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 "fuse_sideload.h"
27
28 struct file_data {
29 int fd; // the underlying sdcard file
30
31 uint64_t file_size;
32 uint32_t block_size;
33 };
34
read_block_file(void * cookie,uint32_t block,uint8_t * buffer,uint32_t fetch_size)35 static int read_block_file(void* cookie, uint32_t block, uint8_t* buffer, uint32_t fetch_size) {
36 file_data* fd = reinterpret_cast<file_data*>(cookie);
37
38 off64_t offset = ((off64_t) block) * fd->block_size;
39 if (TEMP_FAILURE_RETRY(lseek64(fd->fd, offset, SEEK_SET)) == -1) {
40 fprintf(stderr, "seek on sdcard failed: %s\n", strerror(errno));
41 return -EIO;
42 }
43
44 while (fetch_size > 0) {
45 ssize_t r = TEMP_FAILURE_RETRY(read(fd->fd, buffer, fetch_size));
46 if (r == -1) {
47 fprintf(stderr, "read on sdcard failed: %s\n", strerror(errno));
48 return -EIO;
49 }
50 fetch_size -= r;
51 buffer += r;
52 }
53
54 return 0;
55 }
56
close_file(void * cookie)57 static void close_file(void* cookie) {
58 file_data* fd = reinterpret_cast<file_data*>(cookie);
59 close(fd->fd);
60 }
61
start_sdcard_fuse(const char * path)62 bool start_sdcard_fuse(const char* path) {
63 struct stat sb;
64 if (stat(path, &sb) == -1) {
65 fprintf(stderr, "failed to stat %s: %s\n", path, strerror(errno));
66 return false;
67 }
68
69 file_data fd;
70 fd.fd = open(path, O_RDONLY);
71 if (fd.fd == -1) {
72 fprintf(stderr, "failed to open %s: %s\n", path, strerror(errno));
73 return false;
74 }
75 fd.file_size = sb.st_size;
76 fd.block_size = 65536;
77
78 provider_vtab vtab;
79 vtab.read_block = read_block_file;
80 vtab.close = close_file;
81
82 // The installation process expects to find the sdcard unmounted.
83 // Unmount it with MNT_DETACH so that our open file continues to
84 // work but new references see it as unmounted.
85 umount2("/sdcard", MNT_DETACH);
86
87 return run_fuse_sideload(&vtab, &fd, fd.file_size, fd.block_size) == 0;
88 }
89