __u64 next_generation;
108    __u64 next_node_id;
109
110    int fd;
111
112    struct node *all;
113
114    struct node root;
115    char rootpath[1024];
116};
117
118static unsigned uid = -1;
119static unsigned gid = -1;
120
121#define PATH_BUFFER_SIZE 1024
122
123#define NO_CASE_SENSITIVE_MATCH 0
124#define CASE_SENSITIVE_MATCH 1
125
126/*
127 * Get the real-life absolute path to a node.
128 *   node: start at this node
129 *   buf: storage for returned string
130 *   name: append this string to path if set
131 */
132char *do_node_get_path(struct node *node, char *buf, const char *name, int match_case_insensitive)
133{
134    struct node *in_node = node;
135    const char *in_name = name;
136    char *out = buf + PATH_BUFFER_SIZE - 1;
137    int len;
138    out[0] = 0;
139
140    if (name) {
141        len = strlen(name);
142        goto start;
143    }
144
145    while (node) {
146        name = (node->actual_name ? node->actual_name : node->name);
147        len = node->namelen;
148        node = node->parent;
149    start:
150        if ((len + 1) > (out - buf))
151            return 0;
152        out -= len;
153        memcpy(out, name, len);
154        /* avoid double slash at beginning of path */
155        if (out[0] != '/') {
156            out --;
157            out[0] = '/';
158        }
159    }
160
161    /* If we are searching for a file within node (rather than computing node's path)
162     * and fail, then we need to look for a case insensitive match.
163     */
164    if (in_name && match_case_insensitive && access(out, F_OK) != 0) {
165        char *path, buffer[PATH_BUFFER_SIZE];
166        DIR* dir;
167        struct dirent* entry;
168        path = do_node_get_path(in_node, buffer, NULL, NO_CASE_SENSITIVE_MATCH);
169        dir = opendir(path);
170        if (!dir) {
171            ERROR("opendir %s failed: %s", path, strerror(errno));
172            return out;
173        }
174
175        while ((entry = readdir(dir))) {
176            if (!strcasecmp(entry->d_name, in_name)) {
177                /* we have a match - replace the name */
178                len = strlen(in_name);
179                memcpy(buf + PATH_BUFFER_SIZE - len - 1, entry->d_name, len);
180                break;
181            }
182        }
183        closedir(dir);
184    }
185
186   return out;
187}
188
189char *node_get_path(struct node *node, char *buf, const char *name)
190{
191    /* We look for case insensitive matches by default */
192    return do_node_get_path(node, buf, name, CASE_SENSITIVE_MATCH);
193}
194
195void attr_from_stat(struct fuse_attr *attr, struct stat *s)
196{
197    attr->ino = s->st_ino;
198    attr->size = s->st_size;
199    attr->blocks = s->st_blocks;
200    attr->atime = s->st_atime;
201    attr->mtime = s->st_mtime;
202    attr->ctime = s->st_ctime;
203    attr->atimensec = s->st_atime_nsec;
204    attr->mtimensec = s->st_mtime_nsec;
205    attr->ctimensec = s->st_ctime_nsec;
206    attr->mode = s->st_mode;
207    attr->nlink = s->st_nlink;
208
209        /* force permissions to something reasonable:
210         * world readable
211         * writable by the sdcard group
212         */
213    if (attr->mode & 0100) {
214        attr->mode = (attr->mode & (~0777)) | 0775;
215    } else {
216        attr->mode = (attr->mode & (~0777)) | 0664;
217    }
218
219        /* all files owned by root.sdcard */
220    attr->uid = 0;
221    attr->gid = AID_SDCARD_RW;
222}
223
224int node_get_attr(struct node *node, struct fuse_attr *attr)
225{
226    int res;
227    struct stat s;
228    char *path, buffer[PATH_BUFFER_SIZE];
229
230    path = node_get_path(node, buffer, 0);
231    res = lstat(path, &s);
232    if (res < 0) {
233        ERROR("lstat('%s') errno %d\n", path, errno);
234        return -1;
235    }
236
237    attr_from_stat(attr, &s);
238    attr->ino = node->nid;
239
240    return 0;
241}
242
243static void add_node_to_parent(struct node *node, struct node *parent) {
244    node->parent = parent;
245    node->next = parent->child;
246    parent->child = node;
247    parent->refcount++;
248}
249
250/* Check to see if our parent directory already has a file with a name
251 * that differs only by case.  If we find one, store it in the actual_name
252 * field so node_get_path will map it to this file in the underlying storage.
