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Use C++ smart pointer for caching su_info

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This commit is contained in:
topjohnwu
2019-07-07 00:31:49 -07:00
parent 4f206fd918
commit ab90901793
3 changed files with 67 additions and 82 deletions
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64
native/jni/su/su_daemon.cpp
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@ -20,14 +20,16 @@
#include "su.h"
#include "pts.h"
using namespace std;
#define LOCK_CACHE() pthread_mutex_lock(&cache_lock)
#define UNLOCK_CACHE() pthread_mutex_unlock(&cache_lock)
static pthread_mutex_t cache_lock = PTHREAD_MUTEX_INITIALIZER;
static su_info *cache;
static shared_ptr<su_info> cached;
su_info::su_info(unsigned uid) :
uid(uid), count(0), access(DEFAULT_SU_ACCESS), mgr_st({}), ref(0),
uid(uid), access(DEFAULT_SU_ACCESS), mgr_st({}),
timestamp(0), _lock(PTHREAD_MUTEX_INITIALIZER) {}
su_info::~su_info() {
@ -42,27 +44,20 @@ void su_info::unlock() {
pthread_mutex_unlock(&_lock);
}
bool su_info::isFresh() {
return time(nullptr) - timestamp < 3; /* 3 seconds */
bool su_info::is_fresh() {
timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
long current = ts.tv_sec * 1000L + ts.tv_nsec / 1000L;
return current - timestamp < 3000; /* 3 seconds */
}
void su_info::newRef() {
timestamp = time(nullptr);
++ref;
void su_info::refresh() {
timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
timestamp = ts.tv_sec * 1000L + ts.tv_nsec / 1000L;
}
void su_info::deRef() {
LOCK_CACHE();
--ref;
if (ref == 0 && !isFresh()) {
if (cache == this)
cache = nullptr;
delete this;
}
UNLOCK_CACHE();
}
static void database_check(su_info *info) {
static void database_check(const shared_ptr<su_info> &info) {
int uid = info->uid;
get_db_settings(info->cfg);
get_db_strings(info->str);
@ -91,28 +86,24 @@ static void database_check(su_info *info) {
validate_manager(info->str[SU_MANAGER], uid / 100000, &info->mgr_st);
}
static su_info *get_su_info(unsigned uid) {
su_info *info = nullptr;
static shared_ptr<su_info> get_su_info(unsigned uid) {
shared_ptr<su_info> info;
// Get from cache or new instance
LOCK_CACHE();
if (cache && cache->uid == uid && cache->isFresh()) {
info = cache;
} else {
if (cache && cache->ref == 0)
delete cache;
cache = info = new su_info(uid);
}
info->newRef();
if (!cached || cached->uid != uid || !cached->is_fresh())
cached = make_shared<su_info>(uid);
info = cached;
info->refresh();
UNLOCK_CACHE();
LOGD("su: request from uid=[%d] (#%d)\n", info->uid, ++info->count);
LOGD("su: request from uid=[%d]\n", info->uid);
// Lock before the policy is determined
info->lock();
if (info->access.policy == QUERY) {
// Not cached, get data from database
// Not cached, get data from database
database_check(info);
// Check su access settings
@ -195,13 +186,12 @@ static void set_identity(unsigned uid) {
void su_daemon_handler(int client, struct ucred *credential) {
LOGD("su: request from pid=[%d], client=[%d]\n", credential->pid, client);
su_info *info = get_su_info(credential->uid);
auto info = get_su_info(credential->uid);
// Fail fast
if (info->access.policy == DENY && info->str[SU_MANAGER][0] == '\0') {
LOGD("su: fast deny\n");
info->deRef();
write_int(client, DENY);
close(client);
return;
@ -214,7 +204,7 @@ void su_daemon_handler(int client, struct ucred *credential) {
*/
int child = xfork();
if (child) {
info->deRef();
info.reset();
// Wait result
LOGD("su: waiting child pid=[%d]\n", child);
@ -320,9 +310,9 @@ void su_daemon_handler(int client, struct ucred *credential) {
}
if (info->access.log)
app_log(&ctx);
app_log(ctx);
else if (info->access.notify)
app_notify(&ctx);
app_notify(ctx);
if (info->access.policy == ALLOW) {
const char *argv[] = { nullptr, nullptr, nullptr, nullptr };