Ot ten Thije | ae835ac | 2010-10-18 13:37:37 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2010 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 | /* Limited driver for the Qcow2 filesystem, capable of extracting snapshot |
| 18 | * metadata from Qcow2 formatted image file. |
| 19 | * |
| 20 | * Similar functionality is implemented in block/qcow2.c, block/qcow2-snapshot.c |
| 21 | * and block.c. This separate implementation was made to further decouple the UI |
| 22 | * of the Android emulator from the underlying Qemu system. It allows the UI to |
| 23 | * show snapshot listings without having to fall back on Qemu's block driver |
| 24 | * system, which would pull in a lot of code irrelevant for the UI. |
| 25 | */ |
| 26 | |
| 27 | #include <errno.h> |
| 28 | #include <fcntl.h> |
| 29 | #include <stdint.h> |
| 30 | #include <stdio.h> |
| 31 | #include <stdlib.h> |
| 32 | #include <string.h> |
| 33 | #include <time.h> |
| 34 | #include <unistd.h> |
| 35 | |
| 36 | #include "android/utils/debug.h" |
| 37 | #include "android/utils/system.h" |
| 38 | #include "bswap.h" |
| 39 | #include "snapshot.h" |
| 40 | |
| 41 | #if CONFIG_ANDROID_SNAPSHOTS |
| 42 | |
| 43 | /* "Magic" sequence of four bytes required by spec to be the first four bytes |
| 44 | * of any Qcow file. |
| 45 | */ |
| 46 | #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb) |
| 47 | #define QCOW_VERSION 2 |
| 48 | |
| 49 | /* Reads 'nbyte' bytes from 'fd' into 'buf', retrying on interrupts. |
| 50 | * Exit()s if the read fails for any other reason. |
| 51 | */ |
| 52 | static int |
| 53 | read_or_die(int fd, void *buf, size_t nbyte) |
| 54 | { |
| 55 | int ret = 0; |
| 56 | do { |
| 57 | ret = read(fd, buf, nbyte); |
| 58 | } |
| 59 | while(ret < 0 && errno == EINTR); |
| 60 | |
| 61 | if (ret < 0) { |
| 62 | derror("read failed: %s", strerror(errno)); |
| 63 | exit(1); |
| 64 | } |
| 65 | |
| 66 | return ret; |
| 67 | } |
| 68 | |
| 69 | /* Wrapper around lseek(), exit()s on error. |
| 70 | */ |
| 71 | static off_t |
| 72 | seek_or_die(int fd, off_t offset, int whence) |
| 73 | { |
| 74 | off_t ret = lseek(fd, offset, whence); |
| 75 | if (ret < 0) { |
| 76 | derror("seek failed: %s", strerror(errno)); |
| 77 | exit(1); |
| 78 | } |
| 79 | return ret; |
| 80 | } |
| 81 | |
| 82 | |
| 83 | typedef struct SnapshotInfo { |
| 84 | char *id_str; |
| 85 | char *name; |
| 86 | |
| 87 | uint32_t date_sec; |
| 88 | uint32_t date_nsec; |
| 89 | |
| 90 | uint64_t vm_clock_nsec; |
| 91 | uint32_t vm_state_size; |
| 92 | } SnapshotInfo; |
| 93 | |
| 94 | static SnapshotInfo* |
| 95 | snapshot_info_alloc() |
| 96 | { |
| 97 | return android_alloc(sizeof(SnapshotInfo)); |
| 98 | } |
| 99 | |
| 100 | static void |
| 101 | snapshot_info_free( SnapshotInfo* info ) |
| 102 | { |
| 103 | AFREE(info->id_str); |
| 104 | AFREE(info->name); |
| 105 | AFREE(info); |
| 106 | } |
| 107 | |
| 108 | |
| 109 | /* Reads a snapshot record from a qcow2-formatted file. |
| 110 | * |
| 111 | * The function assumes the file position of 'fd' points to the beginning of a |
| 112 | * QcowSnapshotHeader record. When the call returns, the file position of fd is |
| 113 | * at the place where the next QcowSnapshotHeader should start, if there is one. |
| 114 | * |
| 115 | * C.f. QCowSnapshotHeader in block/qcow2-snapshot.c for the complete layout of |
| 116 | * the header. |
| 117 | */ |
| 118 | static void |
| 119 | snapshot_info_read( int fd, SnapshotInfo* info ) |
| 120 | { |
| 121 | uint64_t start_offset = seek_or_die(fd, 0, SEEK_CUR); |
| 122 | |
| 123 | uint32_t extra_data_size; |
| 124 | uint16_t id_str_size, name_size; |
| 125 | |
| 126 | /* read fixed-length fields */ |
| 127 | seek_or_die(fd, 12, SEEK_CUR); /* skip l1 info */ |
| 128 | read_or_die(fd, &id_str_size, sizeof(id_str_size)); |
