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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* Limited driver for the Qcow2 filesystem, capable of extracting snapshot
* metadata from Qcow2 formatted image file.
*
* Similar functionality is implemented in block/qcow2.c, block/qcow2-snapshot.c
* and block.c. This separate implementation was made to further decouple the UI
* of the Android emulator from the underlying Qemu system. It allows the UI to
* show snapshot listings without having to fall back on Qemu's block driver
* system, which would pull in a lot of code irrelevant for the UI.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "bswap.h"
#include "android/utils/debug.h"
#include "android/utils/system.h"
#include "android/snapshot.h"
/* "Magic" sequence of four bytes required by spec to be the first four bytes
* of any Qcow file.
*/
#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
#define QCOW_VERSION 2
/* Reads 'nbyte' bytes from 'fd' into 'buf', retrying on interrupts.
* Exit()s if the read fails for any other reason.
*/
static int
read_or_die(int fd, void *buf, size_t nbyte)
{
int ret = 0;
do {
ret = read(fd, buf, nbyte);
}
while(ret < 0 && errno == EINTR);
if (ret < 0) {
derror("read failed: %s", strerror(errno));
exit(1);
}
return ret;
}
/* Wrapper around lseek(), exit()s on error.
*/
static off_t
seek_or_die(int fd, off_t offset, int whence)
{
off_t ret = lseek(fd, offset, whence);
if (ret < 0) {
derror("seek failed: %s", strerror(errno));
exit(1);
}
return ret;
}
typedef struct SnapshotInfo {
char *id_str;
char *name;
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
uint32_t vm_state_size;
} SnapshotInfo;
static SnapshotInfo*
snapshot_info_alloc()
{
return android_alloc(sizeof(SnapshotInfo));
}
static void
snapshot_info_free( SnapshotInfo* info )
{
AFREE(info->id_str);
AFREE(info->name);
AFREE(info);
}
/* Reads a snapshot record from a qcow2-formatted file.
*
* The function assumes the file position of 'fd' points to the beginning of a
* QcowSnapshotHeader record. When the call returns, the file position of fd is
* at the place where the next QcowSnapshotHeader should start, if there is one.
*
* C.f. QCowSnapshotHeader in block/qcow2-snapshot.c for the complete layout of
* the header.
*/
static void
snapshot_info_read( int fd, SnapshotInfo* info )
{
uint64_t start_offset = seek_or_die(fd, 0, SEEK_CUR);
uint32_t extra_data_size;
uint16_t id_str_size, name_size;
/* read fixed-length fields */
seek_or_die(fd, 12, SEEK_CUR); /* skip l1 info */
read_or_die(fd, &id_str_size, sizeof(id_str_size));
read_or_die(fd, &name_size, sizeof(name_size));
read_or_die(fd, &info->date_sec, sizeof(info->date_sec));
read_or_die(fd, &info->date_nsec, sizeof(info->date_nsec));
read_or_die(fd, &info->vm_clock_nsec, sizeof(info->vm_clock_nsec));
read_or_die(fd, &info->vm_state_size, sizeof(info->vm_state_size));
read_or_die(fd, &extra_data_size, sizeof(extra_data_size));
/* convert to host endianness */
be16_to_cpus(&id_str_size);
be16_to_cpus(&name_size);
be32_to_cpus(&info->date_sec);
be32_to_cpus(&info->date_nsec);
be64_to_cpus(&info->vm_clock_nsec);
be32_to_cpus(&info->vm_state_size);
be32_to_cpus(&extra_data_size);
be32_to_cpus(&extra_data_size);
/* read variable-length buffers*/
info->id_str = android_alloc(id_str_size + 1); // +1: manual null-termination
info->name = android_alloc(name_size + 1);
seek_or_die(fd, extra_data_size, SEEK_CUR); /* skip extra data */
read_or_die(fd, info->id_str, id_str_size);
read_or_die(fd, info->name, name_size);
info->id_str[id_str_size] = '\0';
info->name[name_size] = '\0';
/* headers are 8 byte aligned, ceil to nearest multiple of 8 */
uint64_t end_offset = seek_or_die(fd, 0, SEEK_CUR);
uint32_t total_size = end_offset - start_offset;
uint32_t aligned_size = ((total_size - 1) / 8 + 1) * 8;
/* skip to start of next record */
seek_or_die(fd, start_offset + aligned_size, SEEK_SET);
}
#define NB_SUFFIXES 4
/* Returns the size of a snapshot in a human-readable format.
