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 */
51static int
52read_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 */
64static off_t
65seek_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
76typedef 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
87static SnapshotInfo*
88snapshot_info_alloc()
89{
90    return android_alloc(sizeof(SnapshotInfo));
91}
92
93static void
94snapshot_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 */
111static void
112snapshot_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 */
165static char*
166snapshot_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
194static char*
195snapshot_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
207static char*
208snapshot_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. */
220static void
221snapshot_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 */
240static void
241snapshot_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 */
263static void
264snapshot_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 */
290static void
291snapshot_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 */
309void
310snapshot_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