windows-nt-4.0/private/sdktools/vctools/crt/crtw32/startup/stdenvp.c

/***
*stdenvp.c - standard _setenvp routine
*
*       Copyright (c) 1989-1995, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       This module is called by the C start-up routine to set up "_environ".
*       Its sets up an array of pointers to strings in the environment.
*       The global symbol "_environ" is set to point to this array.
*
*Revision History:
*       11-07-84  GFW   initial version
*       01-08-86  SKS   Modified for OS/2
*       05-21-86  SKS   Call _stdalloc to get memory for strings
*       09-04-86  SKS   Added check to skip the "*C_FILE_INFO" string
*       10-21-86  SKS   Improved check for "*C_FILE_INFO"/"_C_FILE_INFO"
*       02-19-88  SKS   Handle case where environment starts with a single null
*       05-10-88  JCR   Modified code to accept far pointer from _stdalloc
*       06-01-88  PHG   Merged DLL and normal versions
*       07-12-88  JCR   Largely re-written: (1) split mem allocation into two
*                       seperate malloc() calls to help simplify putenv(),
*                       (2) stdalloc() no longer robs from stack, (3) cProc/cEnd
*                       sequence, (4) misc cleanup
*       09-20-88  WAJ   Initial 386 version
*       12-13-88  JCR   Use rterr.inc parameters for runtime errors
*       04-09-90  GJF   Added #include <cruntime.h>. Made the calling type
*                       _CALLTYPE1. Also, fixed the copyright and cleaned up
*                       up the formatting a bit.
*       06-05-90  GJF   Changed error message interface.
*       10-08-90  GJF   New-style function declarator.
*       10-31-90  GJF   Fixed statement appending the final NULL (Stevewo
*                       found the bug).
*       12-11-90  SRW   Changed to include <oscalls.h> and setup _environ
*                       correctly for Win32
*       01-21-91  GJF   ANSI naming.
*       02-07-91  SRW   Change _WIN32_ specific code to allocate static copy (_WIN32_)
*       02-18-91  SRW   Change _WIN32_ specific code to allocate copy of
*                       variable strings as well [_WIN32_]
*       07-25-91  GJF   Changed strupr to _strupr.
*       03-31-92  DJM   POSIX support.
*       04-20-92  GJF   Removed conversion to upper-case code for Win32.
*       04-06-93  SKS   Replace _CRTAPI* with __cdecl
*       11-24-93  CFW   Rip out Cruiser and filter out "=c:\foo" type.
*       11-29-93  CFW   Remove unused POSIX stuff, wide char enable.
*       12-07-93  CFW   Change _TCHAR to _TSCHAR.
*       01-10-95  CFW   Debug CRT allocs.
*       04-07-95  CFW   Free environment block on demand.
*       07-03-95  GJF   Always free environment block.
*       02-28-96  BWT   Just return if there's no environ.
*
*******************************************************************************/

#include <cruntime.h>
#include <string.h>
#include <stdlib.h>
#include <internal.h>
#include <rterr.h>
#include <oscalls.h>
#include <tchar.h>
#include <dbgint.h>

/***
*_setenvp - set up "envp" for C programs
*
*Purpose:
*       Reads the environment and build the envp array for C programs.
*
*Entry:
*       The environment strings occur at _aenvptr.
*       The list of environment strings is terminated by an extra null
*       byte.  Thus two null bytes in a row indicate the end of the
*       last environment string and the end of the environment, resp.
*
*Exit:
*       "environ" points to a null-terminated list of pointers to ASCIZ
*       strings, each of which is of the form "VAR=VALUE".  The strings
*       are copied from the environment area. This array of pointers will
*       be malloc'ed
*
*Uses:
*       Allocates space on the heap for the environment pointers.
*
*Exceptions:
*       If space cannot be allocated, program is terminated.
*
*******************************************************************************/

#ifdef WPRFLAG
void __cdecl _wsetenvp (
#else
void __cdecl _setenvp (
#endif
        void
        )
{
        _TSCHAR *p;
        _TSCHAR **env;          /* _environ ptr traversal pointer */
        int numstrings;         /* number of environment strings */
        int cchars;

        numstrings = 0;

#ifdef WPRFLAG
        p = _wenvptr;
#else
        p = _aenvptr;
#endif

        if (!p) {
            _tenviron = NULL;
            return;
        }

        /*
         * NOTE: starting with single null indicates no environ.
         * Count the number of strings. Skip drive letter settings
         * ("=C:=C:\foo" type) by skipping all environment variables
         * that begin with '=' character.
         */

        while (*p != _T('\0')) {
            /* don't count "=..." type */
            if (*p != _T('='))
                ++numstrings;
            p += _tcslen(p) + 1;
        }

        /* need pointer for each string, plus one null ptr at end */
        if ( (_tenviron = env = (_TSCHAR **)
            _malloc_crt((numstrings+1) * sizeof(_TSCHAR *))) == NULL )
            _amsg_exit(_RT_SPACEENV);

        /* copy strings to malloc'd memory and save pointers in _environ */
#ifdef WPRFLAG
        for ( p = _wenvptr ; *p != L'\0' ; p += cchars ) {
#else
        for ( p = _aenvptr ; *p != '\0' ; p += cchars ) {
#endif
            cchars = _tcslen(p) + 1;
            /* don't copy "=..." type */
            if (*p != _T('=')) {
                if ( (*env = (_TSCHAR *)_malloc_crt(cchars * sizeof(_TSCHAR))) == NULL )
                    _amsg_exit(_RT_SPACEENV);
                _tcscpy(*env, p);
                env++;
            }
        }

#ifdef WPRFLAG
        _free_crt(_wenvptr);
#else
        _free_crt(_aenvptr);
#endif

        /* and a final NULL pointer */
        *env = NULL;
}