| /* |
| * Copyright (C) 2008 The Android Open Source Project |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
| * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <stddef.h> |
| #include <errno.h> |
| #include <poll.h> |
| #include <fcntl.h> |
| #include <stdbool.h> |
| |
| #include <sys/mman.h> |
| |
| #include <sys/socket.h> |
| #include <sys/un.h> |
| #include <sys/select.h> |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| #include <netinet/in.h> |
| #include <unistd.h> |
| |
| #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_ |
| #include <sys/_system_properties.h> |
| |
| #include <sys/atomics.h> |
| |
| static const char property_service_socket[] = "/dev/socket/" PROP_SERVICE_NAME; |
| |
| static unsigned dummy_props = 0; |
| |
| prop_area *__system_property_area__ = (void*) &dummy_props; |
| |
| static int get_fd_from_env(void) |
| { |
| char *env = getenv("ANDROID_PROPERTY_WORKSPACE"); |
| |
| if (!env) { |
| return -1; |
| } |
| |
| return atoi(env); |
| } |
| |
| int __system_properties_init(void) |
| { |
| bool fromFile = true; |
| int result = -1; |
| |
| if(__system_property_area__ != ((void*) &dummy_props)) { |
| return 0; |
| } |
| |
| int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW); |
| |
| if ((fd < 0) && (errno == ENOENT)) { |
| /* |
| * For backwards compatibility, if the file doesn't |
| * exist, we use the environment to get the file descriptor. |
| * For security reasons, we only use this backup if the kernel |
| * returns ENOENT. We don't want to use the backup if the kernel |
| * returns other errors such as ENOMEM or ENFILE, since it |
| * might be possible for an external program to trigger this |
| * condition. |
| */ |
| fd = get_fd_from_env(); |
| fromFile = false; |
| } |
| |
| if (fd < 0) { |
| return -1; |
| } |
| |
| struct stat fd_stat; |
| if (fstat(fd, &fd_stat) < 0) { |
| goto cleanup; |
| } |
| |
| if ((fd_stat.st_uid != 0) |
| || (fd_stat.st_gid != 0) |
| || ((fd_stat.st_mode & (S_IWGRP | S_IWOTH)) != 0)) { |
| goto cleanup; |
| } |
| |
| prop_area *pa = mmap(NULL, fd_stat.st_size, PROT_READ, MAP_SHARED, fd, 0); |
| |
| if (pa == MAP_FAILED) { |
| goto cleanup; |
| } |
| |
| if((pa->magic != PROP_AREA_MAGIC) || (pa->version != PROP_AREA_VERSION)) { |
| munmap(pa, fd_stat.st_size); |
| goto cleanup; |
| } |
| |
| __system_property_area__ = pa; |
| result = 0; |
| |
| cleanup: |
| if (fromFile) { |
| close(fd); |
| } |
| |
| return result; |
| } |
| |
| const prop_info *__system_property_find_nth(unsigned n) |
| { |
| prop_area *pa = __system_property_area__; |
| |
| if(n >= pa->count) { |
| return 0; |
| } else { |
| return TOC_TO_INFO(pa, pa->toc[n]); |
| } |
| } |
| |
| const prop_info *__system_property_find(const char *name) |
| { |
| prop_area *pa = __system_property_area__; |
| unsigned count = pa->count; |
| unsigned *toc = pa->toc; |
| unsigned len = strlen(name); |
| prop_info *pi; |
| |
| while(count--) { |
| unsigned entry = *toc++; |
| if(TOC_NAME_LEN(entry) != len) continue; |
| |
| pi = TOC_TO_INFO(pa, entry); |
| if(memcmp(name, pi->name, len)) continue; |
| |
| return pi; |
| } |
| |
| return 0; |
| } |
| |
| int __system_property_read(const prop_info *pi, char *name, char *value) |
| { |
| unsigned serial, len; |
| |
| for(;;) { |
| serial = pi->serial; |
| while(SERIAL_DIRTY(serial)) { |
| __futex_wait((volatile void *)&pi->serial, serial, 0); |
