frameworks/native/services/fileinotify/FileInotify.cpp

/*******************************
程序功能：把抖音极速版的数据库文件，挂载到tmpfs内存中。避免频繁写入内部存储，提高EMMC使用寿命。
********************************/

#define LOG_TAG "FileInotify"
#include <utils/RefBase.h>
#include <utils/Log.h>
#include <cutils/properties.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/inotify.h>
#include <pthread.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#define CMD_BASE          0xCBAABC10
#define FK_IS_GET_POWER2  (CMD_BASE + 12)
#define EVENT_SIZE        (sizeof(struct inotify_event))
#define EVENT_BUF_LEN     (1024 * (EVENT_SIZE + 16))
#define MAX_BUF_SIZE      256
#define NOTIFY_DIR_NUM    2

//监控文件名
#define NOTIFY_FILE    "apm_monitor_t1.db"
#define NOTIFY_FILE_2  "apm_monitor_t1.db-journal"

//监听目录
#define NOTIFY_PATH    "/data/data/com.ss.android.ugc.aweme.lite/databases/"
#define NOTIFY_PATH_2  "/data/data/com.ss.android.ugc.live/databases/"

//挂载目录
#define TMPFS_PATH     "/data_mirror/com.ss.android.ugc.aweme.lite/databases/"
#define TMPFS_PATH_2   "/data_mirror/com.ss.android.ugc.live/databases/"

typedef enum INDEX
{
	DIR1,
	DIR2,
}INDEX_T;

typedef struct {
	int dir_exists[NOTIFY_DIR_NUM];
	int wd[NOTIFY_DIR_NUM];
	int fd;
}inotify_info;

void *inotify_func(void *argc)
{
	inotify_info *info = (inotify_info *)argc;
	char buf[MAX_BUF_SIZE];

	while(1)
	{
		if(access(NOTIFY_PATH, F_OK) == 0 && info->dir_exists[DIR1] == 0)
		{
			//监听目录
			info->dir_exists[DIR1] = 1;
			info->wd[DIR1] = inotify_add_watch(info->fd, NOTIFY_PATH, IN_CREATE | IN_DELETE);
			//pthread_exit(NULL);
			//ALOGD("add dir %s,wd=%d\n", NOTIFY_PATH, info->wd[DIR1]);
		}

		if(access(NOTIFY_PATH_2, F_OK) == 0 && info->dir_exists[DIR2] == 0)
		{
			//监听目录
			info->dir_exists[DIR2] = 1;
			info->wd[DIR2] = inotify_add_watch(info->fd, NOTIFY_PATH_2, IN_CREATE | IN_DELETE);
			//pthread_exit(NULL);
			//ALOGD("add dir %s,wd=%d\n", NOTIFY_PATH_2, info->wd[DIR2]);
		}

		//应用卸载目录删除，重新设置标志
		if(access(NOTIFY_PATH, F_OK) != 0)
		{
			info->dir_exists[DIR1] = 0;
		}

		if(access(NOTIFY_PATH_2, F_OK) != 0)
		{
			info->dir_exists[DIR2] = 0;
		}
		sleep(5);
	}
}

int do_mount(char *name, int wd, inotify_info *info)
{
	char buf[MAX_BUF_SIZE];

	//1. 创建tmpfs目录
	if(access(TMPFS_PATH, F_OK) != 0) //如果目录不存在
	{
		sprintf(buf, "mkdir -p %s", TMPFS_PATH);
		system(buf);
		memset(buf, 0, sizeof(buf));
	}

	if(access(TMPFS_PATH_2, F_OK) != 0) //如果目录不存在
	{
		sprintf(buf, "mkdir -p %s", TMPFS_PATH_2);
		system(buf);
		memset(buf, 0, sizeof(buf));
	}

	//2. 创建tmpfs文件
	sprintf(buf, "%s/%s", TMPFS_PATH, name);
	if(access(buf, F_OK) != 0) //如果文件不存在
	{
		sprintf(buf, "touch %s/%s", TMPFS_PATH, name);
		system(buf);
		memset(buf, 0, sizeof(buf));
	}

	sprintf(buf, "%s/%s", TMPFS_PATH_2, name);
	if(access(buf, F_OK) != 0) //如果文件不存在
	{
		sprintf(buf, "touch %s/%s", TMPFS_PATH_2, name);
		system(buf);
		memset(buf, 0, sizeof(buf));
	}

