Load state snapshot rather than booting to start emulator.

This patch adds support for an optional file "snapshots.img" in the
data directory of an AVD. This file should be an image formatted with
the qcow2 file system and will be mounted on -hdb when the emulator
starts up. If present, the emulator will attempt to load the snapshot
named "default-boot" from this image, rather than going through the
full boot procedure.

To control the behaviour of this functionality, this patch introduces
the following new command line options for the emulator:

  -snapstorage <file>: override the default location of the
     snapshot storage file.
  -no-snapstorage: do not load the snapshots file, even if an explicit
     path is given.
  -snapshot <name>: instead of loading "default-boot", load the state
     snapshot with the given name.
  -no-snapshot: do not load a snapshot, but force a full boot
     sequence, even if a snapshots file is mounted. Useful for
     creating snapshots.

Note that this functionality is experimental and will be enabled
only if the constant CONFIG_ANDROID_SNAPSHOTS in
android/config/config.h is set to "1" before building. It is turned
off by default.

Change-Id: Iee2e9096a27f3414bacfc271f90ef93a98730c82

1 files changed, 55 insertions, 6 deletions

diff --git a/android/main.c b/android/main.c
index b88fb5e..a328ad1 100644
--- a/android/main.c
+++ b/android/main.c
@@ -998,6 +998,16 @@ int main(int argc, char **argv)
                 D("autoconfig: -sdcard %s", opts->sdcard);
             }
         }
+
+#if CONFIG_ANDROID_SNAPSHOTS
+        if (!opts->snapstorage && opts->datadir) {
+            bufprint(tmp, tmpend, "%s/snapshots.img", opts->datadir);
+            if (path_exists(tmp)) {
+                opts->snapstorage = qemu_strdup(tmp);
+                D("autoconfig: -snapstorage %s", opts->snapstorage);
+            }
+        }
+#endif
     }
 
     /* setup the virtual device parameters from our options
@@ -1008,16 +1018,24 @@ int main(int argc, char **argv)
     if (opts->wipe_data) {
         android_avdParams->flags |= AVDINFO_WIPE_DATA | AVDINFO_WIPE_CACHE;
     }
+#if CONFIG_ANDROID_SNAPSHOTS
+    if (opts->no_snapstorage) {
+        android_avdParams->flags |= AVDINFO_NO_SNAPSHOTS;
+    }
+#endif
 
     /* if certain options are set, we can force the path of
         * certain kernel/disk image files
         */
-    _forceAvdImagePath(AVD_IMAGE_KERNEL,     opts->kernel, "kernel", 1);
-    _forceAvdImagePath(AVD_IMAGE_INITSYSTEM, opts->system, "system", 1);
-    _forceAvdImagePath(AVD_IMAGE_RAMDISK,    opts->ramdisk,"ramdisk", 1);
-    _forceAvdImagePath(AVD_IMAGE_USERDATA,   opts->data,   "user data", 0);
-    _forceAvdImagePath(AVD_IMAGE_CACHE,      opts->cache,  "cache", 0);
-    _forceAvdImagePath(AVD_IMAGE_SDCARD,     opts->sdcard, "SD Card", 0);
+    _forceAvdImagePath(AVD_IMAGE_KERNEL,     opts->kernel,      "kernel", 1);
+    _forceAvdImagePath(AVD_IMAGE_INITSYSTEM, opts->system,      "system", 1);
+    _forceAvdImagePath(AVD_IMAGE_RAMDISK,    opts->ramdisk,     "ramdisk", 1);
+    _forceAvdImagePath(AVD_IMAGE_USERDATA,   opts->data,        "user data", 0);
+    _forceAvdImagePath(AVD_IMAGE_CACHE,      opts->cache,       "cache", 0);
+    _forceAvdImagePath(AVD_IMAGE_SDCARD,     opts->sdcard,      "SD Card", 0);
+#if CONFIG_ANDROID_SNAPSHOTS
+    _forceAvdImagePath(AVD_IMAGE_SNAPSHOTS,  opts->snapstorage, "snapshots", 0);
+#endif
 
     /* we don't accept -skindir without -skin now
      * to simplify the autoconfig stuff with virtual devices
@@ -1376,6 +1394,37 @@ int main(int argc, char **argv)
         }
     }
 
+#if CONFIG_ANDROID_SNAPSHOTS
+    if (!opts->no_snapstorage) {
+        opts->snapstorage = (char*) avdInfo_getImageFile(avd, AVD_IMAGE_SNAPSHOTS);
+        if(opts->snapstorage) {
+            if (path_exists(opts->snapstorage)) {
+                args[n++] = "-hdb";
+                args[n++] = opts->snapstorage;
+            } else {
+                D("no image at '%s', state snapshots disabled", opts->snapstorage);
+            }
+        }
+
+        if (!opts->no_snapshot) {
+            args[n++] = "-loadvm";
+            if (opts->snapshot) {
+                args[n++] = opts->snapshot;
+            } else {
+                // name of state snapshot to load if not specified by user
+                args[n++] = "default-boot";
+            }
+        } else if (opts->snapshot) {
+            dwarning("option '-no-snapshot' overrides '-snapshot', continuing with boot sequence");
+        }
+    } else if (opts->snapshot || opts->snapstorage) {
+        dwarning("option '-no-snapstorage' overrides '-snapshot' and '-snapstorage', "
+                 "continuing with full boot, state snapshots are disabled");
+    } else if (opts->no_snapshot) {
+        D("ignoring redundant option '-no-snapshot' implied by '-no-snapstorage'");
+    }
+#endif
+
     if (!opts->logcat || opts->logcat[0] == 0) {
         opts->logcat = getenv("ANDROID_LOG_TAGS");
         if (opts->logcat && opts->logcat[0] == 0)