1 files changed, 108 insertions, 0 deletions
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
new file mode 100644
index 0000000..42a7f6c
--- /dev/null
+++ b/libc/include/sys/_system_properties.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _INCLUDE_SYS__SYSTEM_PROPERTIES_H
+#define _INCLUDE_SYS__SYSTEM_PROPERTIES_H
+
+#ifndef _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
+#error you should #include <sys/system_properties.h> instead
+#else
+#include <sys/system_properties.h>
+
+typedef struct prop_area prop_area;
+typedef struct prop_msg prop_msg;
+
+#define PROP_AREA_MAGIC   0x504f5250
+#define PROP_AREA_VERSION 0x45434f76
+
+#define PROP_SERVICE_NAME "property_service"
+
+/* #define PROP_MAX_ENTRIES 247 */
+/* 247 -> 32620 bytes (<32768) */
+
+#define TOC_NAME_LEN(toc)       ((toc) >> 24)
+#define TOC_TO_INFO(area, toc)  ((prop_info*) (((char*) area) + ((toc) & 0xFFFFFF)))
+
+struct prop_area {
+    unsigned volatile count;
+    unsigned volatile serial;
+    unsigned magic;
+    unsigned version;
+    unsigned reserved[4];
+    unsigned toc[1];
+};
+
+#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
+#define SERIAL_DIRTY(serial) ((serial) & 1)
+
+struct prop_info {
+    char name[PROP_NAME_MAX];
+    unsigned volatile serial;
+    char value[PROP_VALUE_MAX];
+};
+
+struct prop_msg 
+{
+    unsigned cmd;
+    char name[PROP_NAME_MAX];
+    char value[PROP_VALUE_MAX];
+};
+
+#define PROP_MSG_SETPROP 1
+    
+/*
+** Rules:
+**
+** - there is only one writer, but many readers
+** - prop_area.count will never decrease in value
+** - once allocated, a prop_info's name will not change
+** - once allocated, a prop_info's offset will not change
+** - reading a value requires the following steps
+**   1. serial = pi->serial
+**   2. if SERIAL_DIRTY(serial), wait*, then goto 1
+**   3. memcpy(local, pi->value, SERIAL_VALUE_LEN(serial) + 1)
+**   4. if pi->serial != serial, goto 2
+**
+** - writing a value requires the following steps
+**   1. pi->serial = pi->serial | 1
+**   2. memcpy(pi->value, local_value, value_len)
+**   3. pi->serial = (value_len << 24) | ((pi->serial + 1) & 0xffffff)
+**
+** Improvements:
+** - maintain the toc sorted by pi->name to allow lookup
+**   by binary search
+**
+*/
+
+#define PROP_PATH_RAMDISK_DEFAULT  "/default.prop"
+#define PROP_PATH_SYSTEM_BUILD     "/system/build.prop"
+#define PROP_PATH_SYSTEM_DEFAULT   "/system/default.prop"
+#define PROP_PATH_LOCAL_OVERRIDE   "/data/local.prop"
+
+#endif
+#endif