init/property_service.c - android_system_core - Gitiles

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <ctype.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <dirent.h>
 #include <limits.h>
 #include <errno.h>

 #include <cutils/misc.h>
 #include <cutils/sockets.h>

 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
 #include <sys/_system_properties.h>

 #include <sys/socket.h>
 #include <sys/un.h>
 #include <sys/select.h>
 #include <sys/types.h>
 #include <netinet/in.h>
 #include <sys/mman.h>
 #include <sys/atomics.h>
 #include <private/android_filesystem_config.h>

 #include "property_service.h"
 #include "init.h"
 #include "util.h"
 #include "log.h"

 #define PERSISTENT_PROPERTY_DIR  "/data/property"

 static int persistent_properties_loaded = 0;
 static int property_area_inited = 0;

 static int property_set_fd = -1;

 /* White list of permissions for setting property services. */
 struct {
     const char *prefix;
     unsigned int uid;
     unsigned int gid;
 } property_perms[] = {
     { "net.rmnet0.",      AID_RADIO,    0 },
     { "net.gprs.",        AID_RADIO,    0 },
     { "net.ppp",          AID_RADIO,    0 },
     { "net.qmi",          AID_RADIO,    0 },
     { "net.lte",          AID_RADIO,    0 },
     { "net.cdma",         AID_RADIO,    0 },
     { "ril.",             AID_RADIO,    0 },
     { "gsm.",             AID_RADIO,    0 },
     { "persist.radio",    AID_RADIO,    0 },
     { "net.dns",          AID_RADIO,    0 },
     { "sys.usb.config",   AID_RADIO,    0 },
     { "net.",             AID_SYSTEM,   0 },
     { "dev.",             AID_SYSTEM,   0 },
     { "runtime.",         AID_SYSTEM,   0 },
     { "hw.",              AID_SYSTEM,   0 },
     { "sys.",             AID_SYSTEM,   0 },
     { "service.",         AID_SYSTEM,   0 },
     { "wlan.",            AID_SYSTEM,   0 },
     { "dhcp.",            AID_SYSTEM,   0 },
     { "dhcp.",            AID_DHCP,     0 },
     { "debug.",           AID_SHELL,    0 },
     { "log.",             AID_SHELL,    0 },
     { "service.adb.root", AID_SHELL,    0 },
     { "service.adb.tcp.port", AID_SHELL,    0 },
     { "persist.sys.",     AID_SYSTEM,   0 },
     { "persist.service.", AID_SYSTEM,   0 },
     { "persist.security.", AID_SYSTEM,   0 },
     { NULL, 0, 0 }
 };

 /*
  * White list of UID that are allowed to start/stop services.
  * Currently there are no user apps that require.
  */
 struct {
     const char *service;
     unsigned int uid;
     unsigned int gid;
 } control_perms[] = {
     { "dumpstate",AID_SHELL, AID_LOG },
     { "ril-daemon",AID_RADIO, AID_RADIO },
      {NULL, 0, 0 }
 };

 typedef struct {
     void *data;
     size_t size;
     int fd;
 } workspace;

 static int init_workspace(workspace *w, size_t size)
 {
     void *data;
     int fd;

         /* dev is a tmpfs that we can use to carve a shared workspace
          * out of, so let's do that...
          */
     fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
     if (fd < 0)
         return -1;

     if (ftruncate(fd, size) < 0)
         goto out;

     data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
     if(data == MAP_FAILED)
         goto out;

     close(fd);

     fd = open("/dev/__properties__", O_RDONLY);
     if (fd < 0)
         return -1;

     unlink("/dev/__properties__");

     w->data = data;
     w->size = size;
     w->fd = fd;
     return 0;

 out:
     close(fd);
     return -1;
 }

 /* (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

 static workspace pa_workspace;
 static prop_info *pa_info_array;

 extern prop_area *__system_property_area__;

 static int init_property_area(void)
 {
     prop_area *pa;

     if(pa_info_array)
         return -1;

     if(init_workspace(&pa_workspace, PA_SIZE))
         return -1;

     fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);

     pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);

     pa = pa_workspace.data;
     memset(pa, 0, PA_SIZE);
     pa->magic = PROP_AREA_MAGIC;
     pa->version = PROP_AREA_VERSION;

