42sh/src/builtins/echo.c


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#include <stdio.h>
#include <string.h>

#include "builtins.h"

static void print_echo(struct string **args, int escapes, int newline, int i)
{
    while (args[i] != NULL)
    {
        if (escapes)
        {
            size_t j = 0;
            while (j < args[i]->length)
            {
                if (args[i]->data[j] == '\\' && args[i]->data[j] != '\0')
                {
                    j += 1;
                    switch (args[i]->data[j])
                    {
                    case 'n':
                        putchar('\n');
                        break;
                    case 't':
                        putchar('\t');
                        break;
                    case '\\':
                        putchar('\\');
                        break;
                    default:
                        putchar('\\');
                        putchar(args[i]->data[j]);
                        break;
                    }
                    j += 1;
                }
                else
                {
                    putchar(args[i]->data[j]);
                    j += 1;
                }
            }
        }
        else
        {
            fputs(args[i]->data, stdout);
        }
        if (args[i + 1] != NULL)
        {
            putchar(' ');
        }
        i += 1;
    }
    if (newline)
    {
        putchar('\n');
    }
}

int echo(struct string **args)
{
    int newline = 1;
    int escapes = 0;
    size_t i = 0;
    if (args[0] == NULL)
    {
        putchar('\n');
        return 0;
    }
    while (args[i] != NULL && args[i]->data[0] == '-')
    {
        if (args[i]->length == 2 && args[i]->data[1] == 'n')
        {
            newline = 0;
            i += 1;
        }
        else if (args[i]->length == 2 && args[i]->data[1] == 'e')
        {
            escapes = 1;
            i += 1;
        }
        else if (args[i]->length == 2 && args[i]->data[1] == 'E')
        {
            escapes = 0;
            i += 1;
        }
        else
        {
            break;
        }
    }
    print_echo(args, escapes, newline, i);
    fflush(stdout);
    return 0;
}