/*++

Copyright (c) 1988-1999  Microsoft Corporation

Module Name:

    cmem.c

Abstract:

    Memory allocation support

--*/

#include "cmd.h"

extern   DWORD DosErr ;

/* Data Stack - a stack of pointers to memory that has been allocated *M005*/

typedef struct _DSTACK {
    ULONG cb ;               /* malloc's length value (M011)            */
    struct _DSTACK *pdstkPrev; /* Pointer to the previous list element    */
    CHAR data ;             /* The data block                          */
} DSTACK, *PDSTACK;

#define PTRSIZE FIELD_OFFSET(DSTACK, data) /* Size of element header*/

PDSTACK DHead = NULL ;   /* Head of the data list           */
ULONG DCount = 0 ;       /* Number of elements in the list  */

#define MAX_NUM_BIG_BUF  2
PVOID BigBufHandle[MAX_NUM_BIG_BUF] = {0, 0};   /* Handle/segment of buffer used by type & copy */


#if DBG




/***    MemChk1 - Sanity check on one element of the data stack
 *
 *  Purpose:
 *      Verifies the integrity and length of a single data element
 *
 *  int MemChk1(PDSTACK s)
 *
 *  Args:
 *      s - Pointer to the data stack element to check on
 *
 *  Returns:
 *      0 - If element is intact and okay
 *      1 - If element size or integrity is off
 *
 */

MemChk1(
    IN  PDSTACK pdstk
    )
{
    return 0;
#if 0
        if (pdstk->cb != HeapSize(GetProcessHeap(), 0, pdstk)) {
            printf( "My Size is %x, heap says %x\n", pdstk->cb,   HeapSize(GetProcessHeap(), 0, pdstk));
            cmd_printf (TEXT("len = %d"), pdstk->cb) ;
                return(1) ;
        } else {
                return(0) ;
        } ;
#endif
}




/***    MemChkBk - Sanity check on data stack elements from here back
 *
 *  Purpose:
 *      Verifies the integrity of the CMD data stack from a single
 *      point back to the beginning.
 *
 *  int MemChkBk(PDSTACK s)
 *
 *  Args:
 *      s - Pointer to the data stack element to start with
 *
 *  Returns:
 *      0 - If elements are intact and okay
 *      1 - If elements' size or integrity are off
 *
 */

MemChkBk(
    IN  PDSTACK pdstk
    )
{
#if 0
        ULONG   cnt ;           // Element counter
        PDSTACK pdstkCur;   // Element pointer

        cnt = DCount ;

        for (pdstkCur = DHead, cnt = DCount ; pdstkCur ; pdstkCur = (PDSTACK)pdstkCur->pdstkPrev, cnt--) {
                if (pdstkCur == pdstk) {
                        break ;
                } ;
        } ;

        while (pdstkCur) {
                if (MemChk1(pdstkCur)) {
                        cmd_printf(TEXT("Memory Element %d @ %04x contaminated!"), cnt, pdstkCur) ;
                        abort() ;
                } ;
                pdstkCur = (PDSTACK)pdstkCur->pdstkPrev ;
                --cnt ;
        } ;

#endif
        return(0) ;
}




/***    MemChkAll - Sanity check on one element of the data stack
 *
 *  Purpose:
 *      Checks the entire data stack for integrity.
 *
 *  int MemChkAll()
 *
 *  Args:
 *
 *  Returns:
 *      0 - If elements are intact and okay
 *      1 - If elements' size or integrity are off
 *
 */

MemChkAll()
{
        return(MemChkBk(DHead)) ;
}

#endif


/***    FreeBigBuf - free the buffer used by the type and copy commands
 *
 *  Purpose:
 *      If BigBufHandle contains a handle, unlock it and free it.
 *
 *  FreeBigBuf()
 *
 * ***  NOTE:   This routine manipulates Command's Buffer handle, and   ***
 * ***          should be called with signal processing postponed.      ***
 */

void FreeBigBuf(
    int BigBufID
    )
{

    if (BigBufID >= MAX_NUM_BIG_BUF)
        return;

    if (BigBufHandle[BigBufID]) {
        DEBUG((MMGRP, LMLVL, "    FREEBIGBUF: Freeing bigbufhandle = 0x%04x", BigBufHandle[BigBufID])) ;

        VirtualFree(BigBufHandle[BigBufID],0,MEM_RELEASE) ;
        BigBufHandle[BigBufID] = 0 ;
    } ;
}




/***    FreeStack - free the memory on the data stack
 *
 *  Purpose:
 *      Free the memory pointed to by all but the first n elements of the
 *      data stack and free BigBufHandle if it is nonzero.
 *
 *  FreeStack(int n)
 *
 *  Args:
 *      n - the number of elements to leave on the stack
 *
 *                              W A R N I N G
 *      !!! THIS ROUTINE CAUSES AN ABORT IF DATA STACK CONTAMINATED !!!
 */

void FreeStack(
    IN ULONG n
    )
{
    PDSTACK pdstkPtr ;
    int i;