         /* plug into the lib property services */
     __system_property_area__ = pa;
     property_area_inited = 1;
     return 0;
 }

 static void update_prop_info(prop_info *pi, const char *value, unsigned len)
 {
     pi->serial = pi->serial | 1;
     memcpy(pi->value, value, len + 1);
     pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
     __futex_wake(&pi->serial, INT32_MAX);
 }

 /*
  * Checks permissions for starting/stoping system services.
  * AID_SYSTEM and AID_ROOT are always allowed.
  *
  * Returns 1 if uid allowed, 0 otherwise.
  */
 static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
     int i;
     if (uid == AID_SYSTEM || uid == AID_ROOT)
         return 1;

     /* Search the ACL */
     for (i = 0; control_perms[i].service; i++) {
         if (strcmp(control_perms[i].service, name) == 0) {
             if ((uid && control_perms[i].uid == uid) ||
                 (gid && control_perms[i].gid == gid)) {
                 return 1;
             }
         }
     }
     return 0;
 }

 /*
  * Checks permissions for setting system properties.
  * Returns 1 if uid allowed, 0 otherwise.
  */
 static int check_perms(const char *name, unsigned int uid, unsigned int gid)
 {
     int i;
     if (uid == 0)
         return 1;

     if(!strncmp(name, "ro.", 3))
         name +=3;

     for (i = 0; property_perms[i].prefix; i++) {
         int tmp;
         if (strncmp(property_perms[i].prefix, name,
                     strlen(property_perms[i].prefix)) == 0) {
             if ((uid && property_perms[i].uid == uid) ||
                 (gid && property_perms[i].gid == gid)) {
                 return 1;
             }
         }
     }

     return 0;
 }

 const char* property_get(const char *name)
 {
     prop_info *pi;

     if(strlen(name) >= PROP_NAME_MAX) return 0;

     pi = (prop_info*) __system_property_find(name);

     if(pi != 0) {
         return pi->value;
     } else {
         return 0;
     }
 }

 static void write_persistent_property(const char *name, const char *value)
 {
     const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
     char path[PATH_MAX];
     int fd, length;

     snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);

     fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
     if (fd < 0) {
         ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
         return;
     }
     write(fd, value, strlen(value));
     close(fd);

     if (rename(tempPath, path)) {
         unlink(tempPath);
         ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
     }
 }

 int property_set(const char *name, const char *value)
 {
     prop_area *pa;
     prop_info *pi;

     int namelen = strlen(name);
     int valuelen = strlen(value);

     if(namelen >= PROP_NAME_MAX) return -1;
     if(valuelen >= PROP_VALUE_MAX) return -1;
     if(namelen < 1) return -1;

     pi = (prop_info*) __system_property_find(name);

     if(pi != 0) {
         /* ro.* properties may NEVER be modified once set */
         if(!strncmp(name, "ro.", 3)) return -1;

         pa = __system_property_area__;
         update_prop_info(pi, value, valuelen);
         pa->serial++;
         __futex_wake(&pa->serial, INT32_MAX);
     } else {
         pa = __system_property_area__;
         if(pa->count == PA_COUNT_MAX) return -1;

         pi = pa_info_array + pa->count;
         pi->serial = (valuelen << 24);
         memcpy(pi->name, name, namelen + 1);
         memcpy(pi->value, value, valuelen + 1);

         pa->toc[pa->count] =
             (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));

