Mac Magazin/MacEasy 24/Mac Magazin and MacEasy Magazine CD - Issue 24.iso/Grafik & Text/Microsoft Installer Patch/patches.c

Text File | 1996-07-13 | 4KB | 186 lines

// patches.c

#include <Traps.h>
#include <A4Stuff.h>

#include "patches.h"

// defines
#define CurApName        (0x911)
#define VALID(name)        ((name) && (((long)(name))&0xFFFF) && ((((long)(name))>>16)&0xFFFF))
#define pstrcpy(s1,s2)    do { *(s1) = 0; pstrcat(s1,s2); } while(false)

// prototypes
inline void pstrcat( StringPtr s1, StringPtr s2 );
Boolean my_strncmp( void* s1, void* s2, short n );

// globals
extern Str63 volumeName;
extern short volumeVRef;




void PatchFSDispatch( void )
{
    short    trap = _FSDispatch;
    Ptr        data;
    Ptr        patch = (Ptr)MyFSDispatch;

    // fill in the necessary fields in
    data = (Ptr)NGetTrapAddress( trap, (trap & 0x0800) ? ToolTrap : OSTrap);
    BlockMove( &data, patch+2, sizeof(data) );

    data = (Ptr)FSDispatchHelper;
    BlockMove( &data, patch+6, sizeof(data) );

    // patch it
    NSetTrapAddress( (UniversalProcPtr)MyFSDispatch, trap, (trap & 0x0800) ? ToolTrap : OSTrap);
}



inline void pstrcat( StringPtr s1, StringPtr s2 )
{
    BlockMoveData( s2+1, s1+s1[0]+1, s2[0] );
    s1[0] += s2[0];
}

Boolean my_strncmp( void* s1, void* s2, short n )
{
    register Ptr p1 = (Ptr)s1, p2 = (Ptr)s2;

    while (n--)
        if (*(p2++) != *(p1++)) return false;

    return true;
}



asm void MyFSDispatch( void )
{
    bra.s    Begin

Real_FSDispatch:
    dc.l    0                        // Saved address of the real FSDispatch code

FSDispatchHelper:
    dc.l    0                        // our helper routine, which messes with the
                                    //   parameter (FileParam*) we pass it...
Begin:

    movem.l    d0-d2/a0-a2, -(a7)        // save volatile registers

    // okay, now we have a selector in D0, and a
    // pointer to a fileParam in A0, because that's
    // the way FSDispatch works.

    // let's jump off to our wonderful friend the helper function,
    // to look at all the crap that got passed and see if we should
    // modify what it says.

    move.l    a0, -(a7)                // push the FileParam onto the stack
    move.l    FSDispatchHelper, a0    // load FSDispatchHelper
    jsr        (a0)                    // call it
    add.l    #4, a7                    // fix the stack

    // Clean up
    movem.l    (a7)+, d0-d2/a0-a2

    // Pass control to the real FSDispatch
    move.l    Real_FSDispatch, a1
    jmp        (a1)
}



void FSDispatchHelper( FileParam *pb )
{
    static Str255 patchedName;

    EnterCodeResource();

    // make sure pb is valid
    if (!pb) goto done;

    // make sure we're only messing with the Microsoft installer
    if ( !(*(long*)CurApName == 'Micr') ) goto done;

    // and make sure we've got a real ptr
    if ( !VALID(pb->ioNamePtr) ) goto done;

    // first, if it's talking about the root directory
    // notice we're not bothering to discuss the parameter; this
    // is bad monkey but it's much easier this way...

    if ((pb->ioVRefNum == -1 || pb->ioVRefNum == 0) &&
        pb->ioFlNum == 2 )
    {
        // see if it's talking about the Microsoft folder
        if ( my_strncmp( pb->ioNamePtr+1, "Microsoft", 9 ) )
        {
            if ( (pb->ioNamePtr[0]==9) ||    // ref to the folder itself
                ((pb->ioNamePtr[0]>=10) && (pb->ioNamePtr[10]==':')) )    // or something inside
            {
                pstrcpy( patchedName, "\p:System Folder:" );
                pstrcat( patchedName, pb->ioNamePtr );
                pstrcpy( pb->ioNamePtr, patchedName );

                goto done;
            }
        }
    }

    // see if it's giving a full pathname
    if ( my_strncmp( pb->ioNamePtr+1, volumeName+1, *volumeName ) &&
         my_strncmp( pb->ioNamePtr+1+*volumeName, ":Microsoft", 10 ) )
    {
        // sure looks like it; check further though
        if ( (pb->ioNamePtr[0]==*volumeName+10) ||    // ref to the folder itself
            ((pb->ioNamePtr[0]>(*volumeName+10)) && (pb->ioNamePtr[*volumeName+12]==':')) ) // something inside
        {
            pstrcpy( patchedName, volumeName );
            pstrcat( patchedName, "\p:System Folder:" );

            pb->ioNamePtr[*volumeName+11] = pb->ioNamePtr[0] - (*volumeName+1);
            pstrcat( patchedName, pb->ioNamePtr );
            pstrcpy( pb->ioNamePtr, patchedName );

            goto done;
        }
    }


    // see if it's a partial path based off the root dir
    if ( pb->ioFlNum == 0 && (pb->ioVRefNum==0 || pb->ioVRefNum==-1) )
    {
        // ok, are we talking about the Microsoft folder?
        if ( my_strncmp(pb->ioNamePtr + 1,":Microsoft",10) )
        {
            if ( (pb->ioNamePtr[0]==10) ||    // ref to the folder itself
                ((pb->ioNamePtr[0]>=11) && (pb->ioNamePtr[11]==':')) )    // something inside
            {
                pstrcpy( patchedName, "\p:System Folder" );
                pstrcat( patchedName, pb->ioNamePtr );
                pstrcpy( pb->ioNamePtr, patchedName );


                goto done;
            }
        }
    }

    // else it looks like we don't do anything.
done:
    ExitCodeResource();
    return;
}