This adds a new helper program (qemu-props) to support the emulated system.

Its purpose is to contact the 'boot-properties' service during the
boot process and to set the list of system properties read from the
emulator program through it.

It must be launched from /system/etc/init.goldfish.rc as root.

It depends on the 'boot-properties' service being implemented by the
emulator (in a later patch). If not available, it will simply timeout.

This also fixes a potential crash in qemud which can happen in the following case:

- client sends a command to a service
- the service responds with one or more message
- the service immediately closes the connection before the client can read the data

what happened is that the FDHandler object was buffering out-going packets to the
client, but the Multiplexer acted on the disconnection immediately. This resulted
in:

- client_free() being called
-   fdhandler_shutdown() being called
-     the FDHandler being placed on the 'closing' list to be able to send
      buffered packets later. And 'receiver_close' being called
-       client_fd_close() being called, which would call client_free()
        recursively
-         the second client_free() call would free the object
-  the first client_free() call would try to free the object again
-  ==> dlmalloc() detects a double-free and immediately aborts.

the fixes simply avoids the calle to receiver_close() in fdhandler_shutdown()
since this function is called from an explicit shutdown request from the multiplexer,
it doesn't correspond to the case where the client has closed the connection itself.

emulator/qemud/qemud.c

@@ -857,8 +857,10 @@ fdhandler_shutdown( FDHandler*  f )
         fdhandler_remove(f);
         fdhandler_prepend(f, &f->list->closing);
 
-        /* notify the receiver that we're closing */
-        receiver_close(f->receiver);
+        /* prevent later fdhandler_close() to
+         * call the receiver's close.
+         */
+        f->receiver->close = NULL;
         return;
     }
 

emulator/tools/Android.mk

@@ -0,0 +1,36 @@
+# Copyright (C) 2009 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.
+
+# this file is used to build emulator-specific program tools
+# that should only run in the emulator.
+#
+
+LOCAL_PATH := $(call my-dir)
+
+ifneq ($(TARGET_PRODUCT),sim)
+
+# The 'qemu-props' program is run from /system/etc/init.goldfish.rc
+# to setup various system properties sent by the emulator program.
+#
+include $(CLEAR_VARS)
+LOCAL_MODULE    := qemu-props
+LOCAL_SRC_FILES := qemu-props.c
+LOCAL_SHARED_LIBRARIES := libcutils
+# we don't want this in 'user' builds which don't have
+# emulator-specific binaries.
+LOCAL_MODULE_TAGS := debug
+include $(BUILD_EXECUTABLE)
+
+endif # TARGET_PRODUCT != sim
+

emulator/tools/qemu-props.c

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2009 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.
+ */
+
+/* this program is used to read a set of system properties and their values
+ * from the emulator program and set them in the currently-running emulated
+ * system. It does so by connecting to the 'boot-properties' qemud service.
+ *
+ * This program should be run as root and called from
+ * /system/etc/init.goldfish.rc exclusively.
+ */
+
+#define LOG_TAG  "qemu-props"
+
+#define DEBUG  1
+
+#if DEBUG
+#  include <cutils/log.h>
+#  define  DD(...)    LOGI(__VA_ARGS__)
+#else
+#  define  DD(...)    ((void)0)
+#endif
+
+#include <cutils/properties.h>
+#include <unistd.h>
+#include <hardware/qemud.h>
+
+/* Name of the qemud service we want to connect to.
+ */
+#define  QEMUD_SERVICE  "boot-properties"
+
+#define  MAX_TRIES      5
+
+int  main(void)
+{
+    int  qemud_fd, count = 0;
+
+    /* try to connect to the qemud service */
+    {
+        int  tries = MAX_TRIES;
+
+        while (1) {
+            qemud_fd = qemud_channel_open( "boot-properties" );
+            if (qemud_fd >= 0)
+                break;
+
+            if (--tries <= 0) {
+                DD("Could not connect after too many tries. Aborting");
+                return 1;
+            }
+
+            DD("waiting 1s to wait for qemud.");
+            sleep(1);
+        }
+    }
+
+    DD("connected to '%s' qemud service.", QEMUD_SERVICE);
+
+    /* send the 'list' command to the service */
+    if (qemud_channel_send(qemud_fd, "list", -1) < 0) {
+        DD("could not send command to '%s' service", QEMUD_SERVICE);
+        return 1;
+    }
+
+    /* read each system property as a single line from the service,
+     * until exhaustion.
+     */
+    for (;;)
+    {
+#define  BUFF_SIZE   (PROPERTY_KEY_MAX + PROPERTY_VALUE_MAX + 2)
+
+        char* q;
+        char  temp[BUFF_SIZE];
+        int   len = qemud_channel_recv(qemud_fd, temp, sizeof temp - 1);
+
+        if (len < 0 || len > BUFF_SIZE-1)
+            break;
+
+        temp[len] = '\0';  /* zero-terminate string */
+
+        DD("received: %.*s", len, temp);
+
+        /* separate propery name from value */
+        q = strchr(temp, '=');
+        if (q == NULL) {
+            DD("invalid format, ignored.");
+            continue;
+        }
+        *q++ = '\0';
+
+        if (property_set(temp, q) < 0) {
+            DD("could not set property '%s' to '%s'", temp, q);
+        } else {
+            count += 1;
+        }
+    }
+
+    /* finally, close the channel and exit */
+    close(qemud_fd);
+    DD("exiting (%d properties set).", count);
+    return 0;
+}