| 129 | read_or_die(fd, &name_size, sizeof(name_size)); |
| 130 | read_or_die(fd, &info->date_sec, sizeof(info->date_sec)); |
| 131 | read_or_die(fd, &info->date_nsec, sizeof(info->date_nsec)); |
| 132 | read_or_die(fd, &info->vm_clock_nsec, sizeof(info->vm_clock_nsec)); |
| 133 | read_or_die(fd, &info->vm_state_size, sizeof(info->vm_state_size)); |
| 134 | read_or_die(fd, &extra_data_size, sizeof(extra_data_size)); |
| 135 | |
| 136 | /* convert to host endianness */ |
| 137 | be16_to_cpus(&id_str_size); |
| 138 | be16_to_cpus(&name_size); |
| 139 | be32_to_cpus(&info->date_sec); |
| 140 | be32_to_cpus(&info->date_nsec); |
| 141 | be64_to_cpus(&info->vm_clock_nsec); |
| 142 | be32_to_cpus(&info->vm_state_size); |
| 143 | be32_to_cpus(&extra_data_size); |
| 144 | be32_to_cpus(&extra_data_size); |
| 145 | |
| 146 | /* read variable-length buffers*/ |
| 147 | info->id_str = android_alloc(id_str_size + 1); // +1: manual null-termination |
| 148 | info->name = android_alloc(name_size + 1); |
| 149 | seek_or_die(fd, extra_data_size, SEEK_CUR); /* skip extra data */ |
| 150 | read_or_die(fd, info->id_str, id_str_size); |
| 151 | read_or_die(fd, info->name, name_size); |
| 152 | |
| 153 | info->id_str[id_str_size] = '\0'; |
| 154 | info->name[name_size] = '\0'; |
| 155 | |
| 156 | /* headers are 8 byte aligned, ceil to nearest multiple of 8 */ |
| 157 | uint64_t end_offset = seek_or_die(fd, 0, SEEK_CUR); |
| 158 | uint32_t total_size = end_offset - start_offset; |
| 159 | uint32_t aligned_size = ((total_size - 1) / 8 + 1) * 8; |
| 160 | |
| 161 | /* skip to start of next record */ |
| 162 | seek_or_die(fd, start_offset + aligned_size, SEEK_SET); |
| 163 | } |
| 164 | |
| 165 | |
| 166 | #define NB_SUFFIXES 4 |
| 167 | |
| 168 | /* Returns the size of a snapshot in a human-readable format. |
| 169 | * |
| 170 | * This function copyright (c) 2003 Fabrice Bellard |
| 171 | */ |
| 172 | static char* |
| 173 | snapshot_format_size( char *buf, int buf_size, int64_t size ) |
| 174 | { |
| 175 | static const char suffixes[NB_SUFFIXES] = "KMGT"; |
| 176 | int64_t base; |
| 177 | int i; |
| 178 | |
| 179 | if (size <= 999) { |
| 180 | snprintf(buf, buf_size, "%" PRId64, size); |
| 181 | } else { |
| 182 | base = 1024; |
| 183 | for(i = 0; i < NB_SUFFIXES; i++) { |
| 184 | if (size < (10 * base)) { |
| 185 | snprintf(buf, buf_size, "%0.1f%c", |
| 186 | (double)size / base, |
| 187 | suffixes[i]); |
| 188 | break; |
| 189 | } else if (size < (1000 * base) || i == (NB_SUFFIXES - 1)) { |
| 190 | snprintf(buf, buf_size, "%" PRId64 "%c", |
| 191 | ((size + (base >> 1)) / base), |
| 192 | suffixes[i]); |
| 193 | break; |
| 194 | } |
| 195 | base = base * 1024; |
| 196 | } |
| 197 | } |
| 198 | return buf; |
| 199 | } |
| 200 | |
| 201 | static char* |
| 202 | snapshot_format_create_date( char *buf, size_t buf_size, time_t *time ) |
| 203 | { |
| 204 | struct tm *tm; |
| 205 | tm = localtime(time); |
| 206 | strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm); |
| 207 | return buf; |
| 208 | } |
| 209 | |
| 210 | static char* |
| 211 | snapshot_format_vm_clock( char *buf, size_t buf_size, uint64_t vm_clock_nsec ) |
| 212 | { |
| 213 | uint64_t secs = vm_clock_nsec / 1000000000; |
| 214 | snprintf(buf, buf_size, "%02d:%02d:%02d.%03d", |
| 215 | (int)(secs / 3600), |
| 216 | (int)((secs / 60) % 60), |
| 217 | (int)(secs % 60), |
| 218 | (int)((vm_clock_nsec / 1000000) % 1000)); |
| 219 | return buf; |
| 220 | } |
| 221 | |
| 222 | /* Prints a row of the snapshot table to stdout. */ |
| 223 | static void |
| 224 | snapshot_info_print( SnapshotInfo *info ) |
| 225 | { |
| 226 | char size_buf[8]; |
| 227 | char date_buf[21]; |
| 228 | char clock_buf[21]; |
| 229 | |
| 230 | snapshot_format_size(size_buf, sizeof(size_buf), info->vm_state_size); |
