Mercurial > ecos
diff packages/language/c/libc/current/src/stdlib/getenv.cxx @ 0:3111d98ba7b3 ecos-v1_1-release
Initial commit of eCos version 1.1
| author | jlarmour |
|---|---|
| date | Tue, 11 May 1999 11:16:07 +0000 |
| parents | |
| children | 443894e2e912 |
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new file mode 100644 --- /dev/null +++ b/packages/language/c/libc/current/src/stdlib/getenv.cxx @@ -0,0 +1,138 @@ +//======================================================================== +// +// getenv.cxx +// +// Implementation of the ISO C standard getenv() function +// +//======================================================================== +//####COPYRIGHTBEGIN#### +// +// ------------------------------------------- +// The contents of this file are subject to the Cygnus eCos Public License +// Version 1.0 (the "License"); you may not use this file except in +// compliance with the License. You may obtain a copy of the License at +// http://sourceware.cygnus.com/ecos +// +// Software distributed under the License is distributed on an "AS IS" +// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the +// License for the specific language governing rights and limitations under +// the License. +// +// The Original Code is eCos - Embedded Cygnus Operating System, released +// September 30, 1998. +// +// The Initial Developer of the Original Code is Cygnus. Portions created +// by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved. +// ------------------------------------------- +// +//####COPYRIGHTEND#### +//======================================================================== +//#####DESCRIPTIONBEGIN#### +// +// Author(s): jlarmour +// Contributors: jlarmour@cygnus.co.uk +// Date: 1998-08-31 +// Purpose: +// Description: +// Usage: +// +//####DESCRIPTIONEND#### +// +//======================================================================== + +// CONFIGURATION + +#include <pkgconf/libc.h> // Configuration header + +// Include the C library? +#if defined(CYGPKG_LIBC) && defined(CYGPKG_LIBC_ENVIRONMENT) + +// INCLUDES + +#include <cyg/infra/cyg_type.h> // Common type definitions and support +#include <cyg/infra/cyg_ass.h> // Tracing support +#include <cyg/infra/cyg_trac.h> // Tracing support +#include <stdlib.h> // Main header for stdlib functions +#include <string.h> // strchr(), strlen() and strncmp() +#include "clibincl/stdlibsupp.hxx" // Support for stdlib functions + + +// VARIABLES + +externC char **environ; // standard definition of environ + +// EXPORTED SYMBOLS + +externC char * +getenv( const char *name ) CYGPRI_LIBC_WEAK_ALIAS("_getenv"); + + +// FUNCTIONS + +extern char * +_getenv( const char *name ) +{ + // This function assumes the POSIX 1003.1 layout of the environment + // in the environ variable, i.e. extern char **environ is a pointer + // to an array of character pointers to the environment strings + // (POSIX 3.1.2.2 and 2.6). + // + // getenv() searches the environment list for a string of the form + // "name=value" (POSIX 4.6.1). The strings must have this form + // (POSIX 2.6) + + CYG_REPORT_FUNCNAMETYPE( "_getenv", "returning %08x" ); + + CYG_PRECONDITION( name != NULL, "getenv() called with NULL string!" ); + + CYG_REPORT_FUNCARG1( "name=%s", name ); + + CYG_PRECONDITION( environ != NULL, + "environ not set i.e. environ == NULL" ); + + CYG_CHECK_DATA_PTR( environ, "environ isn't a valid pointer!" ); + + CYG_CHECK_DATA_PTR( name, "name isn't a valid pointer!" ); + + // check name doesn't contain '=' + CYG_PRECONDITION( strchr(name, '=') == NULL, + "name contains '='!" ); + + char **env_str_p; + cyg_ucount32 len = strlen( name ); + + for (env_str_p = environ; *env_str_p != NULL; ++env_str_p ) { + + CYG_CHECK_DATA_PTR( env_str_p, + "current environment string isn't valid!" ); + + CYG_CHECK_DATA_PTR( *env_str_p, + "current environment string isn't valid!" ); + + // do we have a match? + if ( !strncmp(*env_str_p, name, len) ) { + // but it could be just a prefix i.e. we could have + // matched MYNAMEFRED when we're looking for just MYNAME, so: + + if ( (*env_str_p)[len] == '=' ) { + // we got a match + CYG_REPORT_RETVAL( *env_str_p + len + 1 ); + + return (*env_str_p + len + 1); + } // if + } // if + + // check the next pointer isn't NULL, as we're about to dereference + // it + CYG_ASSERT( env_str_p+1 != NULL, + "environment contains a NULL pointer!" ); + } // for + + CYG_REPORT_RETVAL( NULL ); + return NULL; +} // getenv() + + +#endif // if defined(CYGPKG_LIBC) && defined(CYGPKG_LIBC_ENVIRONMENT) + +// EOF getenv.cxx