253 */
254static void node_find_actual_name(struct node *node)
255{
256    char *path, buffer[PATH_BUFFER_SIZE];
257    const char *node_name = node->name;
258    DIR* dir;
259    struct dirent* entry;
260
261    if (!node->parent) return;
262
263    path = node_get_path(node->parent, buffer, 0);
264    dir = opendir(path);
265    if (!dir) {
266        ERROR("opendir %s failed: %s", path, strerror(errno));
267        return;
268    }
269
270    while ((entry = readdir(dir))) {
271        const char *test_name = entry->d_name;
272        if (strcmp(test_name, node_name) && !strcasecmp(test_name, node_name)) {
273            /* we have a match - differs but only by case */
274            node->actual_name = strdup(test_name);
275            if (!node->actual_name) {
276                ERROR("strdup failed - out of memory\n");
277                exit(1);
278            }
279            break;
280        }
281    }
282    closedir(dir);
283}
284
285struct node *node_create(struct node *parent, const char *name, __u64 nid, __u64 gen)
286{
287    struct node *node;
288    int namelen = strlen(name);
289
290    node = calloc(1, sizeof(struct node));
291    if (node == 0) {
292        return 0;
293    }
294    node->name = malloc(namelen + 1);
295    if (node->name == 0) {
296        free(node);
297        return 0;
298    }
299
300    node->nid = nid;
301    node->gen = gen;
302    add_node_to_parent(node, parent);
303    memcpy(node->name, name, namelen + 1);
304    node->namelen = namelen;
305    node_find_actual_name(node);
306    return node;
307}
308
309static char *rename_node(struct node *node, const char *name)
310{
311    node->namelen = strlen(name);
312    char *newname = realloc(node->name, node->namelen + 1);
313    if (newname == 0)
314        return 0;
315    node->name = newname;
316    memcpy(node->name, name, node->namelen + 1);
317    node_find_actual_name(node);
318    return node->name;
319}
320
321void fuse_init(struct fuse *fuse, int fd, const char *path)
322{
323    fuse->fd = fd;
324    fuse->next_node_id = 2;
325    fuse->next_generation = 0;
326
327    fuse->all = &fuse->root;
328
329    memset(&fuse->root, 0, sizeof(fuse->root));
330    fuse->root.nid = FUSE_ROOT_ID; /* 1 */
331    fuse->root.refcount = 2;
332    rename_node(&fuse->root, path);
333}
334
335static inline void *id_to_ptr(__u64 nid)
336{
337    return (void *) nid;
338}
339
340static inline __u64 ptr_to_id(void *ptr)
341{
342    return (__u64) ptr;
343}
344
345
346struct node *lookup_by_inode(struct fuse *fuse, __u64 nid)
347{
348    if (nid == FUSE_ROOT_ID) {
349        return &fuse->root;
350    } else {
351        return id_to_ptr(nid);
352    }
353}
354
355struct node *lookup_child_by_name(struct node *node, const char *name)
356{
357    for (node = node->child; node; node = node->next) {
358        if (!strcmp(name, node->name)) {
359            return node;
360        }
361    }
362    return 0;
363}
364
365struct node *lookup_child_by_inode(struct node *node, __u64 nid)
366{
367    for (node = node->child; node; node = node->next) {
368        if (node->nid == nid) {
369            return node;
370        }
371    }
372    return 0;
373}
374
375static void dec_refcount(struct node *node) {
376    if (node->refcount > 0) {
377        node->refcount--;
