Project 3 Specification FAT32 File System Utility

Transcription

1 Prject 3 Specificatin FAT32 File System Utility Assigned: Octber 30, 2015 Due: Nvember 30, 11:59 pm, 2015 Yu can use the reminder f the slack days. -10 late penalty fr each 24-hur perid after the due time. Abslutely n submissin after December 6 11:59 pm. Language restrictins: C nly Additinal restrictins: system() and exec() system calls may nt be used Purpse: The purpse f this prject is t familiarize yu with three cncepts: basic file-system design and implementatin, file-system image testing, and data serializatin/de-serializatin. Yu will need t understand varius aspects f the FAT32 file system such as cluster-based strage, FAT tables, sectrs, directry structure, and byte-rdering (endianness). Yu will als be intrduced t munting and unmunting f file system images nt a running Linux system, data serializatin (cnverting data structures int raw bytes fr strage r netwrk transmissins), and de-serializatin (cnverting serialized bytes int data structures again). Prblem Statement: Fr this prject, yu will design and implement a simple, user-space, shell-like utility that is capable f interpreting a FAT32 file system image. The prgram must understand the basic cmmands t manipulate the given file system image. The utility must nt crrupt the file system image and shuld be rbust. Yu may nt reuse kernel file system cde, and yu may nt cpy cde frm ther file system utilities (r frm anywhere else ver the internet, t be precise). Prject Tasks: Yu are tasked with writing a prgram that supprts file system cmmands. Fr gd mdular cding design, please implement each cmmand in a separate functin. Please implement the fllwing functinality: pen <FILE_NAME> <MODE>

2 Opens a file named FILE_NAME in the present wrking directry. A file can nly be read frm r written t if it is pened first. Yu may need t maintain a table f pened files and add FILE_NAME t it when pen functin is called. MODE may be: r read-nly w write-nly rw read and write wr read and write Return an errr if the file is already pened. clse <FILE_NAME> Clses a file. Return an errr if the file is already clsed. Depending n yur implementatin, yu may need t remve FILE_NAME frm the table f pened files. create <FILE_NAME> Creates a file in the present wrking directry f 0 bytes with name FILE_NAME. Return an errr if a file with that name already exists. rm <FILE_NAME> Deletes FILE_NAME frm the current wrking directry. Return an errr if FILE_NAME des nt exist. This nly remves the link frm a directry t a file, nt the actual data. (That is, the file n lnger shws in the utput f ls, and the space is reclaimed). size <FILE_NAME> Prints the size f file FILE_NAME in the current wrking directry, in bytes. Return an errr if FILE_NAME des nt exist. cd <DIR_NAME> Changes the current wrking directry t DIR_NAME. Return an errr if the specified directry des nt exist. Shuld supprt. (here) and.. (up ne directry) directries. ls <DIR_NAME> Lists the cntents f DIR_NAME, including the. (here) and.. (up ne directry) directries. Return an errr if the specified directry des nt exist mkdir <DIR_NAME>

3 Creates a new directry with the name DIR_NAME. Return an errr if the directry already exists r if a file already exists by that name. rmdir <DIR_NAME> Remves a directry called DIR_NAME. Return an errr if the directry is nt empty r the directry des nt exist. (Directry is empty if it cntains nly. And.. ). read FILE_NAME POSITION NUM_BYTES Reads frm a file FILE_NAME, starting at POSITION, and prints NUM-BYTES. Return an errr when trying t read frm an unpened file r frm a file pened nly fr writing, r if POSITION is greater than the size f the file FILE_NAME. write FILE_NAME POSITION NUM_BYTES STRING Writes t a file FILE_NAME, starting at POSITION, fr NUM-BYTES, the qute-enclsed STRING. Over-write the existing bytes at the specified psitin. Return an errr when trying t write an unpened file, r a file pened nly fr reading. If POSITION is utside the bunds f the file, grw the file enugh t make POSITION valid. File hles are supprted. If the length f the data exceeds the bunds f the file, grw the file as necessary. In case f all the functins abve, print an apprpriate errr message if the functin returns an errr. Allwed Assumptins: File and directry names will nt cntain spaces. Yu may assume that STRING always begins and ends with QUOTES FILE_NAME and DIR_NAME will nly cntain the names, nt multi-level paths. Fr example, create afile will create a file named afile in the current directry. It des nt have t supprt cmmands like create adirectry/afile Unless specified, yu may chse any reasnable data type fr the arguments and return values fr yur functins.

4 Grading Criteria: a) Dcumentatin: 30% 5: A Readme file listing grup members names, fsu ids, cntents f the flder, and hw t cmpile and execute. 5: Makefile 10: A reprt explaining hw the prgram wrks, the basic mdules, imprtant data structures and variables, any knwn limitatins/errrs/incmpleteness. Basically, make the grader s jb easier. 5: Cde: Readable 5: Cde: Naming b) Cding: 70% 55: pen, clse, create, rm, size, cd, ls, mkdir, rmdir, read, write ( 5 pints each) 15: input-utput handling c) Deductins: 70: fr nt cmpiling (S make sure it cmpiles at least.) 10: fr crashing at any pint while running 20: fr crrupting the image file Submissin and Grading Guidelines: 1. This is a grup prject. Each grup will have 3 peple. 2. One persn frm each team will submit a tar and gzip d archive cntaining the submissin t Blackbard. He surce cde and Makefile shuld be placed inside a src directry (D nt submit binaries). Other files (e.g. Readme) shuld be placed at the rt f the archive. Uplad yur submissin using Blackbard and verify that yu can dwnlad and extract it successfully. The filename f the submissin file is t be frmatted as: P3_<member_name1>_<member_name2>_<member_name3>.tar.gz At a minimum, the submitted archive shuld cntain: Dcumentatin Surce File Makefile 3. Fr this prject, n demnstratin is necessary. The TA will cntact yu if he thinks a meeting is needed.

5 4. Everyne in the grup will get the same grade. Because it is a grup prject, everyne is expected t share the wrklad equally. If anyne has a majr disagreement abut wrklad distributin, (s)he needs t cntact the TA befrehand.