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Department of Computer Science, Graduate School of Information Science & Technology,Osaka University

Finding File Clones in FreeBSD Ports Collection

Yusuke Sasaki

Tetsuo Yamamoto

Yasuhiro Hayase

Katsuro Inoue

Department of Computer Science, Graduate School of Information Science & Technology, Osaka University

File Clones

Two or more files with the same contentComments and code indentation ignored

Inside a project or between different projects Research about file-clones is scarce

Get new knowledge about file-clones

int main() {printf(“Hello msr!”);return 0;}

Project AProject A Project BProject B


FCFinder

Input .c and .h files

Output File-clone sets

Faster than other tools

Detection Tokenization MD5 Hash Calculation Exact Matching

Tool Speed

CCFinder 1.4M files / 960 hours x1 1PC

D-CCFinder 1.4M files / 51 hours x19 80PCs

FCFinder 1.4M files / 17.16 hours x55 1PC


Experiment

Target Only .c and .h files in the FreeBSD Ports Collection ~1.4M files ~12 GB 17.16 hours

We measured: File size Number of files in each project Size of each file-clone set Number of file-clones in a project

These values follow the power law


population of file clone set

num

ber o

f file

clo

ne s

ets

110

0File-clone Set Size

5 5010 100

Left ： used in PHP5Right ： used in PHP4

DE

used in both of PHP4 and 5

419 setsL:650 setsR:500 sets

L:61 file clonesR:59 file clones

120 file clones

file clone set size R*2 = 0.8508


number of file clones in projects (clones inside project are excluded)

num

ber o

f pro

ject

s w

ith fi

le c

lone

s

15

5050

0

File-clones per Project

Right ： PHP4 modulesCenter ： projects related bin-utilsLeft ： PHP5 modules

G

5 5010 100 500 1K 5K 10K

number of file clone sets R*2 = 0.8263


File-clones Between Projects (1/3)

* Nodes show the projects* Edges between projects show the number of file clones between two projects

Ex) gcc41 and gfortran shares 7691 file clones








Conclusions & Future Work

Conclusions Measured several features of the FreeBSD

Ports collection. Found that the measured features follow the

power law

Future Work Projects logical coupling investigation