378        TRACE("dec_refcount %p(%s) -> %d\n", node, node->name, node->refcount);
379    } else {
380        ERROR("Zero refcnt %p\n", node);
381    }
382 }
383
384static struct node *remove_child(struct node *parent, __u64 nid)
385{
386    struct node *prev = 0;
387    struct node *node;
388
389    for (node = parent->child; node; node = node->next) {
390        if (node->nid == nid) {
391            if (prev) {
392                prev->next = node->next;
393            } else {
394                parent->child = node->next;
395            }
396            node->next = 0;
397            node->parent = 0;
398            dec_refcount(parent);
399            return node;
400        }
401        prev = node;
402    }
403    return 0;
404}
405
406struct node *node_lookup(struct fuse *fuse, struct node *parent, const char *name,
407                         struct fuse_attr *attr)
408{
409    int res;
410    struct stat s;
411    char *path, buffer[PATH_BUFFER_SIZE];
412    struct node *node;
413
414    path = node_get_path(parent, buffer, name);
415        /* XXX error? */
416
417    res = lstat(path, &s);
418    if (res < 0)
419        return 0;
420
421    node = lookup_child_by_name(parent, name);
422    if (!node) {
423        node = node_create(parent, name, fuse->next_node_id++, fuse->next_generation++);
424        if (!node)
425            return 0;
426        node->nid = ptr_to_id(node);
427        node->all = fuse->all;
428        fuse->all = node;
429    }
430
431    attr_from_stat(attr, &s);
432    attr->ino = node->nid;
433
434    return node;
435}
436
437void node_release(struct node *node)
438{
439    TRACE("RELEASE %p (%s) rc=%d\n", node, node->name, node->refcount);
440    dec_refcount(node);
441    if (node->refcount == 0) {
442        if (node->parent->child == node) {
443            node->parent->child = node->parent->child->next;
444        } else {
445            struct node *node2;
446
447            node2 = node->parent->child;
448            while (node2->next != node)
449                node2 = node2->next;
450            node2->next = node->next;
451        }
452
453        TRACE("DESTROY %p (%s)\n", node, node->name);
454
455        node_release(node->parent);
456
457        node->parent = 0;
458        node->next = 0;
459
460            /* TODO: remove debugging - poison memory */
461        memset(node->name, 0xef, node->namelen);
462        free(node->name);
463        free(node->actual_name);
464        memset(node, 0xfc, sizeof(*node));
465        free(node);
466    }
467}
468
469void fuse_status(struct fuse *fuse, __u64 unique, int err)
470{
471    struct fuse_out_header hdr;
472    hdr.len = sizeof(hdr);
473    hdr.error = err;
474    hdr.unique = unique;
475    if (err) {
476//        ERROR("*** %d ***\n", err);
477    }
478    write(fuse->fd, &hdr, sizeof(hdr));
479}
480
481void fuse_reply(struct fuse *fuse, __u64 unique, void *data, int len)
482{
483    struct fuse_out_header hdr;
484    struct iovec vec[2];
485    int res;
486
487    hdr.len = len + sizeof(hdr);
488    hdr.error = 0;
489    hdr.unique = unique;
490
491    vec[0].iov_base = &hdr;
492    vec[0].iov_len = sizeof(hdr);
493    vec[1].iov_base = data;
494    vec[1].iov_len = len;
495
496    res = writev(fuse->fd, vec, 2);
497    if (res < 0) {
