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platform_system_core/sdcard/sdcard.c

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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/uio.h>
#include <dirent.h>
#include <limits.h>
#include <ctype.h>
#include <pthread.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <private/android_filesystem_config.h>
#include "fuse.h"
/* README
*
* What is this?
*
* sdcard is a program that uses FUSE to emulate FAT-on-sdcard style
* directory permissions (all files are given fixed owner, group, and
* permissions at creation, owner, group, and permissions are not
* changeable, symlinks and hardlinks are not createable, etc.
*
* See usage() for command line options.
*
* It must be run as root, but will drop to requested UID/GID as soon as it
* mounts a filesystem. It will refuse to run if requested UID/GID are zero.
*
* Things I believe to be true:
*
* - ops that return a fuse_entry (LOOKUP, MKNOD, MKDIR, LINK, SYMLINK,
* CREAT) must bump that node's refcount
* - don't forget that FORGET can forget multiple references (req->nlookup)
* - if an op that returns a fuse_entry fails writing the reply to the
* kernel, you must rollback the refcount to reflect the reference the
* kernel did not actually acquire
*/
#define FUSE_TRACE 0
#if FUSE_TRACE
#define TRACE(x...) fprintf(stderr,x)
#else
#define TRACE(x...) do {} while (0)
#endif
#define ERROR(x...) fprintf(stderr,x)
#define FUSE_UNKNOWN_INO 0xffffffff
/* Maximum number of bytes to write in one request. */
#define MAX_WRITE (256 * 1024)
/* Maximum number of bytes to read in one request. */
#define MAX_READ (128 * 1024)
/* Largest possible request.
* The request size is bounded by the maximum size of a FUSE_WRITE request because it has
* the largest possible data payload. */
#define MAX_REQUEST_SIZE (sizeof(struct fuse_in_header) + sizeof(struct fuse_write_in) + MAX_WRITE)
/* Default number of threads. */
#define DEFAULT_NUM_THREADS 2
/* Pseudo-error constant used to indicate that no fuse status is needed
* or that a reply has already been written. */
#define NO_STATUS 1
struct handle {
int fd;
};
struct dirhandle {
DIR *d;
};
struct node {
__u32 refcount;
__u64 nid;
__u64 gen;
struct node *next; /* per-dir sibling list */
struct node *child; /* first contained file by this dir */
struct node *parent; /* containing directory */
size_t namelen;
char *name;
/* If non-null, this is the real name of the file in the underlying storage.
* This may differ from the field "name" only by case.
* strlen(actual_name) will always equal strlen(name), so it is safe to use
* namelen for both fields.
*/
char *actual_name;
};
/* Global data structure shared by all fuse handlers. */
struct fuse {
pthread_mutex_t lock;
__u64 next_generation;
int fd;
struct node root;
char rootpath[PATH_MAX];
};
/* Private data used by a single fuse handler. */
struct fuse_handler {
struct fuse* fuse;
int token;
/* To save memory, we never use the contents of the request buffer and the read
* buffer at the same time. This allows us to share the underlying storage. */
union {
__u8 request_buffer[MAX_REQUEST_SIZE];
__u8 read_buffer[MAX_READ];
};
};
static inline void *id_to_ptr(__u64 nid)
{
return (void *) (uintptr_t) nid;
}
static inline __u64 ptr_to_id(void *ptr)
{
return (__u64) (uintptr_t) ptr;
}
static void acquire_node_locked(struct node* node)
{
node->refcount++;
TRACE("ACQUIRE %p (%s) rc=%d\n", node, node->name, node->refcount);
}
static void remove_node_from_parent_locked(struct node* node);
static void release_node_locked(struct node* node)
{
TRACE("RELEASE %p (%s) rc=%d\n", node, node->name, node->refcount);
if (node->refcount > 0) {
node->refcount--;
if (!node->refcount) {
TRACE("DESTROY %p (%s)\n", node, node->name);
remove_node_from_parent_locked(node);
/* TODO: remove debugging - poison memory */
memset(node->name, 0xef, node->namelen);
free(node->name);
free(node->actual_name);
memset(node, 0xfc, sizeof(*node));
free(node);
}
} else {
ERROR("Zero refcnt %p\n", node);
}
}
static void add_node_to_parent_locked(struct node *node, struct node *parent) {
node->parent = parent;
node->next = parent->child;
parent->child = node;
acquire_node_locked(parent);
}
static void remove_node_from_parent_locked(struct node* node)
{
if (node->parent) {
if (node->parent->child == node) {
node->parent->child = node->parent->child->next;
} else {
struct node *node2;
node2 = node->parent->child;
while (node2->next != node)
node2 = node2->next;
node2->next = node->next;
}
release_node_locked(node->parent);
node->parent = NULL;
node->next = NULL;
}
}
/* Gets the absolute path to a node into the provided buffer.
