libc/system_properties/system_properties.cpp - platform/bionic - Git at Google

 /*
  * 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.
  */

 #include "system_properties/system_properties.h"

 #include <errno.h>
 #include <stdatomic.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>

 #include <new>

 #include <async_safe/log.h>

 #include "private/ErrnoRestorer.h"
 #include "private/bionic_futex.h"

 #include "system_properties/context_node.h"
 #include "system_properties/prop_area.h"
 #include "system_properties/prop_info.h"

 #define SERIAL_DIRTY(serial) ((serial)&1)
 #define SERIAL_VALUE_LEN(serial) ((serial) >> 24)

 static bool is_dir(const char* pathname) {
   struct stat info;
   if (stat(pathname, &info) == -1) {
     return false;
   }
   return S_ISDIR(info.st_mode);
 }

 bool SystemProperties::Init(const char* filename) {
   // This is called from __libc_init_common, and should leave errno at 0 (http://b/37248982).
   ErrnoRestorer errno_restorer;

   if (initialized_) {
     contexts_->ResetAccess();
     return true;
   }

   if (strlen(filename) > PROP_FILENAME_MAX) {
     return false;
   }
   strcpy(property_filename_, filename);

   if (is_dir(property_filename_)) {
     if (access("/dev/__properties__/property_info", R_OK) == 0) {
       contexts_ = new (contexts_data_) ContextsSerialized();
       if (!contexts_->Initialize(false, property_filename_, nullptr)) {
         return false;
       }
     } else {
       contexts_ = new (contexts_data_) ContextsSplit();
       if (!contexts_->Initialize(false, property_filename_, nullptr)) {
         return false;
       }
     }
   } else {
     contexts_ = new (contexts_data_) ContextsPreSplit();
     if (!contexts_->Initialize(false, property_filename_, nullptr)) {
       return false;
     }
   }
   initialized_ = true;
   return true;
 }

 bool SystemProperties::AreaInit(const char* filename, bool* fsetxattr_failed) {
   if (strlen(filename) > PROP_FILENAME_MAX) {
     return false;
   }
   strcpy(property_filename_, filename);

   contexts_ = new (contexts_data_) ContextsSerialized();
   if (!contexts_->Initialize(true, property_filename_, fsetxattr_failed)) {
     return false;
   }
   initialized_ = true;
   return true;
 }

 uint32_t SystemProperties::AreaSerial() {
   if (!initialized_) {
     return -1;
   }

   prop_area* pa = contexts_->GetSerialPropArea();
   if (!pa) {
     return -1;
   }

   // Make sure this read fulfilled before __system_property_serial
   return atomic_load_explicit(pa->serial(), memory_order_acquire);
 }

 const prop_info* SystemProperties::Find(const char* name) {
   if (!initialized_) {
     return nullptr;
   }

   prop_area* pa = contexts_->GetPropAreaForName(name);
   if (!pa) {
     async_safe_format_log(ANDROID_LOG_ERROR, "libc", "Access denied finding property \"%s\"", name);
     return nullptr;
   }

   return pa->find(name);
 }

 static bool is_read_only(const char* name) {
   return strncmp(name, "ro.", 3) == 0;
 }

 int SystemProperties::Read(const prop_info* pi, char* name, char* value) {
   while (true) {
     uint32_t serial = Serial(pi);  // acquire semantics
     size_t len = SERIAL_VALUE_LEN(serial);
     memcpy(value, pi->value, len + 1);
     // TODO: Fix the synchronization scheme here.
     // There is no fully supported way to implement this kind
     // of synchronization in C++11, since the memcpy races with
     // updates to pi, and the data being accessed is not atomic.
     // The following fence is unintuitive, but would be the
     // correct one if memcpy used memory_order_relaxed atomic accesses.
     // In practice it seems unlikely that the generated code would
     // would be any different, so this should be OK.
     atomic_thread_fence(memory_order_acquire);
     if (serial == load_const_atomic(&(pi->serial), memory_order_relaxed)) {
       if (name != nullptr) {
         size_t namelen = strlcpy(name, pi->name, PROP_NAME_MAX);
         if (namelen >= PROP_NAME_MAX) {
           async_safe_format_log(ANDROID_LOG_ERROR, "libc",
                                 "The property name length for \"%s\" is >= %d;"
                                 " please use __system_property_read_callback"
                                 " to read this property. (the name is truncated to \"%s\")",
                                 pi->name, PROP_NAME_MAX - 1, name);
         }
       }
       if (is_read_only(pi->name) && pi->is_long()) {
         async_safe_format_log(
             ANDROID_LOG_ERROR, "libc",
             "The property \"%s\" has a value with length %zu that is too large for"
             " __system_property_get()/__system_property_read(); use"
             " __system_property_read_callback() instead.",
             pi->name, strlen(pi->long_value()));
       }
       return len;
     }
   }
 }