498        ERROR("*** REPLY FAILED *** %d\n", errno);
499    }
500}
501
502void lookup_entry(struct fuse *fuse, struct node *node,
503                  const char *name, __u64 unique)
504{
505    struct fuse_entry_out out;
506
507    memset(&out, 0, sizeof(out));
508
509    node = node_lookup(fuse, node, name, &out.attr);
510    if (!node) {
511        fuse_status(fuse, unique, -ENOENT);
512        return;
513    }
514
515    node->refcount++;
516//    fprintf(stderr,"ACQUIRE %p (%s) rc=%d\n", node, node->name, node->refcount);
517    out.nodeid = node->nid;
518    out.generation = node->gen;
519    out.entry_valid = 10;
520    out.attr_valid = 10;
521
522    fuse_reply(fuse, unique, &out, sizeof(out));
523}
524
525void handle_fuse_request(struct fuse *fuse, struct fuse_in_header *hdr, void *data, unsigned len)
526{
527    struct node *node;
528
529    if ((len < sizeof(*hdr)) || (hdr->len != len)) {
530        ERROR("malformed header\n");
531        return;
532    }
533
534    len -= hdr->len;
535
536    if (hdr->nodeid) {
537        node = lookup_by_inode(fuse, hdr->nodeid);
538        if (!node) {
539            fuse_status(fuse, hdr->unique, -ENOENT);
540            return;
541        }
542    } else {
543        node = 0;
544    }
545
546    switch (hdr->opcode) {
547    case FUSE_LOOKUP: { /* bytez[] -> entry_out */
548        TRACE("LOOKUP %llx %s\n", hdr->nodeid, (char*) data);
549        lookup_entry(fuse, node, (char*) data, hdr->unique);
550        return;
551    }
552    case FUSE_FORGET: {
553        struct fuse_forget_in *req = data;
554        TRACE("FORGET %llx (%s) #%lld\n", hdr->nodeid, node->name, req->nlookup);
555            /* no reply */
556        while (req->nlookup--)
557            node_release(node);
558        return;
559    }
560    case FUSE_GETATTR: { /* getattr_in -> attr_out */
561        struct fuse_getattr_in *req = data;
562        struct fuse_attr_out out;
563
564        TRACE("GETATTR flags=%x fh=%llx\n", req->getattr_flags, req->fh);
565
566        memset(&out, 0, sizeof(out));
567        node_get_attr(node, &out.attr);
568        out.attr_valid = 10;
569
570        fuse_reply(fuse, hdr->unique, &out, sizeof(out));
571        return;
572    }
573    case FUSE_SETATTR: { /* setattr_in -> attr_out */
574        struct fuse_setattr_in *req = data;
575        struct fuse_attr_out out;
576        char *path, buffer[PATH_BUFFER_SIZE];
577        int res = 0;
578        struct timespec times[2];
579
580        TRACE("SETATTR fh=%llx id=%llx valid=%x\n",
581              req->fh, hdr->nodeid, req->valid);
582
583        /* XXX: incomplete implementation on purpose.   chmod/chown
584         * should NEVER be implemented.*/
585
586        path = node_get_path(node, buffer, 0);
587        if (req->valid & FATTR_SIZE)
588            res = truncate(path, req->size);
589        if (res)
590            goto getout;
591
592        /* Handle changing atime and mtime.  If FATTR_ATIME_and FATTR_ATIME_NOW
593         * are both set, then set it to the current time.  Else, set it to the
594         * time specified in the request.  Same goes for mtime.  Use utimensat(2)
595         * as it allows ATIME and MTIME to be changed independently, and has
596         * nanosecond resolution which fuse also has.