         pa->count++;
         pa->serial++;
         __futex_wake(&pa->serial, INT32_MAX);
     }
     /* If name starts with "net." treat as a DNS property. */
     if (strncmp("net.", name, strlen("net.")) == 0)  {
         if (strcmp("net.change", name) == 0) {
             return 0;
         }
        /*
         * The 'net.change' property is a special property used track when any
         * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
         * contains the last updated 'net.*' property.
         */
         property_set("net.change", name);
     } else if (persistent_properties_loaded &&
             strncmp("persist.", name, strlen("persist.")) == 0) {
         /*
          * Don't write properties to disk until after we have read all default properties
          * to prevent them from being overwritten by default values.
          */
         write_persistent_property(name, value);
     }
     property_changed(name, value);
     return 0;
 }

 static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
                   void *cookie)
 {
     char name[PROP_NAME_MAX];
     char value[PROP_VALUE_MAX];
     const prop_info *pi;
     unsigned n;

     for(n = 0; (pi = __system_property_find_nth(n)); n++) {
         __system_property_read(pi, name, value);
         propfn(name, value, cookie);
     }
     return 0;
 }

 void handle_property_set_fd()
 {
     prop_msg msg;
     int s;
     int r;
     int res;
     struct ucred cr;
     struct sockaddr_un addr;
     socklen_t addr_size = sizeof(addr);
     socklen_t cr_size = sizeof(cr);

     if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
         return;
     }

     /* Check socket options here */
     if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
         close(s);
         ERROR("Unable to recieve socket options\n");
         return;
     }

     r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
     if(r != sizeof(prop_msg)) {
         ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
               r, sizeof(prop_msg), errno);
         close(s);
         return;
     }

     switch(msg.cmd) {
     case PROP_MSG_SETPROP:
         msg.name[PROP_NAME_MAX-1] = 0;
         msg.value[PROP_VALUE_MAX-1] = 0;

         if(memcmp(msg.name,"ctl.",4) == 0) {
             // Keep the old close-socket-early behavior when handling
             // ctl.* properties.
             close(s);
             if (check_control_perms(msg.value, cr.uid, cr.gid)) {
                 handle_control_message((char*) msg.name + 4, (char*) msg.value);
             } else {
                 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
                         msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
             }
         } else {
             if (check_perms(msg.name, cr.uid, cr.gid)) {
                 property_set((char*) msg.name, (char*) msg.value);
             } else {
                 ERROR("sys_prop: permission denied uid:%d  name:%s\n",
                       cr.uid, msg.name);
             }

             // Note: bionic's property client code assumes that the
             // property server will not close the socket until *AFTER*
             // the property is written to memory.
             close(s);
         }
         break;

     default:
         close(s);
         break;
     }
 }

 void get_property_workspace(int *fd, int *sz)
 {
     *fd = pa_workspace.fd;
     *sz = pa_workspace.size;
 }

 static void load_properties(char *data)
 {
     char *key, *value, *eol, *sol, *tmp;

     sol = data;
     while((eol = strchr(sol, '\n'))) {
         key = sol;
         *eol++ = 0;
         sol = eol;

         value = strchr(key, '=');
         if(value == 0) continue;
         *value++ = 0;

         while(isspace(*key)) key++;
         if(*key == '#') continue;
         tmp = value - 2;
         while((tmp > key) && isspace(*tmp)) *tmp-- = 0;

         while(isspace(*value)) value++;
         tmp = eol - 2;
         while((tmp > value) && isspace(*tmp)) *tmp-- = 0;

         property_set(key, value);
     }
 }

 static void load_properties_from_file(const char *fn)
 {
     char *data;
     unsigned sz;

     data = read_file(fn, &sz);

     if(data != 0) {
         load_properties(data);
         free(data);
     }
 }

 static void load_persistent_properties()
 {
     DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
     struct dirent*  entry;
     char path[PATH_MAX];
     char value[PROP_VALUE_MAX];
     int fd, length;