*
* Populates 'buf' with the path and returns the length of the path on success,
* or returns -1 if the path is too long for the provided buffer.
*/
static ssize_t get_node_path_locked(struct node* node, char* buf, size_t bufsize)
{
size_t namelen = node->namelen;
if (bufsize < namelen + 1) {
return -1;
}
ssize_t pathlen = 0;
if (node->parent) {
pathlen = get_node_path_locked(node->parent, buf, bufsize - namelen - 2);
if (pathlen < 0) {
return -1;
}
buf[pathlen++] = '/';
}
const char* name = node->actual_name ? node->actual_name : node->name;
memcpy(buf + pathlen, name, namelen + 1); /* include trailing \0 */
return pathlen + namelen;
}
/* Finds the absolute path of a file within a given directory.
* Performs a case-insensitive search for the file and sets the buffer to the path
* of the first matching file. If 'search' is zero or if no match is found, sets
* the buffer to the path that the file would have, assuming the name were case-sensitive.
*
* Populates 'buf' with the path and returns the actual name (within 'buf') on success,
* or returns NULL if the path is too long for the provided buffer.
*/
static char* find_file_within(const char* path, const char* name,
char* buf, size_t bufsize, int search)
{
size_t pathlen = strlen(path);
size_t namelen = strlen(name);
size_t childlen = pathlen + namelen + 1;
char* actual;
if (bufsize <= childlen) {
return NULL;
}
memcpy(buf, path, pathlen);
buf[pathlen] = '/';
actual = buf + pathlen + 1;
memcpy(actual, name, namelen + 1);
if (search && access(buf, F_OK)) {
struct dirent* entry;
DIR* dir = opendir(path);
if (!dir) {
ERROR("opendir %s failed: %s", path, strerror(errno));
return actual;
}
while ((entry = readdir(dir))) {
if (!strcasecmp(entry->d_name, name)) {
/* we have a match - replace the name, don't need to copy the null again */
memcpy(actual, entry->d_name, namelen);
break;
}
}
closedir(dir);
}
return actual;
}
static void attr_from_stat(struct fuse_attr *attr, const struct stat *s, __u64 nid)
{
attr->ino = nid;
attr->size = s->st_size;
attr->blocks = s->st_blocks;
attr->atime = s->st_atime;
attr->mtime = s->st_mtime;
attr->ctime = s->st_ctime;
attr->atimensec = s->st_atime_nsec;
attr->mtimensec = s->st_mtime_nsec;
attr->ctimensec = s->st_ctime_nsec;
attr->mode = s->st_mode;
attr->nlink = s->st_nlink;
/* force permissions to something reasonable:
* world readable
* writable by the sdcard group
*/
if (attr->mode & 0100) {
attr->mode = (attr->mode & (~0777)) | 0775;
} else {
attr->mode = (attr->mode & (~0777)) | 0664;
}
/* all files owned by root.sdcard */
attr->uid = 0;
attr->gid = AID_SDCARD_RW;
}
struct node *create_node_locked(struct fuse* fuse,
struct node *parent, const char *name, const char* actual_name)
{
struct node *node;
size_t namelen = strlen(name);
node = calloc(1, sizeof(struct node));
if (!node) {
return NULL;
}
node->name = malloc(namelen + 1);
if (!node->name) {
free(node);
return NULL;
}
memcpy(node->name, name, namelen + 1);
if (strcmp(name, actual_name)) {
node->actual_name = malloc(namelen + 1);
if (!node->actual_name) {
free(node->name);
free(node);
return NULL;
}
memcpy(node->actual_name, actual_name, namelen + 1);
}
node->namelen = namelen;
node->nid = ptr_to_id(node);
node->gen = fuse->next_generation++;
acquire_node_locked(node);
add_node_to_parent_locked(node, parent);
return node;
}
static int rename_node_locked(struct node *node, const char *name,
const char* actual_name)
{
size_t namelen = strlen(name);
int need_actual_name = strcmp(name, actual_name);
/* make the storage bigger without actually changing the name
* in case an error occurs part way */
if (namelen > node->namelen) {
char* new_name = realloc(node->name, namelen + 1);
if (!new_name) {
return -ENOMEM;
}
node->name = new_name;
if (need_actual_name && node->actual_name) {
char* new_actual_name = realloc(node->actual_name, namelen + 1);
if (!new_actual_name) {
return -ENOMEM;
}
node->actual_name = new_actual_name;
}
}
/* update the name, taking care to allocate storage before overwriting the old name */
if (need_actual_name) {
if (!node->actual_name) {