 void SystemProperties::ReadCallback(const prop_info* pi,
                                     void (*callback)(void* cookie, const char* name,
                                                      const char* value, uint32_t serial),
                                     void* cookie) {
   // Read only properties don't need to copy the value to a temporary buffer, since it can never
   // change.
   if (is_read_only(pi->name)) {
     uint32_t serial = Serial(pi);
     if (pi->is_long()) {
       callback(cookie, pi->name, pi->long_value(), serial);
     } else {
       callback(cookie, pi->name, pi->value, serial);
     }
     return;
   }

   while (true) {
     uint32_t serial = Serial(pi);  // acquire semantics
     size_t len = SERIAL_VALUE_LEN(serial);
     char value_buf[len + 1];

     memcpy(value_buf, pi->value, len);
     value_buf[len] = '\0';

     // TODO: see todo in Read function
     atomic_thread_fence(memory_order_acquire);
     if (serial == load_const_atomic(&(pi->serial), memory_order_relaxed)) {
       callback(cookie, pi->name, value_buf, serial);
       return;
     }
   }
 }

 int SystemProperties::Get(const char* name, char* value) {
   const prop_info* pi = Find(name);

   if (pi != 0) {
     return Read(pi, nullptr, value);
   } else {
     value[0] = 0;
     return 0;
   }
 }

 int SystemProperties::Update(prop_info* pi, const char* value, unsigned int len) {
   if (len >= PROP_VALUE_MAX) {
     return -1;
   }

   if (!initialized_) {
     return -1;
   }

   prop_area* pa = contexts_->GetSerialPropArea();
   if (!pa) {
     return -1;
   }

   uint32_t serial = atomic_load_explicit(&pi->serial, memory_order_relaxed);
   serial |= 1;
   atomic_store_explicit(&pi->serial, serial, memory_order_relaxed);
   // The memcpy call here also races.  Again pretend it
   // used memory_order_relaxed atomics, and use the analogous
   // counterintuitive fence.
   atomic_thread_fence(memory_order_release);
   strlcpy(pi->value, value, len + 1);

   atomic_store_explicit(&pi->serial, (len << 24) | ((serial + 1) & 0xffffff), memory_order_release);
   __futex_wake(&pi->serial, INT32_MAX);

   atomic_store_explicit(pa->serial(), atomic_load_explicit(pa->serial(), memory_order_relaxed) + 1,
                         memory_order_release);
   __futex_wake(pa->serial(), INT32_MAX);

   return 0;
 }

 int SystemProperties::Add(const char* name, unsigned int namelen, const char* value,
                           unsigned int valuelen) {
   if (valuelen >= PROP_VALUE_MAX && !is_read_only(name)) {
     return -1;
   }

   if (namelen < 1) {
     return -1;
   }

   if (!initialized_) {
     return -1;
   }

   prop_area* serial_pa = contexts_->GetSerialPropArea();
   if (serial_pa == nullptr) {
     return -1;
   }

   prop_area* pa = contexts_->GetPropAreaForName(name);
   if (!pa) {
     async_safe_format_log(ANDROID_LOG_ERROR, "libc", "Access denied adding property \"%s\"", name);
     return -1;
   }

   bool ret = pa->add(name, namelen, value, valuelen);
   if (!ret) {
     return -1;
   }

   // There is only a single mutator, but we want to make sure that
   // updates are visible to a reader waiting for the update.
   atomic_store_explicit(serial_pa->serial(),
                         atomic_load_explicit(serial_pa->serial(), memory_order_relaxed) + 1,
                         memory_order_release);
   __futex_wake(serial_pa->serial(), INT32_MAX);
   return 0;
 }

