init/property_service.cpp - android-core - Git at Google

 /*
  * 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 <sys/poll.h>

 #include <memory>

 #include <cutils/misc.h>
 #include <cutils/sockets.h>
 #include <cutils/multiuser.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 <private/android_filesystem_config.h>

 #include <selinux/selinux.h>
 #include <selinux/label.h>

 #include <fs_mgr.h>
 #include <base/file.h>
 #include "bootimg.h"

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

 #define PERSISTENT_PROPERTY_DIR  "/data/property"
 #define FSTAB_PREFIX "/fstab."
 #define RECOVERY_MOUNT_POINT "/recovery"

 static int persistent_properties_loaded = 0;
 static bool property_area_initialized = false;

 static int property_set_fd = -1;

 struct workspace {
     size_t size;
     int fd;
 };

 static workspace pa_workspace;

 void property_init() {
     if (property_area_initialized) {
         return;
     }

     property_area_initialized = true;

     if (__system_property_area_init()) {
         return;
     }

     pa_workspace.size = 0;
     pa_workspace.fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
     if (pa_workspace.fd == -1) {
         ERROR("Failed to open %s: %s\n", PROP_FILENAME, strerror(errno));
         return;
     }
 }

 static int check_mac_perms(const char *name, char *sctx)
 {
     if (is_selinux_enabled() <= 0)
         return 1;

     char *tctx = NULL;
     int result = 0;

     if (!sctx)
         goto err;

     if (!sehandle_prop)
         goto err;

     if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
         goto err;

     if (selinux_check_access(sctx, tctx, "property_service", "set", (void*) name) == 0)
         result = 1;

     freecon(tctx);
  err:
     return result;
 }

 static int check_control_mac_perms(const char *name, char *sctx)
 {
     /*
      *  Create a name prefix out of ctl.<service name>
      *  The new prefix allows the use of the existing
      *  property service backend labeling while avoiding
      *  mislabels based on true property prefixes.
      */
     char ctl_name[PROP_VALUE_MAX+4];
     int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);

     if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
         return 0;

     return check_mac_perms(ctl_name, sctx);
 }

 /*
  * Checks permissions for setting system properties.
  * Returns 1 if uid allowed, 0 otherwise.
  */
 static int check_perms(const char *name, char *sctx)
 {
     if(!strncmp(name, "ro.", 3))
         name +=3;

     return check_mac_perms(name, sctx);
 }

 int __property_get(const char *name, char *value)
 {
     return __system_property_get(name, value);
 }

 static void write_persistent_property(const char *name, const char *value)
 {
     char tempPath[PATH_MAX];
     char path[PATH_MAX];
     int fd;

     snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
     fd = mkstemp(tempPath);
     if (fd < 0) {
         ERROR("Unable to write persistent property to temp file %s: %s\n", tempPath, strerror(errno));
         return;
     }
     write(fd, value, strlen(value));
     fsync(fd);
     close(fd);

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

 static bool is_legal_property_name(const char* name, size_t namelen)
 {
     size_t i;
     if (namelen >= PROP_NAME_MAX) return false;
     if (namelen < 1) return false;
     if (name[0] == '.') return false;
     if (name[namelen - 1] == '.') return false;

     /* Only allow alphanumeric, plus '.', '-', or '_' */
     /* Don't allow ".." to appear in a property name */
     for (i = 0; i < namelen; i++) {
         if (name[i] == '.') {
             // i=0 is guaranteed to never have a dot. See above.
             if (name[i-1] == '.') return false;
             continue;
         }
         if (name[i] == '_' || name[i] == '-') continue;
         if (name[i] >= 'a' && name[i] <= 'z') continue;
         if (name[i] >= 'A' && name[i] <= 'Z') continue;
         if (name[i] >= '0' && name[i] <= '9') continue;
         return false;
     }

     return true;
 }

 static int property_set_impl(const char* name, const char* value) {
     size_t namelen = strlen(name);
     size_t valuelen = strlen(value);

     if (!is_legal_property_name(name, namelen)) return -1;
     if (valuelen >= PROP_VALUE_MAX) return -1;

     if (strcmp("selinux.reload_policy", name) == 0 && strcmp("1", value) == 0) {
         if (selinux_reload_policy() != 0) {
             ERROR("Failed to reload policy\n");
         }
     } else if (strcmp("selinux.restorecon_recursive", name) == 0 && valuelen > 0) {
         if (restorecon_recursive(value) != 0) {
             ERROR("Failed to restorecon_recursive %s\n", value);
         }
     }

     prop_info* 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;

