Rainer Orth <[email protected]> writes:
> While debugging why several libgo tests on Solaris 2/SPARC were hanging
> in select (cf. PR go/48242, go/48243), I found that fd_set is
>
> typedef struct fd_set {
> long fds_bits[__howmany(FD_SETSIZE, FD_NFDBITS)];
> } fd_set;
>
> The current implementation of the FD* funcs in sysfile_posix.go assumes
> 64-bit fds_bits. While this doesn't make a difference on little-endian
> hosts, on big-endian SPARC the wrong bits are set, leading to the
> observed hang since there is no activity on those random fds.
>
> The following patch fixes this by moving the FD* implementation to two
> new sysfile_fdset{32, 64}.go files to fix this. There's almost
> certainly a cleaner/shorter implemenation, but this worked for me.
> While the affected tests don't hang anymore now, they still don't finish
> successfully, among others due to PR go/48222.
Thanks. I'm going to try gambling that every uses the type "long" for
the fds_bits array. If so, I think this patch will work. Bootstrapped
and ran Go testsuite on x86_64-unknown-linux-gnu (forcing the use of
select). Committed to mainline.
Ian
diff -r bc59115c58cf libgo/syscalls/sysfile_posix.go
--- a/libgo/syscalls/sysfile_posix.go Thu Mar 31 09:48:32 2011 -0700
+++ b/libgo/syscalls/sysfile_posix.go Thu Mar 31 13:35:30 2011 -0700
@@ -181,20 +181,22 @@
return;
}
+const nfdbits = unsafe.Sizeof(_C_long) * 8
+
type FdSet_t struct {
- Fds_bits [(FD_SETSIZE + 63) / 64]int64;
+ Fds_bits [(FD_SETSIZE + nfdbits - 1) / nfdbits]_C_long
}
func FDSet(fd int, set *FdSet_t) {
- set.Fds_bits[fd / 64] |= (1 << (uint)(fd % 64))
+ set.Fds_bits[fd / nfdbits] |= (1 << (uint)(fd % nfdbits))
}
func FDClr(fd int, set *FdSet_t) {
- set.Fds_bits[fd / 64] &= ^(1 << (uint)(fd % 64))
+ set.Fds_bits[fd / nfdbits] &^= (1 << (uint)(fd % nfdbits))
}
func FDIsSet(fd int, set *FdSet_t) bool {
- if set.Fds_bits[fd / 64] & (1 << (uint)(fd % 64)) != 0 {
+ if set.Fds_bits[fd / nfdbits] & (1 << (uint)(fd % nfdbits)) != 0 {
return true
} else {
return false
@@ -202,7 +204,7 @@
}
func FDZero(set *FdSet_t) {
- for i := 0; i < ((FD_SETSIZE + 63) / 64); i++ {
+ for i := range set.Fds_bits {
set.Fds_bits[i] = 0
}
}