     if (dir) {
         while ((entry = readdir(dir)) != NULL) {
             if (strncmp("persist.", entry->d_name, strlen("persist.")))
                 continue;
 #if HAVE_DIRENT_D_TYPE
             if (entry->d_type != DT_REG)
                 continue;
 #endif
             /* open the file and read the property value */
             snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
             fd = open(path, O_RDONLY);
             if (fd >= 0) {
                 length = read(fd, value, sizeof(value) - 1);
                 if (length >= 0) {
                     value[length] = 0;
                     property_set(entry->d_name, value);
                 } else {
                     ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
                 }
                 close(fd);
             } else {
                 ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
             }
         }
         closedir(dir);
     } else {
         ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
     }

     persistent_properties_loaded = 1;
 }

 void property_init(bool load_defaults)
 {
     init_property_area();
     if (load_defaults)
         load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
 }

 int properties_inited(void)
 {
     return property_area_inited;
 }

 /* When booting an encrypted system, /data is not mounted when the
  * property service is started, so any properties stored there are
  * not loaded.  Vold triggers init to load these properties once it
  * has mounted /data.
  */
 void load_persist_props(void)
 {
     load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
     /* Read persistent properties after all default values have been loaded. */
     load_persistent_properties();
 }

 void start_property_service(void)
 {
     int fd;

     load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
     load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
     load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
     /* Read persistent properties after all default values have been loaded. */
     load_persistent_properties();

     fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
     if(fd < 0) return;
     fcntl(fd, F_SETFD, FD_CLOEXEC);
     fcntl(fd, F_SETFL, O_NONBLOCK);

     listen(fd, 8);
     property_set_fd = fd;
 }

 int get_property_set_fd()
 {
     return property_set_fd;
 }
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <string.h>
	#include <ctype.h>
	#include <fcntl.h>
	#include <stdarg.h>
	#include <dirent.h>
	#include <limits.h>
	#include <errno.h>

	#include <cutils/misc.h>
	#include <cutils/sockets.h>

	#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
	#include <sys/_system_properties.h>

	#include <sys/socket.h>
	#include <sys/un.h>
	#include <sys/select.h>
	#include <sys/types.h>
	#include <netinet/in.h>
	#include <sys/mman.h>
	#include <sys/atomics.h>
	#include <private/android_filesystem_config.h>

	#include "property_service.h"
	#include "init.h"
	#include "util.h"
	#include "log.h"

	#define PERSISTENT_PROPERTY_DIR "/data/property"

	static int persistent_properties_loaded = 0;
	static int property_area_inited = 0;

	static int property_set_fd = -1;

	/* White list of permissions for setting property services. */
	struct {
	const char *prefix;
	unsigned int uid;
	unsigned int gid;
	} property_perms[] = {
	{ "net.rmnet0.", AID_RADIO, 0 },
	{ "net.gprs.", AID_RADIO, 0 },
	{ "net.ppp", AID_RADIO, 0 },
	{ "net.qmi", AID_RADIO, 0 },
	{ "net.lte", AID_RADIO, 0 },
	{ "net.cdma", AID_RADIO, 0 },
	{ "ril.", AID_RADIO, 0 },
	{ "gsm.", AID_RADIO, 0 },
	{ "persist.radio", AID_RADIO, 0 },
	{ "net.dns", AID_RADIO, 0 },
	{ "sys.usb.config", AID_RADIO, 0 },
	{ "net.", AID_SYSTEM, 0 },
	{ "dev.", AID_SYSTEM, 0 },
	{ "runtime.", AID_SYSTEM, 0 },
	{ "hw.", AID_SYSTEM, 0 },
	{ "sys.", AID_SYSTEM, 0 },
	{ "service.", AID_SYSTEM, 0 },
	{ "wlan.", AID_SYSTEM, 0 },
	{ "dhcp.", AID_SYSTEM, 0 },
	{ "dhcp.", AID_DHCP, 0 },
	{ "debug.", AID_SHELL, 0 },
	{ "log.", AID_SHELL, 0 },
	{ "service.adb.root", AID_SHELL, 0 },
	{ "service.adb.tcp.port", AID_SHELL, 0 },
	{ "persist.sys.", AID_SYSTEM, 0 },
	{ "persist.service.", AID_SYSTEM, 0 },
	{ "persist.security.", AID_SYSTEM, 0 },
	{ NULL, 0, 0 }
	};

