Use epoll() and signalfd() in ifchd.

ifchd/TODO

@@ -1,3 +0,0 @@
-write documentation...
-support BSD
-

ifchd/ifchd.c

@@ -1,5 +1,5 @@
 /* ifchd.c - interface change daemon
- * Time-stamp: <2010-11-13 08:07:54 njk>
+ * Time-stamp: <2010-12-01 12:19:39 njk>
  *
  * (C) 2004-2010 Nicholas J. Kain <njkain at gmail dot com>
  *
@@ -26,6 +26,8 @@
 #include <sys/un.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <sys/epoll.h>
+#include <sys/signalfd.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 
@@ -71,7 +73,9 @@ enum states {
     STATE_WINS
 };
 
-static volatile sig_atomic_t pending_exit;
+static int epollfd, signalFd;
+/* Extra two event slots are for signalFd and the listen socket. */
+static struct epoll_event events[SOCK_QUEUE+2];
 
 /* Socket fd, current state, and idle time for connections. */
 static int sks[SOCK_QUEUE], state[SOCK_QUEUE], idle_time[SOCK_QUEUE];
@@ -102,23 +106,6 @@ static pid_t peer_pid;
 static strlist_t *namesvrs[SOCK_QUEUE];
 static strlist_t *domains[SOCK_QUEUE];
 
-static void sighandler(int sig) {
-    pending_exit = 1;
-}
-
-static void fix_signals(void) {
-    disable_signal(SIGPIPE);
-    disable_signal(SIGUSR1);
-    disable_signal(SIGUSR2);
-    disable_signal(SIGTSTP);
-    disable_signal(SIGTTIN);
-    disable_signal(SIGCHLD);
-    disable_signal(SIGHUP);
-
-    hook_signal(SIGINT, sighandler, 0);
-    hook_signal(SIGTERM, sighandler, 0);
-}
-
 static void die_nulstr(strlist_t *p)
 {
     if (!p)
@@ -133,6 +120,29 @@ static void writeordie(int fd, const char *buf, int len)
         suicide("write returned error");
 }
 
+static void epoll_add(int fd)
+{
+    struct epoll_event ev;
+    int r;
+    ev.events = EPOLLIN | EPOLLRDHUP | EPOLLERR | EPOLLHUP;
+    ev.data.fd = fd;
+    r = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
+    if (r == -1)
+        suicide("epoll_add failed %s", strerror(errno));
+}
+
+static void epoll_del(int fd)
+{
+    struct epoll_event ev;
+    int r;
+    ev.events = EPOLLIN | EPOLLRDHUP | EPOLLERR | EPOLLHUP;
+    ev.data.fd = fd;
+    r = epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, &ev);
+    if (r == -1)
+        suicide("epoll_del failed %s", strerror(errno));
+}
+
+/* Abstracts away the details of accept()ing a socket connection. */
 /* Writes out each element in a strlist as an argument to a keyword in
  * a file. */
 static void write_resolve_list(const char *keyword, strlist_t *list)
@@ -297,9 +307,10 @@ static void add_sk(int sk)
     int i;
 
     if (authorized_peer(sk, peer_pid, peer_uid, peer_gid)) {
-        for (i=0; i<SOCK_QUEUE; i++)
+        for (i = 0; i < SOCK_QUEUE; i++)
             if (sks[i] == -1) {
                 new_sk(i, sk);
+                epoll_add(sk);
                 return;
             }
     }
@@ -315,6 +326,7 @@ static void close_idle_sk(void)
         if (sks[i] == -1)
             continue;
         if (time(NULL) - idle_time[i] > CONN_TIMEOUT) {
+            epoll_del(sks[i]);
             close(sks[i]);
             new_sk(i, -1);
         }
@@ -532,7 +544,6 @@ static int get_listen(void)
     return lsock;
 }
 
