552 lines
15 KiB
C
552 lines
15 KiB
C
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <dirent.h>
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#include <limits.h>
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#include <errno.h>
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#include <cutils/misc.h>
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#include <cutils/sockets.h>
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#include <cutils/multiuser.h>
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#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
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#include <sys/_system_properties.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <sys/select.h>
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <sys/mman.h>
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#include <private/android_filesystem_config.h>
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#include <selinux/selinux.h>
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#include <selinux/label.h>
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#include "property_service.h"
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#include "init.h"
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#include "util.h"
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#include "log.h"
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#define PERSISTENT_PROPERTY_DIR "/data/property"
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static int persistent_properties_loaded = 0;
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static int property_area_inited = 0;
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static int property_set_fd = -1;
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typedef struct {
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size_t size;
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int fd;
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} workspace;
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static int init_workspace(workspace *w, size_t size)
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{
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void *data;
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int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
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if (fd < 0)
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return -1;
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w->size = size;
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w->fd = fd;
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return 0;
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}
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static workspace pa_workspace;
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static int init_property_area(void)
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{
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if (property_area_inited)
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return -1;
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if(__system_property_area_init())
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return -1;
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if(init_workspace(&pa_workspace, 0))
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return -1;
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fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
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property_area_inited = 1;
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return 0;
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}
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static int check_mac_perms(const char *name, char *sctx)
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{
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if (is_selinux_enabled() <= 0)
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return 1;
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char *tctx = NULL;
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const char *class = "property_service";
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const char *perm = "set";
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int result = 0;
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if (!sctx)
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goto err;
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if (!sehandle_prop)
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goto err;
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if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
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goto err;
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if (selinux_check_access(sctx, tctx, class, perm, (void*) name) == 0)
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result = 1;
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freecon(tctx);
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err:
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return result;
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}
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static int check_control_mac_perms(const char *name, char *sctx)
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{
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/*
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* Create a name prefix out of ctl.<service name>
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* The new prefix allows the use of the existing
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* property service backend labeling while avoiding
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* mislabels based on true property prefixes.
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*/
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char ctl_name[PROP_VALUE_MAX+4];
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int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
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if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
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return 0;
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return check_mac_perms(ctl_name, sctx);
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}
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/*
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* Checks permissions for setting system properties.
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* Returns 1 if uid allowed, 0 otherwise.
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*/
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static int check_perms(const char *name, char *sctx)
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{
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int i;
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unsigned int app_id;
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if(!strncmp(name, "ro.", 3))
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name +=3;
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return check_mac_perms(name, sctx);
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}
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int __property_get(const char *name, char *value)
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{
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return __system_property_get(name, value);
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}
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static void write_persistent_property(const char *name, const char *value)
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{
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char tempPath[PATH_MAX];
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char path[PATH_MAX];
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int fd;
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snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
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fd = mkstemp(tempPath);
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if (fd < 0) {
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ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
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return;
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}
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write(fd, value, strlen(value));
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fsync(fd);
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close(fd);
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snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
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if (rename(tempPath, path)) {
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unlink(tempPath);
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ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
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}
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}
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static bool is_legal_property_name(const char* name, size_t namelen)
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{
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size_t i;
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bool previous_was_dot = false;
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if (namelen >= PROP_NAME_MAX) return false;
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if (namelen < 1) return false;
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if (name[0] == '.') return false;
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if (name[namelen - 1] == '.') return false;
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/* Only allow alphanumeric, plus '.', '-', or '_' */
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/* Don't allow ".." to appear in a property name */
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for (i = 0; i < namelen; i++) {
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if (name[i] == '.') {
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if (previous_was_dot == true) return false;
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previous_was_dot = true;
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continue;
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}
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previous_was_dot = false;
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if (name[i] == '_' || name[i] == '-') continue;
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if (name[i] >= 'a' && name[i] <= 'z') continue;
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if (name[i] >= 'A' && name[i] <= 'Z') continue;
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if (name[i] >= '0' && name[i] <= '9') continue;
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return false;
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}
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return true;
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}
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int property_set(const char *name, const char *value)
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{
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prop_info *pi;
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int ret;
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size_t namelen = strlen(name);
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size_t valuelen = strlen(value);
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if (!is_legal_property_name(name, namelen)) return -1;
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if (valuelen >= PROP_VALUE_MAX) return -1;
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pi = (prop_info*) __system_property_find(name);
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if(pi != 0) {
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/* ro.* properties may NEVER be modified once set */
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if(!strncmp(name, "ro.", 3)) return -1;
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__system_property_update(pi, value, valuelen);
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} else {
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ret = __system_property_add(name, namelen, value, valuelen);
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if (ret < 0) {
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ERROR("Failed to set '%s'='%s'\n", name, value);
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return ret;
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}
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}
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/* If name starts with "net." treat as a DNS property. */
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if (strncmp("net.", name, strlen("net.")) == 0) {
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if (strcmp("net.change", name) == 0) {
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return 0;
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}
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/*
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* The 'net.change' property is a special property used track when any
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* 'net.*' property name is updated. It is _ONLY_ updated here. Its value
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* contains the last updated 'net.*' property.
