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
33 #include <bootloader.h>
34 #include <fs_mgr.h>
35
36 #include "bootinfo.h"
37
38 // Open the appropriate fstab file and fallback to /fstab.device if
39 // that's what's being used.
open_fstab(void)40 static struct fstab *open_fstab(void)
41 {
42 char propbuf[PROPERTY_VALUE_MAX];
43 char fstab_name[PROPERTY_VALUE_MAX + 32];
44 struct fstab *fstab;
45
46 property_get("ro.hardware", propbuf, "");
47 snprintf(fstab_name, sizeof(fstab_name), "/fstab.%s", propbuf);
48 fstab = fs_mgr_read_fstab(fstab_name);
49 if (fstab != NULL)
50 return fstab;
51
52 fstab = fs_mgr_read_fstab("/fstab.device");
53 return fstab;
54 }
55
boot_info_open_partition(const char * name,uint64_t * out_size,int flags)56 int boot_info_open_partition(const char *name, uint64_t *out_size, int flags)
57 {
58 char *path;
59 int fd;
60 struct fstab *fstab;
61 struct fstab_rec *record;
62
63 // We can't use fs_mgr to look up |name| because fstab doesn't list
64 // every slot partition (it uses the slotselect option to mask the
65 // suffix) and |slot| is expected to be of that form, e.g. boot_a.
66 //
67 // We can however assume that there's an entry for the /misc mount
68 // point and use that to get the device file for the misc
69 // partition. From there we'll assume that a by-name scheme is used
70 // so we can just replace the trailing "misc" by the given |name|,
71 // e.g.
72 //
73 // /dev/block/platform/soc.0/7824900.sdhci/by-name/misc ->
74 // /dev/block/platform/soc.0/7824900.sdhci/by-name/boot_a
75 //
76 // If needed, it's possible to relax this assumption in the future
77 // by trawling /sys/block looking for the appropriate sibling of
78 // misc and then finding an entry in /dev matching the sysfs entry.
79
80 fstab = open_fstab();
81 if (fstab == NULL)
82 return -1;
83 record = fs_mgr_get_entry_for_mount_point(fstab, "/misc");
84 if (record == NULL) {
85 fs_mgr_free_fstab(fstab);
86 return -1;
87 }
88 if (strcmp(name, "misc") == 0) {
89 path = strdup(record->blk_device);
90 } else {
91 size_t trimmed_len, name_len;
92 const char *end_slash = strrchr(record->blk_device, '/');
93 if (end_slash == NULL) {
94 fs_mgr_free_fstab(fstab);
95 return -1;
96 }
97 trimmed_len = end_slash - record->blk_device + 1;
98 name_len = strlen(name);
99 path = calloc(trimmed_len + name_len + 1, 1);
100 strncpy(path, record->blk_device, trimmed_len);
101 strncpy(path + trimmed_len, name, name_len);
102 }
103 fs_mgr_free_fstab(fstab);
104
105 fd = open(path, flags);
106 free(path);
107
108 // If we successfully opened the device, get size if requested.
109 if (fd != -1 && out_size != NULL) {
110 if (ioctl(fd, BLKGETSIZE64, out_size) != 0) {
111 close(fd);
112 return -1;
113 }
114 }
115
116 return fd;
117 }
118
119 // As per struct bootloader_message which is defined in
120 // bootable/recovery/bootloader.h we can use the 32 bytes in the
121 // bootctrl_suffix field provided that they start with the active slot
122 // suffix terminated by NUL. It just so happens that BrilloBootInfo is
123 // laid out this way.
124 #define BOOTINFO_OFFSET offsetof(struct bootloader_message, slot_suffix)
125
boot_info_load(BrilloBootInfo * out_info)126 bool boot_info_load(BrilloBootInfo *out_info)
127 {
128 int fd;
129
130 memset(out_info, '\0', sizeof(BrilloBootInfo));
131
132 fd = boot_info_open_partition("misc", NULL, O_RDONLY);
133 if (fd == -1)
134 return false;
135 if (lseek(fd, BOOTINFO_OFFSET, SEEK_SET) != BOOTINFO_OFFSET) {
136 close(fd);
137 return false;
138 }
139 ssize_t num_read;
140 do {
141 num_read = read(fd, (void*) out_info, sizeof(BrilloBootInfo));
142 } while (num_read == -1 && errno == EINTR);
143 close(fd);
144 if (num_read != sizeof(BrilloBootInfo))
145 return false;
146 return true;
147 }
148
boot_info_save(BrilloBootInfo * info)149 bool boot_info_save(BrilloBootInfo *info)
150 {
151 int fd;
152
153 fd = boot_info_open_partition("misc", NULL, O_RDWR);
154 if (fd == -1)
155 return false;
156 if (lseek(fd, BOOTINFO_OFFSET, SEEK_SET) != BOOTINFO_OFFSET) {
157 close(fd);
158 return false;
159 }
160 ssize_t num_written;
161 do {
162 num_written = write(fd, (void*) info, sizeof(BrilloBootInfo));
163 } while (num_written == -1 && errno == EINTR);
164 close(fd);
165 if (num_written != sizeof(BrilloBootInfo))
166 return false;
167 return true;
168 }
169
boot_info_validate(BrilloBootInfo * info)170 bool boot_info_validate(BrilloBootInfo* info)
171 {
172 if (info->magic[0] != 'B' ||
173 info->magic[1] != 'C' ||
174 info->magic[2] != 'c')
175 return false;
176 if (info->active_slot >= 2)
177 return false;
178 return true;
179 }
180
boot_info_reset(BrilloBootInfo * info)181 void boot_info_reset(BrilloBootInfo* info)
182 {
183 memset(info, '\0', sizeof(BrilloBootInfo));
184 info->magic[0] = 'B';
185 info->magic[1] = 'C';
186 info->magic[2] = 'c';
187 }
188