 // Wait for non-locked serial, and retrieve it with acquire semantics.
 uint32_t SystemProperties::Serial(const prop_info* pi) {
   uint32_t serial = load_const_atomic(&pi->serial, memory_order_acquire);
   while (SERIAL_DIRTY(serial)) {
     __futex_wait(const_cast<_Atomic(uint_least32_t)*>(&pi->serial), serial, nullptr);
     serial = load_const_atomic(&pi->serial, memory_order_acquire);
   }
   return serial;
 }

 uint32_t SystemProperties::WaitAny(uint32_t old_serial) {
   uint32_t new_serial;
   Wait(nullptr, old_serial, &new_serial, nullptr);
   return new_serial;
 }

 bool SystemProperties::Wait(const prop_info* pi, uint32_t old_serial, uint32_t* new_serial_ptr,
                             const timespec* relative_timeout) {
   // Are we waiting on the global serial or a specific serial?
   atomic_uint_least32_t* serial_ptr;
   if (pi == nullptr) {
     if (!initialized_) {
       return -1;
     }

     prop_area* serial_pa = contexts_->GetSerialPropArea();
     if (serial_pa == nullptr) {
       return -1;
     }

     serial_ptr = serial_pa->serial();
   } else {
     serial_ptr = const_cast<atomic_uint_least32_t*>(&pi->serial);
   }

   uint32_t new_serial;
   do {
     int rc;
     if ((rc = __futex_wait(serial_ptr, old_serial, relative_timeout)) != 0 && rc == -ETIMEDOUT) {
       return false;
     }
     new_serial = load_const_atomic(serial_ptr, memory_order_acquire);
   } while (new_serial == old_serial);

   *new_serial_ptr = new_serial;
   return true;
 }

 const prop_info* SystemProperties::FindNth(unsigned n) {
   struct find_nth {
     const uint32_t sought;
     uint32_t current;
     const prop_info* result;

     explicit find_nth(uint32_t n) : sought(n), current(0), result(nullptr) {
     }
     static void fn(const prop_info* pi, void* ptr) {
       find_nth* self = reinterpret_cast<find_nth*>(ptr);
       if (self->current++ == self->sought) self->result = pi;
     }
   } state(n);
   Foreach(find_nth::fn, &state);
   return state.result;
 }

 int SystemProperties::Foreach(void (*propfn)(const prop_info* pi, void* cookie), void* cookie) {
   if (!initialized_) {
     return -1;
   }

   contexts_->ForEach(propfn, cookie);

   return 0;
 }
	/*
	* 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.
	*/

	#include "system_properties/system_properties.h"

	#include <errno.h>
	#include <stdatomic.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <unistd.h>

	#include <new>

	#include <async_safe/log.h>

	#include "private/ErrnoRestorer.h"
	#include "private/bionic_futex.h"

	#include "system_properties/context_node.h"
	#include "system_properties/prop_area.h"
	#include "system_properties/prop_info.h"

	#define SERIAL_DIRTY(serial) ((serial)&1)
	#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)

	static bool is_dir(const char* pathname) {
	struct stat info;
	if (stat(pathname, &info) == -1) {
	return false;
	}
	return S_ISDIR(info.st_mode);
	}

	bool SystemProperties::Init(const char* filename) {
	// This is called from __libc_init_common, and should leave errno at 0 (http://b/37248982).
	ErrnoRestorer errno_restorer;

	if (initialized_) {
	contexts_->ResetAccess();
	return true;
	}

	if (strlen(filename) > PROP_FILENAME_MAX) {
	return false;
	}
	strcpy(property_filename_, filename);

	if (is_dir(property_filename_)) {
	if (access("/dev/__properties__/property_info", R_OK) == 0) {
	contexts_ = new (contexts_data_) ContextsSerialized();
	if (!contexts_->Initialize(false, property_filename_, nullptr)) {
	return false;
	}
	} else {
	contexts_ = new (contexts_data_) ContextsSplit();
	if (!contexts_->Initialize(false, property_filename_, nullptr)) {
	return false;
	}
	}
	} else {
	contexts_ = new (contexts_data_) ContextsPreSplit();
	if (!contexts_->Initialize(false, property_filename_, nullptr)) {
	return false;
	}
	}
	initialized_ = true;
	return true;
	}

	bool SystemProperties::AreaInit(const char* filename, bool* fsetxattr_failed) {
	if (strlen(filename) > PROP_FILENAME_MAX) {
	return false;
	}
	strcpy(property_filename_, filename);