node->actual_name = malloc(namelen + 1);
if (!node->actual_name) {
return -ENOMEM;
}
}
memcpy(node->actual_name, actual_name, namelen + 1);
} else {
free(node->actual_name);
node->actual_name = NULL;
}
memcpy(node->name, name, namelen + 1);
node->namelen = namelen;
return 0;
}
static struct node *lookup_node_by_id_locked(struct fuse *fuse, __u64 nid)
{
if (nid == FUSE_ROOT_ID) {
return &fuse->root;
} else {
return id_to_ptr(nid);
}
}
static struct node* lookup_node_and_path_by_id_locked(struct fuse* fuse, __u64 nid,
char* buf, size_t bufsize)
{
struct node* node = lookup_node_by_id_locked(fuse, nid);
if (node && get_node_path_locked(node, buf, bufsize) < 0) {
node = NULL;
}
return node;
}
static struct node *lookup_child_by_name_locked(struct node *node, const char *name)
{
for (node = node->child; node; node = node->next) {
/* use exact string comparison, nodes that differ by case
* must be considered distinct even if they refer to the same
* underlying file as otherwise operations such as "mv x x"
* will not work because the source and target nodes are the same. */
if (!strcmp(name, node->name)) {
return node;
}
}
return 0;
}
static struct node* acquire_or_create_child_locked(
struct fuse* fuse, struct node* parent,
const char* name, const char* actual_name)
{
struct node* child = lookup_child_by_name_locked(parent, name);
if (child) {
acquire_node_locked(child);
} else {
child = create_node_locked(fuse, parent, name, actual_name);
}
return child;
}
static void fuse_init(struct fuse *fuse, int fd, const char *source_path)
{
pthread_mutex_init(&fuse->lock, NULL);
fuse->fd = fd;
fuse->next_generation = 0;
memset(&fuse->root, 0, sizeof(fuse->root));
fuse->root.nid = FUSE_ROOT_ID; /* 1 */
fuse->root.refcount = 2;
fuse->root.namelen = strlen(source_path);
fuse->root.name = strdup(source_path);
}
static void fuse_status(struct fuse *fuse, __u64 unique, int err)
{
struct fuse_out_header hdr;
hdr.len = sizeof(hdr);
hdr.error = err;
hdr.unique = unique;
write(fuse->fd, &hdr, sizeof(hdr));
}
static void fuse_reply(struct fuse *fuse, __u64 unique, void *data, int len)
{
struct fuse_out_header hdr;
struct iovec vec[2];
int res;
hdr.len = len + sizeof(hdr);
hdr.error = 0;
hdr.unique = unique;
vec[0].iov_base = &hdr;
vec[0].iov_len = sizeof(hdr);
vec[1].iov_base = data;
vec[1].iov_len = len;
res = writev(fuse->fd, vec, 2);
if (res < 0) {
ERROR("*** REPLY FAILED *** %d\n", errno);
}
}
static int fuse_reply_entry(struct fuse* fuse, __u64 unique,
struct node* parent, const char* name, const char* actual_name,
const char* path)
{
struct node* node;
struct fuse_entry_out out;
struct stat s;
if (lstat(path, &s) < 0) {
return -errno;
}
pthread_mutex_lock(&fuse->lock);
node = acquire_or_create_child_locked(fuse, parent, name, actual_name);
if (!node) {
pthread_mutex_unlock(&fuse->lock);
return -ENOMEM;
}
memset(&out, 0, sizeof(out));
attr_from_stat(&out.attr, &s, node->nid);
out.attr_valid = 10;
out.entry_valid = 10;
out.nodeid = node->nid;
out.generation = node->gen;
pthread_mutex_unlock(&fuse->lock);
fuse_reply(fuse, unique, &out, sizeof(out));
return NO_STATUS;
}
static int fuse_reply_attr(struct fuse* fuse, __u64 unique, __u64 nid,
const char* path)
{
struct fuse_attr_out out;
struct stat s;
if (lstat(path, &s) < 0) {
return -errno;
}
memset(&out, 0, sizeof(out));
attr_from_stat(&out.attr, &s, nid);
out.attr_valid = 10;
fuse_reply(fuse, unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_lookup(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const char* name)
{
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
const char* actual_name;
pthread_mutex_lock(&fuse->lock);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] LOOKUP %s @ %llx (%s)\n", handler->token, name, hdr->nodeid,
parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !(actual_name = find_file_within(parent_path, name,
child_path, sizeof(child_path), 1))) {
return -ENOENT;
}
return fuse_reply_entry(fuse, hdr->unique, parent_node, name, actual_name, child_path);
}
static int handle_forget(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const struct fuse_forget_in *req)