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*/
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property_set("net.change", name);
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} else if (persistent_properties_loaded &&
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strncmp("persist.", name, strlen("persist.")) == 0) {
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/*
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* Don't write properties to disk until after we have read all default properties
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* to prevent them from being overwritten by default values.
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*/
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write_persistent_property(name, value);
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} else if (strcmp("selinux.reload_policy", name) == 0 &&
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strcmp("1", value) == 0) {
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selinux_reload_policy();
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}
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property_changed(name, value);
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return 0;
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}
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void handle_property_set_fd()
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{
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prop_msg msg;
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int s;
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int r;
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int res;
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struct ucred cr;
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struct sockaddr_un addr;
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socklen_t addr_size = sizeof(addr);
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socklen_t cr_size = sizeof(cr);
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char * source_ctx = NULL;
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if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
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return;
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}
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/* Check socket options here */
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if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
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close(s);
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ERROR("Unable to receive socket options\n");
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return;
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}
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r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
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if(r != sizeof(prop_msg)) {
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ERROR("sys_prop: mis-match msg size received: %d expected: %zu errno: %d\n",
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r, sizeof(prop_msg), errno);
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close(s);
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return;
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}
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switch(msg.cmd) {
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case PROP_MSG_SETPROP:
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msg.name[PROP_NAME_MAX-1] = 0;
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msg.value[PROP_VALUE_MAX-1] = 0;
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if (!is_legal_property_name(msg.name, strlen(msg.name))) {
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ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
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close(s);
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return;
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}
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getpeercon(s, &source_ctx);
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if(memcmp(msg.name,"ctl.",4) == 0) {
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// Keep the old close-socket-early behavior when handling
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// ctl.* properties.
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close(s);
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if (check_control_mac_perms(msg.value, source_ctx)) {
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handle_control_message((char*) msg.name + 4, (char*) msg.value);
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} else {
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ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
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msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
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}
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} else {
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if (check_perms(msg.name, source_ctx)) {
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property_set((char*) msg.name, (char*) msg.value);
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} else {
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ERROR("sys_prop: permission denied uid:%d name:%s\n",
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cr.uid, msg.name);
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}
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// Note: bionic's property client code assumes that the
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// property server will not close the socket until *AFTER*
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// the property is written to memory.