         __system_property_update(pi, value, valuelen);
     } else {
         int rc = __system_property_add(name, namelen, value, valuelen);
         if (rc < 0) {
             return rc;
         }
     }
     /* 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;
 }

 int property_set(const char* name, const char* value) {
     int rc = property_set_impl(name, value);
     if (rc == -1) {
         ERROR("property_set(\"%s\", \"%s\") failed\n", name, value);
     }
     return rc;
 }

 static void handle_property_set_fd()
 {
     prop_msg msg;
     int s;
     int r;
     struct ucred cr;
     struct sockaddr_un addr;
     socklen_t addr_size = sizeof(addr);
     socklen_t cr_size = sizeof(cr);
     char * source_ctx = NULL;
     struct pollfd ufds[1];
     const int timeout_ms = 2 * 1000;  /* Default 2 sec timeout for caller to send property. */
     int nr;

     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 receive socket options\n");
         return;
     }

     ufds[0].fd = s;
     ufds[0].events = POLLIN;
     ufds[0].revents = 0;
     nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
     if (nr == 0) {
         ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
         close(s);
         return;
     } else if (nr < 0) {
         ERROR("sys_prop: error waiting for uid=%d to send property message: %s\n", cr.uid, strerror(errno));
         close(s);
         return;
     }

     r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
     if(r != sizeof(prop_msg)) {
         ERROR("sys_prop: mis-match msg size received: %d expected: %zu: %s\n",
               r, sizeof(prop_msg), strerror(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 (!is_legal_property_name(msg.name, strlen(msg.name))) {
             ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
             close(s);
             return;
         }

         getpeercon(s, &source_ctx);

         if(memcmp(msg.name,"ctl.",4) == 0) {
             // Keep the old close-socket-early behavior when handling
             // ctl.* properties.
             close(s);
             if (check_control_mac_perms(msg.value, source_ctx)) {
                 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, source_ctx)) {
                 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);
         }
         freecon(source_ctx);
         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_from_file(const char *, const char *);

 /*
  * Filter is used to decide which properties to load: NULL loads all keys,
  * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
  */
 static void load_properties(char *data, const char *filter)
 {
     char *key, *value, *eol, *sol, *tmp, *fn;
     size_t flen = 0;

     if (filter) {
         flen = strlen(filter);
     }

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

         while (isspace(*key)) key++;
         if (*key == '#') continue;

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

         if (!strncmp(key, "import ", 7) && flen == 0) {
             fn = key + 7;
             while (isspace(*fn)) fn++;

             key = strchr(fn, ' ');
             if (key) {
                 *key++ = 0;
                 while (isspace(*key)) key++;
             }

             load_properties_from_file(fn, key);

         } else {
             value = strchr(key, '=');
             if (!value) continue;
             *value++ = 0;

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

             while (isspace(*value)) value++;

             if (flen > 0) {
                 if (filter[flen - 1] == '*') {
                     if (strncmp(key, filter, flen - 1)) continue;
                 } else {
                     if (strcmp(key, filter)) continue;
                 }
             }

             property_set(key, value);
         }
     }
 }

 /*
  * Filter is used to decide which properties to load: NULL loads all keys,
  * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
  */
 static void load_properties_from_file(const char* filename, const char* filter) {
     Timer t;
     std::string data;
     if (read_file(filename, &data)) {
         data.push_back('\n');
         load_properties(&data[0], filter);
     }
     NOTICE("(Loading properties from %s took %.2fs.)\n", filename, t.duration());
 }

 static void load_persistent_properties() {
     persistent_properties_loaded = 1;

     std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir);
     if (!dir) {
         ERROR("Unable to open persistent property directory \"%s\": %s\n",
               PERSISTENT_PROPERTY_DIR, strerror(errno));
         return;
     }

     struct dirent* entry;
     while ((entry = readdir(dir.get())) != NULL) {
         if (strncmp("persist.", entry->d_name, strlen("persist."))) {
             continue;
         }
         if (entry->d_type != DT_REG) {
             continue;
         }