{
struct node* node;
pthread_mutex_lock(&fuse->lock);
node = lookup_node_by_id_locked(fuse, hdr->nodeid);
TRACE("[%d] FORGET #%lld @ %llx (%s)\n", handler->token, req->nlookup,
hdr->nodeid, node ? node->name : "?");
if (node) {
__u64 n = req->nlookup;
while (n--) {
release_node_locked(node);
}
}
pthread_mutex_unlock(&fuse->lock);
return NO_STATUS; /* no reply */
}
static int handle_getattr(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const struct fuse_getattr_in *req)
{
struct node* node;
char path[PATH_MAX];
pthread_mutex_lock(&fuse->lock);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] GETATTR flags=%x fh=%llx @ %llx (%s)\n", handler->token,
req->getattr_flags, req->fh, hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
return fuse_reply_attr(fuse, hdr->unique, hdr->nodeid, path);
}
static int handle_setattr(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const struct fuse_setattr_in *req)
{
struct node* node;
char path[PATH_MAX];
struct timespec times[2];
pthread_mutex_lock(&fuse->lock);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] SETATTR fh=%llx valid=%x @ %llx (%s)\n", handler->token,
req->fh, req->valid, hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
/* XXX: incomplete implementation on purpose.
* chmod/chown should NEVER be implemented.*/
if ((req->valid & FATTR_SIZE) && truncate(path, req->size) < 0) {
return -errno;
}
/* Handle changing atime and mtime. If FATTR_ATIME_and FATTR_ATIME_NOW
* are both set, then set it to the current time. Else, set it to the
* time specified in the request. Same goes for mtime. Use utimensat(2)
* as it allows ATIME and MTIME to be changed independently, and has
* nanosecond resolution which fuse also has.
*/
if (req->valid & (FATTR_ATIME | FATTR_MTIME)) {
times[0].tv_nsec = UTIME_OMIT;
times[1].tv_nsec = UTIME_OMIT;
if (req->valid & FATTR_ATIME) {
if (req->valid & FATTR_ATIME_NOW) {
times[0].tv_nsec = UTIME_NOW;
} else {
times[0].tv_sec = req->atime;
times[0].tv_nsec = req->atimensec;
}
}
if (req->valid & FATTR_MTIME) {
if (req->valid & FATTR_MTIME_NOW) {
times[1].tv_nsec = UTIME_NOW;
} else {
times[1].tv_sec = req->mtime;
times[1].tv_nsec = req->mtimensec;
}
}
TRACE("[%d] Calling utimensat on %s with atime %ld, mtime=%ld\n",
handler->token, path, times[0].tv_sec, times[1].tv_sec);
if (utimensat(-1, path, times, 0) < 0) {
return -errno;
}
}
return fuse_reply_attr(fuse, hdr->unique, hdr->nodeid, path);
}
static int handle_mknod(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_mknod_in* req, const char* name)
{
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
const char* actual_name;
pthread_mutex_lock(&fuse->lock);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] MKNOD %s 0%o @ %llx (%s)\n", handler->token,
name, req->mode, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !(actual_name = find_file_within(parent_path, name,
child_path, sizeof(child_path), 1))) {
return -ENOENT;
}
__u32 mode = (req->mode & (~0777)) | 0664;
if (mknod(child_path, mode, req->rdev) < 0) {
return -errno;
}
return fuse_reply_entry(fuse, hdr->unique, parent_node, name, actual_name, child_path);
}
static int handle_mkdir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_mkdir_in* req, const char* name)
{
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
const char* actual_name;
pthread_mutex_lock(&fuse->lock);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] MKDIR %s 0%o @ %llx (%s)\n", handler->token,
name, req->mode, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !(actual_name = find_file_within(parent_path, name,
child_path, sizeof(child_path), 1))) {
return -ENOENT;
}
__u32 mode = (req->mode & (~0777)) | 0775;
if (mkdir(child_path, mode) < 0) {
return -errno;
}
return fuse_reply_entry(fuse, hdr->unique, parent_node, name, actual_name, child_path);
}
static int handle_unlink(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const char* name)
{
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
pthread_mutex_lock(&fuse->lock);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] UNLINK %s @ %llx (%s)\n", handler->token,
name, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !find_file_within(parent_path, name,
child_path, sizeof(child_path), 1)) {
return -ENOENT;
}
if (unlink(child_path) < 0) {
return -errno;
}
return 0;
}
static int handle_rmdir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const char* name)
{
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
pthread_mutex_lock(&fuse->lock);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] RMDIR %s @ %llx (%s)\n", handler->token,
name, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !find_file_within(parent_path, name,
child_path, sizeof(child_path), 1)) {
return -ENOENT;
}
if (rmdir(child_path) < 0) {
return -errno;
}
return 0;
}
static int handle_rename(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_rename_in* req,
const char* old_name, const char* new_name)
{
struct node* old_parent_node;
struct node* new_parent_node;
struct node* child_node;
char old_parent_path[PATH_MAX];
char new_parent_path[PATH_MAX];
char old_child_path[PATH_MAX];
char new_child_path[PATH_MAX];
const char* new_actual_name;
int res;
pthread_mutex_lock(&fuse->lock);
old_parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
old_parent_path, sizeof(old_parent_path));
new_parent_node = lookup_node_and_path_by_id_locked(fuse, req->newdir,
new_parent_path, sizeof(new_parent_path));
TRACE("[%d] RENAME %s->%s @ %llx (%s) -> %llx (%s)\n", handler->token,
old_name, new_name,
hdr->nodeid, old_parent_node ? old_parent_node->name : "?",
req->newdir, new_parent_node ? new_parent_node->name : "?");
if (!old_parent_node || !new_parent_node) {
res = -ENOENT;
goto lookup_error;
}
child_node = lookup_child_by_name_locked(old_parent_node, old_name);
if (!child_node || get_node_path_locked(child_node,
old_child_path, sizeof(old_child_path)) < 0) {
res = -ENOENT;
goto lookup_error;
}
acquire_node_locked(child_node);
pthread_mutex_unlock(&fuse->lock);
/* Special case for renaming a file where destination is same path
* differing only by case. In this case we don't want to look for a case
* insensitive match. This allows commands like "mv foo FOO" to work as expected.
*/
int search = old_parent_node != new_parent_node
|| strcasecmp(old_name, new_name);
if (!(new_actual_name = find_file_within(new_parent_path, new_name,
new_child_path, sizeof(new_child_path), search))) {
res = -ENOENT;
goto io_error;
}
TRACE("[%d] RENAME %s->%s\n", handler->token, old_child_path, new_child_path);
res = rename(old_child_path, new_child_path);
if (res < 0) {
res = -errno;
goto io_error;
}
pthread_mutex_lock(&fuse->lock);
res = rename_node_locked(child_node, new_name, new_actual_name);
if (!res) {
remove_node_from_parent_locked(child_node);
add_node_to_parent_locked(child_node, new_parent_node);
}
goto done;
io_error:
pthread_mutex_lock(&fuse->lock);
done:
release_node_locked(child_node);
lookup_error:
pthread_mutex_unlock(&fuse->lock);
return res;
}
static int handle_open(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_open_in* req)
{
struct node* node;
char path[PATH_MAX];
struct fuse_open_out out;
struct handle *h;
pthread_mutex_lock(&fuse->lock);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] OPEN 0%o @ %llx (%s)\n", handler->token,
req->flags, hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
h = malloc(sizeof(*h));
if (!h) {
return -ENOMEM;
}
TRACE("[%d] OPEN %s\n", handler->token, path);
h->fd = open(path, req->flags);
if (h->fd < 0) {
free(h);
return -errno;
}
out.fh = ptr_to_id(h);
out.open_flags = 0;
out.padding = 0;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_read(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_read_in* req)
{
struct handle *h = id_to_ptr(req->fh);
__u64 unique = hdr->unique;
__u32 size = req->size;
__u64 offset = req->offset;
int res;
/* Don't access any other fields of hdr or req beyond this point, the read buffer
* overlaps the request buffer and will clobber data in the request. This
* saves us 128KB per request handler thread at the cost of this scary comment. */
TRACE("[%d] READ %p(%d) %u@%llu\n", handler->token,