	contexts_ = new (contexts_data_) ContextsSerialized();
	if (!contexts_->Initialize(true, property_filename_, fsetxattr_failed)) {
	return false;
	}
	initialized_ = true;
	return true;
	}

	uint32_t SystemProperties::AreaSerial() {
	if (!initialized_) {
	return -1;
	}

	prop_area* pa = contexts_->GetSerialPropArea();
	if (!pa) {
	return -1;
	}

	// Make sure this read fulfilled before __system_property_serial
	return atomic_load_explicit(pa->serial(), memory_order_acquire);
	}

	const prop_info* SystemProperties::Find(const char* name) {
	if (!initialized_) {
	return nullptr;
	}

	prop_area* pa = contexts_->GetPropAreaForName(name);
	if (!pa) {
	async_safe_format_log(ANDROID_LOG_ERROR, "libc", "Access denied finding property \"%s\"", name);
	return nullptr;
	}

	return pa->find(name);
	}

	static bool is_read_only(const char* name) {
	return strncmp(name, "ro.", 3) == 0;
	}

	int SystemProperties::Read(const prop_info* pi, char* name, char* value) {
	while (true) {
	uint32_t serial = Serial(pi); // acquire semantics
	size_t len = SERIAL_VALUE_LEN(serial);
	memcpy(value, pi->value, len + 1);
	// TODO: Fix the synchronization scheme here.
	// There is no fully supported way to implement this kind
	// of synchronization in C++11, since the memcpy races with
	// updates to pi, and the data being accessed is not atomic.
	// The following fence is unintuitive, but would be the
	// correct one if memcpy used memory_order_relaxed atomic accesses.
	// In practice it seems unlikely that the generated code would
	// would be any different, so this should be OK.
	atomic_thread_fence(memory_order_acquire);
	if (serial == load_const_atomic(&(pi->serial), memory_order_relaxed)) {
	if (name != nullptr) {
	size_t namelen = strlcpy(name, pi->name, PROP_NAME_MAX);
	if (namelen >= PROP_NAME_MAX) {
	async_safe_format_log(ANDROID_LOG_ERROR, "libc",
	"The property name length for \"%s\" is >= %d;"
	" please use __system_property_read_callback"
	" to read this property. (the name is truncated to \"%s\")",
	pi->name, PROP_NAME_MAX - 1, name);
	}
	}
	if (is_read_only(pi->name) && pi->is_long()) {
	async_safe_format_log(
	ANDROID_LOG_ERROR, "libc",
	"The property \"%s\" has a value with length %zu that is too large for"
	" __system_property_get()/__system_property_read(); use"
	" __system_property_read_callback() instead.",
	pi->name, strlen(pi->long_value()));
	}
	return len;
	}
	}
	}

	void SystemProperties::ReadCallback(const prop_info* pi,
	void (callback)(void cookie, const char* name,
	const char* value, uint32_t serial),
	void* cookie) {
	// Read only properties don't need to copy the value to a temporary buffer, since it can never
	// change.
	if (is_read_only(pi->name)) {
	uint32_t serial = Serial(pi);
	if (pi->is_long()) {
	callback(cookie, pi->name, pi->long_value(), serial);
	} else {
	callback(cookie, pi->name, pi->value, serial);
	}
	return;
	}

	while (true) {
	uint32_t serial = Serial(pi); // acquire semantics
	size_t len = SERIAL_VALUE_LEN(serial);
	char value_buf[len + 1];

	memcpy(value_buf, pi->value, len);
	value_buf[len] = '\0';

	// TODO: see todo in Read function
	atomic_thread_fence(memory_order_acquire);
	if (serial == load_const_atomic(&(pi->serial), memory_order_relaxed)) {
	callback(cookie, pi->name, value_buf, serial);
	return;
	}
	}
	}

	int SystemProperties::Get(const char* name, char* value) {
	const prop_info* pi = Find(name);

	if (pi != 0) {
	return Read(pi, nullptr, value);
	} else {
	value[0] = 0;
	return 0;
	}
	}

	int SystemProperties::Update(prop_info* pi, const char* value, unsigned int len) {
	if (len >= PROP_VALUE_MAX) {
	return -1;
	}

	if (!initialized_) {
	return -1;
	}

	prop_area* pa = contexts_->GetSerialPropArea();
	if (!pa) {
	return -1;
	}

	uint32_t serial = atomic_load_explicit(&pi->serial, memory_order_relaxed);
	serial \|= 1;
	atomic_store_explicit(&pi->serial, serial, memory_order_relaxed);
	// The memcpy call here also races. Again pretend it
	// used memory_order_relaxed atomics, and use the analogous
	// counterintuitive fence.
	atomic_thread_fence(memory_order_release);
	strlcpy(pi->value, value, len + 1);

