environments.c

#include "main.h"

char **_copyenv(void);
void free_env(void);
char **_getenv(const char *var);

int shellby_env(char **args, char __attribute__((__unused__)) **front);
int shellby_setenv(char **args, char __attribute__((__unused__)) **front);
int shellby_unsetenv(char **args, char __attribute__((__unused__)) **front);

/**
 * _copyenv - Creates a copy of the environment.
 *
 * Return: If an error occurs - NULL.
 *         O/w - a double pointer to the new copy.
 */
char **_copyenv(void)
{
	char **new_environ;
	size_t size;
	int index;

	for (size = 0; environ[size]; size++)
		;

	new_environ = malloc(sizeof(char *) * (size + 1));
	if (!new_environ)
		return (NULL);

	for (index = 0; environ[index]; index++)
	{
		new_environ[index] = malloc(_strlen(environ[index]) + 1);

		if (!new_environ[index])
		{
			for (index--; index >= 0; index--)
				free(new_environ[index]);
			free(new_environ);
			return (NULL);
		}
		_strcpy(new_environ[index], environ[index]);
	}
	new_environ[index] = NULL;

	return (new_environ);
}

/**
 * free_env - Frees the the environment copy.
 */
void free_env(void)
{
	int index;

	for (index = 0; environ[index]; index++)
		free(environ[index]);
	free(environ);
}

/**
 * _getenv - Gets an environmental variable from the PATH.
 * @var: The name of the environmental variable to get.
 *
 * Return: If the environmental variable does not exist - NULL.
 *         Otherwise - a pointer to the environmental variable.
 */
char **_getenv(const char *var)
{
	int index, len;

	len = _strlen(var);
	for (index = 0; environ[index]; index++)
	{
		if (_strncmp(var, environ[index], len) == 0)
			return (&environ[index]);
	}

	return (NULL);
}

/**
 * shellby_env - Prints the current environment.
 * @args: An array of arguments passed to the shell.
 * @front: A double pointer to the beginning of args.
 *
 * Return: If an error occurs - -1.
 *	   Otherwise - 0.
 *
 * Description: Prints one variable per line in the
 *              format 'variable'='value'.
 */
int shellby_env(char **args, char __attribute__((__unused__)) **front)
{
	int index;
	char nc = '\n';

	if (!environ)
		return (-1);

	for (index = 0; environ[index]; index++)
	{
		write(STDOUT_FILENO, environ[index], _strlen(environ[index]));
		write(STDOUT_FILENO, &nc, 1);
	}

	(void)args;
	return (0);
}

/**
 * shellby_setenv - Changes or adds an environmental variable to the PATH.
 * @args: An array of arguments passed to the shell.
 * @front: A double pointer to the beginning of args.
 * Description: args[1] is the name of the new or existing PATH variable.
 *              args[2] is the value to set the new or changed variable to.
 *
 * Return: If an error occurs - -1.
 *         Otherwise - 0.
 */
int shellby_setenv(char **args, char __attribute__((__unused__)) **front)
{
	char **env_var = NULL, **new_environ, *new_value;
	size_t size;
	int index;

	if (!args[0] || !args[1])
		return (create_error(args, -1));

	new_value = malloc(_strlen(args[0]) + 1 + _strlen(args[1]) + 1);
	if (!new_value)
		return (create_error(args, -1));
	_strcpy(new_value, args[0]);
	_strcat(new_value, "=");
	_strcat(new_value, args[1]);

	env_var = _getenv(args[0]);
	if (env_var)
	{
		free(*env_var);
		*env_var = new_value;
		return (0);
	}
	for (size = 0; environ[size]; size++)
		;

	new_environ = malloc(sizeof(char *) * (size + 2));
	if (!new_environ)
	{
		free(new_value);
		return (create_error(args, -1));
	}

	for (index = 0; environ[index]; index++)
		new_environ[index] = environ[index];

	free(environ);
	environ = new_environ;
	environ[index] = new_value;
	environ[index + 1] = NULL;

	return (0);
}

/**
 * shellby_unsetenv - Deletes an environmental variable from the PATH.
 * @args: An array of arguments passed to the shell.
 * @front: A double pointer to the beginning of args.
 * Description: args[1] is the PATH variable to remove.
 *
 * Return: If an error occurs - -1.
 *         Otherwise - 0.
 */
int shellby_unsetenv(char **args, char __attribute__((__unused__)) **front)
{
	char **env_var, **new_environ;
	size_t size;
	int index, index2;

	if (!args[0])
		return (create_error(args, -1));
	env_var = _getenv(args[0]);
	if (!env_var)
		return (0);

	for (size = 0; environ[size]; size++)
		;

	new_environ = malloc(sizeof(char *) * size);
	if (!new_environ)
		return (create_error(args, -1));

	for (index = 0, index2 = 0; environ[index]; index++)
	{
		if (*env_var == environ[index])
		{
			free(*env_var);
			continue;
		}
		new_environ[index2] = environ[index];
		index2++;
	}
	free(environ);
	environ = new_environ;
	environ[size - 1] = NULL;

	return (0);
}