	/*
	* White list of UID that are allowed to start/stop services.
	* Currently there are no user apps that require.
	*/
	struct {
	const char *service;
	unsigned int uid;
	unsigned int gid;
	} control_perms[] = {
	{ "dumpstate",AID_SHELL, AID_LOG },
	{ "ril-daemon",AID_RADIO, AID_RADIO },
	{NULL, 0, 0 }
	};

	typedef struct {
	void *data;
	size_t size;
	int fd;
	} workspace;

	static int init_workspace(workspace *w, size_t size)
	{
	void *data;
	int fd;

	/* dev is a tmpfs that we can use to carve a shared workspace
	* out of, so let's do that...
	*/
	fd = open("/dev/__properties__", O_RDWR \| O_CREAT, 0600);
	if (fd < 0)
	return -1;

	if (ftruncate(fd, size) < 0)
	goto out;

	data = mmap(NULL, size, PROT_READ \| PROT_WRITE, MAP_SHARED, fd, 0);
	if(data == MAP_FAILED)
	goto out;

	close(fd);

	fd = open("/dev/__properties__", O_RDONLY);
	if (fd < 0)
	return -1;

	unlink("/dev/__properties__");

	w->data = data;
	w->size = size;
	w->fd = fd;
	return 0;

	out:
	close(fd);
	return -1;
	}

	/* (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

	static workspace pa_workspace;
	static prop_info *pa_info_array;

	extern prop_area *__system_property_area__;

	static int init_property_area(void)
	{
	prop_area *pa;

	if(pa_info_array)
	return -1;

	if(init_workspace(&pa_workspace, PA_SIZE))
	return -1;

	fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);

	pa_info_array = (void) (((char) pa_workspace.data) + PA_INFO_START);

	pa = pa_workspace.data;
	memset(pa, 0, PA_SIZE);
	pa->magic = PROP_AREA_MAGIC;
	pa->version = PROP_AREA_VERSION;

	/* plug into the lib property services */
	__system_property_area__ = pa;
	property_area_inited = 1;
	return 0;
	}

	static void update_prop_info(prop_info pi, const char value, unsigned len)
	{
	pi->serial = pi->serial \| 1;
	memcpy(pi->value, value, len + 1);
	pi->serial = (len << 24) \| ((pi->serial + 1) & 0xffffff);
	__futex_wake(&pi->serial, INT32_MAX);
	}

	/*
	* Checks permissions for starting/stoping system services.
	* AID_SYSTEM and AID_ROOT are always allowed.
	*
	* Returns 1 if uid allowed, 0 otherwise.
	*/
	static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
	int i;
	if (uid == AID_SYSTEM \|\| uid == AID_ROOT)
	return 1;

	/* Search the ACL */
	for (i = 0; control_perms[i].service; i++) {
	if (strcmp(control_perms[i].service, name) == 0) {
	if ((uid && control_perms[i].uid == uid) \|\|
	(gid && control_perms[i].gid == gid)) {
	return 1;
	}
	}
	}
	return 0;
	}