597         */
598        if (req->valid & (FATTR_ATIME | FATTR_MTIME)) {
599            times[0].tv_nsec = UTIME_OMIT;
600            times[1].tv_nsec = UTIME_OMIT;
601            if (req->valid & FATTR_ATIME) {
602                if (req->valid & FATTR_ATIME_NOW) {
603                  times[0].tv_nsec = UTIME_NOW;
604                } else {
605                  times[0].tv_sec = req->atime;
606                  times[0].tv_nsec = req->atimensec;
607                }
608            }
609            if (req->valid & FATTR_MTIME) {
610                if (req->valid & FATTR_MTIME_NOW) {
611                  times[1].tv_nsec = UTIME_NOW;
612                } else {
613                  times[1].tv_sec = req->mtime;
614                  times[1].tv_nsec = req->mtimensec;
615                }
616            }
617            TRACE("Calling utimensat on %s with atime %ld, mtime=%ld\n", path, times[0].tv_sec, times[1].tv_sec);
618            res = utimensat(-1, path, times, 0);
619        }
620
621        getout:
622        memset(&out, 0, sizeof(out));
623        node_get_attr(node, &out.attr);
624        out.attr_valid = 10;
625
626        if (res)
627            fuse_status(fuse, hdr->unique, -errno);
628        else
629            fuse_reply(fuse, hdr->unique, &out, sizeof(out));
630        return;
631    }
632//    case FUSE_READLINK:
633//    case FUSE_SYMLINK:
634    case FUSE_MKNOD: { /* mknod_in, bytez[] -> entry_out */
635        struct fuse_mknod_in *req = data;
636        char *path, buffer[PATH_BUFFER_SIZE];
637        char *name = ((char*) data) + sizeof(*req);
638        int res;
639
640        TRACE("MKNOD %s @ %llx\n", name, hdr->nodeid);
641        path = node_get_path(node, buffer, name);
642
643        req->mode = (req->mode & (~0777)) | 0664;
644        res = mknod(path, req->mode, req->rdev); /* XXX perm?*/
645        if (res < 0) {
646            fuse_status(fuse, hdr->unique, -errno);
647        } else {
648            lookup_entry(fuse, node, name, hdr->unique);
649        }
650        return;
651    }
652    case FUSE_MKDIR: { /* mkdir_in, bytez[] -> entry_out */
653        struct fuse_mkdir_in *req = data;
654        struct fuse_entry_out out;
655        char *path, buffer[PATH_BUFFER_SIZE];
656        char *name = ((char*) data) + sizeof(*req);
657        int res;
658
659        TRACE("MKDIR %s @ %llx 0%o\n", name, hdr->nodeid, req->mode);
660        path = node_get_path(node, buffer, name);
661
662        req->mode = (req->mode & (~0777)) | 0775;
663        res = mkdir(path, req->mode);
664        if (res < 0) {
665            fuse_status(fuse, hdr->unique, -errno);
666        } else {
667            lookup_entry(fuse, node, name, hdr->unique);
668        }
669        return;
670    }
671    case FUSE_UNLINK: { /* bytez[] -> */
672        char *path, buffer[PATH_BUFFER_SIZE];
673        int res;
674        TRACE("UNLINK %s @ %llx\n", (char*) data, hdr->nodeid);
675        path = node_get_path(node, buffer, (char*) data);
676        res = unlink(path);
677        fuse_status(fuse, hdr->unique, res ? -errno : 0);
678        return;
679    }
680    case FUSE_RMDIR: { /* bytez[] -> */
681        char *path, buffer[PATH_BUFFER_SIZE];
682        int res;
683        TRACE("RMDIR %s @ %llx\n", (char*) data, hdr->nodeid);
684        path = node_get_path(node, buffer, (char*) data);
685        res = rmdir(path);
686        fuse_status(fuse, hdr->unique, res ? -errno : 0);
687        return;
688    }
689    case FUSE_RENAME: { /* rename_in, oldname, newname ->  */
690        struct fuse_rename_in *req = data;
691        char *oldname = ((char*) data) + sizeof(*req);
692        char *newname = oldname + strlen(oldname) + 1;
693        char *oldpath, oldbuffer[PATH_BUFFER_SIZE];
694        char *newpath, newbuffer[PATH_BUFFER_SIZE];
695        struct node *target;
696        struct node *newparent;
697        int res;
698
699        TRACE("RENAME %s->%s @ %llx\n", oldname, newname, hdr->nodeid);
700
701        target = lookup_child_by_name(node, oldname);
702        if (!target) {
703            fuse_status(fuse, hdr->unique, -ENOENT);
704            return;
705        }
706        oldpath = node_get_path(node, oldbuffer, oldname);
707
708        newparent = lookup_by_inode(fuse, req->newdir);
709        if (!newparent) {
710            fuse_status(fuse, hdr->unique, -ENOENT);
711            return;
712        }
713        if (newparent == node) {
714            /* Special case for renaming a file where destination
715             * is same path differing only by case.
