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    1: /***************************************************************************
    2:  *                                  _   _ ____  _
    3:  *  Project                     ___| | | |  _ \| |
    4:  *                             / __| | | | |_) | |
    5:  *                            | (__| |_| |  _ <| |___
    6:  *                             \___|\___/|_| \_\_____|
    7:  *
    8:  * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
    9:  *
   10:  * This software is licensed as described in the file COPYING, which
   11:  * you should have received as part of this distribution. The terms
   12:  * are also available at https://curl.haxx.se/docs/copyright.html.
   13:  *
   14:  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
   15:  * copies of the Software, and permit persons to whom the Software is
   16:  * furnished to do so, under the terms of the COPYING file.
   17:  *
   18:  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
   19:  * KIND, either express or implied.
   20:  *
   21:  ***************************************************************************/
   22: 
   23: #include "curl_setup.h"
   24: 
   25: #include <curl/curl.h>
   26: #include "curl_memory.h"
   27: 
   28: #include "memdebug.h"
   29: 
   30: static char *GetEnv(const char *variable)
   31: {
   32: #if defined(_WIN32_WCE) || defined(CURL_WINDOWS_APP)
   33:   (void)variable;
   34:   return NULL;
   35: #elif defined(WIN32)
   36:   /* This uses Windows API instead of C runtime getenv() to get the environment
   37:      variable since some changes aren't always visible to the latter. #4774 */
   38:   char *buf = NULL;
   39:   char *tmp;
   40:   DWORD bufsize;
   41:   DWORD rc = 1;
   42:   const DWORD max = 32768; /* max env var size from MSCRT source */
   43: 
   44:   for(;;) {
   45:     tmp = realloc(buf, rc);
   46:     if(!tmp) {
   47:       free(buf);
   48:       return NULL;
   49:     }
   50: 
   51:     buf = tmp;
   52:     bufsize = rc;
   53: 
   54:     /* It's possible for rc to be 0 if the variable was found but empty.
   55:        Since getenv doesn't make that distinction we ignore it as well. */
   56:     rc = GetEnvironmentVariableA(variable, buf, bufsize);
   57:     if(!rc || rc == bufsize || rc > max) {
   58:       free(buf);
   59:       return NULL;
   60:     }
   61: 
   62:     /* if rc < bufsize then rc is bytes written not including null */
   63:     if(rc < bufsize)
   64:       return buf;
   65: 
   66:     /* else rc is bytes needed, try again */
   67:   }
   68: #else
   69:   char *env = getenv(variable);
   70:   return (env && env[0])?strdup(env):NULL;
   71: #endif
   72: }
   73: 
   74: char *curl_getenv(const char *v)
   75: {
   76:   return GetEnv(v);
   77: }