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 "bswap.h" 37 #include "android/utils/debug.h" 38 #include "android/utils/system.h" 39 #include "android/snapshot.h" 40 41 /* "Magic" sequence of four bytes required by spec to be the first four bytes 42 * of any Qcow file. 43 */ 44 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb) 45 #define QCOW_VERSION 2 46 47 /* Reads 'nbyte' bytes from 'fd' into 'buf', retrying on interrupts. 48 * Exit()s if the read fails for any other reason. 49 */ 50 static int 51 read_or_die(int fd, void *buf, size_t nbyte) 52 { 53 int ret = 0; 54 do { 55 ret = read(fd, buf, nbyte); 56 } 57 while(ret < 0 && errno == EINTR); 58 59 if (ret < 0) { 60 derror("read failed: %s", strerror(errno)); 61 exit(1); 62 } 63 64 return ret; 65 } 66 67 /* Wrapper around lseek(), exit()s on error. 68 */ 69 static off_t 70 seek_or_die(int fd, off_t offset, int whence) 71 { 72 off_t ret = lseek(fd, offset, whence); 73 if (ret < 0) { 74 derror("seek failed: %s", strerror(errno)); 75 exit(1); 76 } 77 return ret; 78 } 79 80 81 typedef struct SnapshotInfo { 82 char *id_str; 83 char *name; 84 85 uint32_t date_sec; 86 uint32_t date_nsec; 87 88 uint64_t vm_clock_nsec; 89 uint32_t vm_state_size; 90 } SnapshotInfo; 91 92 static SnapshotInfo* 93 snapshot_info_alloc() 94 { 95 return android_alloc(sizeof(SnapshotInfo)); 96 } 97 98 static void 99 snapshot_info_free( SnapshotInfo* info ) 100 { 101 AFREE(info->id_str); 102 AFREE(info->name); 103 AFREE(info); 104 } 105 106 107 /* Reads a snapshot record from a qcow2-formatted file. 108 * 109 * The function assumes the file position of 'fd' points to the beginning of a 110 * QcowSnapshotHeader record. When the call returns, the file position of fd is 111 * at the place where the next QcowSnapshotHeader should start, if there is one. 112 * 113 * C.f. QCowSnapshotHeader in block/qcow2-snapshot.c for the complete layout of 114 * the header. 115 */ 116 static void 117 snapshot_info_read( int fd, SnapshotInfo* info ) 118 { 119 uint64_t start_offset = seek_or_die(fd, 0, SEEK_CUR); 120 121 uint32_t extra_data_size; 122 uint16_t id_str_size, name_size; 123 124 /* read fixed-length fields */ 125 seek_or_die(fd, 12, SEEK_CUR); /* skip l1 info */ 126 read_or_die(fd, &id_str_size, sizeof(id_str_size)); 127 read_or_die(fd, &name_size, sizeof(name_size)); 128 read_or_die(fd, &info->date_sec, sizeof(info->date_sec)); 129 read_or_die(fd, &info->date_nsec, sizeof(info->date_nsec)); 130 read_or_die(fd, &info->vm_clock_nsec, sizeof(info->vm_clock_nsec)); 131 read_or_die(fd, &info->vm_state_size, sizeof(info->vm_state_size)); 132 read_or_die(fd, &extra_data_size, sizeof(extra_data_size)); 133 134 /* convert to host endianness */ 135 be16_to_cpus(&id_str_size); 136 be16_to_cpus(&name_size); 137 be32_to_cpus(&info->date_sec); 138 be32_to_cpus(&info->date_nsec); 139 be64_to_cpus(&info->vm_clock_nsec); 140 be32_to_cpus(&info->vm_state_size); 141 be32_to_cpus(&extra_data_size); 142 be32_to_cpus(&extra_data_size); 143 144 /* read variable-length buffers*/ 145 info->id_str = android_alloc(id_str_size + 1); // +1: manual null-termination 146 info->name = android_alloc(name_size + 1); 147 seek_or_die(fd, extra_data_size, SEEK_CUR); /* skip extra data */ 148 read_or_die(fd, info->id_str, id_str_size); 149 read_or_die(fd, info->name, name_size); 150 151 info->id_str[id_str_size] = '\0'; 152 info->name[name_size] = '\0'; 153 154 /* headers are 8 byte aligned, ceil to nearest multiple of 8 */ 155 uint64_t end_offset = seek_or_die(fd, 0, SEEK_CUR); 156 uint32_t total_size = end_offset - start_offset; 157 uint32_t aligned_size = ((total_size - 1) / 8 + 1) * 8; 158 159 /* skip to start of next record */ 160 seek_or_die(fd, start_offset + aligned_size, SEEK_SET); 161 } 162 163 164 #define NB_SUFFIXES 4 165 166 /* Returns the size of a snapshot in a human-readable format. 