716             * In this case we don't want to look for a case insensitive match.
717             * This allows commands like "mv foo FOO" to work as expected.
718             */
719            newpath = do_node_get_path(newparent, newbuffer, newname, NO_CASE_SENSITIVE_MATCH);
720        } else {
721            newpath = node_get_path(newparent, newbuffer, newname);
722        }
723
724        if (!remove_child(node, target->nid)) {
725            ERROR("RENAME remove_child not found");
726            fuse_status(fuse, hdr->unique, -ENOENT);
727            return;
728        }
729        if (!rename_node(target, newname)) {
730            fuse_status(fuse, hdr->unique, -ENOMEM);
731            return;
732        }
733        add_node_to_parent(target, newparent);
734
735        res = rename(oldpath, newpath);
736        TRACE("RENAME result %d\n", res);
737
738        fuse_status(fuse, hdr->unique, res ? -errno : 0);
739        return;
740    }
741//    case FUSE_LINK:
742    case FUSE_OPEN: { /* open_in -> open_out */
743        struct fuse_open_in *req = data;
744        struct fuse_open_out out;
745        char *path, buffer[PATH_BUFFER_SIZE];
746        struct handle *h;
747
748        h = malloc(sizeof(*h));
749        if (!h) {
750            fuse_status(fuse, hdr->unique, -ENOMEM);
751            return;
752        }
753
754        path = node_get_path(node, buffer, 0);
755        TRACE("OPEN %llx '%s' 0%o fh=%p\n", hdr->nodeid, path, req->flags, h);
756        h->fd = open(path, req->flags);
757        if (h->fd < 0) {
758            ERROR("ERROR\n");
759            fuse_status(fuse, hdr->unique, errno);
760            free(h);
761            return;
762        }
763        out.fh = ptr_to_id(h);
764        out.open_flags = 0;
765        out.padding = 0;
766        fuse_reply(fuse, hdr->unique, &out, sizeof(out));
767        return;
768    }
769    case FUSE_READ: { /* read_in -> byte[] */
770        char buffer[128 * 1024];
771        struct fuse_read_in *req = data;
772        struct handle *h = id_to_ptr(req->fh);
773        int res;
774        TRACE("READ %p(%d) %u@%llu\n", h, h->fd, req->size, req->offset);
775        if (req->size > sizeof(buffer)) {
776            fuse_status(fuse, hdr->unique, -EINVAL);
777            return;
778        }
779        res = pread64(h->fd, buffer, req->size, req->offset);
780        if (res < 0) {
781            fuse_status(fuse, hdr->unique, errno);
782            return;
783        }
784        fuse_reply(fuse, hdr->unique, buffer, res);
785        return;
786    }
787    case FUSE_WRITE: { /* write_in, byte[write_in.size] -> write_out */
788        struct fuse_write_in *req = data;
789        struct fuse_write_out out;
790        struct handle *h = id_to_ptr(req->fh);
791        int res;
792        TRACE("WRITE %p(%d) %u@%llu\n", h, h->fd, req->size, req->offset);
793        res = pwrite64(h->fd, ((char*) data) + sizeof(*req), req->size, req->offset);
794        if (res < 0) {
795            fuse_status(fuse, hdr->unique, errno);
796            return;
797        }
798        out.size = res;
799        fuse_reply(fuse, hdr->unique, &out, sizeof(out));
800        goto oops;
801    }
802    case FUSE_STATFS: { /* getattr_in -> attr_out */
803        struct statfs stat;
804        struct fuse_statfs_out out;
805        int res;
806
807        TRACE("STATFS\n");
808
809        if (statfs(fuse->root.name, &stat)) {
