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platform_system_core/liblog/properties.c

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/*
** Copyright 2014, 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 <ctype.h>
#include <pthread.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
#include <unistd.h>
#include <private/android_logger.h>
#include "log_portability.h"
static pthread_mutex_t lock_loggable = PTHREAD_MUTEX_INITIALIZER;
static int lock() {
/*
* If we trigger a signal handler in the middle of locked activity and the
* signal handler logs a message, we could get into a deadlock state.
*/
/*
* Any contention, and we can turn around and use the non-cached method
* in less time than the system call associated with a mutex to deal with
* the contention.
*/
return pthread_mutex_trylock(&lock_loggable);
}
static void unlock() {
pthread_mutex_unlock(&lock_loggable);
}
struct cache {
const prop_info* pinfo;
uint32_t serial;
};
struct cache_char {
struct cache cache;
unsigned char c;
};
static int check_cache(struct cache* cache) {
return cache->pinfo && __system_property_serial(cache->pinfo) != cache->serial;
}
#define BOOLEAN_TRUE 0xFF
#define BOOLEAN_FALSE 0xFE
static void refresh_cache(struct cache_char* cache, const char* key) {
char buf[PROP_VALUE_MAX];
if (!cache->cache.pinfo) {
cache->cache.pinfo = __system_property_find(key);
if (!cache->cache.pinfo) {
return;
}
}
cache->cache.serial = __system_property_serial(cache->cache.pinfo);
__system_property_read(cache->cache.pinfo, 0, buf);
switch (buf[0]) {
case 't':
case 'T':
cache->c = strcasecmp(buf + 1, "rue") ? buf[0] : BOOLEAN_TRUE;
break;
case 'f':
case 'F':
cache->c = strcasecmp(buf + 1, "alse") ? buf[0] : BOOLEAN_FALSE;
break;
default:
cache->c = buf[0];
}
}
static int __android_log_level(const char* tag, size_t len, int default_prio) {
/* sizeof() is used on this array below */
static const char log_namespace[] = "persist.log.tag.";
static const size_t base_offset = 8; /* skip "persist." */
/* calculate the size of our key temporary buffer */
const size_t taglen = tag ? len : 0;
/* sizeof(log_namespace) = strlen(log_namespace) + 1 */
char key[sizeof(log_namespace) + taglen];
char* kp;
size_t i;
char c = 0;
/*
* Single layer cache of four properties. Priorities are:
* log.tag.<tag>
* persist.log.tag.<tag>
* log.tag
* persist.log.tag
* Where the missing tag matches all tags and becomes the
* system global default. We do not support ro.log.tag* .
*/
static char* last_tag;
static size_t last_tag_len;
static uint32_t global_serial;
/* some compilers erroneously see uninitialized use. !not_locked */
uint32_t current_global_serial = 0;
static struct cache_char tag_cache[2];
static struct cache_char global_cache[2];
int change_detected;
int global_change_detected;
int not_locked;
strcpy(key, log_namespace);
global_change_detected = change_detected = not_locked = lock();
if (!not_locked) {
/*
* check all known serial numbers to changes.
*/
for (i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
if (check_cache(&tag_cache[i].cache)) {
change_detected = 1;
}
}
for (i = 0; i < (sizeof(global_cache) / sizeof(global_cache[0])); ++i) {
if (check_cache(&global_cache[i].cache)) {
global_change_detected = 1;
}
}
current_global_serial = __system_property_area_serial();
if (current_global_serial != global_serial) {
change_detected = 1;
global_change_detected = 1;
}
}
if (taglen) {
int local_change_detected = change_detected;
if (!not_locked) {
if (!last_tag || !last_tag[0] || (last_tag[0] != tag[0]) ||
strncmp(last_tag + 1, tag + 1, last_tag_len - 1)) {
/* invalidate log.tag.<tag> cache */
for (i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
tag_cache[i].cache.pinfo = NULL;
tag_cache[i].c = '\0';
}
if (last_tag) last_tag[0] = '\0';
local_change_detected = 1;
}
if (!last_tag || !last_tag[0]) {
if (!last_tag) {
last_tag = calloc(1, len + 1);
last_tag_len = 0;
if (last_tag) last_tag_len = len + 1;
} else if (len >= last_tag_len) {
last_tag = realloc(last_tag, len + 1);
last_tag_len = 0;
if (last_tag) last_tag_len = len + 1;
}
if (last_tag) {
strncpy(last_tag, tag, len);
last_tag[len] = '\0';
}
}
}
strncpy(key + sizeof(log_namespace) - 1, tag, len);
key[sizeof(log_namespace) - 1 + len] = '\0';
kp = key;
