High memory: Ensure no "highmem-unsafe" functions are called directly.

[John Small]

Currently there are numerous direct calls to "highmem-unsafe" functions.

If we return to using high memory, we must 1) Make sure we know which functions are "highmem-unsafe". 2) Make sure each of these functions has a wrapper. 3) Replace any direct calls to these functions with calls to the corresponding wrapper function.

[John Small]

CS [1749]

Changed direct calls from DosQueryAppType to xDosQueryAppType where the filename may be pointing to high memory and added comments about the need for such a change if changes are made which could change currently-used low memory addresses into high memory addresses.

[Steven Levine]

There is work left to do on this ticket. kLIBC's os2safe.h defines the following APIs as not highmem safe:

DosForceDelete DosQueryHType DosCreatePipe DosQueryNPHState DosWaitNPipe DosSetFilePtr DosSetFilePtrL DosDupHandle DosOpenL DosQueryFHState DosSetDateTime DosStartSession DosQueryAppType WinUpper

We do not yet wrap all calls to these functions. This is not a significant issues at the moment because fm/2 makes limited use of high memory for data. However, in the future OpenWatcom will support placing the heap in high memory and consistent use of the wrappers will be needed.

[Gregg Young]

Ticket retargeted after milestone closed