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

extern char **environ;
/*
int _getenv(char *key)
{
    char *token;
    unsigned int i = 0;

    for (i = 0; environ[i]; i++)
    {
        token = strtok(environ[i], "=");
        if (strcmp(key, token) == 0)
            return (1);
    }
    return (0);
}
*/
int len_environ(char **env)
{
    int i = 0;

    while (env[i])
        i++;
    return (i);
}

int _setenv(char *key, char *value, int overwrite)
{
    char *new_token;
    size_t len_key, len_value;
    int len_env, i = 0, found = 0;
    char **new_environ;

    if (key == NULL || value == NULL)
        return (-1);

    if (getenv(key) && overwrite == 0)
        return (0);

    len_key = strlen(key);
    len_value = strlen(value);
    new_token = malloc(sizeof(char) * (len_value + len_key + 2));

    strcpy(new_token, key);
    strcat(new_token, "=");
    strcat(new_token, value);
    new_token[len_key + len_value + 1] = '\0';

    len_env = len_environ(environ);
    if (getenv(key))
        new_environ = malloc(sizeof(char *) * len_env);
    else
        new_environ = malloc(sizeof(char *) * len_env + 1);

    while (environ[i])
    {
        if (strncmp(environ[i], key, strlen(key)) == 0)
        {
            new_environ[i] = strdup(new_token);
            found = 1;
        }
        else
            new_environ[i] = environ[i];
        i++;
    }
    if (found == 0)
    {
        new_environ[i] = strdup(new_token);
        new_environ[i + 1] = NULL;
    }
    else
        new_environ[i] = NULL;
    environ = new_environ;
    return (0);
}


int main()
{
    int i = 0;
    _setenv("PATH", "salam", 0);

    for (i = 0; environ[i]; i++)
        printf("%s\n", environ[i]);
}