1 /*
2 FUNCTION
3 <<_getenv_r>>---look up environment variable
4
5 INDEX
6 _getenv_r
7 INDEX
8 environ
9
10 SYNOPSIS
11 #include <stdlib.h>
12 char *_getenv_r(struct _reent *<[reent_ptr]>, const char *<[name]>);
13
14 DESCRIPTION
15 <<_getenv_r>> searches the list of environment variable names and values
16 (using the global pointer ``<<char **environ>>'') for a variable whose
17 name matches the string at <[name]>. If a variable name matches,
18 <<_getenv_r>> returns a pointer to the associated value.
19
20 RETURNS
21 A pointer to the (string) value of the environment variable, or
22 <<NULL>> if there is no such environment variable.
23
24 PORTABILITY
25 <<_getenv_r>> is not ANSI; the rules for properly forming names of environment
26 variables vary from one system to another. This implementation does not
27 permit '=' to be in identifiers.
28
29 <<_getenv_r>> requires a global pointer <<environ>>.
30 */
31
32 /* This file may have been modified by DJ Delorie (Jan 1991). If so,
33 ** these modifications are Copyright (C) 1991 DJ Delorie.
34 */
35
36 /*
37 * Copyright (c) 1987 Regents of the University of California.
38 * All rights reserved.
39 *
40 * Redistribution and use in source and binary forms are permitted
41 * provided that: (1) source distributions retain this entire copyright
42 * notice and comment, and (2) distributions including binaries display
43 * the following acknowledgement: ``This product includes software
44 * developed by the University of California, Berkeley and its contributors''
45 * in the documentation or other materials provided with the distribution
46 * and in all advertising materials mentioning features or use of this
47 * software. Neither the name of the University nor the names of its
48 * contributors may be used to endorse or promote products derived
49 * from this software without specific prior written permission.
50 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
51 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
52 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
53 */
54
55 #include <stdlib.h>
56 #include <stddef.h>
57 #include <string.h>
58 #include "envlock.h"
59
60 extern char **environ;
61
62 /* Only deal with a pointer to environ, to work around subtle bugs with shared
63 libraries and/or small data systems where the user declares his own
64 'environ'. */
65 static char ***p_environ = &environ;
66
67 /*
68 * _findenv --
69 * Returns pointer to value associated with name, if any, else NULL.
70 * Sets offset to be the offset of the name/value combination in the
71 * environmental array, for use by setenv(3) and unsetenv(3).
72 *
73 * This routine *should* be a static; don't use it.
74 */
75
76 char *
_findenv(register const char * name,int * offset)77 _findenv (
78 register const char *name,
79 int *offset)
80 {
81 register int len;
82 register char **p;
83 const char *c;
84
85 ENV_LOCK;
86
87 /* In some embedded systems, this does not get set. This protects
88 newlib from dereferencing a bad pointer. */
89 if (!*p_environ)
90 {
91 ENV_UNLOCK;
92 return NULL;
93 }
94
95 c = name;
96 while (*c && *c != '=') c++;
97
98 /* Identifiers may not contain an '=', so cannot match if does */
99 if(*c != '=')
100 {
101 len = c - name;
102 for (p = *p_environ; *p; ++p)
103 if (!strncmp (*p, name, len))
104 if (*(c = *p + len) == '=')
105 {
106 *offset = p - *p_environ;
107 ENV_UNLOCK;
108 return (char *) (++c);
109 }
110 }
111 ENV_UNLOCK;
112 return NULL;
113 }
114