*
* This function copyright (c) 2003 Fabrice Bellard
*/
static char*
snapshot_format_size( char *buf, int buf_size, int64_t size )
{
static const char suffixes[NB_SUFFIXES] = "KMGT";
int64_t base;
int i;
if (size <= 999) {
snprintf(buf, buf_size, "%" PRId64, size);
} else {
base = 1024;
for(i = 0; i < NB_SUFFIXES; i++) {
if (size < (10 * base)) {
snprintf(buf, buf_size, "%0.1f%c",
(double)size / base,
suffixes[i]);
break;
} else if (size < (1000 * base) || i == (NB_SUFFIXES - 1)) {
snprintf(buf, buf_size, "%" PRId64 "%c",
((size + (base >> 1)) / base),
suffixes[i]);
break;
}
base = base * 1024;
}
}
return buf;
}
static char*
snapshot_format_create_date( char *buf, size_t buf_size, time_t *time )
{
struct tm *tm;
tm = localtime(time);
strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
return buf;
}
static char*
snapshot_format_vm_clock( char *buf, size_t buf_size, uint64_t vm_clock_nsec )
{
uint64_t secs = vm_clock_nsec / 1000000000;
snprintf(buf, buf_size, "%02d:%02d:%02d.%03d",
(int)(secs / 3600),
(int)((secs / 60) % 60),
(int)(secs % 60),
(int)((vm_clock_nsec / 1000000) % 1000));
return buf;
}
/* Prints a row of the snapshot table to stdout. */
static void
snapshot_info_print( SnapshotInfo *info )
{
char size_buf[8];
char date_buf[21];
char clock_buf[21];
snapshot_format_size(size_buf, sizeof(size_buf), info->vm_state_size);
snapshot_format_create_date(date_buf, sizeof(date_buf),
(time_t*) &info->date_sec);
snapshot_format_vm_clock(clock_buf, sizeof(clock_buf), info->vm_clock_nsec);
printf(" %-10s%-20s%7s%20s%15s\n",
info->id_str, info->name, size_buf, date_buf, clock_buf);
}
/* Prints table of all snapshots recorded in the file 'fd'.
*/
static void
snapshot_print_table( int fd, uint32_t nb_snapshots, uint64_t snapshots_offset )
{
printf(" %-10s%-20s%7s%20s%15s\n",
"ID", "TAG", "VM SIZE", "DATE", "VM CLOCK");
/* skip ahead to snapshot data */
seek_or_die(fd, snapshots_offset, SEEK_SET);
/* iterate over snapshot records */
int i;
for (i = 0; i < nb_snapshots; i++) {
SnapshotInfo *info = snapshot_info_alloc();
snapshot_info_read(fd, info);
snapshot_info_print(info);
snapshot_info_free(info);
}
}
/* Validates that 'fd' starts with a correct Qcow 2 header. Prints an error and
* exit()s if validation fails.
*/
static void
snapshot_validate_qcow_file( int fd )
{
/* read magic number and qcow version (2x4 bytes) */
uint32_t magic, version;
read_or_die(fd, &magic, sizeof(magic));
read_or_die(fd, &version, sizeof(version));
be32_to_cpus(&magic);
be32_to_cpus(&version);
if (magic != QCOW_MAGIC) {
derror("Not a valid Qcow snapshot file (expected magic value '%08x', got '%08x').",
QCOW_MAGIC, magic);
exit(1);
}
if (version != QCOW_VERSION) {
derror("Unsupported Qcow version (need %d, got %d).",
QCOW_VERSION, version);
exit(1);
}
}
/* Reads snapshot information from a Qcow2 file header.
*
* C.f. QCowHeader in block/qcow2.h for an exact listing of the header
* contents.
*/
static void
snapshot_read_qcow_header( int fd, uint32_t *nb_snapshots, uint64_t *snapshots_offset )
{
snapshot_validate_qcow_file(fd);
/* skip non-snapshot related metadata (4x8 + 5x4 = 52 bytes)*/
seek_or_die(fd, 52, SEEK_CUR);
read_or_die(fd, nb_snapshots, sizeof(*nb_snapshots));
read_or_die(fd, snapshots_offset, sizeof(*snapshots_offset));
/* convert to host endianness */
be32_to_cpus(nb_snapshots);
be64_to_cpus(snapshots_offset);
}
/* Prints a table with information on the snapshots in the qcow2-formatted file
* 'snapstorage', then exit()s.
*/
void
snapshot_print_and_exit( const char *snapstorage )
{
/* open snapshot file */
int fd = open(snapstorage, O_RDONLY);
if (fd < 0) {
derror("Could not open snapshot file '%s': %s", snapstorage, strerror(errno));
exit(1);
}
/* read snapshot info from file header */
uint32_t nb_snapshots;
uint64_t snapshots_offset;
snapshot_read_qcow_header(fd, &nb_snapshots, &snapshots_offset);
if (nb_snapshots > 0) {
printf("Snapshots in file '%s':\n", snapstorage);
snapshot_print_table(fd, nb_snapshots, snapshots_offset);
}
else {
printf("File '%s' contains no snapshots yet.\n", snapstorage);
}
close(fd);
exit(0);
}
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