reactos/base/shell/cmd/redir.c

/*
 *  REDIR.C - redirection handling.
 *
 *
 *  History:
 *
 *    12/15/95 (Tim Norman)
 *        started.
 *
 *    12 Jul 98 (Hans B Pufal)
 *        Rewrote to make more efficient and to conform to new command.c
 *        and batch.c processing.
 *
 *    27-Jul-1998 (John P Price <linux-guru@gcfl.net>)
 *        Added config.h include
 *
 *    22-Jan-1999 (Eric Kohl)
 *        Unicode safe!
 *        Added new error redirection "2>" and "2>>".
 *
 *    26-Jan-1999 (Eric Kohl)
 *        Added new error AND output redirection "&>" and "&>>".
 *
 *    24-Jun-2005 (Brandon Turner <turnerb7@msu.edu>)
 *        simple check to fix > and | bug with 'rem'
 */

#include <precomp.h>

#ifdef FEATURE_REDIRECTION


/* cmd allows redirection of handles numbered 3-9 even though these don't
 * correspond to any STD_ constant. */
static HANDLE ExtraHandles[10 - 3];

static HANDLE GetHandle(UINT Number)
{
	if (Number < 3)
		return GetStdHandle(STD_INPUT_HANDLE - Number);
	else
		return ExtraHandles[Number - 3];
}

static VOID SetHandle(UINT Number, HANDLE Handle)
{
	if (Number < 3)
		SetStdHandle(STD_INPUT_HANDLE - Number, Handle);
	else
		ExtraHandles[Number - 3] = Handle;
}

BOOL
PerformRedirection(REDIRECTION *RedirList)
{
	REDIRECTION *Redir;
	LPTSTR Filename;
	HANDLE hNew;
	UINT DupNumber;
	static SECURITY_ATTRIBUTES SecAttr = { sizeof(SECURITY_ATTRIBUTES), NULL, TRUE };

	/* Some parameters used for read, write, and append, respectively */
	static const DWORD dwAccess[] = {
		GENERIC_READ, 
		GENERIC_WRITE,
		GENERIC_WRITE
	};
	static const DWORD dwShareMode[] = {
		FILE_SHARE_READ | FILE_SHARE_WRITE,
		FILE_SHARE_READ,
		FILE_SHARE_READ
	};
	static const DWORD dwCreationDisposition[] = {
		OPEN_EXISTING,
		CREATE_ALWAYS,
		OPEN_ALWAYS
	};

	for (Redir = RedirList; Redir; Redir = Redir->Next)
	{
		Filename = DoDelayedExpansion(Redir->Filename);
		if (!Filename)
			goto redir_error;
		StripQuotes(Filename);

		if (*Filename == _T('&'))
		{
			DupNumber = Filename[1] - _T('0');
			if (DupNumber >= 10 ||
			    !DuplicateHandle(GetCurrentProcess(),
			                     GetHandle(DupNumber),
			                     GetCurrentProcess(),
			                     &hNew,
			                     0,
			                     TRUE,
			                     DUPLICATE_SAME_ACCESS))
			{
				hNew = INVALID_HANDLE_VALUE;
			}
		}
		else
		{
			hNew = CreateFile(Filename,
			                  dwAccess[Redir->Type],
			                  dwShareMode[Redir->Type],
			                  &SecAttr,
			                  dwCreationDisposition[Redir->Type],
			                  0,
			                  NULL);
		}

		if (hNew == INVALID_HANDLE_VALUE)
		{
			ConErrResPrintf(Redir->Type == REDIR_READ ? STRING_CMD_ERROR1 : STRING_CMD_ERROR3,
			                Filename);
			cmd_free(Filename);
redir_error:
			/* Undo all the redirections before this one */
			UndoRedirection(RedirList, Redir);
			return FALSE;
		}

		if (Redir->Type == REDIR_APPEND)
			SetFilePointer(hNew, 0, NULL, FILE_END);
		Redir->OldHandle = GetHandle(Redir->Number);
		SetHandle(Redir->Number, hNew);

		TRACE("%d redirected to: %s\n", Redir->Number, debugstr_aw(Filename));
		cmd_free(Filename);
	}
	return TRUE;
}

VOID
UndoRedirection(REDIRECTION *Redir, REDIRECTION *End)
{
	for (; Redir != End; Redir = Redir->Next)
	{
		CloseHandle(GetHandle(Redir->Number));
		SetHandle(Redir->Number, Redir->OldHandle);
		Redir->OldHandle = INVALID_HANDLE_VALUE;
	}
}

VOID
FreeRedirection(REDIRECTION *Redir)
{
	REDIRECTION *Next;
	for (; Redir; Redir = Next)
	{
		Next = Redir->Next;
		ASSERT(Redir->OldHandle == INVALID_HANDLE_VALUE);
		cmd_free(Redir);
	}
}

#endif /* FEATURE_REDIRECTION */