Code:
/***
*system.c - pass a command line to the shell
*
* Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines system() - passes a command to the shell
*
*******************************************************************************/
#include <cruntime.h>
#include <process.h>
#include <io.h>
#include <stdlib.h>
#include <errno.h>
#include <tchar.h>
#include <dbgint.h>
/***
*int system(command) - send the command line to a shell
*
*Purpose:
* Executes a shell and passes the command line to it.
* If command is NULL, determine if a command processor exists.
* The command processor is described by the environment variable
* COMSPEC. If that environment variable does not exist, try the
* name "cmd.exe" for Windows NT and "command.com" for Windows '95.
*
*Entry:
* char *command - command to pass to the shell (if NULL, just determine
* if command processor exists)
*
*Exit:
* if command != NULL returns status of the shell
* if command == NULL returns non-zero if CP exists, zero if CP doesn't exist
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _tsystem (
const _TSCHAR *command
)
{
int catch;
_TSCHAR *argv[4];
argv[0] = _tgetenv(_T("COMSPEC"));
/*
* If command == NULL, return true IFF %COMSPEC%
* is set AND the file it points to exists.
*/
if (command == NULL) {
return argv[0] == NULL ? 0 : (!_taccess(argv[0],0));
}
_ASSERTE(*command != _T('\0'));
argv[1] = _T("/c");
argv[2] = (_TSCHAR *) command;
argv[3] = NULL;
/* If there is a COMSPEC defined, try spawning the shell */
if (argv[0]) /* Do not try to spawn the null string */
if ((catch = (int)_tspawnve(_P_WAIT,argv[0],argv,NULL)) != -1
|| (errno != ENOENT && errno != EACCES))
return(catch);
/* No COMSPEC so set argv[0] to what COMSPEC should be. */
argv[0] = ( _osver & 0x8000 ) ? _T("command.com") : _T("cmd.exe");
/* Let the _spawnvpe routine do the path search and spawn. */
return((int)_tspawnvpe(_P_WAIT,argv[0],argv,NULL));
}