Source code of Windows XP (NT5)
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/***
*system.c - pass a command line to the shell
*
* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines system() - passes a command to the shell
*
*Revision History:
* 12-01-83 RN written
* 10-23-86 SKS Fixed use of strtok(), added check for NULL rtn from getenv
* 12-18-86 SKS PROTMODE symbol used for dual-modal version
* 02-23-86 JCR Put in support for NULL command pointer (MSDOS only)
* 04-13-86 JCR Added const to declaration
* 06-30-87 JCR Re-wrote system to use spawnvpe, removed XENIX conditional
* code, lots of general cleaning up.
* 07-01-87 PHG removed P->PROTMODE compile switch hack
* 09-22-87 SKS remove extern variable declarations, add ";" to assert()'s
* 11-10-87 SKS Removed IBMC20 switch, change PROTMODE to OS2
* 12-11-87 JCR Added "_LOAD_DS" to declaration
* 02-22-88 JCR Added cast to get rid of cl const warning
* 09-05-88 SKS Treat EACCES the same as ENOENT -- keep trying
* 03-08-90 GJF Replaced _LOAD_DS with _CALLTYPE1, added #include
* <cruntime.h>, removed some leftover DOS support and
* fixed the copyright. Also, cleaned up the formatting
* formatting a bit.
* 07-23-90 SBM Compiles cleanly with -W3 (removed unreferenced
* variable), removed redundant includes, replaced
* <assertm.h> by <assert.h>, minor optimizations
* 09-27-90 GJF New-style function declarator.
* 01-17-91 GJF ANSI naming.
* 02-14-90 SRW Use NULL instead of _environ to get default.
* 02-23-93 SKS Remove reference to _osmode and use of "command.com"
* 04-06-93 SKS Replace _CRTAPI* with __cdecl
* 12-07-93 CFW Wide char enable.
* 12-06-94 SKS Assume command.com for Win95, but cmd.exe for Win. NT.
* 01-16-95 SKS Avoid calling access(NULL) if command==NULL and
* %COMSPEC% is unset.
* 02-06-95 CFW assert -> _ASSERTE.
* 02-06-98 GJF Changes for Win64: added cast to int where necessary
*
*******************************************************************************/
#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));
}