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 "qemu/bswap.h" 37 #include "android/utils/debug.h" 38 #include "android/utils/eintr_wrapper.h" 39 #include "android/utils/system.h" 40 #include "android/snapshot.h" 41 42 /* "Magic" sequence of four bytes required by spec to be the first four bytes 43 * of any Qcow file. 44 */ 45 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb) 46 #define QCOW_VERSION 2 47 48 /* Reads 'nbyte' bytes from 'fd' into 'buf', retrying on interrupts. 49 * Exit()s if the read fails for any other reason. 50 */ 51 static int 52 read_or_die(int fd, void *buf, size_t nbyte) 53 { 54 int ret = HANDLE_EINTR(read(fd, buf, nbyte)); 55 if (ret < 0) { 56 derror("read failed: %s", strerror(errno)); 57 exit(1); 58 } 59 return ret; 60 } 61 62 /* Wrapper around lseek(), exit()s on error. 63 */ 64 static off_t 65 seek_or_die(int fd, off_t offset, int whence) 66 { 67 off_t ret = lseek(fd, offset, whence); 68 if (ret < 0) { 69 derror("seek failed: %s", strerror(errno)); 70 exit(1); 71 } 72 return ret; 73 } 74 75 76 typedef struct SnapshotInfo { 77 char *id_str; 78 char *name; 79 80 uint32_t date_sec; 81 uint32_t date_nsec; 82 83 uint64_t vm_clock_nsec; 84 uint32_t vm_state_size; 85 } SnapshotInfo; 86 87 static SnapshotInfo* 88 snapshot_info_alloc() 89 { 90 return android_alloc(sizeof(SnapshotInfo)); 91 } 92 93 static void 94 snapshot_info_free( SnapshotInfo* info ) 95 { 96 AFREE(info->id_str); 97 AFREE(info->name); 98 AFREE(info); 99 } 100 101 102 /* Reads a snapshot record from a qcow2-formatted file. 103 * 104 * The function assumes the file position of 'fd' points to the beginning of a 105 * QcowSnapshotHeader record. When the call returns, the file position of fd is 106 * at the place where the next QcowSnapshotHeader should start, if there is one. 107 * 108 * C.f. QCowSnapshotHeader in block/qcow2-snapshot.c for the complete layout of 109 * the header. 110 */ 111 static void 112 snapshot_info_read( int fd, SnapshotInfo* info ) 113 { 114 uint64_t start_offset = seek_or_die(fd, 0, SEEK_CUR); 115 116 uint32_t extra_data_size; 117 uint16_t id_str_size, name_size; 118 119 /* read fixed-length fields */ 120 seek_or_die(fd, 12, SEEK_CUR); /* skip l1 info */ 121 read_or_die(fd, &id_str_size, sizeof(id_str_size)); 122 read_or_die(fd, &name_size, sizeof(name_size)); 123 read_or_die(fd, &info->date_sec, sizeof(info->date_sec)); 124 read_or_die(fd, &info->date_nsec, sizeof(info->date_nsec)); 125 read_or_die(fd, &info->vm_clock_nsec, sizeof(info->vm_clock_nsec)); 126 read_or_die(fd, &info->vm_state_size, sizeof(info->vm_state_size)); 127 read_or_die(fd, &extra_data_size, sizeof(extra_data_size)); 128 129 /* convert to host endianness */ 130 be16_to_cpus(&id_str_size); 131 be16_to_cpus(&name_size); 132 be32_to_cpus(&info->date_sec); 133 be32_to_cpus(&info->date_nsec); 134 be64_to_cpus(&info->vm_clock_nsec); 135 be32_to_cpus(&info->vm_state_size); 136 be32_to_cpus(&extra_data_size); 137 be32_to_cpus(&extra_data_size); 138 139 /* read variable-length buffers*/ 140 info->id_str = android_alloc(id_str_size + 1); // +1: manual null-termination 141 info->name = android_alloc(name_size + 1); 142 seek_or_die(fd, extra_data_size, SEEK_CUR); /* skip extra data */ 143 read_or_die(fd, info->id_str, id_str_size); 144 read_or_die(fd, info->name, name_size); 145 146 info->id_str[id_str_size] = '\0'; 147 info->name[name_size] = '\0'; 148 149 /* headers are 8 byte aligned, ceil to nearest multiple of 8 */ 150 uint64_t end_offset = seek_or_die(fd, 0, SEEK_CUR); 151 uint32_t total_size = end_offset - start_offset; 152 uint32_t aligned_size = ((total_size - 1) / 8 + 1) * 8; 153 154 /* skip to start of next record */ 155 seek_or_die(fd, start_offset + aligned_size, SEEK_SET); 156 } 157 158 159 #define NB_SUFFIXES 4 160 161 /* Returns the size of a snapshot in a human-readable format. 