cosmopolitan/libc/mem/putenv.c

73 lines
2.9 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ 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; version 2 of the License. │
│ │
│ 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, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/alg/alg.h"
#include "libc/mem/internal.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"
#define MAX_VARS 512
int PutEnvImpl(char *s, bool overwrite) {
char *p;
unsigned i, namelen;
p = strchr(s, '=');
if (!p) goto fail;
namelen = p + 1 - s;
for (i = 0; environ[i]; ++i) {
if (strncmp(environ[i], s, namelen) == 0) {
if (!overwrite) {
free(s);
return 0;
}
goto replace;
}
}
if (i + 1 >= MAX_VARS) goto fail;
environ[i + 1] = NULL;
replace:
free(environ[i]);
environ[i] = s;
return 0;
fail:
free(s);
return einval();
}
/**
* Emplaces environment key=value.
* @see setenv(), getenv()
*/
int putenv(char *string) {
return PutEnvImpl(strdup(string), true);
}
textstartup static void putenv_init(void) {
char **pin, **pout;
pin = environ;
pout = malloc(sizeof(char *) * MAX_VARS);
environ = pout;
while (*pin) *pout++ = strdup(*pin++);
*pout = NULL;
}
const void *const putenv_ctor[] initarray = {putenv_init};