🚀 go-pugleaf

While prying the lemmings from hir ankles 23 Apr 1996 20:45:30 GMT,
myao@mailhost.ecn.uoknor.edu (Minghua Yao) wrote:

>I have a C module which uses "fopen()" to open a file. When called by a
> C main(), the module works well and the file can be opened. But if this
> module is called by a TSR code (which is loaded at an interrupt not used
> by the DOS, and is executed by activating this interrupt), the file which does
> exist cannot be opened often times. Sometimes (seldom,though) the file
> can be opened. If so, the machine will die. The behavior seems to be
> undefinte.

Could you be running afoul of the InDos problem?  Sometimes in a TSR
it's not safe to use some int 21h functions; if fopen() uses int 21h
you could sometimes run into problems.  Others here will be able to
say with better certainty how likely this is and suggest workarounds
if this is your problem.