for (i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
struct cache_char* cache = &tag_cache[i];
struct cache_char temp_cache;
if (not_locked) {
temp_cache.cache.pinfo = NULL;
temp_cache.c = '\0';
cache = &temp_cache;
}
if (local_change_detected) {
refresh_cache(cache, kp);
}
if (cache->c) {
c = cache->c;
break;
}
kp = key + base_offset;
}
}
switch (toupper(c)) { /* if invalid, resort to global */
case 'V':
case 'D':
case 'I':
case 'W':
case 'E':
case 'F': /* Not officially supported */
case 'A':
case 'S':
case BOOLEAN_FALSE: /* Not officially supported */
break;
default:
/* clear '.' after log.tag */
key[sizeof(log_namespace) - 2] = '\0';
kp = key;
for (i = 0; i < (sizeof(global_cache) / sizeof(global_cache[0])); ++i) {
struct cache_char* cache = &global_cache[i];
struct cache_char temp_cache;
if (not_locked) {
temp_cache = *cache;
if (temp_cache.cache.pinfo != cache->cache.pinfo) { /* check atomic */
temp_cache.cache.pinfo = NULL;
temp_cache.c = '\0';
}
cache = &temp_cache;
}
if (global_change_detected) {
refresh_cache(cache, kp);
}
if (cache->c) {
c = cache->c;
break;
}
kp = key + base_offset;
}
break;
}
if (!not_locked) {
global_serial = current_global_serial;
unlock();
}
switch (toupper(c)) {
/* clang-format off */
case 'V': return ANDROID_LOG_VERBOSE;
case 'D': return ANDROID_LOG_DEBUG;
case 'I': return ANDROID_LOG_INFO;
case 'W': return ANDROID_LOG_WARN;
case 'E': return ANDROID_LOG_ERROR;
case 'F': /* FALLTHRU */ /* Not officially supported */
case 'A': return ANDROID_LOG_FATAL;
case BOOLEAN_FALSE: /* FALLTHRU */ /* Not Officially supported */
case 'S': return -1; /* ANDROID_LOG_SUPPRESS */
/* clang-format on */
}
return default_prio;
}
LIBLOG_ABI_PUBLIC int __android_log_is_loggable_len(int prio, const char* tag,
size_t len,
int default_prio) {
int logLevel = __android_log_level(tag, len, default_prio);
return logLevel >= 0 && prio >= logLevel;
}
LIBLOG_ABI_PUBLIC int __android_log_is_loggable(int prio, const char* tag,
int default_prio) {
int logLevel =
__android_log_level(tag, (tag && *tag) ? strlen(tag) : 0, default_prio);
return logLevel >= 0 && prio >= logLevel;
}
LIBLOG_ABI_PUBLIC int __android_log_is_debuggable() {
static uint32_t serial;
static struct cache_char tag_cache;
static const char key[] = "ro.debuggable";
int ret;
if (tag_cache.c) { /* ro property does not change after set */
ret = tag_cache.c == '1';
} else if (lock()) {
struct cache_char temp_cache = { { NULL, -1 }, '\0' };
refresh_cache(&temp_cache, key);
ret = temp_cache.c == '1';
} else {
int change_detected = check_cache(&tag_cache.cache);
uint32_t current_serial = __system_property_area_serial();
if (current_serial != serial) {
change_detected = 1;
}
if (change_detected) {
refresh_cache(&tag_cache, key);
serial = current_serial;
}
ret = tag_cache.c == '1';
unlock();
}
return ret;
}
/*
* For properties that are read often, but generally remain constant.
* Since a change is rare, we will accept a trylock failure gracefully.
* Use a separate lock from is_loggable to keep contention down b/25563384.
*/
struct cache2_char {
pthread_mutex_t lock;
uint32_t serial;
const char* key_persist;
struct cache_char cache_persist;
const char* key_ro;
struct cache_char cache_ro;
unsigned char (*const evaluate)(const struct cache2_char* self);
};
static inline unsigned char do_cache2_char(struct cache2_char* self) {
uint32_t current_serial;
int change_detected;
unsigned char c;
if (pthread_mutex_trylock(&self->lock)) {
/* We are willing to accept some race in this context */
return self->evaluate(self);
}
change_detected = check_cache(&self->cache_persist.cache) ||
check_cache(&self->cache_ro.cache);
current_serial = __system_property_area_serial();
if (current_serial != self->serial) {
change_detected = 1;
}
if (change_detected) {
refresh_cache(&self->cache_persist, self->key_persist);
refresh_cache(&self->cache_ro, self->key_ro);
self->serial = current_serial;
}
c = self->evaluate(self);
pthread_mutex_unlock(&self->lock);
return c;
}
static unsigned char evaluate_persist_ro(const struct cache2_char* self) {
unsigned char c = self->cache_persist.c;
if (c) {
return c;
}
return self->cache_ro.c;
}
/*
* Timestamp state generally remains constant, but can change at any time
* to handle developer requirements.