810            fuse_status(fuse, hdr->unique, -errno);
811            return;
812        }
813
814        memset(&out, 0, sizeof(out));
815        out.st.blocks = stat.f_blocks;
816        out.st.bfree = stat.f_bfree;
817        out.st.bavail = stat.f_bavail;
818        out.st.files = stat.f_files;
819        out.st.ffree = stat.f_ffree;
820        out.st.bsize = stat.f_bsize;
821        out.st.namelen = stat.f_namelen;
822        out.st.frsize = stat.f_frsize;
823        fuse_reply(fuse, hdr->unique, &out, sizeof(out));
824        return;
825    }
826    case FUSE_RELEASE: { /* release_in -> */
827        struct fuse_release_in *req = data;
828        struct handle *h = id_to_ptr(req->fh);
829        TRACE("RELEASE %p(%d)\n", h, h->fd);
830        close(h->fd);
831        free(h);
832        fuse_status(fuse, hdr->unique, 0);
833        return;
834    }
835//    case FUSE_FSYNC:
836//    case FUSE_SETXATTR:
837//    case FUSE_GETXATTR:
838//    case FUSE_LISTXATTR:
839//    case FUSE_REMOVEXATTR:
840    case FUSE_FLUSH:
841        fuse_status(fuse, hdr->unique, 0);
842        return;
843    case FUSE_OPENDIR: { /* open_in -> open_out */
844        struct fuse_open_in *req = data;
845        struct fuse_open_out out;
846        char *path, buffer[PATH_BUFFER_SIZE];
847        struct dirhandle *h;
848
849        h = malloc(sizeof(*h));
850        if (!h) {
851            fuse_status(fuse, hdr->unique, -ENOMEM);
852            return;
853        }
854
855        path = node_get_path(node, buffer, 0);
856        TRACE("OPENDIR %llx '%s'\n", hdr->nodeid, path);
857        h->d = opendir(path);
858        if (h->d == 0) {
859            ERROR("ERROR\n");
860            fuse_status(fuse, hdr->unique, -errno);
861            free(h);
862            return;
863        }
864        out.fh = ptr_to_id(h);
865        fuse_reply(fuse, hdr->unique, &out, sizeof(out));
866        return;
867    }
868    case FUSE_READDIR: {
869        struct fuse_read_in *req = data;
870        char buffer[8192];
871        struct fuse_dirent *fde = (struct fuse_dirent*) buffer;
872        struct dirent *de;
873        struct dirhandle *h = id_to_ptr(req->fh);
874        TRACE("READDIR %p\n", h);
875        if (req->offset == 0) {
876            /* rewinddir() might have been called above us, so rewind here too */
877            TRACE("calling rewinddir()\n");
878            rewinddir(h->d);
879        }
880        de = readdir(h->d);
881        if (!de) {
882            fuse_status(fuse, hdr->unique, 0);
883            return;
884        }
885        fde->ino = FUSE_UNKNOWN_INO;
886        /* increment the offset so we can detect when rewinddir() seeks back to the beginning */
887        fde->off = req->offset + 1;
888        fde->type = de->d_type;
889        fde->namelen = strlen(de->d_name);
890        memcpy(fde->name, de->d_name, fde->namelen + 1);
891        fuse_reply(fuse, hdr->unique, fde,
892                   FUSE_DIRENT_ALIGN(sizeof(struct fuse_dirent) + fde->namelen));
893        return;
894    }
895    case FUSE_RELEASEDIR: { /* release_in -> */
896        struct fuse_release_in *req = data;
897        struct dirhandle *h = id_to_ptr(req->fh);
898        TRACE("RELEASEDIR %p\n",h);
899        closedir(h->d);
900        free(h);
901        fuse_status(fuse, hdr->unique, 0);
902        return;
903    }
904//    case FUSE_FSYNCDIR:
905    case FUSE_INIT: { /* init_in -> init_out */
906        struct fuse_init_in *req = data;