         // Open the file and read the property value.
         int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW);
         if (fd == -1) {
             ERROR("Unable to open persistent property file \"%s\": %s\n",
                   entry->d_name, strerror(errno));
             continue;
         }

         struct stat sb;
         if (fstat(fd, &sb) == -1) {
             ERROR("fstat on property file \"%s\" failed: %s\n", entry->d_name, strerror(errno));
             close(fd);
             continue;
         }

         // File must not be accessible to others, be owned by root/root, and
         // not be a hard link to any other file.
         if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || (sb.st_uid != 0) || (sb.st_gid != 0) ||
                 (sb.st_nlink != 1)) {
             ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%u mode=%o)\n",
                   entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
                   (unsigned int)sb.st_nlink, sb.st_mode);
             close(fd);
             continue;
         }

         char value[PROP_VALUE_MAX];
         int 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: %s\n",
                   entry->d_name, strerror(errno));
         }
         close(fd);
     }
 }

 void property_load_boot_defaults() {
     load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
 }

 bool properties_initialized() {
     return property_area_initialized;
 }

 static void load_override_properties() {
     if (ALLOW_LOCAL_PROP_OVERRIDE) {
         char debuggable[PROP_VALUE_MAX];
         int ret = property_get("ro.debuggable", debuggable);
         if (ret && (strcmp(debuggable, "1") == 0)) {
             load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
         }
     }
 }

 /* 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_override_properties();
     /* Read persistent properties after all default values have been loaded. */
     load_persistent_properties();
 }

 void load_recovery_id_prop() {
     char fstab_filename[PROP_VALUE_MAX + sizeof(FSTAB_PREFIX)];
     char propbuf[PROP_VALUE_MAX];
     int ret = property_get("ro.hardware", propbuf);
     if (!ret) {
         ERROR("ro.hardware not set - unable to load recovery id\n");
         return;
     }
     snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX "%s", propbuf);

     std::unique_ptr<fstab, void(*)(fstab*)> tab(fs_mgr_read_fstab(fstab_filename),
             fs_mgr_free_fstab);
     if (!tab) {
         ERROR("unable to read fstab %s: %s\n", fstab_filename, strerror(errno));
         return;
     }

     fstab_rec* rec = fs_mgr_get_entry_for_mount_point(tab.get(), RECOVERY_MOUNT_POINT);
     if (rec == NULL) {
         ERROR("/recovery not specified in fstab\n");
         return;
     }

     int fd = open(rec->blk_device, O_RDONLY);
     if (fd == -1) {
         ERROR("error opening block device %s: %s\n", rec->blk_device, strerror(errno));
         return;
     }

     boot_img_hdr hdr;
     if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) {
         std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id));
         property_set("ro.recovery_id", hex.c_str());
     } else {
         ERROR("error reading /recovery: %s\n", strerror(errno));
     }

     close(fd);
 }

 void load_system_props() {
     load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
     load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
     load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
     load_recovery_id_prop();
 }

 void start_property_service() {
     property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
                                     0666, 0, 0, NULL);
     if (property_set_fd == -1) {
         ERROR("start_property_service socket creation failed: %s\n", strerror(errno));
         exit(1);
     }

     listen(property_set_fd, 8);

     register_epoll_handler(property_set_fd, handle_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 <sys/poll.h>

	#include <memory>

	#include <cutils/misc.h>
	#include <cutils/sockets.h>
	#include <cutils/multiuser.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 <private/android_filesystem_config.h>