*/
LIBLOG_ABI_PUBLIC clockid_t android_log_clockid() {
static struct cache2_char clockid = {
PTHREAD_MUTEX_INITIALIZER, 0,
"persist.logd.timestamp", { { NULL, -1 }, '\0' },
"ro.logd.timestamp", { { NULL, -1 }, '\0' },
evaluate_persist_ro
};
return (tolower(do_cache2_char(&clockid)) == 'm') ? CLOCK_MONOTONIC
: CLOCK_REALTIME;
}
/*
* Security state generally remains constant, but the DO must be able
* to turn off logging should it become spammy after an attack is detected.
*/
static unsigned char evaluate_security(const struct cache2_char* self) {
unsigned char c = self->cache_ro.c;
return (c != BOOLEAN_FALSE) && c && (self->cache_persist.c == BOOLEAN_TRUE);
}
LIBLOG_ABI_PUBLIC int __android_log_security() {
static struct cache2_char security = {
PTHREAD_MUTEX_INITIALIZER, 0,
"persist.logd.security", { { NULL, -1 }, BOOLEAN_FALSE },
"ro.device_owner", { { NULL, -1 }, BOOLEAN_FALSE },
evaluate_security
};
return do_cache2_char(&security);
}
/*
* Interface that represents the logd buffer size determination so that others
* need not guess our intentions.
*/
/* Property helper */
static bool check_flag(const char* prop, const char* flag) {
const char* cp = strcasestr(prop, flag);
if (!cp) {
return false;
}
/* We only will document comma (,) */
static const char sep[] = ",:;|+ \t\f";
if ((cp != prop) && !strchr(sep, cp[-1])) {
return false;
}
cp += strlen(flag);
return !*cp || !!strchr(sep, *cp);
}
/* cache structure */
struct cache_property {
struct cache cache;
char property[PROP_VALUE_MAX];
};
static void refresh_cache_property(struct cache_property* cache,
const char* key) {
if (!cache->cache.pinfo) {
cache->cache.pinfo = __system_property_find(key);
if (!cache->cache.pinfo) {
return;
}
}
cache->cache.serial = __system_property_serial(cache->cache.pinfo);
__system_property_read(cache->cache.pinfo, 0, cache->property);
}
/* get boolean with the logger twist that supports eng adjustments */
LIBLOG_ABI_PRIVATE bool __android_logger_property_get_bool(const char* key,
int flag) {
struct cache_property property = { { NULL, -1 }, { 0 } };
if (flag & BOOL_DEFAULT_FLAG_PERSIST) {
char newkey[strlen("persist.") + strlen(key) + 1];
snprintf(newkey, sizeof(newkey), "ro.%s", key);
refresh_cache_property(&property, newkey);
property.cache.pinfo = NULL;
property.cache.serial = -1;
snprintf(newkey, sizeof(newkey), "persist.%s", key);
refresh_cache_property(&property, newkey);
property.cache.pinfo = NULL;
property.cache.serial = -1;
}
refresh_cache_property(&property, key);
if (check_flag(property.property, "true")) {
return true;
}
if (check_flag(property.property, "false")) {
return false;
}
if (property.property[0]) {
flag &= ~(BOOL_DEFAULT_FLAG_ENG | BOOL_DEFAULT_FLAG_SVELTE);
}
if (check_flag(property.property, "eng")) {
flag |= BOOL_DEFAULT_FLAG_ENG;
}
/* this is really a "not" flag */
if (check_flag(property.property, "svelte")) {
flag |= BOOL_DEFAULT_FLAG_SVELTE;
}
/* Sanity Check */
if (flag & (BOOL_DEFAULT_FLAG_SVELTE | BOOL_DEFAULT_FLAG_ENG)) {
flag &= ~BOOL_DEFAULT_FLAG_TRUE_FALSE;
flag |= BOOL_DEFAULT_TRUE;
}
if ((flag & BOOL_DEFAULT_FLAG_SVELTE) &&
__android_logger_property_get_bool("ro.config.low_ram",
BOOL_DEFAULT_FALSE)) {
return false;
}
if ((flag & BOOL_DEFAULT_FLAG_ENG) && !__android_log_is_debuggable()) {
return false;
}
return (flag & BOOL_DEFAULT_FLAG_TRUE_FALSE) != BOOL_DEFAULT_FALSE;
}
LIBLOG_ABI_PRIVATE bool __android_logger_valid_buffer_size(unsigned long value) {
static long pages, pagesize;
unsigned long maximum;
if ((value < LOG_BUFFER_MIN_SIZE) || (LOG_BUFFER_MAX_SIZE < value)) {
