Add command line flag to show list of snapshots.
This patch introduces the flag '-snapshot-list', which causes the
emulator to output a table of snapshots in the currently mounted
snapshot storage file.
The snapshot file is accessed with a very simple driver for the Qcow2
file system, independent of Qemu's block driver framework. This way,
the flag is available in the emulator-ui builds as well. Using Qemu's
framework would have resulted in adding a lot of Qemu dependencies to
the UI build, which we are explicitly trying to avoid.
Change-Id: I059b9ac53e2f8e051757a5c637761eccf8ea17cb
diff --git a/Makefile.android b/Makefile.android
index 1cc904a..1d82197 100644
--- a/Makefile.android
+++ b/Makefile.android
@@ -693,6 +693,7 @@
android/hw-qemud.c \
android/core-init-utils.c \
android/config.c \
+ android/snapshot.c \
ifeq ($(HOST_ARCH),x86)
CORE_MISC_SOURCES += i386-dis.c
@@ -1181,6 +1182,7 @@
android/cmdline-option.c \
android/config.c \
android/display.c \
+ android/snapshot.c \
android/main.c \
qemu-timer-ui.c \
vl-android-ui.c \
diff --git a/android/cmdline-options.h b/android/cmdline-options.h
index a9b02ac..da8f375 100644
--- a/android/cmdline-options.h
+++ b/android/cmdline-options.h
@@ -81,6 +81,7 @@
OPT_FLAG ( no_snapstorage, "do not mount a snapshot storage file (this disables all snapshot functionality)" )
OPT_PARAM( snapshot, "<name>", "immediately load state snapshot rather than doing a full boot (default 'default-boot')" )
OPT_FLAG ( no_snapshot, "do not start from snapshot, but perform a full boot sequence" )
+OPT_FLAG ( snapshot_list, "show a list of available snapshots" )
#endif
OPT_FLAG ( wipe_data, "reset the use data image (copy it from initdata)" )
CFG_PARAM( avd, "<name>", "use a specific android virtual device" )
diff --git a/android/help.c b/android/help.c
index 17e7a90..f589b3e 100644
--- a/android/help.c
+++ b/android/help.c
@@ -700,6 +700,21 @@
);
}
+static void
+help_snapshot_list(stralloc_t* out)
+{
+ PRINTF(
+ " This prints a table of snapshots that are stored in the snapshot storage\n"
+ " file that the emulator was started with, then exits. Values from the 'ID'\n"
+ " and 'TAG' columns can be used as arguments for the '-snapshot' parameter.\n\n"
+
+ " If '-snapstorage <file>' was specified as well, this command prints a "
+ " table of the snapshots stored in <file>.\n\n"
+
+ " See '-help-snapshot' for more information on snapshots.\n\n"
+ );
+}
+
#endif
static void
diff --git a/android/main.c b/android/main.c
index a328ad1..6b3bea6 100644
--- a/android/main.c
+++ b/android/main.c
@@ -59,6 +59,8 @@
#include "android/qemulator.h"
#include "android/display.h"
+#include "android/snapshot.h"
+
#include "framebuffer.h"
AndroidRotation android_framebuffer_rotation;
@@ -1003,11 +1005,11 @@
if (!opts->snapstorage && opts->datadir) {
bufprint(tmp, tmpend, "%s/snapshots.img", opts->datadir);
if (path_exists(tmp)) {
- opts->snapstorage = qemu_strdup(tmp);
+ opts->snapstorage = android_strdup(tmp);
D("autoconfig: -snapstorage %s", opts->snapstorage);
}
}
-#endif
+#endif // CONFIG_ANDROID_SNAPSHOTS
}
/* setup the virtual device parameters from our options
@@ -1423,7 +1425,11 @@
} else if (opts->no_snapshot) {
D("ignoring redundant option '-no-snapshot' implied by '-no-snapstorage'");
}
-#endif
+
+ if (opts->snapshot_list) {
+ snapshot_print_and_exit(opts->snapstorage);
+ }
+#endif // CONFIG_ANDROID_SNAPSHOTS
if (!opts->logcat || opts->logcat[0] == 0) {
opts->logcat = getenv("ANDROID_LOG_TAGS");
diff --git a/android/snapshot.c b/android/snapshot.c
new file mode 100644
index 0000000..ca86700
--- /dev/null
+++ b/android/snapshot.c
@@ -0,0 +1,336 @@
+/*
+ * 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 "android/utils/debug.h"
+#include "android/utils/system.h"
+#include "bswap.h"
+#include "snapshot.h"
+
+#if CONFIG_ANDROID_SNAPSHOTS
+
+/* "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) {
+ 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);
+}
+#endif // CONFIG_ANDROID_SNAPSHOTS
diff --git a/android/snapshot.h b/android/snapshot.h
new file mode 100644
index 0000000..be03818
--- /dev/null
+++ b/android/snapshot.h
@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+
+#ifndef SNAPSHOTS_H_
+#define SNAPSHOTS_H_
+
+#include "config/config.h"
+
+#if CONFIG_ANDROID_SNAPSHOTS
+
+/* Prints a table with information on the snapshot stored in the file
+ * 'snapstorage', then exit()s.
+ */
+void snapshot_print_and_exit( const char *snapstorage );
+
+#endif
+
+#endif /* SNAPSHOTS_H_ */