	#include <selinux/selinux.h>
	#include <selinux/label.h>

	#include <fs_mgr.h>
	#include <base/file.h>
	#include "bootimg.h"

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

	#define PERSISTENT_PROPERTY_DIR "/data/property"
	#define FSTAB_PREFIX "/fstab."
	#define RECOVERY_MOUNT_POINT "/recovery"

	static int persistent_properties_loaded = 0;
	static bool property_area_initialized = false;

	static int property_set_fd = -1;

	struct workspace {
	size_t size;
	int fd;
	};

	static workspace pa_workspace;

	void property_init() {
	if (property_area_initialized) {
	return;
	}

	property_area_initialized = true;

	if (__system_property_area_init()) {
	return;
	}

	pa_workspace.size = 0;
	pa_workspace.fd = open(PROP_FILENAME, O_RDONLY \| O_NOFOLLOW \| O_CLOEXEC);
	if (pa_workspace.fd == -1) {
	ERROR("Failed to open %s: %s\n", PROP_FILENAME, strerror(errno));
	return;
	}
	}

	static int check_mac_perms(const char name, char sctx)
	{
	if (is_selinux_enabled() <= 0)
	return 1;

	char *tctx = NULL;
	int result = 0;

	if (!sctx)
	goto err;

	if (!sehandle_prop)
	goto err;

	if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
	goto err;

	if (selinux_check_access(sctx, tctx, "property_service", "set", (void*) name) == 0)
	result = 1;

	freecon(tctx);
	err:
	return result;
	}

	static int check_control_mac_perms(const char name, char sctx)
	{
	/*
	* Create a name prefix out of ctl.<service name>
	* The new prefix allows the use of the existing
	* property service backend labeling while avoiding
	* mislabels based on true property prefixes.
	*/
	char ctl_name[PROP_VALUE_MAX+4];
	int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);

	if (ret < 0 \|\| (size_t) ret >= sizeof(ctl_name))
	return 0;

	return check_mac_perms(ctl_name, sctx);
	}

	/*
	* Checks permissions for setting system properties.
	* Returns 1 if uid allowed, 0 otherwise.
	*/
	static int check_perms(const char name, char sctx)
	{
	if(!strncmp(name, "ro.", 3))
	name +=3;

	return check_mac_perms(name, sctx);
	}

	int __property_get(const char name, char value)
	{
	return __system_property_get(name, value);
	}

	static void write_persistent_property(const char name, const char value)
	{
	char tempPath[PATH_MAX];
	char path[PATH_MAX];
	int fd;

	snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
	fd = mkstemp(tempPath);
	if (fd < 0) {
	ERROR("Unable to write persistent property to temp file %s: %s\n", tempPath, strerror(errno));
	return;
	}
	write(fd, value, strlen(value));
	fsync(fd);
	close(fd);

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

	static bool is_legal_property_name(const char* name, size_t namelen)
	{
	size_t i;
	if (namelen >= PROP_NAME_MAX) return false;
	if (namelen < 1) return false;
	if (name[0] == '.') return false;
	if (name[namelen - 1] == '.') return false;

	/* Only allow alphanumeric, plus '.', '-', or '_' */
	/* Don't allow ".." to appear in a property name */
	for (i = 0; i < namelen; i++) {
	if (name[i] == '.') {
	// i=0 is guaranteed to never have a dot. See above.
	if (name[i-1] == '.') return false;
	continue;
	}
	if (name[i] == '_' \|\| name[i] == '-') continue;
	if (name[i] >= 'a' && name[i] <= 'z') continue;
	if (name[i] >= 'A' && name[i] <= 'Z') continue;
	if (name[i] >= '0' && name[i] <= '9') continue;
	return false;
	}

	return true;
	}

	static int property_set_impl(const char* name, const char* value) {
	size_t namelen = strlen(name);
	size_t valuelen = strlen(value);

	if (!is_legal_property_name(name, namelen)) return -1;
	if (valuelen >= PROP_VALUE_MAX) return -1;

	if (strcmp("selinux.reload_policy", name) == 0 && strcmp("1", value) == 0) {
	if (selinux_reload_policy() != 0) {
	ERROR("Failed to reload policy\n");
	}
	} else if (strcmp("selinux.restorecon_recursive", name) == 0 && valuelen > 0) {
	if (restorecon_recursive(value) != 0) {
	ERROR("Failed to restorecon_recursive %s\n", value);
	}
	}

	prop_info* 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;

