if.c

PocketCMD是与pocketconsole配合实用的命令行解释器（Shell）

/*
 *  IF.C - if internal batch command.
 *
 *
 *  History:
 *
 *    16 Jul 1998 (Hans B Pufal)
 *        started.
 *
 *    16 Jul 1998 (John P Price)
 *        Seperated commands into individual files.
 *
 *    27-Jul-1998 (John P Price <[e-mail]>)
 *        added config.h include
 *
 *    07-Jan-1999 (Eric Kohl <[e-mail]>)
 *        Added help text ("if /?") and cleaned up.
 *
 *    21-Jan-1999 (Eric Kohl <[e-mail]>)
 *        Unicode and redirection ready!
 *
 *    01-Sep-1999 (Eric Kohl <[e-mail]>)
 *        Fixed help text.
 *
 *    17-Feb-2001 (ea)
 *        IF DEFINED variable command
 */

#include "config.h"

#include "cmd.h"


#define X_EXEC 1
#define X_EMPTY 0x80

INT cmd_if (LPTSTR cmd, LPTSTR param)
{
	INT x_flag = 0; /* when set cause 'then' clause to be executed */
	LPTSTR pp;

#ifdef _DEBUG
	DebugPrintf (_T("cmd_if: (\'%s\', \'%s\'\n"), cmd, param);
#endif

	if (!_tcsncmp (param, _T("/?"), 2))
	{
		ConOutPuts (_T("Performs conditional processing in batch programs.\n")
			_T("\n")
			_T("  IF [NOT] ERRORLEVEL number command\n")
			_T("  IF [NOT] string1==string2 command\n")
			_T("  IF [NOT] EXIST filename command\n")
			_T("  IF [NOT] DEFINED variable command\n")
			_T("\n")
			_T("NOT               Specifies that CMD should carry out the command only if\n")
			_T("                  the condition is false\n")
			_T("ERRORLEVEL number Specifies a true condition if the last program run returned\n")
			_T("                  an exit code equal or greater than the number specified.\n")
			_T("command           Specifies the command to carry out if the condition is met.\n")
			_T("string1==string2  Specifies a true condition if the specified text strings\n")
			_T("                  match.\n")
			_T("EXIST filename    Specifies a true condition if the specified filename exists.\n")
			_T("DEFINED variable  Specifies a true condition if the specified variable is\n")
			_T("                  defined."));
		return 0;
	}

	/* First check if param string begins with word 'not' */
	if (!_tcsnicmp (param, _T("not"), 3) && _istspace (*(param + 3)))
	{
		x_flag = X_EXEC;            /* Remember 'NOT' */
		param += 3;                 /* Step over 'NOT' */
		while (_istspace (*param))  /* And subsequent spaces */
			param++;
	}

	/* Check for 'exist' form */
	if (!_tcsnicmp (param, _T("exist"), 5) && _istspace (*(param + 5)))
	{
		param += 5;
		while (_istspace (*param))
			param++;

		pp = param;
		while (*pp && !_istspace (*pp))
			pp++;

		if (*pp)
		{
			WIN32_FIND_DATA f;
			HANDLE hFind;

			*pp++ = _T('\0');
			hFind = FindFirstFile (param, &f);
			x_flag ^= (hFind == INVALID_HANDLE_VALUE) ? 0 : X_EXEC;
			if (hFind != INVALID_HANDLE_VALUE)
			{
				FindClose (hFind);
			}
		}
		else
			return 0;
	}

	/* Check for 'defined' form */
	else if (!_tcsnicmp (param, _T("defined"), 7) && _istspace (*(param + 7)))
	{
		TCHAR Value [1];
		INT   ValueSize = 0;

		param += 7;
		/* IF [NOT] DEFINED var COMMAND */
		/*                 ^            */
		while (_istspace (*param))
			param++;
		/* IF [NOT] DEFINED var COMMAND */
		/*                  ^           */
		pp = param;
		while (*pp && !_istspace (*pp))
			pp++;
		/* IF [NOT] DEFINED var COMMAND */
		/*                     ^        */
		if (*pp)
		{
			*pp++ = _T('\0');
			ValueSize = GetEnvironmentVariable(param, Value, sizeof Value);
			x_flag ^= (0 == ValueSize)
					? 0 
					: X_EXEC;
			x_flag |= X_EMPTY;
		}
		else
			return 0;
	}

	/* Check for 'errorlevel' form */
	else if (!_tcsnicmp (param, _T("errorlevel"), 10) && _istspace (*(param + 10)))
	{
		INT n = 0;

		pp = param + 10;
		while (_istspace (*pp))
			pp++;

		while (_istdigit (*pp))
			n = n * 10 + (*pp++ - _T('0'));

		x_flag ^= (nErrorLevel < n) ? 0 : X_EXEC;

		x_flag |= X_EMPTY;          /* Syntax error if comd empty */
	}

	/* Check that '==' is present, syntax error if not */
	else if (NULL == (pp = _tcsstr (param, _T("=="))))
	{
		error_syntax (NULL);
		return 1;
	}

	else
	{
		/* Change first '='to space to terminate comparison loop */

		*pp = _T(' ');   /* Need a space to terminate comparison loop */
		pp += 2;                /* over '==' */
		while (_istspace (*pp)) /* Skip subsequent spaces */
			pp++;

		_tcscat (pp, _T(" "));  /* Add one space to ensure comparison ends */

		while (*param == *pp)       /* Comparison loop */
		{
			if (_istspace (*param))      /* Terminates on space */
				break;

			param++, pp++;
		}

		if (x_flag ^= (*param != *pp) ? 0 : X_EXEC)
		{
			while (*pp && !_istspace (*pp))  /* Find first space, */
				pp++;

			x_flag |= X_EMPTY;
		}
	}

	if (x_flag & X_EMPTY)
	{
		while (_istspace (*pp)) /* Then skip spaces */
			pp++;

		if (*pp == _T('\0'))    /* If nothing left then syntax err */
		{
			error_syntax (NULL);
			return 1;
		}
	}

	if (x_flag & X_EXEC)
	{
		ParseCommandLine (pp);
	}

	return 0;
}