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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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Disc2.iso
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vc98
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crt
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src
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execvpe.c
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C/C++ Source or Header
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1998-06-17
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/***
*execvpe.c - execute a file with given environ; search along PATH
*
* Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _execvpe() - execute a file with given environ
*
*******************************************************************************/
#include <cruntime.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <process.h>
#include <mbstring.h>
#include <tchar.h>
#include <dbgint.h>
#define SLASHCHAR _T('\\')
#define XSLASHCHAR _T('/')
#define SLASH _T("\\")
#define DELIMITER _T(";")
#ifdef _MBCS
/* note, the macro below assumes p is to pointer to a single-byte character
* or the 1st byte of a double-byte character, in a string.
*/
#define ISPSLASH(p) ( ((p) == _mbschr((p), SLASHCHAR)) || ((p) == \
_mbschr((p), XSLASHCHAR)) )
#else /* _MBCS */
#define ISSLASH(c) ( ((c) == SLASHCHAR) || ((c) == XSLASHCHAR) )
#endif /* _MBCS */
/***
*int _execvpe(filename, argvector, envvector) - execute a file
*
*Purpose:
* Executes a file with given arguments and environment.
* try to execute the file. start with the name itself (directory '.'),
* and if that doesn't work start prepending pathnames from the
* environment until one works or we run out. if the file is a pathname,
* don't go to the environment to get alternate paths. If a needed text
* file is busy, wait a little while and try again before despairing
* completely
*
*Entry:
* _TSCHAR *filename - file to execute
* _TSCHAR **argvector - vector of arguments
* _TSCHAR **envvector - vector of environment variables
*
*Exit:
* destroys the calling process (hopefully)
* if fails, returns -1
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _texecvpe (
REG3 const _TSCHAR *filename,
const _TSCHAR * const *argvector,
const _TSCHAR * const *envptr
)
{
REG1 _TSCHAR *env;
_TSCHAR *bbuf = NULL;
REG2 _TSCHAR *buf;
_TSCHAR *pfin;
_ASSERTE(filename != NULL);
_ASSERTE(*filename != _T('\0'));
_ASSERTE(argvector != NULL);
_ASSERTE(*argvector != NULL);
_ASSERTE(**argvector != _T('\0'));
_texecve(filename,argvector,envptr);
if ( (errno != ENOENT)
|| (_tcschr(filename, SLASHCHAR) != NULL)
|| (_tcschr(filename, XSLASHCHAR) != NULL)
|| *filename && *(filename+1) == _T(':')
|| !(env=_tgetenv(_T("PATH"))) )
goto reterror;
/* allocate a buffer to hold alternate pathnames for the executable
*/
if ( (buf = bbuf = _malloc_crt(_MAX_PATH * sizeof(_TSCHAR))) == NULL )
goto reterror;
do {
/* copy a component into bbuf[], taking care not to overflow it
*/
/* UNDONE: make sure ';' isn't 2nd byte of DBCS char */
while ( (*env) && (*env != _T(';')) && (buf < bbuf+(_MAX_PATH-2)*sizeof(_TSCHAR)) )
*buf++ = *env++;
*buf = _T('\0');
pfin = --buf;
buf = bbuf;
#ifdef _MBCS
if (*pfin == SLASHCHAR) {
if (pfin != _mbsrchr(buf,SLASHCHAR))
/* *pfin is the second byte of a double-byte
* character
*/
strcat( buf, SLASH );
}
else if (*pfin != XSLASHCHAR)
strcat(buf, SLASH);
#else /* _MBCS */
if (*pfin != SLASHCHAR && *pfin != XSLASHCHAR)
_tcscat(buf, SLASH);
#endif /* _MBCS */
/* check that the final path will be of legal size. if so,
* build it. otherwise, return to the caller (return value
* and errno rename set from initial call to _execve()).
*/
if ( (_tcslen(buf) + _tcslen(filename)) < _MAX_PATH )
_tcscat(buf, filename);
else
break;
_texecve(buf, argvector, envptr);
if ( (errno != ENOENT)
#ifdef _MBCS
&& (!ISPSLASH(buf) || !ISPSLASH(buf+1)) )
#else /* _MBCS */
&& (!ISSLASH(*buf) || !ISSLASH(*(buf+1))) )
#endif /* _MBCS */
break;
} while ( *env && env++ );
reterror:
if (bbuf != NULL)
_free_crt(bbuf);
return(-1);
}