h, h->fd, size, offset);
if (size > sizeof(handler->read_buffer)) {
return -EINVAL;
}
res = pread64(h->fd, handler->read_buffer, size, offset);
if (res < 0) {
return -errno;
}
fuse_reply(fuse, unique, handler->read_buffer, res);
return NO_STATUS;
}
static int handle_write(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_write_in* req,
const void* buffer)
{
struct fuse_write_out out;
struct handle *h = id_to_ptr(req->fh);
int res;
TRACE("[%d] WRITE %p(%d) %u@%llu\n", handler->token,
h, h->fd, req->size, req->offset);
res = pwrite64(h->fd, buffer, req->size, req->offset);
if (res < 0) {
return -errno;
}
out.size = res;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_statfs(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr)
{
char path[PATH_MAX];
struct statfs stat;
struct fuse_statfs_out out;
int res;
pthread_mutex_lock(&fuse->lock);
TRACE("[%d] STATFS\n", handler->token);
res = get_node_path_locked(&fuse->root, path, sizeof(path));
pthread_mutex_unlock(&fuse->lock);
if (res < 0) {
return -ENOENT;
}
if (statfs(fuse->root.name, &stat) < 0) {
return -errno;
}
memset(&out, 0, sizeof(out));
out.st.blocks = stat.f_blocks;
out.st.bfree = stat.f_bfree;
out.st.bavail = stat.f_bavail;
out.st.files = stat.f_files;
out.st.ffree = stat.f_ffree;
out.st.bsize = stat.f_bsize;
out.st.namelen = stat.f_namelen;
out.st.frsize = stat.f_frsize;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_release(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_release_in* req)
{
struct handle *h = id_to_ptr(req->fh);
TRACE("[%d] RELEASE %p(%d)\n", handler->token, h, h->fd);
close(h->fd);
free(h);
return 0;
}
static int handle_fsync(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_fsync_in* req)
{
int is_data_sync = req->fsync_flags & 1;
struct handle *h = id_to_ptr(req->fh);
int res;
TRACE("[%d] FSYNC %p(%d) is_data_sync=%d\n", handler->token,
h, h->fd, is_data_sync);
res = is_data_sync ? fdatasync(h->fd) : fsync(h->fd);
if (res < 0) {
return -errno;
}
return 0;
}
static int handle_flush(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr)
{
TRACE("[%d] FLUSH\n", handler->token);
return 0;
}
static int handle_opendir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_open_in* req)
{
struct node* node;
char path[PATH_MAX];
struct fuse_open_out out;
struct dirhandle *h;
pthread_mutex_lock(&fuse->lock);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] OPENDIR @ %llx (%s)\n", handler->token,
hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
h = malloc(sizeof(*h));
if (!h) {
return -ENOMEM;
}
TRACE("[%d] OPENDIR %s\n", handler->token, path);
h->d = opendir(path);
if (!h->d) {
free(h);
return -errno;
}
out.fh = ptr_to_id(h);
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_readdir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_read_in* req)
{
char buffer[8192];
struct fuse_dirent *fde = (struct fuse_dirent*) buffer;
struct dirent *de;
struct dirhandle *h = id_to_ptr(req->fh);
TRACE("[%d] READDIR %p\n", handler->token, h);
if (req->offset == 0) {
/* rewinddir() might have been called above us, so rewind here too */
TRACE("[%d] calling rewinddir()\n", handler->token);
rewinddir(h->d);
}
de = readdir(h->d);
if (!de) {
return 0;
}
fde->ino = FUSE_UNKNOWN_INO;
/* increment the offset so we can detect when rewinddir() seeks back to the beginning */
fde->off = req->offset + 1;
fde->type = de->d_type;
fde->namelen = strlen(de->d_name);
memcpy(fde->name, de->d_name, fde->namelen + 1);
fuse_reply(fuse, hdr->unique, fde,
FUSE_DIRENT_ALIGN(sizeof(struct fuse_dirent) + fde->namelen));
return NO_STATUS;
}
static int handle_releasedir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_release_in* req)
{
struct dirhandle *h = id_to_ptr(req->fh);
TRACE("[%d] RELEASEDIR %p\n", handler->token, h);
closedir(h->d);
free(h);
return 0;
}
static int handle_init(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_init_in* req)
{
struct fuse_init_out out;
TRACE("[%d] INIT ver=%d.%d maxread=%d flags=%x\n",
handler->token, req->major, req->minor, req->max_readahead, req->flags);
out.major = FUSE_KERNEL_VERSION;