	/*
	* Checks permissions for setting system properties.
	* Returns 1 if uid allowed, 0 otherwise.
	*/
	static int check_perms(const char *name, unsigned int uid, unsigned int gid)
	{
	int i;
	if (uid == 0)
	return 1;

	if(!strncmp(name, "ro.", 3))
	name +=3;

	for (i = 0; property_perms[i].prefix; i++) {
	int tmp;
	if (strncmp(property_perms[i].prefix, name,
	strlen(property_perms[i].prefix)) == 0) {
	if ((uid && property_perms[i].uid == uid) \|\|
	(gid && property_perms[i].gid == gid)) {
	return 1;
	}
	}
	}

	return 0;
	}

	const char* property_get(const char *name)
	{
	prop_info *pi;

	if(strlen(name) >= PROP_NAME_MAX) return 0;

	pi = (prop_info*) __system_property_find(name);

	if(pi != 0) {
	return pi->value;
	} else {
	return 0;
	}
	}

	static void write_persistent_property(const char name, const char value)
	{
	const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
	char path[PATH_MAX];
	int fd, length;

	snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);

	fd = open(tempPath, O_WRONLY\|O_CREAT\|O_TRUNC, 0600);
	if (fd < 0) {
	ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
	return;
	}
	write(fd, value, strlen(value));
	close(fd);

	if (rename(tempPath, path)) {
	unlink(tempPath);
	ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
	}
	}

	int property_set(const char name, const char value)
	{
	prop_area *pa;
	prop_info *pi;

	int namelen = strlen(name);
	int valuelen = strlen(value);

	if(namelen >= PROP_NAME_MAX) return -1;
	if(valuelen >= PROP_VALUE_MAX) return -1;
	if(namelen < 1) return -1;

	pi = (prop_info*) __system_property_find(name);

	if(pi != 0) {
	/* ro.* properties may NEVER be modified once set */
	if(!strncmp(name, "ro.", 3)) return -1;

	pa = __system_property_area__;
	update_prop_info(pi, value, valuelen);
	pa->serial++;
	__futex_wake(&pa->serial, INT32_MAX);
	} else {
	pa = __system_property_area__;
	if(pa->count == PA_COUNT_MAX) return -1;

	pi = pa_info_array + pa->count;
	pi->serial = (valuelen << 24);
	memcpy(pi->name, name, namelen + 1);
	memcpy(pi->value, value, valuelen + 1);

	pa->toc[pa->count] =
	(namelen << 24) \| (((unsigned) pi) - ((unsigned) pa));

	pa->count++;
	pa->serial++;
	__futex_wake(&pa->serial, INT32_MAX);
	}
	/* If name starts with "net." treat as a DNS property. */
	if (strncmp("net.", name, strlen("net.")) == 0) {
	if (strcmp("net.change", name) == 0) {
	return 0;
	}
	/*
	* The 'net.change' property is a special property used track when any
	* 'net.*' property name is updated. It is _ONLY_ updated here. Its value
	* contains the last updated 'net.*' property.
	*/
	property_set("net.change", name);
	} else if (persistent_properties_loaded &&
	strncmp("persist.", name, strlen("persist.")) == 0) {
	/*
	* Don't write properties to disk until after we have read all default properties
	* to prevent them from being overwritten by default values.
	*/
	write_persistent_property(name, value);
	}
	property_changed(name, value);
	return 0;
	}

	static int property_list(void (propfn)(const char key, const char value, void cookie),
	void *cookie)
	{
	char name[PROP_NAME_MAX];
	char value[PROP_VALUE_MAX];
	const prop_info *pi;
	unsigned n;

	for(n = 0; (pi = __system_property_find_nth(n)); n++) {
	__system_property_read(pi, name, value);
	propfn(name, value, cookie);
	}
	return 0;
	}

	void handle_property_set_fd()
	{
	prop_msg msg;
	int s;
	int r;
	int res;
	struct ucred cr;
	struct sockaddr_un addr;
	socklen_t addr_size = sizeof(addr);
	socklen_t cr_size = sizeof(cr);

	if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
	return;
	}

	/* Check socket options here */
	if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
	close(s);
	ERROR("Unable to recieve socket options\n");
	return;
	}

	r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
	if(r != sizeof(prop_msg)) {
	ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
	r, sizeof(prop_msg), errno);
	close(s);
	return;
	}