    DEBUG((MMGRP, LMLVL, "    FREESTACK: n = %d  DCount = %d", n, DCount)) ;

    while (DCount > n && (pdstkPtr = DHead)) {
        /* Free the top item in the data stack and pop the stack */

        DHead = (PDSTACK)DHead->pdstkPrev ;
        -- DCount ;
        DEBUG((MMGRP, LMLVL, "    FREESTACK: Freeing %x", pdstkPtr)) ;
        pdstkPtr->cb = 0;
        pdstkPtr->pdstkPrev = NULL;
        HeapFree(GetProcessHeap(), 0, pdstkPtr) ;
    }

#if DBG

    MemChkAll() ;           /* CAUSES abort() IF CONTAMINATED          */

#endif
    for (i=0; i<MAX_NUM_BIG_BUF; i++) {
        FreeBigBuf(i) ;
    }

    DEBUG((MMGRP, LMLVL, "    FREESTACK: n = %d, DCount = %d", n, DCount)) ;
}

/***    FreeStr - free a memory block 
 *
 *  Purpose:
 *      Free a single memory block from the stack.
 *
 *  Args:
 *      pbFree - pointer to block being freed.
 *
 *                              W A R N I N G
 *      !!! THIS ROUTINE CAUSES AN ABORT IF DATA STACK CONTAMINATED !!!
 */

void
FreeStr(
    IN  PVOID   pbFree
    )
{

    PDSTACK pdstkCur;
    PDSTACK pdstkPtr, pdstkLast ;
    ULONG   cdstk;

    DEBUG(( MMGRP, LMLVL, "    FreeStr: pbFree = %x DCount = %d", pbFree, DCount )) ;

    if ((pbFree == NULL) || (DHead == NULL)) {
        return;
    }

    pdstkPtr = (PDSTACK)((CHAR*)pbFree - PTRSIZE);

    //
    //  Walk through current stack trying to find object
    //
    
    for (pdstkCur = DHead, cdstk = DCount; cdstk; cdstk--) {

        //
        //  If we've found the object, remove it from the list
        //
        
        if (pdstkCur == pdstkPtr) {

            //
            // remove from chain
            //
            DEBUG(( MMGRP, LMLVL, "    FreeStr: Prev %x, Cur %x, DCount %d",
                   pdstkLast, pdstkCur, DCount )) ;
            
            if (pdstkCur == DHead) {

                DHead = (PDSTACK)pdstkCur->pdstkPrev;

            } else {

                pdstkLast->pdstkPrev = pdstkCur->pdstkPrev;

            }

            HeapFree( GetProcessHeap( ), 0, pdstkCur );
            DCount--;
#if DBG
            MemChkAll( ) ;
#endif

            return;
        }
        pdstkLast = pdstkCur;
        pdstkCur = (PDSTACK)pdstkCur->pdstkPrev;

    }

    //
    //  The object wasn't in the stack at all!
    //

#if DBG
    DEBUG((MMGRP, LMLVL, "    FreeStr: object not in stack")) ;
    //  cmd_printf( TEXT( "Object @ %04x not in memory stack!" ), pbFree ) ;
    MemChkAll( ) ;
#endif
}


/***    GetBigBuf -  allocate a large buffer
 *
 *  Purpose:
 *      To allocate a buffer for data transferrals.
 *      The buffer will be as large as possible, up to MAXBUFSIZE bytes,
 *      but no smaller than MINBUFSIZE bytes.
 *
 *  TCHAR *GetBigBuf(unsigned *blen)
 *
 *  Args:
 *      blen = the variable pointed to by blen will be assigned the size of
 *          the buffer
 *
 *  Returns:
 *      A TCHAR pointer containing segment:0.
 *      Returns 0L if unable to allocate a reasonable length buffer
 *
 */

PVOID

GetBigBuf(
    IN  ULONG   CbMaxToAllocate,
    IN  ULONG   CbMinToAllocate,
    OUT unsigned int *CbAllocated,
    IN  int     BigBufID
    )


/*++

Routine Description:

    To allocate a buffer for data transferrals.

