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 */
50static int
51read_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 */
69static off_t
70seek_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
81typedef 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
92static SnapshotInfo*
93snapshot_info_alloc()
94{
95    return android_alloc(sizeof(SnapshotInfo));
96}
97
98static void
99snapshot_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 */
116static void
117snapshot_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 */
170static char*
171snapshot_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
199static char*
200snapshot_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
208static char*
209snapshot_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. */
221static void
222snapshot_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 */
239static void
240snapshot_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 */
262static void
263snapshot_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 */
289static void
290snapshot_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 */
308void
309snapshot_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