	//3. 挂载
	if(info->wd[DIR1] == wd)
	{
		sprintf(buf, "%s/%s", NOTIFY_PATH, name);
		if(access(buf, F_OK) == 0) //如果文件存在
		{
			//mount -o vcloud --bind /data_mirror/com.ss.android.ugc.aweme.lite/apm_monitor_t1.db /data/data/com.ss.android.ugc.aweme.lite/databases/apm_monitor_t1.db
			sprintf(buf, "mount -o vcloud --bind %s/%s %s/%s", TMPFS_PATH, name, NOTIFY_PATH, name);
			system(buf);
			memset(buf, 0, sizeof(buf));
		}
	}

	if(info->wd[DIR2] == wd)
	{
		sprintf(buf, "%s/%s", NOTIFY_PATH_2, name);
		if(access(buf, F_OK) == 0) //如果文件存在
		{
			sprintf(buf, "mount -o vcloud --bind %s/%s %s/%s", TMPFS_PATH_2, name, NOTIFY_PATH_2, name);
			system(buf);
			memset(buf, 0, sizeof(buf));
		}
	}
	return 0;
}

int do_umount(char *name, int wd, inotify_info *info)
{
	char buf[MAX_BUF_SIZE];

	if(info->wd[DIR1] == wd)
	{
		//1. 卸载
		sprintf(buf, "%s/%s", NOTIFY_PATH, name);
		if(access(buf, F_OK) == 0) //如果文件存在
		{
			sprintf(buf, "umount %s/%s", NOTIFY_PATH, name);
			system(buf);
			memset(buf, 0, sizeof(buf));
		}

		//2. 删除文件
		memset(buf, 0, sizeof(buf));
		sprintf(buf, "rm %s/%s", TMPFS_PATH, name);
		system(buf);
	}

	if(info->wd[DIR2] == wd)
	{
		//1. 卸载
		sprintf(buf, "%s/%s", NOTIFY_PATH_2, name);
		if(access(buf, F_OK) == 0) //如果文件存在
		{
			sprintf(buf, "umount %s/%s", NOTIFY_PATH_2, name);
			system(buf);
			memset(buf, 0, sizeof(buf));
		}

		//2. 删除文件
		memset(buf, 0, sizeof(buf));
		sprintf(buf, "rm %s/%s", TMPFS_PATH_2, name);
		system(buf);
	}

	return 0;
}

void do_rmfile(char *name)
{
	char buf[MAX_BUF_SIZE];

	memset(buf, 0, sizeof(buf));
	sprintf(buf, "rm %s/%s", NOTIFY_PATH, name);
	system(buf);

	memset(buf, 0, sizeof(buf));
	sprintf(buf, "rm %s/%s", NOTIFY_PATH_2, name);
	system(buf);
}

int main(void)
{
	inotify_info info;
	pthread_t tid;
	int length, i = 0;
	char buf[EVENT_BUF_LEN];

	//selinux
	prctl(FK_IS_GET_POWER2, 0, 0, 0);

	//inotify初始化
	info.fd = inotify_init();
	if (info.fd < 0)
	{
		perror("inotify_init");
		return -1;
	}

	//监听目录
	pthread_create(&tid, NULL, inotify_func, &info);

	while(1)
	{
		i = 0;
		length = read(info.fd, buf, EVENT_BUF_LEN);
		if (length < 0)
		{
			perror("read");
			continue;
		}
		while (i < length)
		{
			struct inotify_event *event = (struct inotify_event *) &buf[i];
			if (event->len)
			{
				if (event->mask & IN_CREATE)
				{
					if (!(event->mask & IN_ISDIR))
					{
						if(strcmp(NOTIFY_FILE, event->name) == 0 || strcmp(NOTIFY_FILE_2, event->name) == 0)
						{
							//ALOGD("file %s created wd=%d\n", event->name, event->wd);
							#if 0
							do_mount(event->name, event->wd, &info);
							#else
							//直接删除文件
							do_rmfile(event->name);
							#endif
						}
					}
				}
				else if (event->mask & IN_DELETE)
				{
					if (!(event->mask & IN_ISDIR))
					{
						if(strcmp(NOTIFY_FILE, event->name) == 0 || strcmp(NOTIFY_FILE_2, event->name) == 0)
						{
							//ALOGD("file %s deleted wd=%d\n", event->name, event->wd);
							#if 0
							do_umount(event->name, event->wd, &info);
							#endif
						}
					}
				}
			}
			i += EVENT_SIZE + event->len;
		}
	}

	inotify_rm_watch(info.fd, info.wd[DIR1]);
	inotify_rm_watch(info.fd, info.wd[DIR2]);
	close(info.fd);
	return 0;
}