Arguments:

    CbMinToAllocate - Fail if can't allocate this number
    CbMaxToAllocate - Initial try and allocation will use this number
    CbAllocated - Number of bytes allocated
    BigBufID - BigBuf index

Return Value:

    Return: NULL - if failed to allocate anything
            pointer to allocated buffer if success
--*/

{
    ULONG   cbToDecrease;
    PVOID   handle ;

    DEBUG((MMGRP, MALVL, "GETBIGBUF: MinToAlloc %d, MaxToAlloc %d", CbMinToAllocate, CbMaxToAllocate)) ;

    cbToDecrease = CbMaxToAllocate;
    //bytesdecrease = CbMaxToAllocate ;

    while (!(handle = VirtualAlloc(NULL, CbMaxToAllocate,MEM_COMMIT,PAGE_READWRITE))) {

        //
        // Decrease the desired buffer size by CbToDecrease
        // If the decrease is too large, make it smaller
        //
        if ( cbToDecrease >= CbMaxToAllocate ) {
            cbToDecrease = ((CbMaxToAllocate >> 2) & 0xFE00) + 0x200;
        }

        if ( cbToDecrease < CbMinToAllocate ) {
            cbToDecrease = CbMinToAllocate ;
        }

        CbMaxToAllocate -= cbToDecrease ;

        if ( CbMaxToAllocate < CbMinToAllocate ) {

            //
            // Unable to allocate a reasonable buffer
            //
            *CbAllocated = 0 ;
            PutStdErr(ERROR_NOT_ENOUGH_MEMORY, NOARGS);
            return ( NULL ) ;
        }
    }

    *CbAllocated = CbMaxToAllocate ;

    FreeBigBuf(BigBufID) ;
    BigBufHandle[BigBufID] = handle ;

    DEBUG((MMGRP, MALVL, " GETBIGBUF: Bytes Allocated = %d  Handle = 0x%04x", *CbAllocated, BigBufHandle[BigBufID])) ;

    return(handle) ;
}




/***    mknode - allocata a parse tree node
 *
 *  Purpose:
 *      To allocate space for a new parse tree node.  Grow the data segment
 *      if necessary.
 *
 *  struct node *mknode()
 *
 *  Returns:
 *      A pointer to the node that was just allocated.
 *
 *  Notes:
 *      This routine must always use calloc().  Many other parts of Command
 *      depend on the fact that the fields in these nodes are initialized to 0.
 *
 *      THIS ROUTINE RETURNS `NULL' IF THE C RUN-TIME CANNOT ALLOCATE MEMORY
 */

struct node *mknode()
{
    struct node *Node = (struct node *) mkstr( sizeof( struct node ));
    DEBUG((MMGRP, MALVL, "    MKNODE: Entered")) ;
    return Node;
}




/***    mkstr -  allocate space for a string
 *
 *  Purpose:
 *      To allocate space for a new string.  Grow the data segment if necessary.
 *
 *  TCHAR *mkstr(size)
 *
 *  Args:
 *      size - size of the string to be allocated
 *
 *  Returns:
 *      A pointer to the string that was just allocated.
 *
 *  Notes:
 *      This routine must always use calloc().  Many other parts of Command
 *      depend on the fact that memory that is allocated is initialized to 0.
 *
 *    - M005 * The piece of memory allocated is large enough to include
 *      a pointer at the beginning.  This pointer is part of the list of
 *      allocated memory.  The routine calling mkstr() receives the address
 *      of the first byte after that pointer.  resize() knows about this,
 *      and so must any other routines which directly modify memory
 *      allocation.
 *    - M011 * This function is the same as mentioned above except that the
 *      pointer is now preceeded by a header consisting of two signature
 *      bytes and the length of the memory allocated.  This was added for
 *      sanity checks.
 *
 *      THIS ROUTINE RETURNS `NULL' IF THE C RUN-TIME CANNOT ALLOCATE MEMORY
 *
 *                              W A R N I N G
 *      !!! THIS ROUTINE CAUSES AN ABORT IF DATA STACK CONTAMINATED !!!
 */

void*
mkstr(
    IN  int  cbNew
    )
{
    PDSTACK pdstkCur ;  // Ptr to the memory being allocated

    DEBUG((MMGRP, MALVL, "    MKSTR: Entered.")) ;

#if DBG

        MemChkAll() ;           /* CAUSES abort() IF CONTAMINATED          */

#endif

    if ((pdstkCur = (PDSTACK)(HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, cbNew + PTRSIZE + 4))) == NULL) {
            PutStdErr(ERROR_NOT_ENOUGH_MEMORY, NOARGS);
            return(0) ;
    } ;

    DEBUG((MMGRP, MALVL, "    MKSTR: Adding to stack")) ;

    pdstkCur->cb   = cbNew + PTRSIZE + 4;
    pdstkCur->pdstkPrev = (PDSTACK)DHead ;
    DHead = pdstkCur ;
    DCount++ ;

    DEBUG((MMGRP, MALVL, "    MKSTR: ptr = %04x  cbNew = %04x  DCount = %d",
           pdstkCur, cbNew, DCount)) ;