	switch(msg.cmd) {
	case PROP_MSG_SETPROP:
	msg.name[PROP_NAME_MAX-1] = 0;
	msg.value[PROP_VALUE_MAX-1] = 0;

	if(memcmp(msg.name,"ctl.",4) == 0) {
	// Keep the old close-socket-early behavior when handling
	// ctl.* properties.
	close(s);
	if (check_control_perms(msg.value, cr.uid, cr.gid)) {
	handle_control_message((char) msg.name + 4, (char) msg.value);
	} else {
	ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
	msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
	}
	} else {
	if (check_perms(msg.name, cr.uid, cr.gid)) {
	property_set((char) msg.name, (char) msg.value);
	} else {
	ERROR("sys_prop: permission denied uid:%d name:%s\n",
	cr.uid, msg.name);
	}

	// Note: bionic's property client code assumes that the
	// property server will not close the socket until AFTER
	// the property is written to memory.
	close(s);
	}
	break;

	default:
	close(s);
	break;
	}
	}

	void get_property_workspace(int fd, int sz)
	{
	*fd = pa_workspace.fd;
	*sz = pa_workspace.size;
	}

	static void load_properties(char *data)
	{
	char key, value, eol, sol, *tmp;

	sol = data;
	while((eol = strchr(sol, '\n'))) {
	key = sol;
	*eol++ = 0;
	sol = eol;

	value = strchr(key, '=');
	if(value == 0) continue;
	*value++ = 0;

	while(isspace(*key)) key++;
	if(*key == '#') continue;
	tmp = value - 2;
	while((tmp > key) && isspace(tmp)) tmp-- = 0;

	while(isspace(*value)) value++;
	tmp = eol - 2;
	while((tmp > value) && isspace(tmp)) tmp-- = 0;

	property_set(key, value);
	}
	}

	static void load_properties_from_file(const char *fn)
	{
	char *data;
	unsigned sz;

	data = read_file(fn, &sz);

	if(data != 0) {
	load_properties(data);
	free(data);
	}
	}

	static void load_persistent_properties()
	{
	DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
	struct dirent* entry;
	char path[PATH_MAX];
	char value[PROP_VALUE_MAX];
	int fd, length;

	if (dir) {
	while ((entry = readdir(dir)) != NULL) {
	if (strncmp("persist.", entry->d_name, strlen("persist.")))
	continue;
	#if HAVE_DIRENT_D_TYPE
	if (entry->d_type != DT_REG)
	continue;
	#endif
	/* open the file and read the property value */
	snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
	fd = open(path, O_RDONLY);
	if (fd >= 0) {
	length = read(fd, value, sizeof(value) - 1);
	if (length >= 0) {
	value[length] = 0;
	property_set(entry->d_name, value);
	} else {
	ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
	}
	close(fd);
	} else {
	ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
	}
	}
	closedir(dir);
	} else {
	ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
	}

	persistent_properties_loaded = 1;
	}

	void property_init(bool load_defaults)
	{
	init_property_area();
	if (load_defaults)
	load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
	}

	int properties_inited(void)
	{
	return property_area_inited;
	}

	/* When booting an encrypted system, /data is not mounted when the
	* property service is started, so any properties stored there are
	* not loaded. Vold triggers init to load these properties once it
	* has mounted /data.
	*/
	void load_persist_props(void)
	{
	load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
	/* Read persistent properties after all default values have been loaded. */
	load_persistent_properties();
	}

	void start_property_service(void)
	{
	int fd;

	load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
	load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
	load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
	/* Read persistent properties after all default values have been loaded. */
	load_persistent_properties();

	fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
	if(fd < 0) return;
	fcntl(fd, F_SETFD, FD_CLOEXEC);
	fcntl(fd, F_SETFL, O_NONBLOCK);

	listen(fd, 8);
	property_set_fd = fd;
	}

	int get_property_set_fd()
	{
	return property_set_fd;
	}