diff options
Diffstat (limited to 'usr/src/lib/libc/port/gen/select.c')
| -rw-r--r-- | usr/src/lib/libc/port/gen/select.c | 94 |
1 files changed, 82 insertions, 12 deletions
diff --git a/usr/src/lib/libc/port/gen/select.c b/usr/src/lib/libc/port/gen/select.c index ed39ba9efb..24852149ed 100644 --- a/usr/src/lib/libc/port/gen/select.c +++ b/usr/src/lib/libc/port/gen/select.c @@ -27,8 +27,6 @@ /* Copyright (c) 1988 AT&T */ /* All Rights Reserved */ -#pragma ident "%Z%%M% %I% %E% SMI" - /* * Emulation of select() system call using poll() system call. * @@ -47,6 +45,7 @@ #include <values.h> #include <pthread.h> #include <errno.h> +#include <stdlib.h> #include <sys/time.h> #include <sys/types.h> #include <sys/select.h> @@ -54,9 +53,58 @@ #include <alloca.h> #include "libc.h" +/* + * STACK_PFD_LIM + * + * The limit at which pselect allocates pollfd structures in the heap, + * rather than on the stack. These limits match the historical behaviour + * with the * _large_fdset implementations. + * + * BULK_ALLOC_LIM + * + * The limit below which we'll just allocate nfds pollfds, rather than + * counting how many we actually need. + */ +#if defined(_LP64) +#define STACK_PFD_LIM FD_SETSIZE +#define BULK_ALLOC_LIM 8192 +#else +#define STACK_PFD_LIM 1024 +#define BULK_ALLOC_LIM 1024 +#endif + +/* + * The previous _large_fdset implementations are, unfortunately, baked into + * the ABI. + */ +#pragma weak select_large_fdset = select +#pragma weak pselect_large_fdset = pselect + +#define fd_set_size(nfds) (((nfds) + (NFDBITS - 1)) / NFDBITS) + +static nfds_t +fd_sets_count(int limit, fd_set *in, fd_set *out, fd_set *ex) +{ + nfds_t total = 0; + + if (limit <= 0) + return (0); + + for (int i = 0; i < fd_set_size(limit); i++) { + long v = (in->fds_bits[i] | out->fds_bits[i] | ex->fds_bits[i]); + + while (v != 0) { + v &= v - 1; + total++; + } + } + + return (total); +} + int pselect(int nfds, fd_set *in0, fd_set *out0, fd_set *ex0, - const timespec_t *tsp, const sigset_t *sigmask) + const timespec_t *tsp, const sigset_t *sigmask) { long *in, *out, *ex; ulong_t m; /* bit mask */ @@ -66,6 +114,8 @@ pselect(int nfds, fd_set *in0, fd_set *out0, fd_set *ex0, struct pollfd *pfd; struct pollfd *p; int lastj = -1; + nfds_t npfds = 0; + boolean_t heap_pfds = B_FALSE; /* "zero" is read-only, it could go in the text segment */ static fd_set zero = { 0 }; @@ -80,7 +130,6 @@ pselect(int nfds, fd_set *in0, fd_set *out0, fd_set *ex0, errno = EINVAL; return (-1); } - p = pfd = (struct pollfd *)alloca(nfds * sizeof (struct pollfd)); if (tsp != NULL) { /* check timespec validity */ @@ -102,6 +151,21 @@ pselect(int nfds, fd_set *in0, fd_set *out0, fd_set *ex0, if (ex0 == NULL) ex0 = &zero; + if (nfds <= BULK_ALLOC_LIM) { + p = pfd = alloca(nfds * sizeof (struct pollfd)); + } else { + npfds = fd_sets_count(nfds, in0, out0, ex0); + + if (npfds > STACK_PFD_LIM) { + p = pfd = malloc(npfds * sizeof (struct pollfd)); + if (p == NULL) + return (-1); + heap_pfds = B_TRUE; + } else { + p = pfd = alloca(npfds * sizeof (struct pollfd)); + } + } + /* * For each fd, if any bits are set convert them into * the appropriate pollfd struct. @@ -134,13 +198,13 @@ done: /* * Now do the poll. */ - n = (int)(p - pfd); /* number of pollfd's */ + npfds = (int)(p - pfd); do { - rv = _pollsys(pfd, (nfds_t)n, tsp, sigmask); + rv = _pollsys(pfd, npfds, tsp, sigmask); } while (rv < 0 && errno == EAGAIN); if (rv < 0) /* no need to set bit masks */ - return (rv); + goto out; if (rv == 0) { /* @@ -163,14 +227,15 @@ done: for (n = 0; n < nfds; n += NFDBITS) *ex++ = 0; } - return (0); + rv = 0; + goto out; } /* * Check for EINVAL error case first to avoid changing any bits * if we're going to return an error. */ - for (p = pfd, j = n; j-- > 0; p++) { + for (p = pfd, n = npfds; n-- > 0; p++) { /* * select will return EBADF immediately if any fd's * are bad. poll will complete the poll on the @@ -181,7 +246,8 @@ done: */ if (p->revents & POLLNVAL) { errno = EBADF; - return (-1); + rv = -1; + goto out; } /* * We would like to make POLLHUP available to select, @@ -194,7 +260,8 @@ done: * if ((p->revents & POLLHUP) && * !(p->revents & (POLLRDNORM|POLLRDBAND))) { * errno = EINTR; - * return (-1); + * rv = -1; + * goto out; * } */ } @@ -212,7 +279,7 @@ done: * (as the man page says, and as poll() does). */ rv = 0; - for (p = pfd; n-- > 0; p++) { + for (p = pfd, n = npfds; n-- > 0; p++) { j = (int)(p->fd / NFDBITS); /* have we moved into another word of the bit mask yet? */ if (j != lastj) { @@ -278,6 +345,9 @@ done: } } } +out: + if (heap_pfds) + free(pfd); return (rv); } |