#if DBG

    MemChkBk(pdstkCur) ;           /* CAUSES abort() IF CONTAMINATED          */

#endif

    return(&(pdstkCur->data)) ;    /*M005*/
}


/***    dupstr -  Duplicate a string
 *
 *  Purpose:
 *      Create a copy of a string in a new heap block
 *
 *  TCHAR *dupstr( TCHAR *String )
 *
 *  Args:
 *      String to be duplicated
 *
 *  Returns:
 *      A pointer to the string that was just allocated and copied. The caller retains
 *      ownership of the input string and the returned string.
 *
 *  Notes:
 *
 *                              W A R N I N G
 *      !!! THIS ROUTINE CAUSES AN ABORT IF DATA STACK CONTAMINATED !!!
 */

TCHAR *
dupstr( TCHAR *String )
{
    TCHAR *New = mkstr( (mystrlen( String ) + 1) * sizeof( TCHAR ));

    mystrcpy( New, String );
    return New;
}



/***    gmkstr - allocate a piece of memory, with no return on failure
 *
 *  Purpose:
 *      Same as "mkstr" except that if memory cannot be allocated, this
 *      routine will jump out to code which will clean things up and
 *      return to the top level of command.
 *
 */

void*
gmkstr(
    IN  int   cbNew
    )

{
        PTCHAR pbNew ;

        if (!(pbNew = (PTCHAR)mkstr(cbNew)))
                Abort() ;

        return(pbNew) ;
}




/***    resize - resize a piece of memory
 *
 *  Purpose:
 *      Change the size of a previously allocated piece of memory.  Grow the
 *      data segment if necessary.  If a new different pointer is returned by
 *      realloc(0), search the dstk for the pointer to the old piece and
 *      update that pointer to point to the new piece.
 *
 *  TCHAR *resize(TCHAR *ptr, unsigned size)
 *
 *  Args:
 *      ptr - pointer to the memory to be resized
 *      size - the new size for the block of memory
 *
 *  Returns:
 *      A pointer to the new piece of memory.
 *
 *    - M005 * Modified for the new scheme for keeping a list of allocated
 *      blocks
 *    - M011 * Modified to use and check new header.
 *
 *      THIS ROUTINE RETURNS `NULL' IF THE C RUN-TIME CANNOT ALLOCATE MEMORY
 *
 *                              W A R N I N G
 *      !!! THIS ROUTINE CAUSES AN ABORT IF DATA STACK CONTAMINATED !!!
 */

void*
resize (
    IN  void* pv,
    IN  unsigned int cbNew
    )

{
    PDSTACK pdstkCur ;
             PDSTACK pdstkNew, pdstkOld;
    CHAR* pbOld = pv;

    DEBUG((MMGRP, MALVL, "    RESIZE: Entered %x.", pv)) ;

    pbOld -= PTRSIZE ;
    pdstkOld = (PDSTACK)pbOld ;

#if DBG

    if (MemChk1(pdstkOld)) {

        cmd_printf(TEXT("Memory Element @ %04x contaminated!"), pdstkOld) ;
        abort() ;

    } ;

#endif

    if (!(pdstkNew = (PDSTACK)HeapReAlloc(GetProcessHeap(), 0, pbOld, cbNew + PTRSIZE + 4))) {
            PutStdErr(ERROR_NOT_ENOUGH_MEMORY, NOARGS);
            return(0) ;
    } ;



    pdstkNew->cb = cbNew + PTRSIZE + 4 ;   // Update to new length
    if (HeapSize(GetProcessHeap(), 0, pdstkNew) != pdstkNew->cb) {
        DEBUG((MMGRP, LMLVL, "    resize: My Size is %x, heap says %x", pdstkNew->cb,   HeapSize(GetProcessHeap(), 0, pdstkNew)));
    }

    //
    // revise Data Stack information, updating chain of pdstk's with
    // new pointer
    //
    if (pdstkNew != pdstkOld) {
        if (DHead == pdstkOld) {        // Is head of List
            DHead = pdstkNew ;
        } else {                        // Is in middle of list
            for (pdstkCur = DHead ; pdstkCur ; pdstkCur = (PDSTACK)(pdstkCur->pdstkPrev)) {
                if ((PDSTACK)(pdstkCur->pdstkPrev) == pdstkOld) {

                    pdstkCur->pdstkPrev = (PDSTACK)pdstkNew ;
                    break ;

                }
            }
        }
    }

#if DBG

    MemChkBk(pdstkOld) ;  // CAUSES abort() IF CONTAMINATED

#endif

    DEBUG((MMGRP, MALVL, "    RESIZE: pbOld = %04x  cbNew = %04x",&(pdstkNew->data),cbNew)) ;

    return(&(pdstkNew->data)) ;
}