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. 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 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) 125 126 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 } 148 149 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 } 169 170 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 } 180 181 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
