redir.c

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/*
 *  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 */