1 /*
2 * Copyright (C) 2014 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 <stdlib.h>
18 #include <stdio.h>
19 #include <string.h>
20 #include <errno.h>
21 #include <sys/mount.h>
22 #include <sys/stat.h>
23 #include <unistd.h>
24 #include <fcntl.h>
25
26 #include <android-base/file.h>
27
28 #include "fuse_sideload.h"
29
30 struct file_data {
31 int fd; // the underlying sdcard file
32
33 uint64_t file_size;
34 uint32_t block_size;
35 };
36
read_block_file(void * cookie,uint32_t block,uint8_t * buffer,uint32_t fetch_size)37 static int read_block_file(void* cookie, uint32_t block, uint8_t* buffer, uint32_t fetch_size) {
38 file_data* fd = reinterpret_cast<file_data*>(cookie);
39
40 off64_t offset = ((off64_t) block) * fd->block_size;
41 if (TEMP_FAILURE_RETRY(lseek64(fd->fd, offset, SEEK_SET)) == -1) {
42 fprintf(stderr, "seek on sdcard failed: %s\n", strerror(errno));
43 return -EIO;
44 }
45
46 if (!android::base::ReadFully(fd->fd, buffer, fetch_size)) {
47 fprintf(stderr, "read on sdcard failed: %s\n", strerror(errno));
48 return -EIO;
49 }
50
51 return 0;
52 }
53
close_file(void * cookie)54 static void close_file(void* cookie) {
55 file_data* fd = reinterpret_cast<file_data*>(cookie);
56 close(fd->fd);
57 }
58
start_sdcard_fuse(const char * path)59 bool start_sdcard_fuse(const char* path) {
60 struct stat sb;
61 if (stat(path, &sb) == -1) {
62 fprintf(stderr, "failed to stat %s: %s\n", path, strerror(errno));
63 return false;
64 }
65
66 file_data fd;
67 fd.fd = open(path, O_RDONLY);
68 if (fd.fd == -1) {
69 fprintf(stderr, "failed to open %s: %s\n", path, strerror(errno));
70 return false;
71 }
72 fd.file_size = sb.st_size;
73 fd.block_size = 65536;
74
75 provider_vtab vtab;
76 vtab.read_block = read_block_file;
77 vtab.close = close_file;
78
79 // The installation process expects to find the sdcard unmounted.
80 // Unmount it with MNT_DETACH so that our open file continues to
81 // work but new references see it as unmounted.
82 umount2("/sdcard", MNT_DETACH);
83
84 return run_fuse_sideload(&vtab, &fd, fd.file_size, fd.block_size) == 0;
85 }
86