162 * 163 * This function copyright (c) 2003 Fabrice Bellard 164 */ 165 static char* 166 snapshot_format_size( char *buf, int buf_size, int64_t size ) 167 { 168 static const char suffixes[NB_SUFFIXES] = "KMGT"; 169 int64_t base; 170 int i; 171 172 if (size <= 999) { 173 snprintf(buf, buf_size, "%" PRId64, size); 174 } else { 175 base = 1024; 176 for(i = 0; i < NB_SUFFIXES; i++) { 177 if (size < (10 * base)) { 178 snprintf(buf, buf_size, "%0.1f%c", 179 (double)size / base, 180 suffixes[i]); 181 break; 182 } else if (size < (1000 * base) || i == (NB_SUFFIXES - 1)) { 183 snprintf(buf, buf_size, "%" PRId64 "%c", 184 ((size + (base >> 1)) / base), 185 suffixes[i]); 186 break; 187 } 188 base = base * 1024; 189 } 190 } 191 return buf; 192 } 193 194 static char* 195 snapshot_format_create_date( char *buf, size_t buf_size, time_t *time ) 196 { 197 struct tm *tm; 198 tm = localtime(time); 199 if (!tm) { 200 snprintf(buf, buf_size, "<invalid-snapshot-date>"); 201 } else { 202 strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm); 203 } 204 return buf; 205 } 206 207 static char* 208 snapshot_format_vm_clock( char *buf, size_t buf_size, uint64_t vm_clock_nsec ) 209 { 210 uint64_t secs = vm_clock_nsec / 1000000000; 211 snprintf(buf, buf_size, "%02d:%02d:%02d.%03d", 212 (int)(secs / 3600), 213 (int)((secs / 60) % 60), 214 (int)(secs % 60), 215 (int)((vm_clock_nsec / 1000000) % 1000)); 216 return buf; 217 } 218 219 /* Prints a row of the snapshot table to stdout. */ 220 static void 221 snapshot_info_print( SnapshotInfo *info ) 222 { 223 char size_buf[8]; 224 char date_buf[21]; 225 char clock_buf[21]; 226 227 // Note: time_t might be larger than uint32_t. 228 time_t date_sec = info->date_sec; 229 230 snapshot_format_size(size_buf, sizeof(size_buf), info->vm_state_size); 231 snapshot_format_create_date(date_buf, sizeof(date_buf), &date_sec); 232 snapshot_format_vm_clock(clock_buf, sizeof(clock_buf), info->vm_clock_nsec); 233 234 printf(" %-10s%-20s%7s%20s%15s\n", 235 info->id_str, info->name, size_buf, date_buf, clock_buf); 236 } 237 238 /* Prints table of all snapshots recorded in the file 'fd'. 239 */ 240 static void 241 snapshot_print_table( int fd, uint32_t nb_snapshots, uint64_t snapshots_offset ) 242 { 243 printf(" %-10s%-20s%7s%20s%15s\n", 244 "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK"); 245 246 /* skip ahead to snapshot data */ 247 seek_or_die(fd, snapshots_offset, SEEK_SET); 248 249 /* iterate over snapshot records */ 250 int i; 251 for (i = 0; i < nb_snapshots; i++) { 252 SnapshotInfo *info = snapshot_info_alloc(); 253 snapshot_info_read(fd, info); 254 snapshot_info_print(info); 255 256 snapshot_info_free(info); 257 } 258 } 259 260 /* Validates that 'fd' starts with a correct Qcow 2 header. Prints an error and 261 * exit()s if validation fails. 262 */ 263 static void 264 snapshot_validate_qcow_file( int fd ) 265 { 266 /* read magic number and qcow version (2x4 bytes) */ 267 uint32_t magic, version; 268 read_or_die(fd, &magic, sizeof(magic)); 269 read_or_die(fd, &version, sizeof(version)); 270 be32_to_cpus(&magic); 271 be32_to_cpus(&version); 272 273 if (magic != QCOW_MAGIC) { 274 derror("Not a valid Qcow snapshot file (expected magic value '%08x', got '%08x').", 275 QCOW_MAGIC, magic); 276 exit(1); 277 } 278 if (version != QCOW_VERSION) { 279 derror("Unsupported Qcow version (need %d, got %d).", 280 QCOW_VERSION, version); 281 exit(1); 282 } 283 } 284 285 /* Reads snapshot information from a Qcow2 file header. 286 * 287 * C.f. QCowHeader in block/qcow2.h for an exact listing of the header 288 * contents. 289 */ 290 static void 291 snapshot_read_qcow_header( int fd, uint32_t *nb_snapshots, uint64_t *snapshots_offset ) 292 { 293 snapshot_validate_qcow_file(fd); 294 295 /* skip non-snapshot related metadata (4x8 + 5x4 = 52 bytes)*/ 296 seek_or_die(fd, 52, SEEK_CUR); 297 298 read_or_die(fd, nb_snapshots, sizeof(*nb_snapshots)); 299 read_or_die(fd, snapshots_offset, sizeof(*snapshots_offset)); 300 301 /* convert to host endianness */ 302 be32_to_cpus(nb_snapshots); 303 be64_to_cpus(snapshots_offset); 304 } 305 306 /* Prints a table with information on the snapshots in the qcow2-formatted file 307 * 'snapstorage', then exit()s. 308 */ 309 void 310 snapshot_print_and_exit( const char *snapstorage ) 311 { 312 /* open snapshot file */ 313 int fd = open(snapstorage, O_RDONLY); 314 if (fd < 0) { 315 derror("Could not open snapshot file '%s': %s", snapstorage, strerror(errno)); 316 exit(1); 317 } 318 319 /* read snapshot info from file header */ 320 uint32_t nb_snapshots; 321 uint64_t snapshots_offset; 322 snapshot_read_qcow_header(fd, &nb_snapshots, &snapshots_offset); 323 324 if (nb_snapshots > 0) { 325 printf("Snapshots in file '%s':\n", snapstorage); 326 snapshot_print_table(fd, nb_snapshots, snapshots_offset); 327 } 328 else { 329 printf("File '%s' contains no snapshots yet.\n", snapstorage); 330 } 331 332 close(fd); 333 exit(0); 334 } 335
