mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-12-04 01:43:11 +00:00
337 lines
7.4 KiB
C
337 lines
7.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Generic non-forking server infrastructure.
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* Intended to make writing telnetd-type servers easier.
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*
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* Copyright (C) 2007 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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#include "isrv.h"
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#define DEBUG 0
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#if DEBUG
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#define DPRINTF(args...) bb_error_msg(args)
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#else
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#define DPRINTF(args...) ((void)0)
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#endif
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/* Helpers */
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/* Opaque structure */
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struct isrv_state_t {
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short *fd2peer; /* one per registered fd */
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void **param_tbl; /* one per registered peer */
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/* one per registered peer; doesn't exist if !timeout */
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time_t *timeo_tbl;
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int (*new_peer)(isrv_state_t *state, int fd);
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time_t curtime;
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int timeout;
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int fd_count;
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int peer_count;
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int wr_count;
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fd_set rd;
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fd_set wr;
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};
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#define FD2PEER (state->fd2peer)
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#define PARAM_TBL (state->param_tbl)
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#define TIMEO_TBL (state->timeo_tbl)
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#define CURTIME (state->curtime)
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#define TIMEOUT (state->timeout)
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#define FD_COUNT (state->fd_count)
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#define PEER_COUNT (state->peer_count)
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#define WR_COUNT (state->wr_count)
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/* callback */
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void isrv_want_rd(isrv_state_t *state, int fd)
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{
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FD_SET(fd, &state->rd);
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}
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/* callback */
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void isrv_want_wr(isrv_state_t *state, int fd)
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{
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if (!FD_ISSET(fd, &state->wr)) {
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WR_COUNT++;
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FD_SET(fd, &state->wr);
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}
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}
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/* callback */
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void isrv_dont_want_rd(isrv_state_t *state, int fd)
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{
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FD_CLR(fd, &state->rd);
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}
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/* callback */
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void isrv_dont_want_wr(isrv_state_t *state, int fd)
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{
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if (FD_ISSET(fd, &state->wr)) {
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WR_COUNT--;
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FD_CLR(fd, &state->wr);
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}
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}
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/* callback */
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int isrv_register_fd(isrv_state_t *state, int peer, int fd)
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{
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int n;
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DPRINTF("register_fd(peer:%d,fd:%d)", peer, fd);
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if (FD_COUNT >= FD_SETSIZE) return -1;
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if (FD_COUNT <= fd) {
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n = FD_COUNT;
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FD_COUNT = fd + 1;
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DPRINTF("register_fd: FD_COUNT %d", FD_COUNT);
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FD2PEER = xrealloc(FD2PEER, FD_COUNT * sizeof(FD2PEER[0]));
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while (n < fd) FD2PEER[n++] = -1;
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}
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DPRINTF("register_fd: FD2PEER[%d] = %d", fd, peer);
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FD2PEER[fd] = peer;
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return 0;
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}
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/* callback */
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void isrv_close_fd(isrv_state_t *state, int fd)
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{
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DPRINTF("close_fd(%d)", fd);
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close(fd);
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isrv_dont_want_rd(state, fd);
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if (WR_COUNT) isrv_dont_want_wr(state, fd);
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FD2PEER[fd] = -1;
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if (fd == FD_COUNT-1) {
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do fd--; while (fd >= 0 && FD2PEER[fd] == -1);
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FD_COUNT = fd + 1;
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DPRINTF("close_fd: FD_COUNT %d", FD_COUNT);
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FD2PEER = xrealloc(FD2PEER, FD_COUNT * sizeof(FD2PEER[0]));
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}
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}
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/* callback */
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int isrv_register_peer(isrv_state_t *state, void *param)
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{
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int n;
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if (PEER_COUNT >= FD_SETSIZE) return -1;
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n = PEER_COUNT++;
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DPRINTF("register_peer: PEER_COUNT %d", PEER_COUNT);
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PARAM_TBL = xrealloc(PARAM_TBL, PEER_COUNT * sizeof(PARAM_TBL[0]));
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PARAM_TBL[n] = param;
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if (TIMEOUT) {
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TIMEO_TBL = xrealloc(TIMEO_TBL, PEER_COUNT * sizeof(TIMEO_TBL[0]));
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TIMEO_TBL[n] = CURTIME;
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}
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return n;
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}
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static void remove_peer(isrv_state_t *state, int peer)
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{
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int movesize;
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int fd;
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DPRINTF("remove_peer(%d)", peer);
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fd = FD_COUNT - 1;
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while (fd >= 0) {
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if (FD2PEER[fd] == peer) {
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isrv_close_fd(state, fd);
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fd--;
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continue;
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}
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if (FD2PEER[fd] > peer)
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FD2PEER[fd]--;
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fd--;
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}
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PEER_COUNT--;
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DPRINTF("remove_peer: PEER_COUNT %d", PEER_COUNT);
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movesize = (PEER_COUNT - peer) * sizeof(void*);
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if (movesize > 0) {
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memcpy(&PARAM_TBL[peer], &PARAM_TBL[peer+1], movesize);
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if (TIMEOUT)
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memcpy(&TIMEO_TBL[peer], &TIMEO_TBL[peer+1], movesize);
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}
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PARAM_TBL = xrealloc(PARAM_TBL, PEER_COUNT * sizeof(PARAM_TBL[0]));
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if (TIMEOUT)
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TIMEO_TBL = xrealloc(TIMEO_TBL, PEER_COUNT * sizeof(TIMEO_TBL[0]));
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}
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static void handle_accept(isrv_state_t *state, int fd)
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{
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int n, newfd;
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/* suppress gcc warning "cast from ptr to int of different size" */
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fcntl(fd, F_SETFL, (int)(ptrdiff_t)(PARAM_TBL[0]) | O_NONBLOCK);
