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comparison packages/language/c/libc/current/src/stdlib/getenv.cxx @ 0:3111d98ba7b3 ecos-v1_1-release

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Initial commit of eCos version 1.1
author jlarmour
date Tue, 11 May 1999 11:16:07 +0000
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children 443894e2e912
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-1:000000000000 0:3111d98ba7b3
1 //========================================================================
2 //
3 // getenv.cxx
4 //
5 // Implementation of the ISO C standard getenv() function
6 //
7 //========================================================================
8 //####COPYRIGHTBEGIN####
9 //
10 // -------------------------------------------
11 // The contents of this file are subject to the Cygnus eCos Public License
12 // Version 1.0 (the "License"); you may not use this file except in
13 // compliance with the License. You may obtain a copy of the License at
14 // http://sourceware.cygnus.com/ecos
15 //
16 // Software distributed under the License is distributed on an "AS IS"
17 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
18 // License for the specific language governing rights and limitations under
19 // the License.
20 //
21 // The Original Code is eCos - Embedded Cygnus Operating System, released
22 // September 30, 1998.
23 //
24 // The Initial Developer of the Original Code is Cygnus. Portions created
25 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved.
26 // -------------------------------------------
27 //
28 //####COPYRIGHTEND####
29 //========================================================================
30 //#####DESCRIPTIONBEGIN####
31 //
32 // Author(s): jlarmour
33 // Contributors: jlarmour@cygnus.co.uk
34 // Date: 1998-08-31
35 // Purpose:
36 // Description:
37 // Usage:
38 //
39 //####DESCRIPTIONEND####
40 //
41 //========================================================================
42
43 // CONFIGURATION
44
45 #include <pkgconf/libc.h> // Configuration header
46
47 // Include the C library?
48 #if defined(CYGPKG_LIBC) && defined(CYGPKG_LIBC_ENVIRONMENT)
49
50 // INCLUDES
51
52 #include <cyg/infra/cyg_type.h> // Common type definitions and support
53 #include <cyg/infra/cyg_ass.h> // Tracing support
54 #include <cyg/infra/cyg_trac.h> // Tracing support
55 #include <stdlib.h> // Main header for stdlib functions
56 #include <string.h> // strchr(), strlen() and strncmp()
57 #include "clibincl/stdlibsupp.hxx" // Support for stdlib functions
58
59
60 // VARIABLES
61
62 externC char **environ; // standard definition of environ
63
64 // EXPORTED SYMBOLS
65
66 externC char *
67 getenv( const char *name ) CYGPRI_LIBC_WEAK_ALIAS("_getenv");
68
69
70 // FUNCTIONS
71
72 extern char *
73 _getenv( const char *name )
74 {
75 // This function assumes the POSIX 1003.1 layout of the environment
76 // in the environ variable, i.e. extern char **environ is a pointer
77 // to an array of character pointers to the environment strings
78 // (POSIX 3.1.2.2 and 2.6).
79 //
80 // getenv() searches the environment list for a string of the form
81 // "name=value" (POSIX 4.6.1). The strings must have this form
82 // (POSIX 2.6)
83
84 CYG_REPORT_FUNCNAMETYPE( "_getenv", "returning %08x" );
85
86 CYG_PRECONDITION( name != NULL, "getenv() called with NULL string!" );
87
88 CYG_REPORT_FUNCARG1( "name=%s", name );
89
90 CYG_PRECONDITION( environ != NULL,
91 "environ not set i.e. environ == NULL" );
92
93 CYG_CHECK_DATA_PTR( environ, "environ isn't a valid pointer!" );
94
95 CYG_CHECK_DATA_PTR( name, "name isn't a valid pointer!" );
96
97 // check name doesn't contain '='
98 CYG_PRECONDITION( strchr(name, '=') == NULL,
99 "name contains '='!" );
100
101 char **env_str_p;
102 cyg_ucount32 len = strlen( name );
103
104 for (env_str_p = environ; *env_str_p != NULL; ++env_str_p ) {
105
106 CYG_CHECK_DATA_PTR( env_str_p,
107 "current environment string isn't valid!" );
108
109 CYG_CHECK_DATA_PTR( *env_str_p,
110 "current environment string isn't valid!" );
111
112 // do we have a match?
113 if ( !strncmp(*env_str_p, name, len) ) {
114 // but it could be just a prefix i.e. we could have
115 // matched MYNAMEFRED when we're looking for just MYNAME, so:
116
117 if ( (*env_str_p)[len] == '=' ) {
118 // we got a match
119 CYG_REPORT_RETVAL( *env_str_p + len + 1 );
120
121 return (*env_str_p + len + 1);
122 } // if
123 } // if
124
125 // check the next pointer isn't NULL, as we're about to dereference
126 // it
127 CYG_ASSERT( env_str_p+1 != NULL,
128 "environment contains a NULL pointer!" );
129 } // for
130
131 CYG_REPORT_RETVAL( NULL );
132 return NULL;
133 } // getenv()
134
135
136 #endif // if defined(CYGPKG_LIBC) && defined(CYGPKG_LIBC_ENVIRONMENT)
137
138 // EOF getenv.cxx