getln.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <unistd.h>
#include <wait.h>

#define CHUNK 1

char** res = NULL;
char* _getln();
char** _strtok_by_space(char* str, int* len);
void exit_handler(void);

int main(int argv, char* argc[]){
    if(atexit(exit_handler))
        printf("Failed to register exit_handler\n");

    /* Example of _getln() and _strtok()
    */
    int len, i;
    char* a = _getln();
    char** res = _strtok_by_space(a, &len);

    for(i = 0; i < (len+1); ++i)
        printf("res[%d] = %s\n", i, res[i]);

    /* execvp TEST
    */
    char *name[] = {
        "/bin/bash",
        "-c",
        "echo 'Hello World'",
        NULL
    };

    execvp(name[0], name);

    free(a);
    //free(*res);
    //free(res);
    return 0;
}

// _getln() : Read string input with memory-efficient dynamic allocation
// IN : 
// OUT : 
// RETURN : dynamic allocated string input
char* _getln(){
    char *line = NULL, *tmp = NULL;
    size_t size = 0, index = 0;
    int ch = EOF;

    while (ch) {
        ch = getc(stdin);

        /* Check if we need to stop. */
        if (ch == EOF || ch == '\n')
            ch = 0;

        /* Check if we need to expand. */
        if (size <= index) {
            size += CHUNK;
            tmp = realloc(line, size);
            if (!tmp) {
                free(line);
                line = NULL;
                break;
            }
            line = tmp;
        }

        /* Actually store the thing. */
        line[index++] = ch;
    }

    return line;
}

// _strtok_by_space : Return arr of string splited by space with dynamic allocation
// IN : str(char*)
// OUT : len(int*) - length of arr of string
// RETURN : dynamic allocated arr of string
char** _strtok_by_space(char* str, int* len){
    char*  p    = strtok(str, " ");
    int n_spaces = 0, i;
    char** res = NULL;

    /* split string and append tokens to 'res' */
    while (p) {
        res = realloc(res, sizeof (char*) * ++n_spaces);

        if (res == NULL)
            exit(-1); /* memory allocation failed */

        res[n_spaces-1] = p;

        p = strtok(NULL, " ");
    }

    /* realloc one extra element for the last NULL */
    res = realloc(res, sizeof (char*) * (n_spaces+1));
    res[n_spaces] = 0;

    *len = n_spaces;
    return res;
}

void exit_handler(void){
    printf("Bye :)\n");
}