out.minor = FUSE_KERNEL_MINOR_VERSION;
out.max_readahead = req->max_readahead;
out.flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES;
out.max_background = 32;
out.congestion_threshold = 32;
out.max_write = MAX_WRITE;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_fuse_request(struct fuse *fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const void *data, size_t data_len)
{
switch (hdr->opcode) {
case FUSE_LOOKUP: { /* bytez[] -> entry_out */
const char* name = data;
return handle_lookup(fuse, handler, hdr, name);
}
case FUSE_FORGET: {
const struct fuse_forget_in *req = data;
return handle_forget(fuse, handler, hdr, req);
}
case FUSE_GETATTR: { /* getattr_in -> attr_out */
const struct fuse_getattr_in *req = data;
return handle_getattr(fuse, handler, hdr, req);
}
case FUSE_SETATTR: { /* setattr_in -> attr_out */
const struct fuse_setattr_in *req = data;
return handle_setattr(fuse, handler, hdr, req);
}
// case FUSE_READLINK:
// case FUSE_SYMLINK:
case FUSE_MKNOD: { /* mknod_in, bytez[] -> entry_out */
const struct fuse_mknod_in *req = data;
const char *name = ((const char*) data) + sizeof(*req);
return handle_mknod(fuse, handler, hdr, req, name);
}
case FUSE_MKDIR: { /* mkdir_in, bytez[] -> entry_out */
const struct fuse_mkdir_in *req = data;
const char *name = ((const char*) data) + sizeof(*req);
return handle_mkdir(fuse, handler, hdr, req, name);
}
case FUSE_UNLINK: { /* bytez[] -> */
const char* name = data;
return handle_unlink(fuse, handler, hdr, name);
}
case FUSE_RMDIR: { /* bytez[] -> */
const char* name = data;
return handle_rmdir(fuse, handler, hdr, name);
}
case FUSE_RENAME: { /* rename_in, oldname, newname -> */
const struct fuse_rename_in *req = data;
const char *old_name = ((const char*) data) + sizeof(*req);
const char *new_name = old_name + strlen(old_name) + 1;
return handle_rename(fuse, handler, hdr, req, old_name, new_name);
}
// case FUSE_LINK:
case FUSE_OPEN: { /* open_in -> open_out */
const struct fuse_open_in *req = data;
return handle_open(fuse, handler, hdr, req);
}
case FUSE_READ: { /* read_in -> byte[] */
const struct fuse_read_in *req = data;
return handle_read(fuse, handler, hdr, req);
}
case FUSE_WRITE: { /* write_in, byte[write_in.size] -> write_out */
const struct fuse_write_in *req = data;
const void* buffer = (const __u8*)data + sizeof(*req);
return handle_write(fuse, handler, hdr, req, buffer);
}
case FUSE_STATFS: { /* getattr_in -> attr_out */
return handle_statfs(fuse, handler, hdr);
}
case FUSE_RELEASE: { /* release_in -> */
const struct fuse_release_in *req = data;
return handle_release(fuse, handler, hdr, req);
}
case FUSE_FSYNC: {
const struct fuse_fsync_in *req = data;
return handle_fsync(fuse, handler, hdr, req);
}
// case FUSE_SETXATTR:
// case FUSE_GETXATTR:
// case FUSE_LISTXATTR:
// case FUSE_REMOVEXATTR:
case FUSE_FLUSH: {
return handle_flush(fuse, handler, hdr);
}
case FUSE_OPENDIR: { /* open_in -> open_out */
const struct fuse_open_in *req = data;
return handle_opendir(fuse, handler, hdr, req);
}
case FUSE_READDIR: {
const struct fuse_read_in *req = data;
return handle_readdir(fuse, handler, hdr, req);
}
case FUSE_RELEASEDIR: { /* release_in -> */
const struct fuse_release_in *req = data;
return handle_releasedir(fuse, handler, hdr, req);
}
// case FUSE_FSYNCDIR:
case FUSE_INIT: { /* init_in -> init_out */
const struct fuse_init_in *req = data;
return handle_init(fuse, handler, hdr, req);
}
default: {
TRACE("[%d] NOTIMPL op=%d uniq=%llx nid=%llx\n",
handler->token, hdr->opcode, hdr->unique, hdr->nodeid);
return -ENOSYS;
}
}
}
static void handle_fuse_requests(struct fuse_handler* handler)
{
struct fuse* fuse = handler->fuse;
for (;;) {
ssize_t len = read(fuse->fd,
handler->request_buffer, sizeof(handler->request_buffer));
if (len < 0) {
if (errno != EINTR) {
ERROR("[%d] handle_fuse_requests: errno=%d\n", handler->token, errno);
}
continue;
}
if ((size_t)len < sizeof(struct fuse_in_header)) {
ERROR("[%d] request too short: len=%zu\n", handler->token, (size_t)len);
continue;
}
const struct fuse_in_header *hdr = (void*)handler->request_buffer;
