214 lines
6.1 KiB
C
214 lines
6.1 KiB
C
/***
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*getenv.c - get the value of an environment variable
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines getenv() - searches the environment for a string variable
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* and returns the value of it.
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*
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*Revision History:
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* 11-22-83 RN initial version
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* 04-13-87 JCR added const to declaration
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* 11-09-87 SKS avoid indexing past end of strings (add strlen check)
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* 12-11-87 JCR Added "_LOAD_DS" to declaration
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* 06-01-88 PHG Merged normal/DLL versions
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* 03-14-90 GJF Replaced _LOAD_DS with _CALLTYPE1, added #include
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* <cruntime.h>, removed #include <register.h> and fixed
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* the copyright. Also, cleaned up the formatting a bit.
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* 04-05-90 GJF Added #include <string.h>.
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* 07-25-90 SBM Removed redundant include (stdio.h)
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* 08-13-90 SBM Compiles cleanly with -W3 (made length unsigned int)
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* 10-04-90 GJF New-style function declarator.
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* 01-18-91 GJF ANSI naming.
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* 02-06-91 SRW Added _WIN32_ conditional for GetEnvironmentVariable
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* 02-18-91 SRW Removed _WIN32_ conditional for GetEnvironmentVariable
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* 01-10-92 GJF Final unlock and return statements shouldn't be in
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* if-block.
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* 03-11-92 GJF Use case-insensitive comparison for Win32.
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* 04-27-92 GJF Repackaged MTHREAD support for Win32 to create a
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* _getenv_lk.
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* 06-05-92 PLM Added _MAC_
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* 06-10-92 PLM Added _envinit for _MAC_
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* Remove OS/2, POSIX support
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* 04-08-93 SKS Replace strnicmp() with ANSI-conforming _strnicmp()
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* 09-14-93 GJF Small change for Posix compatibility.
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* 11-29-93 CFW Wide char enable.
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* 12-07-93 CFW Change _TCHAR to _TSCHAR.
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* 01-15-94 CFW Use _tcsnicoll for global match.
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* 02-04-94 CFW POSIXify.
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* 03-31-94 CFW Should be ifndef POSIX.
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* 02-14-95 CFW Debug CRT allocs.
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* 02-16-95 JWM Spliced _WIN32 & Mac versions.
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* 08-01-96 RDK For Pmac, change data type of initialization pointer.
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* 07-09-97 GJF Added a check that the environment initialization has
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* been executed. Also, detab-ed and got rid of obsolete
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* _CALLTYPE1 macros.
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* 03-05-98 GJF Exception-safe locking.
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* 12-18-98 GJF Changes for 64-bit size_t.
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* 04-28-99 PML Wrap __declspec(allocate()) in _CRTALLOC macro.
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* 05-17-99 PML Remove all Macintosh support.
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*
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*******************************************************************************/
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#include <sect_attribs.h>
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#include <cruntime.h>
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#include <internal.h>
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#include <mtdll.h>
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#include <stdlib.h>
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#include <string.h>
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#include <tchar.h>
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#ifndef CRTDLL
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/*
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* Flag checked by getenv() and _putenv() to determine if the environment has
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* been initialized.
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*/
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extern int __env_initialized;
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#endif
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/***
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*char *getenv(option) - search environment for a string
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*
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*Purpose:
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* searches the environment for a string of the form "option=value",
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* if found, return value, otherwise NULL.
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*
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*Entry:
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* const char *option - variable to search for in environment
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*
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*Exit:
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* returns the value part of the environment string if found,
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* otherwise NULL
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*
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*Exceptions:
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*
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*******************************************************************************/
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#ifdef _MT
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#ifdef WPRFLAG
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wchar_t * __cdecl _wgetenv (
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#else
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char * __cdecl getenv (
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#endif
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const _TSCHAR *option
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)
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{
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_TSCHAR *retval;
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_mlock( _ENV_LOCK );
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__try {
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#ifdef WPRFLAG
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retval = _wgetenv_lk(option);
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#else
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retval = _getenv_lk(option);
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#endif
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}
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__finally {
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_munlock( _ENV_LOCK );
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}
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return(retval);
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}
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#ifdef WPRFLAG
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wchar_t * __cdecl _wgetenv_lk (
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#else
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char * __cdecl _getenv_lk (
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#endif
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const _TSCHAR *option
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)
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#else /* ndef _MT */
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#ifdef WPRFLAG
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wchar_t * __cdecl _wgetenv (
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#else
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char * __cdecl getenv (
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#endif
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const _TSCHAR *option
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)
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#endif /* _MT */
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{
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#ifdef _POSIX_
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char **search = environ;
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#else
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_TSCHAR **search = _tenviron;
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#endif
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size_t length;
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#ifndef CRTDLL
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/*
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* Make sure the environment is initialized.
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*/
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if ( !__env_initialized )
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return NULL;
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#endif /* CRTDLL */
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/*
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* At startup, we obtain the 'native' flavor of environment strings
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* from the OS. So a "main" program has _environ and a "wmain" has
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* _wenviron loaded at startup. Only when the user gets or puts the
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* 'other' flavor do we convert it.
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*/
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#ifndef _POSIX_
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#ifdef WPRFLAG
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if (!search && _environ)
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{
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/* don't have requested type, but other exists, so convert it */
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if (__mbtow_environ() != 0)
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return NULL;
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/* now requested type exists */
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search = _wenviron;
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}
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#else
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if (!search && _wenviron)
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{
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/* don't have requested type, but other exists, so convert it */
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if (__wtomb_environ() != 0)
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return NULL;
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/* now requested type exists */
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search = _environ;
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}
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#endif
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#endif /* _POSIX_ */
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if (search && option)
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{
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length = _tcslen(option);
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/*
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** Make sure `*search' is long enough to be a candidate
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** (We must NOT index past the '\0' at the end of `*search'!)
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** and that it has an equal sign (`=') in the correct spot.
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** If both of these requirements are met, compare the strings.
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*/
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while (*search)
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{
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if (_tcslen(*search) > length && (*(*search + length)
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== _T('=')) && (_tcsnicoll(*search, option, length) == 0)) {
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return(*search + length + 1);
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}
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search++;
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}
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}
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return(NULL);
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}
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