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.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
30static 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
74char *curl_getenv(const char *v)
75{
76 return GetEnv(v);
77}
78