907        struct fuse_init_out out;
908
909        TRACE("INIT ver=%d.%d maxread=%d flags=%x\n",
910                req->major, req->minor, req->max_readahead, req->flags);
911
912        out.major = FUSE_KERNEL_VERSION;
913        out.minor = FUSE_KERNEL_MINOR_VERSION;
914        out.max_readahead = req->max_readahead;
915        out.flags = FUSE_ATOMIC_O_TRUNC;
916        out.max_background = 32;
917        out.congestion_threshold = 32;
918        out.max_write = 256 * 1024;
919
920        fuse_reply(fuse, hdr->unique, &out, sizeof(out));
921        return;
922    }
923    default: {
924        struct fuse_out_header h;
925        ERROR("NOTIMPL op=%d uniq=%llx nid=%llx\n",
926                hdr->opcode, hdr->unique, hdr->nodeid);
927
928        oops:
929        h.len = sizeof(h);
930        h.error = -ENOSYS;
931        h.unique = hdr->unique;
932        write(fuse->fd, &h, sizeof(h));
933        break;
934    }
935    }
936}
937
938void handle_fuse_requests(struct fuse *fuse)
939{
940    unsigned char req[256 * 1024 + 128];
941    int len;
942
943    for (;;) {
944        len = read(fuse->fd, req, 8192);
945        if (len < 0) {
946            if (errno == EINTR)
947                continue;
948            ERROR("handle_fuse_requests: errno=%d\n", errno);
949            return;
950        }
951        handle_fuse_request(fuse, (void*) req, (void*) (req + sizeof(struct fuse_in_header)), len);
952    }
953}
954
955static int usage()
956{
957    ERROR("usage: sdcard [-l -f] <path> <uid> <gid>\n\n\t-l force file names to lower case when creating new files\n\t-f fix up file system before starting (repairs bad file name case and group ownership)\n");
958    return -1;
959}
960
961int main(int argc, char **argv)
962{
963    struct fuse fuse;
964    char opts[256];
965    int fd;
966    int res;
967    const char *path = NULL;
968    int i;
969
970    for (i = 1; i < argc; i++) {
971        char* arg = argv[i];
972        if (!path)
973            path = arg;
974        else if (uid == -1)
975            uid = strtoul(arg, 0, 10);
976        else if (gid == -1)
977            gid = strtoul(arg, 0, 10);
978        else {
979            ERROR("too many arguments\n");
980            return usage();
981        }
982    }
983
984    if (!path) {
985        ERROR("no path specified\n");
986        return usage();
987    }
988    if (uid <= 0 || gid <= 0) {
989        ERROR("uid and gid must be nonzero\n");
990        return usage();
991    }
992
993        /* cleanup from previous instance, if necessary */
994    umount2(MOUNT_POINT, 2);
995
996    fd = open("/dev/fuse", O_RDWR);
997    if (fd < 0){
998        ERROR("cannot open fuse device (%d)\n", errno);
999        return -1;
1000    }
1001
1002    sprintf(opts, "fd=%i,rootmode=40000,default_permissions,allow_other,"
1003            "user_id=%d,group_id=%d", fd, uid, gid);
1004
1005    res = mount("/dev/fuse", MOUNT_POINT, "fuse", MS_NOSUID | MS_NODEV, opts);
1006    if (res < 0) {
1007        ERROR("cannot mount fuse filesystem (%d)\n", errno);
1008        return -1;
1009    }
1010
1011    if (setgid(gid) < 0) {
1012        ERROR("cannot setgid!\n");
1013        return -1;
1014    }
1015    if (setuid(uid) < 0) {
1016        ERROR("cannot setuid!\n");
1017        return -1;
1018    }
1019
1020    fuse_init(&fuse, fd, path);
1021
1022    umask(0);
1023    handle_fuse_requests(&fuse);
1024
1025    return 0;
1026}
1027