	atomic_store_explicit(&pi->serial, (len << 24) \| ((serial + 1) & 0xffffff), memory_order_release);
	__futex_wake(&pi->serial, INT32_MAX);

	atomic_store_explicit(pa->serial(), atomic_load_explicit(pa->serial(), memory_order_relaxed) + 1,
	memory_order_release);
	__futex_wake(pa->serial(), INT32_MAX);

	return 0;
	}

	int SystemProperties::Add(const char* name, unsigned int namelen, const char* value,
	unsigned int valuelen) {
	if (valuelen >= PROP_VALUE_MAX && !is_read_only(name)) {
	return -1;
	}

	if (namelen < 1) {
	return -1;
	}

	if (!initialized_) {
	return -1;
	}

	prop_area* serial_pa = contexts_->GetSerialPropArea();
	if (serial_pa == nullptr) {
	return -1;
	}

	prop_area* pa = contexts_->GetPropAreaForName(name);
	if (!pa) {
	async_safe_format_log(ANDROID_LOG_ERROR, "libc", "Access denied adding property \"%s\"", name);
	return -1;
	}

	bool ret = pa->add(name, namelen, value, valuelen);
	if (!ret) {
	return -1;
	}

	// There is only a single mutator, but we want to make sure that
	// updates are visible to a reader waiting for the update.
	atomic_store_explicit(serial_pa->serial(),
	atomic_load_explicit(serial_pa->serial(), memory_order_relaxed) + 1,
	memory_order_release);
	__futex_wake(serial_pa->serial(), INT32_MAX);
	return 0;
	}

	// Wait for non-locked serial, and retrieve it with acquire semantics.
	uint32_t SystemProperties::Serial(const prop_info* pi) {
	uint32_t serial = load_const_atomic(&pi->serial, memory_order_acquire);
	while (SERIAL_DIRTY(serial)) {
	__futex_wait(const_cast<_Atomic(uint_least32_t)*>(&pi->serial), serial, nullptr);
	serial = load_const_atomic(&pi->serial, memory_order_acquire);
	}
	return serial;
	}

	uint32_t SystemProperties::WaitAny(uint32_t old_serial) {
	uint32_t new_serial;
	Wait(nullptr, old_serial, &new_serial, nullptr);
	return new_serial;
	}

	bool SystemProperties::Wait(const prop_info* pi, uint32_t old_serial, uint32_t* new_serial_ptr,
	const timespec* relative_timeout) {
	// Are we waiting on the global serial or a specific serial?
	atomic_uint_least32_t* serial_ptr;
	if (pi == nullptr) {
	if (!initialized_) {
	return -1;
	}

	prop_area* serial_pa = contexts_->GetSerialPropArea();
	if (serial_pa == nullptr) {
	return -1;
	}

	serial_ptr = serial_pa->serial();
	} else {
	serial_ptr = const_cast<atomic_uint_least32_t*>(&pi->serial);
	}

	uint32_t new_serial;
	do {
	int rc;
	if ((rc = __futex_wait(serial_ptr, old_serial, relative_timeout)) != 0 && rc == -ETIMEDOUT) {
	return false;
	}
	new_serial = load_const_atomic(serial_ptr, memory_order_acquire);
	} while (new_serial == old_serial);

	*new_serial_ptr = new_serial;
	return true;
	}

	const prop_info* SystemProperties::FindNth(unsigned n) {
	struct find_nth {
	const uint32_t sought;
	uint32_t current;
	const prop_info* result;

	explicit find_nth(uint32_t n) : sought(n), current(0), result(nullptr) {
	}
	static void fn(const prop_info* pi, void* ptr) {
	find_nth* self = reinterpret_cast<find_nth*>(ptr);
	if (self->current++ == self->sought) self->result = pi;
	}
	} state(n);
	Foreach(find_nth::fn, &state);
	return state.result;
	}

	int SystemProperties::Foreach(void (propfn)(const prop_info pi, void* cookie), void* cookie) {
	if (!initialized_) {
	return -1;
	}

	contexts_->ForEach(propfn, cookie);

	return 0;
	}