1 /*
2 * Copyright (C) 2015 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 <errno.h>
18 #include <fcntl.h>
19 #include <linux/fs.h>
20 #include <sys/ioctl.h>
21 #include <sys/stat.h>
22 #include <sys/types.h>
23 #include <unistd.h>
24
25 #include <arpa/inet.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29
30 #include <cutils/properties.h>
31 #include <fs_mgr.h>
32
33 #include "bootinfo.h"
34
35 using android::fs_mgr::Fstab;
36 using android::fs_mgr::GetEntryForMountPoint;
37 using android::fs_mgr::ReadDefaultFstab;
38 using android::fs_mgr::ReadFstabFromFile;
39
40 // Open the appropriate fstab file and fallback to /fstab.device if
41 // that's what's being used.
open_fstab(Fstab * fstab)42 static bool open_fstab(Fstab* fstab) {
43 return ReadDefaultFstab(fstab) || ReadFstabFromFile("/fstab.device", fstab);
44 }
45
boot_info_open_partition(const char * name,uint64_t * out_size,int flags)46 int boot_info_open_partition(const char* name, uint64_t* out_size, int flags) {
47 char* path;
48 int fd;
49
50 // We can't use fs_mgr to look up |name| because fstab doesn't list
51 // every slot partition (it uses the slotselect option to mask the
52 // suffix) and |slot| is expected to be of that form, e.g. boot_a.
53 //
54 // We can however assume that there's an entry for the /misc mount
55 // point and use that to get the device file for the misc
56 // partition. From there we'll assume that a by-name scheme is used
57 // so we can just replace the trailing "misc" by the given |name|,
58 // e.g.
59 //
60 // /dev/block/platform/soc.0/7824900.sdhci/by-name/misc ->
61 // /dev/block/platform/soc.0/7824900.sdhci/by-name/boot_a
62 //
63 // If needed, it's possible to relax this assumption in the future
64 // by trawling /sys/block looking for the appropriate sibling of
65 // misc and then finding an entry in /dev matching the sysfs entry.
66
67 Fstab fstab;
68 if (!open_fstab(&fstab)) {
69 return -1;
70 }
71 auto record = GetEntryForMountPoint(&fstab, "/misc");
72 if (record == nullptr) {
73 return -1;
74 }
75 if (strcmp(name, "misc") == 0) {
76 path = strdup(record->blk_device.c_str());
77 } else {
78 size_t trimmed_len, name_len;
79 const char* end_slash = strrchr(record->blk_device.c_str(), '/');
80 if (end_slash == NULL) {
81 return -1;
82 }
83 trimmed_len = end_slash - record->blk_device.c_str() + 1;
84 name_len = strlen(name);
85 path = static_cast<char*>(calloc(trimmed_len + name_len + 1, 1));
86 strncpy(path, record->blk_device.c_str(), trimmed_len);
87 strncpy(path + trimmed_len, name, name_len);
88 }
89
90 fd = open(path, flags);
91 free(path);
92
93 // If we successfully opened the device, get size if requested.
94 if (fd != -1 && out_size != NULL) {
95 if (ioctl(fd, BLKGETSIZE64, out_size) != 0) {
96 close(fd);
97 return -1;
98 }
99 }
100
101 return fd;
102 }
103
104 // As per struct bootloader_message_ab which is defined in
105 // boot/1.1/default.
106 // struct bootloader_message_ab {
107 // struct bootloader_message message;
108 // char slot_suffix[32];
109 // char update_channel[128];
110 //
111 // // Round up the entire struct to 4096-byte.
112 // char reserved[1888];
113 // };
114 //
115 // We can use the 32 bytes in the bootctrl_suffix field provided that they
116 // start with the active slot suffix terminated by NUL. It just so happens
117 // that BrilloBootInfo is laid out this way.
118 #define BOOTINFO_OFFSET 2048
119
boot_info_load(BrilloBootInfo * out_info)120 bool boot_info_load(BrilloBootInfo* out_info) {
121 int fd;
122
123 memset(out_info, '\0', sizeof(BrilloBootInfo));
124
125 fd = boot_info_open_partition("misc", NULL, O_RDONLY);
126 if (fd == -1) return false;
127 if (lseek(fd, BOOTINFO_OFFSET, SEEK_SET) != BOOTINFO_OFFSET) {
128 close(fd);
129 return false;
130 }
131 ssize_t num_read;
132 do {
133 num_read = read(fd, (void*)out_info, sizeof(BrilloBootInfo));
134 } while (num_read == -1 && errno == EINTR);
135 close(fd);
136 if (num_read != sizeof(BrilloBootInfo)) return false;
137 return true;
138 }
139
boot_info_save(BrilloBootInfo * info)140 bool boot_info_save(BrilloBootInfo* info) {
141 int fd;
142
143 fd = boot_info_open_partition("misc", NULL, O_RDWR);
144 if (fd == -1) return false;
145 if (lseek(fd, BOOTINFO_OFFSET, SEEK_SET) != BOOTINFO_OFFSET) {
146 close(fd);
147 return false;
148 }
149 ssize_t num_written;
150 do {
151 num_written = write(fd, (void*)info, sizeof(BrilloBootInfo));
152 } while (num_written == -1 && errno == EINTR);
153 close(fd);
154 if (num_written != sizeof(BrilloBootInfo)) return false;
155 return true;
156 }
157
boot_info_validate(BrilloBootInfo * info)158 bool boot_info_validate(BrilloBootInfo* info) {
159 if (info->magic[0] != 'B' || info->magic[1] != 'C' || info->magic[2] != 'c') return false;
160 if (info->active_slot >= 2) return false;
161 return true;
162 }
163
boot_info_reset(BrilloBootInfo * info)164 void boot_info_reset(BrilloBootInfo* info) {
165 memset(info, '\0', sizeof(BrilloBootInfo));
166 info->magic[0] = 'B';
167 info->magic[1] = 'C';
168 info->magic[2] = 'c';
169 }
170