if (hdr->len != (size_t)len) {
ERROR("[%d] malformed header: len=%zu, hdr->len=%u\n",
handler->token, (size_t)len, hdr->len);
continue;
}
const void *data = handler->request_buffer + sizeof(struct fuse_in_header);
size_t data_len = len - sizeof(struct fuse_in_header);
__u64 unique = hdr->unique;
int res = handle_fuse_request(fuse, handler, hdr, data, data_len);
/* We do not access the request again after this point because the underlying
* buffer storage may have been reused while processing the request. */
if (res != NO_STATUS) {
if (res) {
TRACE("[%d] ERROR %d\n", handler->token, res);
}
fuse_status(fuse, unique, res);
}
}
}
static void* start_handler(void* data)
{
struct fuse_handler* handler = data;
handle_fuse_requests(handler);
return NULL;
}
static int ignite_fuse(struct fuse* fuse, int num_threads)
{
struct fuse_handler* handlers;
int i;
handlers = malloc(num_threads * sizeof(struct fuse_handler));
if (!handlers) {
ERROR("cannot allocate storage for threads");
return -ENOMEM;
}
for (i = 0; i < num_threads; i++) {
handlers[i].fuse = fuse;
handlers[i].token = i;
}
for (i = 1; i < num_threads; i++) {
pthread_t thread;
int res = pthread_create(&thread, NULL, start_handler, &handlers[i]);
if (res) {
ERROR("failed to start thread #%d, error=%d", i, res);
goto quit;
}
}
handle_fuse_requests(&handlers[0]);
ERROR("terminated prematurely");
/* don't bother killing all of the other threads or freeing anything,
* should never get here anyhow */
quit:
exit(1);
}
static int usage()
{
ERROR("usage: sdcard [-t<threads>] <source_path> <dest_path> <uid> <gid>\n"
" -t<threads>: specify number of threads to use, default -t%d\n"
"\n", DEFAULT_NUM_THREADS);
return 1;
}
static int run(const char* source_path, const char* dest_path, uid_t uid, gid_t gid,
int num_threads) {
int fd;
char opts[256];
int res;
struct fuse fuse;
/* cleanup from previous instance, if necessary */
umount2(dest_path, 2);
fd = open("/dev/fuse", O_RDWR);
if (fd < 0){
ERROR("cannot open fuse device (error %d)\n", errno);
return -1;
}
snprintf(opts, sizeof(opts),
"fd=%i,rootmode=40000,default_permissions,allow_other,user_id=%d,group_id=%d",
fd, uid, gid);
res = mount("/dev/fuse", dest_path, "fuse", MS_NOSUID | MS_NODEV, opts);
if (res < 0) {
ERROR("cannot mount fuse filesystem (error %d)\n", errno);
goto error;
}
res = setgid(gid);
if (res < 0) {
ERROR("cannot setgid (error %d)\n", errno);
goto error;
}
res = setuid(uid);
if (res < 0) {
ERROR("cannot setuid (error %d)\n", errno);
goto error;
}
fuse_init(&fuse, fd, source_path);
umask(0);
res = ignite_fuse(&fuse, num_threads);
/* we do not attempt to umount the file system here because we are no longer
* running as the root user */
error:
close(fd);
return res;
}
int main(int argc, char **argv)
{
int res;
const char *source_path = NULL;
const char *dest_path = NULL;
uid_t uid = 0;
gid_t gid = 0;
int num_threads = DEFAULT_NUM_THREADS;
int i;
struct rlimit rlim;
for (i = 1; i < argc; i++) {
char* arg = argv[i];
if (!strncmp(arg, "-t", 2))
num_threads = strtoul(arg + 2, 0, 10);
else if (!source_path)
source_path = arg;
else if (!dest_path)
dest_path = arg;
else if (!uid) {
char* endptr = NULL;
errno = 0;
uid = strtoul(arg, &endptr, 10);
if (*endptr != '\0' || errno != 0) {
ERROR("Invalid uid");
return usage();
}
} else if (!gid) {
char* endptr = NULL;
errno = 0;
gid = strtoul(arg, &endptr, 10);
if (*endptr != '\0' || errno != 0) {
ERROR("Invalid gid");
return usage();
}
} else {
ERROR("too many arguments\n");
return usage();
}
}
if (!source_path) {
ERROR("no source path specified\n");
return usage();
}
if (!dest_path) {
ERROR("no dest path specified\n");
return usage();
}
if (!uid || !gid) {
ERROR("uid and gid must be nonzero\n");
return usage();
}
if (num_threads < 1) {
ERROR("number of threads must be at least 1\n");
return usage();
}
rlim.rlim_cur = 8192;
rlim.rlim_max = 8192;
if (setrlimit(RLIMIT_NOFILE, &rlim)) {
ERROR("Error setting RLIMIT_NOFILE, errno = %d\n", errno);
}
res = run(source_path, dest_path, uid, gid, num_threads);
return res < 0 ? 1 : 0;
}
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