	__system_property_update(pi, value, valuelen);
	} else {
	int rc = __system_property_add(name, namelen, value, valuelen);
	if (rc < 0) {
	return rc;
	}
	}
	/* 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;
	}

	int property_set(const char* name, const char* value) {
	int rc = property_set_impl(name, value);
	if (rc == -1) {
	ERROR("property_set(\"%s\", \"%s\") failed\n", name, value);
	}
	return rc;
	}

	static void handle_property_set_fd()
	{
	prop_msg msg;
	int s;
	int r;
	struct ucred cr;
	struct sockaddr_un addr;
	socklen_t addr_size = sizeof(addr);
	socklen_t cr_size = sizeof(cr);
	char * source_ctx = NULL;
	struct pollfd ufds[1];
	const int timeout_ms = 2 * 1000; /* Default 2 sec timeout for caller to send property. */
	int nr;

	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 receive socket options\n");
	return;
	}

	ufds[0].fd = s;
	ufds[0].events = POLLIN;
	ufds[0].revents = 0;
	nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
	if (nr == 0) {
	ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
	close(s);
	return;
	} else if (nr < 0) {
	ERROR("sys_prop: error waiting for uid=%d to send property message: %s\n", cr.uid, strerror(errno));
	close(s);
	return;
	}

	r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
	if(r != sizeof(prop_msg)) {
	ERROR("sys_prop: mis-match msg size received: %d expected: %zu: %s\n",
	r, sizeof(prop_msg), strerror(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 (!is_legal_property_name(msg.name, strlen(msg.name))) {
	ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
	close(s);
	return;
	}

	getpeercon(s, &source_ctx);

	if(memcmp(msg.name,"ctl.",4) == 0) {
	// Keep the old close-socket-early behavior when handling
	// ctl.* properties.
	close(s);
	if (check_control_mac_perms(msg.value, source_ctx)) {
	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, source_ctx)) {
	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);
	}
	freecon(source_ctx);
	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_from_file(const char , const char );

	/*
	* Filter is used to decide which properties to load: NULL loads all keys,
	* "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
	*/
	static void load_properties(char data, const char filter)
	{
	char key, value, eol, sol, tmp, fn;
	size_t flen = 0;

	if (filter) {
	flen = strlen(filter);
	}

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

	while (isspace(*key)) key++;
	if (*key == '#') continue;

	tmp = eol - 2;
	while ((tmp > key) && isspace(tmp)) tmp-- = 0;

	if (!strncmp(key, "import ", 7) && flen == 0) {
	fn = key + 7;
	while (isspace(*fn)) fn++;

	key = strchr(fn, ' ');
	if (key) {
	*key++ = 0;
	while (isspace(*key)) key++;
	}

	load_properties_from_file(fn, key);

	} else {
	value = strchr(key, '=');
	if (!value) continue;
	*value++ = 0;

	tmp = value - 2;
	while ((tmp > key) && isspace(tmp)) tmp-- = 0;

	while (isspace(*value)) value++;

	if (flen > 0) {
	if (filter[flen - 1] == '*') {
	if (strncmp(key, filter, flen - 1)) continue;
	} else {
	if (strcmp(key, filter)) continue;
	}
	}

	property_set(key, value);
	}
	}
	}

	/*
	* Filter is used to decide which properties to load: NULL loads all keys,
	* "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
	*/
	static void load_properties_from_file(const char* filename, const char* filter) {
	Timer t;
	std::string data;
	if (read_file(filename, &data)) {
	data.push_back('\n');
	load_properties(&data[0], filter);
	}
	NOTICE("(Loading properties from %s took %.2fs.)\n", filename, t.duration());
	}

	static void load_persistent_properties() {
	persistent_properties_loaded = 1;

	std::unique_ptr<DIR, int()(DIR)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir);
	if (!dir) {
	ERROR("Unable to open persistent property directory \"%s\": %s\n",
	PERSISTENT_PROPERTY_DIR, strerror(errno));
	return;
	}

	struct dirent* entry;
	while ((entry = readdir(dir.get())) != NULL) {
	if (strncmp("persist.", entry->d_name, strlen("persist."))) {
	continue;
	}
	if (entry->d_type != DT_REG) {
	continue;
	}

