bionic: move system property writing from init to bionic
Move the implementation of writing to the system property area
from init to bionic, next to the reader implementation. This
will allow full property testing to be added to bionic tests.
Add new accessor and waiting functions to hide the implementation
from watchprops and various bionic users.
Also hide some of the implementation details of the property area
from init by moving them into _system_properties.h, and other details
from everybody by moving them into system_properties.h.
(cherry picked from commit dc1038b7900acb664e99643d2974e1a0f4703781)
Change-Id: I192d3825ee276c5047bc751039fe6cfe226a7cca
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 5d2043d..c5bc223 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -34,7 +34,6 @@
#else
#include <sys/system_properties.h>
-typedef struct prop_area prop_area;
typedef struct prop_msg prop_msg;
#define PROP_AREA_MAGIC 0x504f5250
@@ -43,29 +42,20 @@
#define PROP_SERVICE_NAME "property_service"
#define PROP_FILENAME "/dev/__properties__"
-/* #define PROP_MAX_ENTRIES 247 */
-/* 247 -> 32620 bytes (<32768) */
+/* (8 header words + 247 toc words) = 1020 bytes */
+/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
+
+#define PA_COUNT_MAX 247
+#define PA_INFO_START 1024
+#define PA_SIZE 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];
-};
+__BEGIN_DECLS
struct prop_msg
{
@@ -106,5 +96,47 @@
#define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop"
#define PROP_PATH_FACTORY "/factory/factory.prop"
+/*
+** Initialize the area to be used to store properties. Can
+** only be done by a single process that has write access to
+** the property area.
+*/
+void __system_property_area_init(void *data);
+
+/* Add a new system property. Can only be done by a single
+** process that has write access to the property area, and
+** that process must handle sequencing to ensure the property
+** does not already exist and that only one property is added
+** or updated at a time.
+**
+** Returns 0 on success, -1 if the property area is full.
+*/
+int __system_property_add(const char *name, unsigned int namelen,
+ const char *value, unsigned int valuelen);
+
+/* Update the value of a system property returned by
+** __system_property_find. Can only be done by a single process
+** that has write access to the property area, and that process
+** must handle sequencing to ensure that only one property is
+** updated at a time.
+**
+** Returns 0 on success, -1 if the parameters are incorrect.
+*/
+int __system_property_update(prop_info *pi, const char *value, unsigned int len);
+
+/* Read the serial number of a system property returned by
+** __system_property_find.
+**
+** Returns the serial number on success, -1 on error.
+*/
+unsigned int __system_property_serial(const prop_info *pi);
+
+/* Wait for any system property to be updated. Caller must pass
+** in 0 the first time, and the previous return value on each
+** successive call. */
+unsigned int __system_property_wait_any(unsigned int serial);
+
+__END_DECLS
+
#endif
#endif