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close(s);
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}
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freecon(source_ctx);
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break;
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default:
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close(s);
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break;
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}
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}
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void get_property_workspace(int *fd, int *sz)
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{
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*fd = pa_workspace.fd;
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*sz = pa_workspace.size;
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}
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static void load_properties_from_file(const char *, const char *);
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/*
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* Filter is used to decide which properties to load: NULL loads all keys,
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* "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
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*/
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static void load_properties(char *data, const char *filter)
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{
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char *key, *value, *eol, *sol, *tmp, *fn;
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size_t flen = 0;
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if (filter) {
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flen = strlen(filter);
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}
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sol = data;
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while ((eol = strchr(sol, '\n'))) {
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key = sol;
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*eol++ = 0;
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sol = eol;
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while (isspace(*key)) key++;
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if (*key == '#') continue;
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tmp = eol - 2;
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while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
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if (!strncmp(key, "import ", 7) && flen == 0) {
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fn = key + 7;
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while (isspace(*fn)) fn++;
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key = strchr(fn, ' ');
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if (key) {
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*key++ = 0;
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while (isspace(*key)) key++;
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}
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load_properties_from_file(fn, key);
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} else {
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value = strchr(key, '=');
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if (!value) continue;
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*value++ = 0;
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tmp = value - 2;
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while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
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while (isspace(*value)) value++;
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if (flen > 0) {
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if (filter[flen - 1] == '*') {
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if (strncmp(key, filter, flen - 1)) continue;
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} else {
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if (strcmp(key, filter)) continue;
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}
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}
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property_set(key, value);
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}
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}
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}
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/*
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* Filter is used to decide which properties to load: NULL loads all keys,
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* "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
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*/
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static void load_properties_from_file(const char *fn, const char *filter)
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{
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char *data;
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unsigned sz;
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data = read_file(fn, &sz);
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if(data != 0) {
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load_properties(data, filter);
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free(data);
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}
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}
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static void load_persistent_properties()
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{
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DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
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int dir_fd;
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struct dirent* entry;
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char value[PROP_VALUE_MAX];
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int fd, length;
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struct stat sb;
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if (dir) {
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dir_fd = dirfd(dir);
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while ((entry = readdir(dir)) != NULL) {
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if (strncmp("persist.", entry->d_name, strlen("persist.")))
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continue;
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#if HAVE_DIRENT_D_TYPE
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if (entry->d_type != DT_REG)
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continue;
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#endif
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/* open the file and read the property value */
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fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
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if (fd < 0) {
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ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
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entry->d_name, errno);
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continue;
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}
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if (fstat(fd, &sb) < 0) {
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ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
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close(fd);
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continue;
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}
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// File must not be accessible to others, be owned by root/root, and
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// not be a hard link to any other file.
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if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
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|| (sb.st_uid != 0)
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|| (sb.st_gid != 0)
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|| (sb.st_nlink != 1)) {
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ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%d mode=%o)\n",
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entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
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sb.st_nlink, sb.st_mode);
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close(fd);
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continue;
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}
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length = read(fd, value, sizeof(value) - 1);
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if (length >= 0) {
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value[length] = 0;
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property_set(entry->d_name, value);
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} else {
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ERROR("Unable to read persistent property file %s errno: %d\n",
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entry->d_name, errno);
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}
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close(fd);
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}
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closedir(dir);
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} else {
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ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
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}
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persistent_properties_loaded = 1;
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}
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void property_init(void)
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{
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init_property_area();
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}
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void property_load_boot_defaults(void)
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{
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load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
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}
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int properties_inited(void)
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{
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return property_area_inited;
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}
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static void load_override_properties() {
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#ifdef ALLOW_LOCAL_PROP_OVERRIDE
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char debuggable[PROP_VALUE_MAX];
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int ret;
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ret = property_get("ro.debuggable", debuggable);
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if (ret && (strcmp(debuggable, "1") == 0)) {
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load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
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}
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#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
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}
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/* When booting an encrypted system, /data is not mounted when the
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* property service is started, so any properties stored there are
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* not loaded. Vold triggers init to load these properties once it
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* has mounted /data.
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*/
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void load_persist_props(void)
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{
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load_override_properties();
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/* Read persistent properties after all default values have been loaded. */
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load_persistent_properties();
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}
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void load_all_props(void)
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{
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load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
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load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT, NULL);
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load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
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load_override_properties();
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/* Read persistent properties after all default values have been loaded. */
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load_persistent_properties();
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}
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void start_property_service(void)
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{
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int fd;
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fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0, NULL);
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if(fd < 0) return;
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fcntl(fd, F_SETFD, FD_CLOEXEC);
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fcntl(fd, F_SETFL, O_NONBLOCK);
|
|
|
|
listen(fd, 8);
|
|
property_set_fd = fd;
|
|
}
|
|
|
|
int get_property_set_fd()
|
|
{
|
|
return property_set_fd;
|
|
}
|