167 * 168 * This function copyright (c) 2003 Fabrice Bellard 169 */ 170 static char* 171 snapshot_format_size( char *buf, int buf_size, int64_t size ) 172 { 173 static const char suffixes[NB_SUFFIXES] = "KMGT"; 174 int64_t base; 175 int i; 176 177 if (size <= 999) { 178 snprintf(buf, buf_size, "%" PRId64, size); 179 } else { 180 base = 1024; 181 for(i = 0; i < NB_SUFFIXES; i++) { 182 if (size < (10 * base)) { 183 snprintf(buf, buf_size, "%0.1f%c", 184 (double)size / base, 185 suffixes[i]); 186 break; 187 } else if (size < (1000 * base) || i == (NB_SUFFIXES - 1)) { 188 snprintf(buf, buf_size, "%" PRId64 "%c", 189 ((size + (base >> 1)) / base), 190 suffixes[i]); 191 break; 192 } 193 base = base * 1024; 194 } 195 } 196 return buf; 197 } 198 199 static char* 200 snapshot_format_create_date( char *buf, size_t buf_size, time_t *time ) 201 { 202 struct tm *tm; 203 tm = localtime(time); 204 strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm); 205 return buf; 206 } 207 208 static char* 209 snapshot_format_vm_clock( char *buf, size_t buf_size, uint64_t vm_clock_nsec ) 210 { 211 uint64_t secs = vm_clock_nsec / 1000000000; 212 snprintf(buf, buf_size, "%02d:%02d:%02d.%03d", 213 (int)(secs / 3600), 214 (int)((secs / 60) % 60), 215 (int)(secs % 60), 216 (int)((vm_clock_nsec / 1000000) % 1000)); 217 return buf; 218 } 219 220 /* Prints a row of the snapshot table to stdout. */ 221 static void 222 snapshot_info_print( SnapshotInfo *info ) 223 { 224 char size_buf[8]; 225 char date_buf[21]; 226 char clock_buf[21]; 227 228 snapshot_format_size(size_buf, sizeof(size_buf), info->vm_state_size); 229 snapshot_format_create_date(date_buf, sizeof(date_buf), 230 (time_t*) &info->date_sec); 231 snapshot_format_vm_clock(clock_buf, sizeof(clock_buf), info->vm_clock_nsec); 232 233 printf(" %-10s%-20s%7s%20s%15s\n", 234 info->id_str, info->name, size_buf, date_buf, clock_buf); 235 } 236 237 /* Prints table of all snapshots recorded in the file 'fd'. 238 */ 239 static void 240 snapshot_print_table( int fd, uint32_t nb_snapshots, uint64_t snapshots_offset ) 241 { 242 printf(" %-10s%-20s%7s%20s%15s\n", 243 "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK"); 244 245 /* skip ahead to snapshot data */ 246 seek_or_die(fd, snapshots_offset, SEEK_SET); 247 248 /* iterate over snapshot records */ 249 int i; 250 for (i = 0; i < nb_snapshots; i++) { 251 SnapshotInfo *info = snapshot_info_alloc(); 252 snapshot_info_read(fd, info); 253 snapshot_info_print(info); 254 255 snapshot_info_free(info); 256 } 257 } 258 259 /* Validates that 'fd' starts with a correct Qcow 2 header. Prints an error and 260 * exit()s if validation fails. 261 */ 262 static void 263 snapshot_validate_qcow_file( int fd ) 264 { 265 /* read magic number and qcow version (2x4 bytes) */ 266 uint32_t magic, version; 267 read_or_die(fd, &magic, sizeof(magic)); 268 read_or_die(fd, &version, sizeof(version)); 269 be32_to_cpus(&magic); 270 be32_to_cpus(&version); 271 272 if (magic != QCOW_MAGIC) { 273 derror("Not a valid Qcow snapshot file (expected magic value '%08x', got '%08x').", 274 QCOW_MAGIC, magic); 275 exit(1); 276 } 277 if (version != QCOW_VERSION) { 278 derror("Unsupported Qcow version (need %d, got %d).", 279 QCOW_VERSION, version); 280 exit(1); 281 } 282 } 283 284 /* Reads snapshot information from a Qcow2 file header. 285 * 286 * C.f. QCowHeader in block/qcow2.h for an exact listing of the header 287 * contents. 288 */ 289 static void 290 snapshot_read_qcow_header( int fd, uint32_t *nb_snapshots, uint64_t *snapshots_offset ) 291 { 292 snapshot_validate_qcow_file(fd); 293 294 /* skip non-snapshot related metadata (4x8 + 5x4 = 52 bytes)*/ 295 seek_or_die(fd, 52, SEEK_CUR); 296 297 read_or_die(fd, nb_snapshots, sizeof(*nb_snapshots)); 298 read_or_die(fd, snapshots_offset, sizeof(*snapshots_offset)); 299 300 /* convert to host endianness */ 301 be32_to_cpus(nb_snapshots); 302 be64_to_cpus(snapshots_offset); 303 } 304 305 /* Prints a table with information on the snapshots in the qcow2-formatted file 306 * 'snapstorage', then exit()s. 307 */ 308 void 309 snapshot_print_and_exit( const char *snapstorage ) 310 { 311 /* open snapshot file */ 312 int fd = open(snapstorage, O_RDONLY); 313 if (fd < 0) { 314 derror("Could not open snapshot file '%s': %s", snapstorage, strerror(errno)); 315 exit(1); 316 } 317 318 /* read snapshot info from file header */ 319 uint32_t nb_snapshots; 320 uint64_t snapshots_offset; 321 snapshot_read_qcow_header(fd, &nb_snapshots, &snapshots_offset); 322 323 if (nb_snapshots > 0) { 324 printf("Snapshots in file '%s':\n", snapstorage); 325 snapshot_print_table(fd, nb_snapshots, snapshots_offset); 326 } 327 else { 328 printf("File '%s' contains no snapshots yet.\n", snapstorage); 329 } 330 331 close(fd); 332 exit(0); 333 } 334
