Searching for files that its filename matches a wildcard strings in a directory

[Weijye Wang]

Greetings,I am writting a program that simulate cp command in linux. Here's the part code I have so far:

int main( int argc, char *argv[] )
{
	if (argc != 3)
	{
		cerr << "Program must take 2 arguments from terminal. Exiting now!" << endl;
		return 1;	// End the program with error.
	}

	char *source = argv[1];
	char *destination = argv[2];

	validateSource(source);

	ifstream infile(source);	
	if (!infile)
	{
		cerr << "Error: Input file could not be opened." << endl;
		return 1;
	}

	infile.seekg(0, infile.end);			
	unsigned int filesize = infile.tellg();	
	infile.seekg(0, infile.beg);			

	char *buffer = new char[filesize];		// Allocate size for buffer.

	infile.read(buffer, filesize);	// Read all the file content into memory.

	string filename;

	getSourceFilename(filename, source);	// Call function to get the source filename.
	
	bool destinationExist;

	int destinationIsValid = open(destination, O_RDONLY);

	if (destinationIsValid < 0)
	{
		destinationExist = false;	
	}
	else
	{
		destinationExist = true;	
	}

	bool sourceIsWildcard;

	sourceIsWildcard = checkIsWildcard(filename);

	bool isDirectoryPath = false;	
	bool isFile = false;	

	// If directory of file exist.
	if (destinationExist)
	{
		checkDestinationIsDirectoryPathOrFile(isDirectoryPath, isFile, destination);

		if (!sourceIsWildcard)
		{
			// User did not enter wildcard for source.
			if(isDirectoryPath)
			{
				string newPath;	

				for (int i = 0; i< strlen(destination); ++i)
				{
					newPath += destination[i];	
				}
				newPath += filename;			

				// Copy files to destination.
				ofstream outfile( newPath.c_str() );		// Create output file stream to create a file and write the contents.
				if (!outfile)
				{
					cerr << "Error: Output file could not be opened." << endl;
					return 1;
				}
				outfile.write(buffer, filesize);	// Write the file content to the file.
			}
			else if(isFile)
			{
				string input;	// Field for confirmation input.
				// Overwrite files.
				cout << "Overwrite " << filename << " ? y/n" << endl;
				getline(cin, input, '\n');	// Read in the user input into the field.
			
				if (input == "y" || input == "Y")	// Case where user choose yes to overwrite.
				{
					// Write to the same file and overwrite its content.
					// Copy files to destination.
					ofstream outfile(destination);	// Create output file stream to create a file and write the contents.
					if (!outfile)
					{
						cerr << "Error: Output file could not be opened." << endl;
						return 1;	// Exit the program with error.
					}
					outfile.write(buffer, filesize);	// Write the file content to the file.
				}
				else if (input == "n" || input == "N")	// Case where user choose not to overwrite.
				{
					return 0; 	// Exit the program without doing anything.	
				}
				else	// Case where user enter anything other than 'y' or 'n'.
				{
					cerr << "Error: Invalid input. Please try again later."	<< endl;		
				}
			}
		}
		// User enter wildcard for source.
		else if (sourceIsWildcard)
		{
			
			// Use regex (regular expression) from regex class in c++ to do the searching and matching of wildcards.
			regex alphanum ("[A-Za-z0-9]+");   // Matches any alphanum.
			// Count how many files match the wildcard result.
		}
	}
	// If directory or file does not exist.
	else
	{
		checkDestinationIsDirectoryPathOrFile(isDirectoryPath, isFile, destination);

		// If destination is a directory path.
		if (isDirectoryPath)
		{
			int status;	// Field for the mkdir function status (success or fail).
			// Make the directory path.
			status = mkdir(destination, S_IRWXU);

			if (status == -1)
			{
				cerr << "Error: Directory path could not be created." << endl;
				return 1;	// Exit with error.
			}

			string newDir;	// Field to store the directory path with the filename.

			for (int i = 0; i < strlen(destination); ++i)
			{
				newDir += destination[i];	// Assign the path to the field.
			}
			newDir += '/' + filename;		// Add the filename to the field.

