CN103853850A - Method and system for eliminating data for user-centered Android system - Google Patents
Method and system for eliminating data for user-centered Android system Download PDFInfo
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- CN103853850A CN103853850A CN201410123655.8A CN201410123655A CN103853850A CN 103853850 A CN103853850 A CN 103853850A CN 201410123655 A CN201410123655 A CN 201410123655A CN 103853850 A CN103853850 A CN 103853850A
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F16/00—Information retrieval; Database structures therefor; File system structures therefor
- G06F16/10—File systems; File servers
- G06F16/16—File or folder operations, e.g. details of user interfaces specifically adapted to file systems
- G06F16/162—Delete operations
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
- G06F3/0601—Interfaces specially adapted for storage systems
- G06F3/0628—Interfaces specially adapted for storage systems making use of a particular technique
- G06F3/0646—Horizontal data movement in storage systems, i.e. moving data in between storage devices or systems
- G06F3/0652—Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
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Abstract
The invention provides a method and system for eliminating data for a user-centered Android system. The method comprises the following steps: 1, inputting file information of an object to be processed by the user, and reversely scanning all object head pages matched with the file information; 2, judging according to the object head information matched in the step 1 and correspondingly operating the object to be processed; 3, calling a write operation function of a file system, and performing full zero overwrite on a target surface of the object to be processed according to the block number and physical page address stored in the step 2; 4, checking whether effective pages of other files exist in target blocks of the object to be processed, and performing corresponding processing; and 5, triggering a garbage collection mechanism of the file system, recovering the target blocks according to the block number, and inserting the target blocks into a free block linked list to serve as a distributable storage space for reutilization. According to the system, the storage space of the object files can be recovered, and the utilization rate of the storage space is improved.
Description
Technical field
The present invention relates to Android intellectual technology field, relate in particular to a kind of Android system data sweep-out method and system of user-center.
Background technology
Along with the widespread use of Android intelligent platform of new generation; there are increasing user profile and data to be stored on the Flash flash memory of Android intelligent terminal; such as data such as address list, note, picture, p.m.entrys; the sensitive information, the significant data that wherein comprise, user can use common deletion action that its deletion is prevented to data leakage conventionally.But common deletion action is not deleted data from storage medium, just the index that is designated idle condition or deleted file of the file system modification object page, does not present to operating system and user deleted file; Common format can not have influence on the data on storage medium yet, is only that allowing operating system think does not have file on storage medium for operating system creates an empty file index.In this case, can recover deleting data by logical method or physical method, can not guarantee that user data is not revealed.The least unit of flash memory write operation is page, but erase operation is using piece as least unit, so storage medium release physically will wait until that in a piece, all pages all become idle condition, file system just can be carried out garbage reclamation this piece is wiped.
Android adopts nand flash memory as kernel memory, and YAFFS2 is the log type file system that aims at nand flash memory design, has the characteristic that some are different from alternative document system.Flash data logic destroy technology mainly contains zero and overrides technology at present, block delete technology, and encryption technology, but in the time of search page to be deleted, all do not have to consider time performance in conjunction with data structure and the memory mechanism of file system.
Summary of the invention
For solving above-mentioned deficiency, the invention provides a kind of Android system data sweep-out method and system of customer-centric.
The Android system data sweep-out method of customer-centric of the present invention, it comprises:
If the type of described pending object is file, according to all page of data that comprise under this file of Parent_Objectid inverted order scanning place, these all page of data are pages identical with No. ID of the object head page in described step 1; Obtain piece sequence number and the page physical address of described all page of data, and it be stored in respectively to array block[m] and adress[n] in;
If the type of described pending object is ordinary file, find the page with the object head page in described step 1 with identical Objectid, this Objectid is the unique ID number for identifying the obj ect file under the page; Obtain piece sequence number and the page physical address of the described page, and it be stored in respectively to array block[m] and adress[n] in;
If there is effective page, this effective page is dumped to other less than piece on;
If there is not effective page, directly perform step 5;
Step 5, the garbage reclamation mechanism of triggering file system, reclaims object block according to the piece sequence number of storage, and this object block is inserted in free block chained list, waits for recycling as assignable storage space.
