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29 #ifndef _INCLUDE_SYS_SYSTEM_PROPERTIES_H
30 #define _INCLUDE_SYS_SYSTEM_PROPERTIES_H
32 #include <sys/cdefs.h>
36 typedef struct prop_info prop_info;
38 #define PROP_NAME_MAX 32
39 #define PROP_VALUE_MAX 92
41 /* Look up a system property by name, copying its value and a
42 ** \0 terminator to the provided pointer. The total bytes
43 ** copied will be no greater than PROP_VALUE_MAX. Returns
44 ** the string length of the value. A property that is not
45 ** defined is identical to a property with a length 0 value.
47 int __system_property_get(const char *name, char *value);
49 /* Return a pointer to the system property named name, if it
50 ** exists, or NULL if there is no such property. Use
51 ** __system_property_read() to obtain the string value from
52 ** the returned prop_info pointer.
54 ** It is safe to cache the prop_info pointer to avoid future
55 ** lookups. These returned pointers will remain valid for
56 ** the lifetime of the system.
58 const prop_info *__system_property_find(const char *name);
60 /* Read the value of a system property. Returns the length
61 ** of the value. Copies the value and \0 terminator into
62 ** the provided value pointer. Total length (including
63 ** terminator) will be no greater that PROP_VALUE_MAX.
65 ** If name is nonzero, up to PROP_NAME_MAX bytes will be
66 ** copied into the provided name pointer. The name will
69 int __system_property_read(const prop_info *pi, char *name, char *value);
71 /* Return a prop_info for the nth system property, or NULL if
72 ** there is no nth property. Use __system_property_read() to
73 ** read the value of this property.
75 ** This method is for inspecting and debugging the property
76 ** system. Please use __system_property_find() instead.
78 ** Order of results may change from call to call. This is
81 const prop_info *__system_property_find_nth(unsigned n);