Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH 11/42] tools/nolibc/types: move the FD_* functions to macros in types.h | Date | Mon, 7 Feb 2022 17:05:21 +0000 |
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From: Willy Tarreau > Sent: 07 February 2022 16:23 > > FD_SET, FD_CLR, FD_ISSET, FD_ZERO are supposed to be macros and not > functions.
Are you sure? I'd have thought they could be either. There are certainly systems where they are functions. They can be implemented as an array of fd numbers rather than a bitmap.
> In addition we already have a file dedicated to such macros > and types used by syscalls, it's types.h, so let's move them > there and turn them to macros. FD_CLR() and FD_ISSET() were missing, > so they were added. FD_ZERO() now deals with its own loop so that it > doesn't rely on memset() that sets one byte at a time. > .... > +#define FD_CLR(fd, set) do { \ > + int __fd = (int)(fd); \ > + fd_set *__set = (fd_set *)(set); \
I'm not sure you really want either cast. They are just likely to hide some horrid bugs.
+ if (__fd >= 0 && __fd < FD_SETSIZE) \ + __set->fd32[__fd / 32] &= ~(1U << (__fd & 31)); \ + } while (0) +
Do you need the range check? I don't think glibc has one. Things just break in obscure ways when you use select on big fd.
David
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