Eric Blake wrote: > The use case where I discovered this bug was with m4 1.4.11. Compare: > > mingw$ m4 . > m4.exe: .: Permission denied > Linux$ m4 . > m4:/:1: Read error > OpenBSD$ m4 . && echo done > done > EMX$ m4 . > <starts trying to interpret struct dirent records as m4 input> > > In an effort to unify this behavior, I was considering making m4 1.4.12 > pre-reject directories with EISDIR (POSIX allows this, since directories > are not text files, and m4 is only required to operate on text files), > while remembering that doing stat() prior to fopen() is racy.
Then I would split the fopen() call into open() + fdopen(), and use fstat() between the two operations to detect the case of a directory. This is not racy, and it never runs into the EACCES case on mingw. Bruno
