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