The Android system data scavenge system of customer-centric of the present invention, it comprises:
Input matching module, user inputs the fileinfo of pending object, all object head pages of inverted order scanning and this file information matches;
The first processing module, judges described pending object according to the object header of described input matching module coupling:
If the type of described pending object is file, according to all page of data that comprise under this file of Parent_Objectid inverted order scanning place, these all page of data are pages identical with No. ID of the object head page in described the first processing module; Obtain piece sequence number and the page physical address of described all page of data, and it be stored in respectively to array block[m] and adress[n] in;
If the type of described pending object is ordinary file, find the page with the object head page in described the first processing module with identical Objectid, this Objectid is the unique ID number for identifying the obj ect file under the page; Obtain piece sequence number and the page physical address of the described page, and it be stored in respectively to array block[m] and adress[n] in;
Override module, call the write operation function of file system, according to the piece sequence number of described the first processing module storage and page physical address, the target pages of described pending object is carried out to complete zero and override;
The second processing module, check through described in override the effective page that whether has other file of existence in the object block of the described pending object after resume module:
If there is effective page, this effective page is dumped to other less than piece on;
If there is not effective page, directly carry out recycling module;
Recycling module, the garbage reclamation mechanism of triggering file system, reclaims object block according to the piece sequence number of storage, and this object block is inserted in free block chained list, waits for recycling as assignable storage space.
Beneficial effect of the present invention is:
The storage space of energy recycle object file of the present invention, improves storage space utilization factor.
Accompanying drawing explanation
Fig. 1 is the operation chart to page of data in the Android system data sweep-out method of customer-centric of the present invention and system;
Fig. 2 is the Android system data sweep-out method process flow diagram of customer-centric of the present invention;
Fig. 3 be in the Android system data sweep-out method of customer-centric of the present invention and system file and ordinary file be related to schematic diagram;
Fig. 4 is the Android system data scavenge system schematic diagram of customer-centric of the present invention.
Embodiment
Fig. 2 is the Android system data sweep-out method process flow diagram of customer-centric of the present invention.As shown in Figure 2, the Android system data sweep-out method of customer-centric of the present invention, it comprises:
If the type of described pending object is file, according to all page of data that comprise under this file of Parent_Objectid inverted order scanning place, these all page of data are pages identical with No. ID of the object head page in described step 1; Obtain piece sequence number and the page physical address of described all page of data, and it be stored in respectively to array block[m] and adress[n] in;
If the type of described pending object is ordinary file, find the page with the object head page in described step 1 with identical Objectid, this Objectid is for identifying the unique ID number of the obj ect file under the page; Obtain piece sequence number and the page physical address of this page, and it be stored in respectively to array block[m] and adress[n] in;
Whether step 4, have the effective page that has other file in the object block of the described pending object of inspection after described step 3 overrides:
If there is effective page, this effective page is dumped to other less than piece on;
If there is not effective page, directly perform step 5;
Step 5, the garbage reclamation mechanism of triggering file system, reclaims object block according to piece sequence number, and this object block is inserted in free block chained list, waits for recycling as assignable storage space.
Fig. 4 is the Android system data scavenge system schematic diagram of customer-centric of the present invention.As shown in Figure 4, the Android system data scavenge system of customer-centric of the present invention, it comprises:
The first processing module 102, the object header mating according to described input matching module 101 judges described pending object:
If the type of described pending object is file, according to all page of data that comprise under this file of Parent_Objectid inverted order scanning place, these all page of data are pages identical with No. ID of the object head page in described input matching module 101; Obtain piece sequence number and the page physical address of described all page of data, and it be stored in respectively to array block[m] and adress[n] in;
If the type of described pending object is ordinary file, find the page with the object head page in described input matching module 101 with identical Objectid, this Objectid is for identifying the unique ID number of the obj ect file under the page; Obtain piece sequence number and the page physical address of this page, and it be stored in respectively to array block[m] and adress[n] in;
The second processing module 104, check through described in override in the object block of module 103 described pending objects after treatment, whether there is the effective page that has other file:
If there is effective page, this effective page is dumped to other less than piece on;
If there is not effective page, directly carry out recycling module 105;
The invention provides a kind of YAFFS2 file system extensively adopting for Android intelligent platform, from user perspective, remove the method for nand flash memory data, to protect user sensitive information and significant data not to be revealed.Be different from common deletion action, this method is in conjunction with data structure and the data access method of YAFFS2 file system, adopt inverted order scanning algorithm to carry out search subscriber and want the file of deleting, then call write operation and the piece erase operation of file system, data are removed from flash memory, can not be recovered by logical method.The file that can remove not only comprises simple binary stream file, also comprises jpeg file and pdf file etc. that structural comparing is strong, can guarantee the security of various types of user data.
