setenv.c

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/*-------------------------------------------------------------------------
 *
 * setenv.c
 *    setenv() emulation for machines without it
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/port/setenv.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "c.h"
 
 
int
setenv(const char *name, const char *value, int overwrite)
{
    char       *envstr;
 
    /* Error conditions, per POSIX */
    if (name == NULL || name[0] == '\0' || strchr(name, '=') != NULL ||
        value == NULL)
    {
        errno = EINVAL;
        return -1;
    }
 
    /* No work if variable exists and we're not to replace it */
    if (overwrite == 0 && getenv(name) != NULL)
        return 0;
 
    /*
     * Add or replace the value using putenv().  This will leak memory if the
     * same variable is repeatedly redefined, but there's little we can do
     * about that when sitting atop putenv().
     */
    envstr = (char *) malloc(strlen(name) + strlen(value) + 2);
    if (!envstr)                /* not much we can do if no memory */
        return -1;
 
    sprintf(envstr, "%s=%s", name, value);
 
    return putenv(envstr);
}