	// Open the file and read the property value.
	int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY \| O_NOFOLLOW);
	if (fd == -1) {
	ERROR("Unable to open persistent property file \"%s\": %s\n",
	entry->d_name, strerror(errno));
	continue;
	}

	struct stat sb;
	if (fstat(fd, &sb) == -1) {
	ERROR("fstat on property file \"%s\" failed: %s\n", entry->d_name, strerror(errno));
	close(fd);
	continue;
	}

	// File must not be accessible to others, be owned by root/root, and
	// not be a hard link to any other file.
	if (((sb.st_mode & (S_IRWXG \| S_IRWXO)) != 0) \|\| (sb.st_uid != 0) \|\| (sb.st_gid != 0) \|\|
	(sb.st_nlink != 1)) {
	ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%u mode=%o)\n",
	entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
	(unsigned int)sb.st_nlink, sb.st_mode);
	close(fd);
	continue;
	}

	char value[PROP_VALUE_MAX];
	int 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: %s\n",
	entry->d_name, strerror(errno));
	}
	close(fd);
	}
	}

	void property_load_boot_defaults() {
	load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
	}

	bool properties_initialized() {
	return property_area_initialized;
	}

	static void load_override_properties() {
	if (ALLOW_LOCAL_PROP_OVERRIDE) {
	char debuggable[PROP_VALUE_MAX];
	int ret = property_get("ro.debuggable", debuggable);
	if (ret && (strcmp(debuggable, "1") == 0)) {
	load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
	}
	}
	}

	/* 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_override_properties();
	/* Read persistent properties after all default values have been loaded. */
	load_persistent_properties();
	}

	void load_recovery_id_prop() {
	char fstab_filename[PROP_VALUE_MAX + sizeof(FSTAB_PREFIX)];
	char propbuf[PROP_VALUE_MAX];
	int ret = property_get("ro.hardware", propbuf);
	if (!ret) {
	ERROR("ro.hardware not set - unable to load recovery id\n");
	return;
	}
	snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX "%s", propbuf);

	std::unique_ptr<fstab, void()(fstab)> tab(fs_mgr_read_fstab(fstab_filename),
	fs_mgr_free_fstab);
	if (!tab) {
	ERROR("unable to read fstab %s: %s\n", fstab_filename, strerror(errno));
	return;
	}

	fstab_rec* rec = fs_mgr_get_entry_for_mount_point(tab.get(), RECOVERY_MOUNT_POINT);
	if (rec == NULL) {
	ERROR("/recovery not specified in fstab\n");
	return;
	}

	int fd = open(rec->blk_device, O_RDONLY);
	if (fd == -1) {
	ERROR("error opening block device %s: %s\n", rec->blk_device, strerror(errno));
	return;
	}

	boot_img_hdr hdr;
	if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) {
	std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id));
	property_set("ro.recovery_id", hex.c_str());
	} else {
	ERROR("error reading /recovery: %s\n", strerror(errno));
	}

	close(fd);
	}

	void load_system_props() {
	load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
	load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
	load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
	load_recovery_id_prop();
	}

	void start_property_service() {
	property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM \| SOCK_CLOEXEC \| SOCK_NONBLOCK,
	0666, 0, 0, NULL);
	if (property_set_fd == -1) {
	ERROR("start_property_service socket creation failed: %s\n", strerror(errno));
	exit(1);
	}

	listen(property_set_fd, 8);

	register_epoll_handler(property_set_fd, handle_property_set_fd);
	}