return false;
}
if (!pages) {
pages = sysconf(_SC_PHYS_PAGES);
}
if (pages < 1) {
return true;
}
if (!pagesize) {
pagesize = sysconf(_SC_PAGESIZE);
if (pagesize <= 1) {
pagesize = PAGE_SIZE;
}
}
/* maximum memory impact a somewhat arbitrary ~3% */
pages = (pages + 31) / 32;
maximum = pages * pagesize;
if ((maximum < LOG_BUFFER_MIN_SIZE) || (LOG_BUFFER_MAX_SIZE < maximum)) {
return true;
}
return value <= maximum;
}
struct cache2_property_size {
pthread_mutex_t lock;
uint32_t serial;
const char* key_persist;
struct cache_property cache_persist;
const char* key_ro;
struct cache_property cache_ro;
unsigned long (*const evaluate)(const struct cache2_property_size* self);
};
static inline unsigned long do_cache2_property_size(
struct cache2_property_size* self) {
uint32_t current_serial;
int change_detected;
unsigned long v;
if (pthread_mutex_trylock(&self->lock)) {
/* We are willing to accept some race in this context */
return self->evaluate(self);
}
change_detected = check_cache(&self->cache_persist.cache) ||
check_cache(&self->cache_ro.cache);
current_serial = __system_property_area_serial();
if (current_serial != self->serial) {
change_detected = 1;
}
if (change_detected) {
refresh_cache_property(&self->cache_persist, self->key_persist);
refresh_cache_property(&self->cache_ro, self->key_ro);
self->serial = current_serial;
}
v = self->evaluate(self);
pthread_mutex_unlock(&self->lock);
return v;
}
static unsigned long property_get_size_from_cache(
const struct cache_property* cache) {
char* cp;
unsigned long value = strtoul(cache->property, &cp, 10);
switch (*cp) {
case 'm':
case 'M':
value *= 1024;
/* FALLTHRU */
case 'k':
case 'K':
value *= 1024;
/* FALLTHRU */
case '\0':
break;
default:
value = 0;
}
if (!__android_logger_valid_buffer_size(value)) {
value = 0;
}
return value;
}
static unsigned long evaluate_property_get_size(
const struct cache2_property_size* self) {
unsigned long size = property_get_size_from_cache(&self->cache_persist);
if (size) {
return size;
}
return property_get_size_from_cache(&self->cache_ro);
}
LIBLOG_ABI_PRIVATE unsigned long __android_logger_get_buffer_size(log_id_t logId) {
static const char global_tunable[] = "persist.logd.size"; /* Settings App */
static const char global_default[] = "ro.logd.size"; /* BoardConfig.mk */
static struct cache2_property_size global = {
/* clang-format off */
PTHREAD_MUTEX_INITIALIZER, 0,
global_tunable, { { NULL, -1 }, {} },
global_default, { { NULL, -1 }, {} },
evaluate_property_get_size
/* clang-format on */
};
char key_persist[strlen(global_tunable) + strlen(".security") + 1];
char key_ro[strlen(global_default) + strlen(".security") + 1];
struct cache2_property_size local = {
/* clang-format off */
PTHREAD_MUTEX_INITIALIZER, 0,
key_persist, { { NULL, -1 }, {} },
key_ro, { { NULL, -1 }, {} },
evaluate_property_get_size
/* clang-format on */
};
unsigned long property_size, default_size;
default_size = do_cache2_property_size(&global);
if (!default_size) {
default_size = __android_logger_property_get_bool("ro.config.low_ram",
BOOL_DEFAULT_FALSE)
? LOG_BUFFER_MIN_SIZE /* 64K */
: LOG_BUFFER_SIZE; /* 256K */
}
snprintf(key_persist, sizeof(key_persist), "%s.%s", global_tunable,
android_log_id_to_name(logId));
snprintf(key_ro, sizeof(key_ro), "%s.%s", global_default,
android_log_id_to_name(logId));
property_size = do_cache2_property_size(&local);
if (!property_size) {
property_size = default_size;
}
if (!property_size) {
property_size = LOG_BUFFER_SIZE;
}
return property_size;
}
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