The Android data clearing method of customer-centric, mainly comprises user interface, page to be deleted search, data dump, space reclamation Four processes.The first step, the information of deleted file, filename, file type are wanted in user's input.Second step, searches for page to be deleted.Concrete searching method is: adopt inverted order scanning algorithm, from largest block sequence number, according to the first sweep object head of the filename page of user's input.Due to the characteristic that nand flash memory strange land is upgraded, have different old versions through the file of retouching operation and be present on flash memory, so the file header page searching may be for one or more.Search all page of data of file according to the ObjectID in the object head page.
It is that page of data to searching is carried out complete zero and override that the bit manipulation of nand flash memory can only become 0, the three step from 1.Carry out complete zero override after, if stored effective page of alternative document in the piece at page of data place of deleting, need active page to be dumped to other piece, then to object block execution block erase operation, as shown in Figure 1.Carrying out after erase operation, trigger the garbage reclamation mechanism of file system, object block is reclaimed, insert in free block chained list, wait for again as storage space utilization and distribute a new piece sequence number.
In Android system, not only storing a large amount of user data, also comprising the data of system itself, application program operation generation etc., search page to be deleted by scanning the method for whole nand flash memory, time overhead is larger.
Present embodiment is to adopt nand flash memory as storage medium, the Android smart mobile phone that loads YAFFS2 file system is example, a kind of user data sweep-out method of customer-centric is provided, and the storage space of energy recycle object file, storage space utilization factor improved.
In YAFFS2 file system, there are two kinds of different pages: page of data (Data chunk) and the object head page (Object header), page of data is used for the data content of storage object, and the object head page is for establishment, the modification time etc. of the type of storage object, file size, object name, object.The data structure yaffs_ObjectHeader that object head is corresponding comprises that member has (only listing for explaining member of the present invention):
Yaffs_ObjectType type; The type (file, catalogue etc.) of // description object
Int parentObjectid; No. ID of // parent directory
YCHAR name[YAFFS_MAX_NAME_lenth+1]; // object name
Can judge that current object to be dealt with is ordinary file or file according to the type field in object head.As shown in Figure 3, Fig. 3 is the relation between file and its son file.
Page search to be deleted is that the data block from having largest block sequence number starts to scan successively, and each piece is started to traversal to first page from last page of this piece, and concrete scanning algorithm step is as follows:
(1) scanning BlockN;
(2) pageM in scanning current block; If PageM is first page in current block, forward (4) to;
(3) M=M-1, forwards (2) to;
(4) if current block piece is smallest blocks in current block, the end of scan;
(5) N=N-1, forwards (1) to.
User-in file name, inverted order scans all object head pages that mate with this filename, if judge that according to object header pending object is ordinary file, find and have the page of identical Objectid with the object head page and obtain their piece sequence number and Chunkid, wherein Objectid is for identifying the unique ID number of the obj ect file under the page.Nand flash memory array is divided into a series of block, and each comprises 32 or 64 or 128 pages, and each page all comprises the data field of 2048kb and the free area of 64kb.Initialization int type array block[m] and adress[n] be used for respectively depositing the piece sequence number that gets and the physical address of the page.If object type is file, all Parent_Objectid page identical with No. ID of the object head page in the first step found in inverted order scanning, obtain equally their piece sequence number and page physical address, be stored in respectively array block[m] and adress[n], now traveling through the gained page is the All Files under current pending file.YAFFS2 file system is in strict accordance with order-assigned piece sequence number in the time of storage data, and in the time of a piece of new distribution, piece sequence number adds 1, and in this piece, all pages are shared this part sequence number.So adopt above inverted order traversal method, be the equal of that the distribution time inverted order according to the page travels through completely, therefore save sweep time.
