main.c

/**
 * @author Harsh Rawat, harsh-rawat, hrawat2
 * @author Sidharth Gurbani, gurbani, gurbani
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "error_handle.h"
#include "makefile_parser.h"
#include "execution_engine.h"

/**
 * These are internal methods used in this main file
 * */
void findMakefileTargetAndName(int argc, char *argv[], char **makefile_args);

char *findMakefile(char *name);

/**
 * main method of this project.
 * We parse the makefile to build an execution graph and then we execute it
 * */
int main(int argc, char *argv[]) {

    //makefile_args contain target_name and makefile_name
    char **makefile_args = malloc(sizeof(char *) * 2);
    ValidateMemoryAllocationError(makefile_args);

    //Find the appropriate target and file name based on the input args
    findMakefileTargetAndName(argc, argv, makefile_args);

    FILE *file = fopen(makefile_args[1], "r");
    if (file == NULL) {
        FileOpenError(makefile_args[1], errno);
    }

    //Generate execution graph by calling ParseMakefile. Then check for any cyclic dependencies in the graph.
    list_node *execution_graph = ParseMakefile(file);
    DetectCycleInGraph(execution_graph);

    //Execute the execution graph from the node which has the target name as provided (In case of NULL, we use the first rule).
    ExecuteExecutionGraph(execution_graph, makefile_args[0]);

    //Close the file and perform other cleanup
    fclose(file);
    free(makefile_args);
    return 1;
}

/**
 * This method is used to find the makefile name and target from the arguments passed to main
 * We can pass 0,1,2 or 3 parameters. In case of incorrect number or format of parameters, we raise an error
 * */
void findMakefileTargetAndName(int argc, char *argv[], char **makefile_args) {
    if (argc < 1 || argc > 4)
        InvalidArgumentsError("Error: Number of arguments to main should be between 0 and 3.\nExiting!");

    if (argc == 1) {
        //Usage as "make537"
        makefile_args[0] = NULL;
        makefile_args[1] = findMakefile(NULL);
    } else if (argc == 2) {
        //Usage as "make537 clean"
        makefile_args[0] = argv[1];
        makefile_args[1] = findMakefile(NULL);
    } else if (argc == 3) {
        //Usage as "make537 -f custom_makefile"
        if (strcmp(argv[1], "-f") == 0) {
            makefile_args[0] = NULL;
            makefile_args[1] = findMakefile(argv[2]);
        } else
            InvalidArgumentsError(
                    "Error: If 2 arguments are being passed to main then first argument should be -f.\nExiting!");
    } else if (argc == 4) {
        //Usage as "make537 -f custom_makefile clean"
        if (strcmp(argv[1], "-f") != 0)
            InvalidArgumentsError(
                    "Error: If 3 arguments are being passed to main then first argument should be -f.\nExiting!");
        makefile_args[0] = argv[3];
        makefile_args[1] = findMakefile(argv[2]);
    }
}

/**
 * This method is used to find the name of appropriate makefile
 * If we have passed a name then we check for its presence, else we check for makefile or Makefile
 * */
char *findMakefile(char *name) {
    if (name == NULL) {
        char *makefile_1 = "makefile";
        char *makefile_2 = "Makefile";
        if (access(makefile_1, F_OK) != -1)
            return makefile_1;
        else if (access(makefile_2, F_OK) != -1)
            return makefile_2;
        else {
            FileNotFoundError("makefile and Makefile", -1, NULL);
            return NULL;
        }
    } else {
        if (access(name, F_OK) == -1) {
            FileNotFoundError(name, -1, NULL);
            return NULL;
        } else
            return name;
    }
}