Introduce plugin_crt0.c that every plugin links.

It handles exit() properly, calling the handler also when the plugin returns
normally (also it makes exit() more standard compliant while at it).
It also holds PLUGIN_HEADER, so that it doesn't need to be in each plugin anymore.

To work better together with callbacks passed to rb->default_event_handler_ex introduce exit_on_usb() which will call the exit handler before showing the usb screen and exit() after it.
In most cases it was passed a callback which was manually called at all other return points. This can now be done via atexit().

In future plugin_crt0.c could also handle clearing bss, initializing iram and more.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27862 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 116 insertions, 0 deletions

diff --git a/apps/plugins/plugin_crt0.c b/apps/plugins/plugin_crt0.c
new file mode 100755
index 0000000000..e9e2bcb8aa
--- /dev/null
+++ b/apps/plugins/plugin_crt0.c
@@ -0,0 +1,116 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id$
+*
+* Copyright (C) 2010 by Thomas Martitz
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License
+* as published by the Free Software Foundation; either version 2
+* of the License, or (at your option) any later version.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+
+
+#include "plugin.h"
+#if (CONFIG_PLATFORM & PLATFORM_NATIVE)
+#include "../codecs/lib/setjmp.h"
+#else
+#include <setjmp.h>
+#endif
+
+PLUGIN_HEADER
+
+/*
+ * EXIT_MAGIC magic, because 0 cannot be used due to setjmp()
+ * must be > 0
+ */                      
+#define EXIT_MAGIC 0x0CDEBABE
+
+extern enum plugin_status plugin_start(const void*);
+
+static jmp_buf __exit_env;
+/* only 1 atexit handler for now, chain in the exit handler if you need more */
+static void (*atexit_handler)(void);
+
+int atexit(void (*fn)(void))
+{
+    if (atexit_handler)
+        return -1;
+    atexit_handler = fn;
+    return 0;
+}
+
+void exit(int status)
+{   /* jump back in time to before starting the plugin */
+    longjmp(__exit_env, status != 0 ? status : EXIT_MAGIC);
+}
+
+void _exit(int status)
+{   /* don't call exit handler */
+    atexit_handler = NULL;
+    exit(status);
+}
+
+enum plugin_status plugin__start(const void *param)
+{
+    int exit_ret;
+    enum plugin_status ret;
+
+    /* we come back here if exit() was called or the plugin returned normally */
+    exit_ret = setjmp(__exit_env);
+    if (exit_ret == 0)
+    {   /* start the plugin */
+        ret = plugin_start(param);
+    }
+    else
+    {   /* plugin exit via exit() */
+        if (exit_ret == EXIT_MAGIC)
+        {   /* exit(EXIT_SUCCESS) */
+            ret = PLUGIN_OK;
+        }
+        else if (exit_ret < INTERNAL_PLUGIN_RETVAL_START)
+        {   /* exit(EXIT_FAILURE) */
+            ret = PLUGIN_ERROR;
+        }
+        else
+        {   /* exit(PLUGIN_XXX) */
+            ret = (enum plugin_status)exit_ret;
+        }
+    }
+
+    /* before finishing, call the exit handler if there was one */
+    if (atexit_handler != NULL)
+        atexit_handler();
+
+    return ret;
+}
+
+static void cleanup_wrapper(void *param)
+{
+    (void)param;
+    if (atexit_handler)
+        atexit_handler();
+}
+
+void exit_on_usb(int button)
+{   /* the default handler will call the exit handler before
+     * showing the usb screen; after that we don't want the exit handler
+     * to be called a second time, hence _exit()
+     *
+     * if not usb, then the handler will only be called if powering off
+     * if poweroff, the plugin doesn't want to run any further so exit as well*/
+    long result = rb->default_event_handler_ex(button, cleanup_wrapper, NULL);
+    if (result == SYS_USB_CONNECTED)
+        _exit(PLUGIN_USB_CONNECTED);
+    else if (result == SYS_POWEROFF)
+        _exit(PLUGIN_POWEROFF);
+}