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newfd = accept(fd, NULL, 0);
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fcntl(fd, F_SETFL, (int)(ptrdiff_t)(PARAM_TBL[0]));
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if (newfd < 0) {
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if (errno == EAGAIN) return;
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/* Most probably someone gave us wrong fd type
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* (for example, non-socket). Don't want
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* to loop forever. */
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bb_perror_msg_and_die("accept");
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}
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DPRINTF("new_peer(%d)", newfd);
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n = state->new_peer(state, newfd);
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if (n)
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remove_peer(state, n); /* unsuccesful peer start */
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}
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static void handle_fd_set(isrv_state_t *state, fd_set *fds, int (*h)(int, void **))
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{
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enum { LONG_CNT = sizeof(fd_set) / sizeof(long) };
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int fds_pos;
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int fd, peer;
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/* need to know value at _the beginning_ of this routine */
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int fd_cnt = FD_COUNT;
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BUILD_BUG_ON(LONG_CNT * sizeof(long) != sizeof(fd_set));
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fds_pos = 0;
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while (1) {
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/* Find next nonzero bit */
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while (fds_pos < LONG_CNT) {
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if (((long*)fds)[fds_pos] == 0) {
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fds_pos++;
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continue;
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}
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/* Found non-zero word */
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fd = fds_pos * sizeof(long)*8; /* word# -> bit# */
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while (1) {
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if (FD_ISSET(fd, fds)) {
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FD_CLR(fd, fds);
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goto found_fd;
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}
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fd++;
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}
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}
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break; /* all words are zero */
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found_fd:
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if (fd >= fd_cnt) { /* paranoia */
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DPRINTF("handle_fd_set: fd > fd_cnt?? (%d > %d)",
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fd, fd_cnt);
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break;
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}
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DPRINTF("handle_fd_set: fd %d is active", fd);
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peer = FD2PEER[fd];
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if (peer < 0)
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continue; /* peer is already gone */
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if (peer == 0) {
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handle_accept(state, fd);
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continue;
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}
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DPRINTF("h(fd:%d)", fd);
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if (h(fd, &PARAM_TBL[peer])) {
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/* this peer is gone */
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remove_peer(state, peer);
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} else if (TIMEOUT) {
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TIMEO_TBL[peer] = monotonic_sec();
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}
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}
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}
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static void handle_timeout(isrv_state_t *state, int (*do_timeout)(void **))
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{
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int n, peer;
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peer = PEER_COUNT-1;
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/* peer 0 is not checked */
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while (peer > 0) {
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DPRINTF("peer %d: time diff %d", peer,
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(int)(CURTIME - TIMEO_TBL[peer]));
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if ((CURTIME - TIMEO_TBL[peer]) >= TIMEOUT) {
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DPRINTF("peer %d: do_timeout()", peer);
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n = do_timeout(&PARAM_TBL[peer]);
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if (n)
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remove_peer(state, peer);
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}
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peer--;
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}
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}
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/* Driver */
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void isrv_run(
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int listen_fd,
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int (*new_peer)(isrv_state_t *state, int fd),
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int (*do_rd)(int fd, void **),
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int (*do_wr)(int fd, void **),
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int (*do_timeout)(void **),
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int timeout,
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int linger_timeout)
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{
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isrv_state_t *state = xzalloc(sizeof(*state));
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state->new_peer = new_peer;
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state->timeout = timeout;
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/* register "peer" #0 - it will accept new connections */
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isrv_register_peer(state, NULL);
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isrv_register_fd(state, /*peer:*/ 0, listen_fd);
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isrv_want_rd(state, listen_fd);
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/* remember flags to make blocking<->nonblocking switch faster */
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/* (suppress gcc warning "cast from ptr to int of different size") */
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PARAM_TBL[0] = (void*)(ptrdiff_t)(fcntl(listen_fd, F_GETFL));
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while (1) {
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struct timeval tv;
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fd_set rd;
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fd_set wr;
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fd_set *wrp = NULL;
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int n;
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tv.tv_sec = timeout;
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if (PEER_COUNT <= 1)
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tv.tv_sec = linger_timeout;
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tv.tv_usec = 0;
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rd = state->rd;
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if (WR_COUNT) {
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wr = state->wr;
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wrp = ≀
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}
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DPRINTF("run: select(FD_COUNT:%d,timeout:%d)...",
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FD_COUNT, (int)tv.tv_sec);
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n = select(FD_COUNT, &rd, wrp, NULL, tv.tv_sec ? &tv : NULL);
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DPRINTF("run: ...select:%d", n);
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if (n < 0) {
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if (errno != EINTR)
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bb_perror_msg("select");
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continue;
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}
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if (n == 0 && linger_timeout && PEER_COUNT <= 1)
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break;
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if (timeout) {
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time_t t = monotonic_sec();
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if (t != CURTIME) {
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CURTIME = t;
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handle_timeout(state, do_timeout);
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}
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}
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if (n > 0) {
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handle_fd_set(state, &rd, do_rd);
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if (wrp)
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handle_fd_set(state, wrp, do_wr);
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}
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}
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DPRINTF("run: bailout");
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/* NB: accept socket is not closed. Caller is to decide what to do */
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}
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