diff options
| -rw-r--r-- | include/stdlib.h | 26 | ||||
| -rw-r--r-- | src/stdlib/getenv.c | 73 |
2 files changed, 99 insertions, 0 deletions
diff --git a/include/stdlib.h b/include/stdlib.h index ebfb5e2..0cb5f49 100644 --- a/include/stdlib.h +++ b/include/stdlib.h @@ -330,6 +330,32 @@ int clearenv(void) __warning("It may be better to use `if (environ) *environ = NULL;`."); #endif +/** + * 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*) + __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__))); + /* TODO implement rand-functions */ diff --git a/src/stdlib/getenv.c b/src/stdlib/getenv.c new file mode 100644 index 0000000..e0302f1 --- /dev/null +++ b/src/stdlib/getenv.c @@ -0,0 +1,73 @@ +/** + * 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; +} + |