commit 86b5d591d from 20241004 by me, modified return type of
GrTextSize API in the graphics from 'void' to 'int' to convey
and error scenario to indicate when 'r' was not filled in for
the caller, but this is a multi graphics driver API interface
so requires all downstream graphics engines to also support
the return type change.
This API can error and indicates when 'Rect *r' was
successfully updated.
The old code would only work is the fileno(stream) returned an fd
in the range 0 <= 19. It would silently fail, if the fd was in
the range 20..1023 because FD_SET() would work and syscall select()
would be limited to only look at the first 20 fd's. Ignoring any
fd's higher even if set.
This would theoretically cause high CPU usage due to select()
never blocking because there are no active fd's in the fd_set
as far as the kernel interprets the request and the kernel would
immediately return.
But reading the code the 1st argument to select() seems self
limiting for no good reason. It should be fileno(stream)+1 as
documented in man select(2).
Added the assertion as well, because we are trying to allow magic
to use fd's beyond the standard environmental limits. So it
becomes an assertion condition if the fd is outside the range
0..1023 because the FD_SET() macro will not operate correctly /
undefined-behaviour.
I can't find any user of this func in the codebase right now.
If you look at sim/SimRsim.c and the use of select() there, it is
correctly using select() to wait on a single fd over there. This
commit changes this code to match this correct usage.
This commit makes the code (mostly) C99-compatible, enabling to compile
it without the -Wno-error=implicit-function-declaration flag. This
way, Magic becomes usable on arm64 architectures, specifically on Apple
computers with M1/M2 SoC.
Darryl L. Miles
Alessandro De Laurenzis
Tim Edwards
Chuan Chen