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Fix select(2) for the Alpha. (!!) It was never returning true for

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fd's in the range of 32-63, 96-127 etc.  The first problem was the
FD_*() macros were shifting a 32 bit integer "1" left by more than
32 bits.  The same problem happened in selscan().  ffs() also takes
an int argument and causes failure.  For cases where int == long
(ie: the usual case for x86, but not always as gcc can have long
being a 64 bit quantity) ffs() could be used.

Reported by:	Marian Stagarescu <marian@bile.skycache.com>
Reviewed by:	dfr, gallatin (sys/types.h only)
Approved by:	jkh
This commit is contained in:
peter 2000-02-20 13:36:26 +00:00
parent c4d21ca229
commit 21e6913264
2 changed files with 12 additions and 9 deletions
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14
sys/kern/sys_generic.c
View File

@ -730,9 +730,9 @@ selscan(p, ibits, obits, nfd)
fd_mask **ibits, **obits;
int nfd;
{
register struct filedesc *fdp = p->p_fd;
register int msk, i, j, fd;
register fd_mask bits;
struct filedesc *fdp = p->p_fd;
int msk, i, fd;
fd_mask bits;
struct file *fp;
int n = 0;
/* Note: backend also returns POLLHUP/POLLERR if appropriate. */
@ -743,14 +743,16 @@ selscan(p, ibits, obits, nfd)
continue;
for (i = 0; i < nfd; i += NFDBITS) {
bits = ibits[msk][i/NFDBITS];
while ((j = ffs(bits)) && (fd = i + --j) < nfd) {
bits &= ~(1 << j);
/* ffs(int mask) not portable, fd_mask is long */
for (fd = i; bits && fd < nfd; fd++, bits >>= 1) {
if (!(bits & 1))
continue;
fp = fdp->fd_ofiles[fd];
if (fp == NULL)
return (EBADF);
if (fo_poll(fp, flag[msk], fp->f_cred, p)) {
obits[msk][(fd)/NFDBITS] |=
(1 << ((fd) % NFDBITS));
((fd_mask)1 << ((fd) % NFDBITS));
n++;
}
}

7
sys/sys/types.h
View File

@ -178,9 +178,10 @@ typedef struct fd_set {
fd_mask fds_bits[howmany(FD_SETSIZE, NFDBITS)];
} fd_set;
#define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
#define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define _fdset_mask(n) ((fd_mask)1 << ((n) % NFDBITS))
#define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= _fdset_mask(n))
#define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~_fdset_mask(n))
#define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & _fdset_mask(n))
#define FD_COPY(f, t) bcopy(f, t, sizeof(*(f)))
#define FD_ZERO(p) bzero(p, sizeof(*(p)))