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