			// Create another file with the same file name as source and copy over the content.
			ofstream outfile( newDir.c_str() );	// Create output file stream to create a file and write the contents.
			if (!outfile)
			{
				cerr << "Error: Output file could not be opened." << endl;
				return 1;	// Exit the program with error.
			}
			outfile.write(buffer, filesize);	// Write the file content to the file.
		}
		// If destination contain a filename.
		else if (isFile)
		{
			string directory; // Field for directory.

			unsigned int filename_charCount = 0;	// Field to store the number of characters of the filename.
		
			for (int i = strlen(source) - 1; i >= 0; --i)
			{
				if (source[i] != '/')
				{
					++filename_charCount;	// Count increment.
				}
				else
				{
					break;	// Break free from the loop to get the last segment of the directory string.
				}
			}

			// Read the directory by lefting out the filename from the string.
			for (int i = 0; i < strlen(destination) - filename_charCount; ++i)
			{
				directory += destination[i];
			}

			// Create the new directory.
			int status;
			// Create the directory path.
			status = mkdir(directory.c_str(), S_IRWXU);

			if (status == -1)
			{
				cerr << "Error: Directory path could not be created." << endl;
				return 1;	
			}

			// Create another file with the same file name as source and copy over the content.
			ofstream outfile(destination);	
			if (!outfile)
			{
				cerr << "Error: Output file could not be opened." << endl;
				return 1;	// Exit the program with error.
			}
			outfile.write(buffer, filesize);	// Write the file content to the file.
		}
	}
	return 0;
}

void validateSource(char *&source)
{
	// Open function return negative value if error occurs.
	int sourceIsValid = open(source, O_RDONLY);

	if (sourceIsValid < 0)
	{
		cerr << "Source path or file does not existed!" << endl;
		exit(1);	// Exit program with error.
	}

	struct stat st_buf;
	// Get the status of the file system object.
	int status = stat(source, &st_buf);

	if (status != 0) 
	{
		cerr << "Destination file status is bad!" << endl;

		exit(1);	// Exit the program with error if file status is bad.
	}
	
	// Check whether the source is a directory or file. If it is a directory, exit with error.
	if ( S_ISDIR (st_buf.st_mode) ) 
	{
		cerr << "Selected source is not a file!" << endl;
		exit(1);
	}
}

bool checkIsWildcard(string &filename)
{
	// Loop the last segment of source string to search for asterisk character.
	for (int i = 0; i < filename.length(); ++i)
	{
		if (filename.at(i) == '*')
		{
			return true;	// Wildcard is detected.
		}
	}
	return false;	// Not wildcard.
}

void getSourceFilename(string &filename, char *&source)
{
	int filename_charCount = 0;	// Field to store the number of characters of the filename.

	for (int i = strlen(source) - 1; i >= 0; i--)
	{
		if (source[i] != '/')
		{
			++filename_charCount;	// Count increment.
		}
		else
		{
			break;	// Break free from the loop to get the last segment of the directory string.
		}
	}

	for (int i = strlen(source) - filename_charCount; i < strlen(source); ++i)
	{
		filename += source[i];	// Add in all the characters to form the filename.
	}
}
void checkDestinationIsDirectoryPathOrFile(bool &isDirectoryPath, bool &isFile, char *&destination)
{
	int filename_charCount = 0;	// Field to store the number of characters of the filename.

	for (int i = strlen(destination) - 1; i >= 0; i--)
	{
		if (destination[i] != '/')
		{
			++filename_charCount;
		}
		else
		{
			break;
		}
	}

	for (int i = strlen(destination) - filename_charCount; i < strlen(destination); ++i)
	{
		// A filename contain extension indicated by '.'.
		if (destination[i] == '.')
		{
			isFile = true;
		}
	}

	if (!isFile)
	{
		isDirectoryPath = true;
	}
}

I'm currently stuck at processing the wildcard part. I found out about regex but i'm not sure whether that's a good way to do this.

When the user runs "./program /home/user/*.cpp /home/user/results" in the terminal, the program will search for any cpp files in the home directory and copy those file to a folder named "results" in home directory.

[ne555]

1 2 3 4 5 6

#include <iostream> int main(int argc, char **argv){ for(int K=0; K<argc; ++K) std::cout << K << ' ' << argv[K] << '\n'; return 0; }

$ ./a.out *.cpp /home/ 0 ./a.out 1 args.cpp 2 list.cpp 3 main.cpp 4 /home/

[Weijye Wang]

Thanks for the tips. Appreciate it!