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/**
* slibc — Yet another C library
* Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
/**
* The process's environment variables.
*/
extern char** environ;
/**
* This function returns the value assoicated with a
* specified environment variable.
*
* Portable program must not check `errno`. No errors
* are defined by POSIX.
*
* @etymology (Get) the value of an (env)ironment variable!
*
* @param name The name of the sought environment variable.
* Must not be `NULL`.
* @return The value of the environment variable.
* `NULL` on error, or if not found. This
* pointer is subpointer, and must not be
* modified except for in-place changes.
*
* @throws 0 No such environment variable found.
* This is a slibc extensions.
* @throws EINVAL `name` is `NULL` (must not be the case), empty,
* or contains a '='. This is a slibc extensions.
*
* @since Always.
*/
char* getenv(const char* name)
{
size_t i, n;
if (!name || !*name || strchr(name, '='))
return errno = EINVAL, NULL;
errno = 0;
if (environ == NULL)
return NULL;
n = strlen(name);
for (i = 0; environ[i] != NULL; i++)
if (!strncmp(name, environ[i], n))
if (environ[i][n] == '=')
return environ[i] + n + 1;
return NULL;
}
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