Call the write operation function of file system, according to the piece sequence number of earlier stored and page physical address, target pages is carried out to complete zero and override.Because the erase operation of YAFFS2 is carried out take piece as least unit, so before carrying out erase operation, should first check whether there is the effective page that belongs to other file in this piece.If have, these pages be dumped to flash memory other less than piece on.The garbage reclamation mechanism that then just can trigger file system, reclaims object block according to piece sequence number, is inserted in free block chained list, waits for recycling as assignable storage space.
Only as described above, be only preferred embodiment of the present invention, such as professional who are familiar with this art.After understanding technological means of the present invention, natural energy, according to actual needs, is changed under instruction of the present invention.Therefore all equal variation and modifications of doing according to the present patent application the scope of the claims, all should still remain within the scope of the patent.
Claims (2)
1. an Android system data sweep-out method for customer-centric, is characterized in that, comprising:
Step 1, user inputs the fileinfo of pending object, all object head pages of inverted order scanning and this file information matches;
Step 2, the object header mating according to described step 1 judges described pending object:
If the type of described pending object is file, scan according to Parent_Objectid inverted order all page of data that comprise under this file, these all page of data are pages identical with No. ID of the object head page in described step 1; Obtain piece sequence number and the page physical address of described all page of data, and it be stored in respectively to array block[m] and adress[n] in;
If the type of described pending object is ordinary file, find the page with the object head page in described step 1 with identical Objectid, this Objectid is the unique ID number for identifying the obj ect file under the page; Obtain piece sequence number and the page physical address of the described page, and it be stored in respectively to array block[m] and adress[n] in;
Step 3, calls the write operation function of file system, and the piece sequence number of storing according to described step 2 and page physical address are undertaken complete zero by the target pages of described pending object and override;
Step 4, checks in the object block of described pending object, whether there is the effective page that has other file:
If there is effective page, this effective page is dumped to other less than piece on;
If there is not effective page, directly perform step 5;
Step 5, the garbage reclamation mechanism of triggering file system, reclaims object block according to the piece sequence number of storage, and this object block is inserted in free block chained list, waits for recycling as assignable storage space.
2. an Android system data scavenge system for customer-centric, is characterized in that, comprising:
Input matching module, user inputs the fileinfo of pending object, all object head pages of inverted order scanning and this file information matches;
The first processing module, judges described pending object according to the object header of described input matching module coupling:
If the type of described pending object is file, according to all page of data that comprise under this file of Parent_Objectid inverted order scanning place, these all page of data are pages identical with No. ID of the object head page in described step 1; Obtain piece sequence number and the page physical address of described all page of data, and it be stored in respectively to array block[m] and adress[n] in;
If the type of described pending object is ordinary file, find the page with the object head page in described step 1 with identical Objectid, this Objectid is the unique ID number for identifying the obj ect file under the page; Obtain piece sequence number and the page physical address of the described page, and it be stored in respectively to array block[m] and adress[n] in;
Override module, call the write operation function of file system, according to the piece sequence number of described the first processing module storage and page physical address, the target pages of described pending object is carried out to complete zero and override;
The second processing module, checks in the object block of described pending object, whether there is the effective page that has other file:
If there is effective page, this effective page is dumped to other less than piece on;
If there is not effective page, directly carry out recycling module;
Recycling module, the garbage reclamation mechanism of triggering file system, reclaims object block according to the piece sequence number of storage, and this object block is inserted in free block chained list, waits for recycling as assignable storage space.
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Effective date of registration: 20170803 Address after: 518026 C, building 31B, electronic technology building, No. 2070 Shennan Road, Shenzhen, Guangdong, Futian District Patentee after: Shenzhen City, the number of principal Yuan Science and Technology Co Ltd Address before: 100124 Chaoyang District, Beijing Ping Park, No. 100 Patentee before: Beijing University of Technology |
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Inventor after: Zhao Bin Inventor after: Huang Na Inventor after: Zhang Yuqiang Inventor after: He Jingsha Inventor after: Liu Gongzheng Inventor after: Wan Xuejiao Inventor before: He Jingsha Inventor before: Huang Na Inventor before: Zhang Yuqiang Inventor before: Zhao Bin Inventor before: Liu Gongzheng Inventor before: Wan Xuejiao |