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
18 #include <errno.h>
19 #include <fcntl.h>
20 #include <linux/fs.h>
21 #include <sys/ioctl.h>
22 #include <sys/stat.h>
23 #include <sys/types.h>
24 #include <unistd.h>
25
26 #include <arpa/inet.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30
31 #include <cutils/properties.h>
32 #include <fs_mgr.h>
33
34 #include "bootinfo.h"
35
36 using android::fs_mgr::Fstab;
37 using android::fs_mgr::GetEntryForMountPoint;
38 using android::fs_mgr::ReadDefaultFstab;
39 using android::fs_mgr::ReadFstabFromFile;
40
41 // Open the appropriate fstab file and fallback to /fstab.device if
42 // that's what's being used.
open_fstab(Fstab * fstab)43 static bool open_fstab(Fstab* fstab)
44 {
45 return ReadDefaultFstab(fstab) || ReadFstabFromFile("/fstab.device", fstab);
46 }
47
boot_info_open_partition(const char * name,uint64_t * out_size,int flags)48 int boot_info_open_partition(const char *name, uint64_t *out_size, int flags)
49 {
50 char *path;
51 int fd;
52
53 // We can't use fs_mgr to look up |name| because fstab doesn't list
54 // every slot partition (it uses the slotselect option to mask the
55 // suffix) and |slot| is expected to be of that form, e.g. boot_a.
56 //
57 // We can however assume that there's an entry for the /misc mount
58 // point and use that to get the device file for the misc
59 // partition. From there we'll assume that a by-name scheme is used
60 // so we can just replace the trailing "misc" by the given |name|,
61 // e.g.
62 //
63 // /dev/block/platform/soc.0/7824900.sdhci/by-name/misc ->
64 // /dev/block/platform/soc.0/7824900.sdhci/by-name/boot_a
65 //
66 // If needed, it's possible to relax this assumption in the future
67 // by trawling /sys/block looking for the appropriate sibling of
68 // misc and then finding an entry in /dev matching the sysfs entry.
69
70 Fstab fstab;
71 if (!open_fstab(&fstab)) {
72 return -1;
73 }
74 auto record = GetEntryForMountPoint(&fstab, "/misc");
75 if (record == nullptr) {
76 return -1;
77 }
78 if (strcmp(name, "misc") == 0) {
79 path = strdup(record->blk_device.c_str());
80 } else {
81 size_t trimmed_len, name_len;
82 const char *end_slash = strrchr(record->blk_device.c_str(), '/');
83 if (end_slash == NULL) {
84 return -1;
85 }
86 trimmed_len = end_slash - record->blk_device.c_str() + 1;
87 name_len = strlen(name);
88 path = static_cast<char *>(calloc(trimmed_len + name_len + 1, 1));
89 strncpy(path, record->blk_device.c_str(), trimmed_len);
90 strncpy(path + trimmed_len, name, name_len);
91 }
92
93 fd = open(path, flags);
94 free(path);
95
96 // If we successfully opened the device, get size if requested.
97 if (fd != -1 && out_size != NULL) {
98 if (ioctl(fd, BLKGETSIZE64, out_size) != 0) {
99 close(fd);
100 return -1;
101 }
102 }
103
104 return fd;
105 }
106
107 // As per struct bootloader_message_ab which is defined in
108 // boot/1.1/default.
109 // struct bootloader_message_ab {
110 // struct bootloader_message message;
111 // char slot_suffix[32];
112 // char update_channel[128];
113 //
114 // // Round up the entire struct to 4096-byte.
115 // char reserved[1888];
116 // };
117 //
118 // We can use the 32 bytes in the bootctrl_suffix field provided that they
119 // start with the active slot suffix terminated by NUL. It just so happens
120 // that BrilloBootInfo is laid out this way.
121 #define BOOTINFO_OFFSET 2048
122
boot_info_load(BrilloBootInfo * out_info)123 bool boot_info_load(BrilloBootInfo *out_info)
124 {
125 int fd;
126
127 memset(out_info, '\0', sizeof(BrilloBootInfo));
128
129 fd = boot_info_open_partition("misc", NULL, O_RDONLY);
130 if (fd == -1)
131 return false;
132 if (lseek(fd, BOOTINFO_OFFSET, SEEK_SET) != BOOTINFO_OFFSET) {
133 close(fd);
134 return false;
135 }
136 ssize_t num_read;
137 do {
138 num_read = read(fd, (void*) out_info, sizeof(BrilloBootInfo));
139 } while (num_read == -1 && errno == EINTR);
140 close(fd);
141 if (num_read != sizeof(BrilloBootInfo))
142 return false;
143 return true;
144 }
145
boot_info_save(BrilloBootInfo * info)146 bool boot_info_save(BrilloBootInfo *info)
147 {
148 int fd;
149
150 fd = boot_info_open_partition("misc", NULL, O_RDWR);
151 if (fd == -1)
152 return false;
153 if (lseek(fd, BOOTINFO_OFFSET, SEEK_SET) != BOOTINFO_OFFSET) {
154 close(fd);
155 return false;
156 }
157 ssize_t num_written;
158 do {
159 num_written = write(fd, (void*) info, sizeof(BrilloBootInfo));
160 } while (num_written == -1 && errno == EINTR);
161 close(fd);
162 if (num_written != sizeof(BrilloBootInfo))
163 return false;
164 return true;
165 }
166
boot_info_validate(BrilloBootInfo * info)167 bool boot_info_validate(BrilloBootInfo* info)
168 {
169 if (info->magic[0] != 'B' ||
170 info->magic[1] != 'C' ||
171 info->magic[2] != 'c')
172 return false;
173 if (info->active_slot >= 2)
174 return false;
175 return true;
176 }
177
boot_info_reset(BrilloBootInfo * info)178 void boot_info_reset(BrilloBootInfo* info)
179 {
180 memset(info, '\0', sizeof(BrilloBootInfo));
181 info->magic[0] = 'B';
182 info->magic[1] = 'C';
183 info->magic[2] = 'c';
184 }
185