stream-processing/filter.c at master · marcospgp/stream-processing · GitHub

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#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <limits.h>

#include "includes/globals.h"
#include "includes/readLine.h"

int main(int argc, char** argv) {

	// Chamada com o formato "filter colunaA operador colunaB", exemplo: "filter 2 > 4"
	// Operadores possíveis: =, >=, <=, >, <, !=

	if (argc < 4) {
		return EXIT_FAILURE;
	}

	char* end;

	long columnA = strtol(argv[1], &end, 10);
	char* operator = argv[2];
	long columnB = strtol(argv[3], &end, 10);

	// strtol error handling (strtol retorna 0 quando há um erro)
	if ( (columnA == 0 || columnB == 0) && errno != 0 ) {

		fprintf(stderr, "(filter) Error reading arguments: %s\n", strerror(errno));
		return EXIT_FAILURE;

	} else if (columnA < 1 || columnB < 1) {

		fprintf(stderr, "(filter) Error reading arguments (column value < 1): %ld %ld\n", columnA, columnB);
		return EXIT_FAILURE;
	}

	// Ler linhas do stdin

	char buffer[PIPE_BUF];
	char* columnAValue = (char*) malloc(PIPE_BUF);
	char* columnBValue = (char*) malloc(PIPE_BUF);

	ssize_t i;

	while ( (i = readLine(0, buffer, (long) PIPE_BUF)) > 0) {

		// Obter valores das colunas
		if (
			getElementValue(buffer, columnA, columnAValue, (long) PIPE_BUF) < 1 ||
			getElementValue(buffer, columnB, columnBValue, (long) PIPE_BUF) < 1
		) {
			fprintf(stderr, "(filter) Error obtaining column values (getElementValue returned 0)");
			return EXIT_FAILURE;
		}

		long columnAValueLong;
		long columnBValueLong;
		char* end2;

		columnAValueLong = strtol(columnAValue, &end2, 10);
		columnBValueLong = strtol(columnBValue, &end2, 10);

		if ( (columnAValueLong == 0 || columnBValueLong == 0) && errno != 0 ) {

			fprintf(stderr, "(filter) Error converting column values to long (strtol returned 0 and set errno)");
			return EXIT_FAILURE;
		}

		// Determinar operador a usar

		int echoLine = 0;

		if (strcmp(operator, "<") == 0) {

			if (columnAValueLong < columnBValueLong) {
				echoLine = 1;
			}

		} else if (strcmp(operator, "<=") == 0) {

			if (columnAValueLong < columnBValueLong) {
				echoLine = 1;
			}

		} else if (strcmp(operator, ">") == 0) {

			if (columnAValueLong > columnBValueLong) {
				echoLine = 1;
			}

		} else if (strcmp(operator, ">=") == 0) {

			if (columnAValueLong >= columnBValueLong) {
				echoLine = 1;
			}

		} else if (strcmp(operator, "!=") == 0) {

			if (columnAValueLong != columnBValueLong) {
				echoLine = 1;
			}

		} else if (strcmp(operator, "=") == 0) {

			if (columnAValueLong == columnBValueLong) {
				echoLine = 1;
			}
		}

		if (echoLine) {
			write(1, buffer, i);
		}
	}

	if (i < 0) {

		fprintf(stderr, "(filter) Error reading input: %s (read() returned %ld)\n", strerror(errno), i);
		return EXIT_FAILURE;

	} else {

		return EXIT_SUCCESS;
	}
}