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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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spawnvpe.c
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C/C++ Source or Header
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1998-06-17
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6KB
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163 lines
/***
*spawnvpe.c - spawn a child process with given environ (search PATH)
*
* Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _spawnvpe() - spawn a child process with given environ (search
* PATH)
*
*******************************************************************************/
#include <cruntime.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <malloc.h>
#include <internal.h>
#include <process.h>
#include <mbstring.h>
#include <tchar.h>
#include <dbgint.h>
#define SLASH _T("\\")
#define SLASHCHAR _T('\\')
#define XSLASHCHAR _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 */
/***
*_spawnvpe(modeflag, filename, argv, envptr) - spawn a child process
*
*Purpose:
* Spawns a child process with the given arguments and environ,
* searches along PATH for given file until found.
* Formats the parameters and calls _spawnve to do the actual work. The
* NULL environment pointer indicates that the new process will inherit
* the parents process's environment. NOTE - at least one argument must
* be present. This argument is always, by convention, the name of the
* file being spawned.
*
*Entry:
* int modeflag - defines mode of spawn (WAIT, NOWAIT, or OVERLAY)
* only WAIT and OVERLAY supported
* _TSCHAR *filename - name of file to execute
* _TSCHAR **argv - vector of parameters
* _TSCHAR **envptr - vector of environment variables
*
*Exit:
* returns exit code of spawned process
* if fails, returns -1
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _tspawnvpe (
int modeflag,
REG3 const _TSCHAR *filename,
const _TSCHAR * const *argv,
const _TSCHAR * const *envptr
)
{
int i;
REG1 _TSCHAR *env;
REG2 _TSCHAR *buf = NULL;
_TSCHAR *pfin;
_ASSERTE(filename != NULL);
_ASSERTE(*filename != _T('\0'));
_ASSERTE(argv != NULL);
_ASSERTE(*argv != NULL);
_ASSERTE(**argv != _T('\0'));
if (
(i = _tspawnve(modeflag, filename, argv, envptr)) != -1
/* everything worked just fine; return i */
|| (errno != ENOENT)
/* couldn't spawn the process, return failure */
|| (_tcschr(filename, XSLASHCHAR) != NULL)
/* filename contains a '/', return failure */
|| !(env = _tgetenv(_T("PATH")))
/* no PATH environment string name, return failure */
|| ( (buf = _malloc_crt(_MAX_PATH * sizeof(_TSCHAR))) == NULL )
/* cannot allocate buffer to build alternate pathnames, return
* failure */
) {
goto done;
}
/* could not find the file as specified, search PATH. try each
* component of the PATH until we get either no error return, or the
* error is not ENOENT and the component is not a UNC name, or we run
* out of components to try.
*/
#ifdef WPRFLAG
while ( (env = _wgetpath(env, buf, _MAX_PATH - 1)) && (*buf) ) {
#else /* WPRFLAG */
while ( (env = _getpath(env, buf, _MAX_PATH - 1)) && (*buf) ) {
#endif /* WPRFLAG */
pfin = buf + _tcslen(buf) - 1;
/* if necessary, append a '/'
*/
#ifdef _MBCS
if (*pfin == SLASHCHAR) {
if (pfin != _mbsrchr(buf,SLASHCHAR))
/* fin is the second byte of a double-byte char */
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 _spawnve()).
*/
if ( (_tcslen(buf) + _tcslen(filename)) < _MAX_PATH )
_tcscat(buf, filename);
else
break;
/* try spawning it. if successful, or if errno comes back with a
* value other than ENOENT and the pathname is not a UNC name,
* return to the caller.
*/
if ( (i = _tspawnve(modeflag, buf, argv, envptr)) != -1
|| ((errno != ENOENT)
#ifdef _MBCS
&& (!ISPSLASH(buf) || !ISPSLASH(buf+1))) )
#else /* _MBCS */
&& (!ISSLASH(*buf) || !ISSLASH(*(buf+1)))) )
#endif /* _MBCS */
break;
}
done:
if (buf != NULL)
_free_crt(buf);
return(i);
}