CSCI4061 - Parallel String Matching - Solved

Background
Grep is a linux command that is used to find patterns in each file. It prints each line that matches the pattern. In this project I implemented “Parallel String Matching”, a program that will search for a string in all files and subdirectories of a root directory using multiple processes.

 
Project Overview
I used File I/O, Pipes, directory operations, links and I/O redirection. In this project, I spawned multiple child processes. Each child process is responsible for searching some portion of the root directory and communicates the search results to the parent using pipes. Parent is responsible for reading from these pipes and printing the output to the terminal. Only the parent prints the output to the terminal.

 
Input
This program takes 2 arguments:

inputdirectorypath: The path to the root directory
wordtosearch: The string to be searched
```bash

./master 
```
 
Output
The program will print all the lines containing wordtosearch.

The output format is as follows:

[Path to the file containing wordtosearch]: [Line containing the string]

Example:  
 
String Matching
String matching is case sensitive. Use of the strstr() function provided by the string library is strongly recommended.

 
Child Processes and Root Directory
The root directory may contain multiple first level subdirectories and files. One child process needs to be created for every first level subdirectory. This child process is responsible for searching all the files in its sub directories.

A pipe must also be created for every child. Pipe is used by the child to communicate the results back to the parent.

Consider a possible directory structure as shown in Fig 1. Here, the root directory /root contains 2 first level subdirectories, namely /root/f1 and /root/f2. Child 1 as shown in the figure, is responsible for searching files in /root/f1. Child 2 as shown in the figure is responsible for searching files in /root/f2.
Note that no new child is created for the /root/f2/f3 directory. Child processes are only created for the first level directories.
Also, note that parent is responsible for searching first level files (in this case File 5) and no new child is created for this.

  Fig. 1

 
Pipes and I/O Redirection
Pipe will be used by the child to communicate search results to the parent. Parent reads from the pipe and prints it to the console. Each child’s STDOUT must be redirected to the write end of the pipe. One pipe must be created for each child process. In Fig 1, two pipes are created, one for each child.

 
Directory Traversal and Soft Links
Each child process needs to traverse the sub-directory assigned to it recursively, searching every file in its directory sub structure and writing search results to the pipe. A file may be a regular file, link, directory etc. While traversing the directory, make sure to not parse soft links files.

 
Project Folder Structure
The project folder contains “include”, “lib”, “src”, “input” and “output” folders, as well as Makefile, README and two executables.

include folder: .h header files
lib folder: .o library files
src folder: .c source files
input folder: contains input folders
output folder: Use "make run" to create output files for all test cases
Two executables: master and child
 
Execution Syntax
Run Master Program Directly
```bash

./master 
```
Run Test Cases
For test case 1:

bash make run1 

For test case 2:

bash make run2 

And so on...