| serial = pi->serial; |
| } |
| len = SERIAL_VALUE_LEN(serial); |
| memcpy(value, pi->value, len + 1); |
| if(serial == pi->serial) { |
| if(name != 0) { |
| strcpy(name, pi->name); |
| } |
| return len; |
| } |
| } |
| } |
| |
| int __system_property_get(const char *name, char *value) |
| { |
| const prop_info *pi = __system_property_find(name); |
| |
| if(pi != 0) { |
| return __system_property_read(pi, 0, value); |
| } else { |
| value[0] = 0; |
| return 0; |
| } |
| } |
| |
| |
| static int send_prop_msg(prop_msg *msg) |
| { |
| struct pollfd pollfds[1]; |
| struct sockaddr_un addr; |
| socklen_t alen; |
| size_t namelen; |
| int s; |
| int r; |
| int result = -1; |
| |
| s = socket(AF_LOCAL, SOCK_STREAM, 0); |
| if(s < 0) { |
| return result; |
| } |
| |
| memset(&addr, 0, sizeof(addr)); |
| namelen = strlen(property_service_socket); |
| strlcpy(addr.sun_path, property_service_socket, sizeof addr.sun_path); |
| addr.sun_family = AF_LOCAL; |
| alen = namelen + offsetof(struct sockaddr_un, sun_path) + 1; |
| |
| if(TEMP_FAILURE_RETRY(connect(s, (struct sockaddr *) &addr, alen)) < 0) { |
| close(s); |
| return result; |
| } |
| |
| r = TEMP_FAILURE_RETRY(send(s, msg, sizeof(prop_msg), 0)); |
| |
| if(r == sizeof(prop_msg)) { |
| // We successfully wrote to the property server but now we |
| // wait for the property server to finish its work. It |
| // acknowledges its completion by closing the socket so we |
| // poll here (on nothing), waiting for the socket to close. |
| // If you 'adb shell setprop foo bar' you'll see the POLLHUP |
| // once the socket closes. Out of paranoia we cap our poll |
| // at 250 ms. |
| pollfds[0].fd = s; |
| pollfds[0].events = 0; |
| r = TEMP_FAILURE_RETRY(poll(pollfds, 1, 250 /* ms */)); |
| if (r == 1 && (pollfds[0].revents & POLLHUP) != 0) { |
| result = 0; |
| } else { |
| // Ignore the timeout and treat it like a success anyway. |
| // The init process is single-threaded and its property |
| // service is sometimes slow to respond (perhaps it's off |
| // starting a child process or something) and thus this |
| // times out and the caller thinks it failed, even though |
| // it's still getting around to it. So we fake it here, |
| // mostly for ctl.* properties, but we do try and wait 250 |
| // ms so callers who do read-after-write can reliably see |
| // what they've written. Most of the time. |
| // TODO: fix the system properties design. |
| result = 0; |
| } |
| } |
| |
| close(s); |
| return result; |
| } |
| |
| int __system_property_set(const char *key, const char *value) |
| { |
| int err; |
| prop_msg msg; |
| |
| if(key == 0) return -1; |
| if(value == 0) value = ""; |
| if(strlen(key) >= PROP_NAME_MAX) return -1; |
| if(strlen(value) >= PROP_VALUE_MAX) return -1; |
| |
| memset(&msg, 0, sizeof msg); |
| msg.cmd = PROP_MSG_SETPROP; |
| strlcpy(msg.name, key, sizeof msg.name); |
| strlcpy(msg.value, value, sizeof msg.value); |
| |
| err = send_prop_msg(&msg); |
| if(err < 0) { |
| return err; |
| } |
| |
| return 0; |
| } |
| |
| int __system_property_wait(const prop_info *pi) |
| { |
| unsigned n; |
| if(pi == 0) { |
| prop_area *pa = __system_property_area__; |
| n = pa->serial; |
| do { |
| __futex_wait(&pa->serial, n, 0); |
| } while(n == pa->serial); |
| } else { |
| n = pi->serial; |
| do { |
| __futex_wait((volatile void *)&pi->serial, n, 0); |
| } while(n == pi->serial); |
| } |
| return 0; |
| } |