| 231 | snapshot_format_create_date(date_buf, sizeof(date_buf), |
| 232 | (time_t*) &info->date_sec); |
| 233 | snapshot_format_vm_clock(clock_buf, sizeof(clock_buf), info->vm_clock_nsec); |
| 234 | |
| 235 | printf(" %-10s%-20s%7s%20s%15s\n", |
| 236 | info->id_str, info->name, size_buf, date_buf, clock_buf); |
| 237 | } |
| 238 | |
| 239 | /* Prints table of all snapshots recorded in the file 'fd'. |
| 240 | */ |
| 241 | static void |
| 242 | snapshot_print_table( int fd, uint32_t nb_snapshots, uint64_t snapshots_offset ) |
| 243 | { |
| 244 | printf(" %-10s%-20s%7s%20s%15s\n", |
| 245 | "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK"); |
| 246 | |
| 247 | /* skip ahead to snapshot data */ |
| 248 | seek_or_die(fd, snapshots_offset, SEEK_SET); |
| 249 | |
| 250 | /* iterate over snapshot records */ |
| 251 | int i; |
| 252 | for (i = 0; i < nb_snapshots; i++) { |
| 253 | SnapshotInfo *info = snapshot_info_alloc(); |
| 254 | snapshot_info_read(fd, info); |
| 255 | snapshot_info_print(info); |
| 256 | |
| 257 | snapshot_info_free(info); |
| 258 | } |
| 259 | } |
| 260 | |
| 261 | /* Validates that 'fd' starts with a correct Qcow 2 header. Prints an error and |
| 262 | * exit()s if validation fails. |
| 263 | */ |
| 264 | static void |
| 265 | snapshot_validate_qcow_file( int fd ) |
| 266 | { |
| 267 | /* read magic number and qcow version (2x4 bytes) */ |
| 268 | uint32_t magic, version; |
| 269 | read_or_die(fd, &magic, sizeof(magic)); |
| 270 | read_or_die(fd, &version, sizeof(version)); |
| 271 | be32_to_cpus(&magic); |
| 272 | be32_to_cpus(&version); |
| 273 | |
| 274 | if (magic != QCOW_MAGIC) { |
| 275 | derror("Not a valid Qcow snapshot file (expected magic value '%08x', got '%08x').", |
| 276 | QCOW_MAGIC, magic); |
| 277 | exit(1); |
| 278 | } |
| 279 | if (version != QCOW_VERSION) { |
| 280 | derror("Unsupported Qcow version (need %d, got %d).", |
| 281 | QCOW_VERSION, version); |
| 282 | exit(1); |
| 283 | } |
| 284 | } |
| 285 | |
| 286 | /* Reads snapshot information from a Qcow2 file header. |
| 287 | * |
| 288 | * C.f. QCowHeader in block/qcow2.h for an exact listing of the header |
| 289 | * contents. |
| 290 | */ |
| 291 | static void |
| 292 | snapshot_read_qcow_header( int fd, uint32_t *nb_snapshots, uint64_t *snapshots_offset ) |
| 293 | { |
| 294 | snapshot_validate_qcow_file(fd); |
| 295 | |
| 296 | /* skip non-snapshot related metadata (4x8 + 5x4 = 52 bytes)*/ |
| 297 | seek_or_die(fd, 52, SEEK_CUR); |
| 298 | |
| 299 | read_or_die(fd, nb_snapshots, sizeof(*nb_snapshots)); |
| 300 | read_or_die(fd, snapshots_offset, sizeof(*snapshots_offset)); |
| 301 | |
| 302 | /* convert to host endianness */ |
| 303 | be32_to_cpus(nb_snapshots); |
| 304 | be64_to_cpus(snapshots_offset); |
| 305 | } |
| 306 | |
| 307 | /* Prints a table with information on the snapshots in the qcow2-formatted file |
| 308 | * 'snapstorage', then exit()s. |
| 309 | */ |
| 310 | void |
| 311 | snapshot_print_and_exit( const char *snapstorage ) |
| 312 | { |
| 313 | /* open snapshot file */ |
| 314 | int fd = open(snapstorage, O_RDONLY); |
| 315 | if (!fd) { |
| 316 | derror("Could not open snapshot file '%s': %s", snapstorage, strerror(errno)); |
| 317 | exit(1); |
| 318 | } |
| 319 | |
| 320 | /* read snapshot info from file header */ |
| 321 | uint32_t nb_snapshots; |
| 322 | uint64_t snapshots_offset; |
| 323 | snapshot_read_qcow_header(fd, &nb_snapshots, &snapshots_offset); |
| 324 | |
| 325 | if (nb_snapshots > 0) { |
| 326 | printf("Snapshots in file '%s':\n", snapstorage); |
| 327 | snapshot_print_table(fd, nb_snapshots, snapshots_offset); |
| 328 | } |
| 329 | else { |
| 330 | printf("File '%s' contains no snapshots yet.\n", snapstorage); |
| 331 | } |
| 332 | |
| 333 | close(fd); |
| 334 | exit(0); |
| 335 | } |
| 336 | #endif // CONFIG_ANDROID_SNAPSHOTS |