env_handlers.c

#include "shell.h"

char *get_env_value(char *beginning, int len);
char **_getenv(const char *var);
int sh_env(char **args, char __attribute__((__unused__)) **front);
int sh_setenv(char **args, char __attribute__((__unused__)) **front);
int sh_unsetenv(char **args, char __attribute__((__unused__)) **front);

/**
 * get_env_value - Gets the value corresponding to an environmental variable.
 * @beginning: The environmental variable to search for.
 * @len: The length of the environmental variable to search for.
 * Return: If the variable is not found - an empty string.
 *         Otherwise - the value of the environmental variable.
 * Description: Variables are stored in the format VARIABLE=VALUE.
 */

char *get_env_value(char *beginning, int len)
{
	char **var_addr;
	char *replacement = NULL, *temp, *var;

	var = malloc(len + 1);
	if (!var)
		return (NULL);
	var[0] = '\0';
	_strncat(var, beginning, len);
	var_addr = _getenv(var);
	free(var);
	if (var_addr)
	{
		temp = *var_addr;
		while (*temp != '=')
			temp++;
		temp++;
		replacement = malloc(_strlen(temp) + 1);
		if (replacement)
			_strcpy(replacement, temp);
	}
	return (replacement);
}

/**
 * sh_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 sh_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);
}

/**
 * sh_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 sh_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);
}

/**
 * sh_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 sh_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);
}

/**
 * _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);
}