-/* Abstracts away the details of accept()ing a socket connection. */
 static void accept_conns(int *lsock)
 {
     int ret;
@@ -567,8 +578,12 @@ static void accept_conns(int *lsock)
             case ENOTSOCK:
             case EINVAL:
                 log_line("warning: accept returned %s!\n", strerror(errno));
+
+                epoll_del(*lsock);
                 close(*lsock);
+
                 *lsock = get_listen();
+                epoll_add(*lsock);
                 return;
 
             case ECONNABORTED:
@@ -585,110 +600,138 @@ static void accept_conns(int *lsock)
     }
 }
 
+static void setup_signals()
+{
+    sigset_t mask;
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGPIPE);
+    sigaddset(&mask, SIGUSR1);
+    sigaddset(&mask, SIGUSR2);
+    sigaddset(&mask, SIGTSTP);
+    sigaddset(&mask, SIGTTIN);
+    sigaddset(&mask, SIGCHLD);
+    sigaddset(&mask, SIGHUP);
+    sigaddset(&mask, SIGINT);
+    sigaddset(&mask, SIGTERM);
+    if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0)
+        suicide("sigprocmask failed");
+    signalFd = signalfd(-1, &mask, SFD_NONBLOCK);
+    if (signalFd < 0)
+        suicide("signalfd failed");
+}
+
+static void signal_dispatch()
+{
+    int t, off = 0;
+    struct signalfd_siginfo si;
+  again:
+    t = read(signalFd, (char *)&si + off, sizeof si - off);
+    if (t < sizeof si - off) {
+        if (t < 0) {
+            if (t == EAGAIN || t == EWOULDBLOCK || t == EINTR)
+                goto again;
+            else
+                suicide("signalfd read error");
+        }
+        off += t;
+    }
+    switch (si.ssi_signo) {
+        case SIGINT:
+        case SIGTERM:
+            exit(EXIT_SUCCESS);
+        default:
+            break;
+    }
+}
+
+static void process_client_fd(int fd)
+{
+    char buf[MAX_BUF];
+    int r, index, sqidx = -1;
+    for (int j = 0; j < SOCK_QUEUE; ++j) {
+        if (sks[j] == fd) {
+            sqidx = j;
+            break;
+        }
+    }
+    if (sqidx == -1)
+        suicide("epoll returned pending read for untracked fd");
+
+    idle_time[sqidx] = time(NULL);
+    memset(buf, '\0', sizeof buf);
+
+    r = safe_read(sks[sqidx], buf, sizeof buf / 2 - 1);
+    if (r <= 0) {
+        if (r != 0)
+            log_line("error reading from client fd: %s", strerror(errno));
+        goto fail;
+    }
+
+    /* Discard everything and close connection if we risk overflow.
+     * This approach is maximally conservative... worst case is that
+     * some client requests will get dropped. */
+    index = strlen(ibuf[sqidx]);
+    if (index + strlen(buf) > sizeof buf - 2)
+        goto fail;
+
+    /* Append new stream input avoiding overflow. */
+    strlcpy(ibuf[sqidx] + index, buf, sizeof ibuf[sqidx] - index);
+
+    /* Decompose ibuf contents onto strlist. */
+    index = stream_onto_list(sqidx);
+
+    /* Remove everything that we've parsed into the list. */
+    strlcpy(buf, ibuf[sqidx] + index, sizeof buf);
+    strlcpy(ibuf[sqidx], buf, sizeof ibuf[sqidx]);
+
+    /* Now we have a strlist of commands and arguments.
+     * Decompose and execute it. */
+    if (!head[sqidx])
+        return;
+    curl[sqidx] = head[sqidx];
+    execute_list(sqidx);
+    return;
+  fail:
+    epoll_del(sks[sqidx]);
+    close(sks[sqidx]);
+    new_sk(sqidx, -1);
+}
+
 /* Core function that handles connections, gathers input, and calls
  * the state machine to do actual work. */
 static void dispatch_work(void)
 {
-    int lsock, ret, highfd, i, index;
+    int lsock;
-    fd_set rfds;
-    char buf[MAX_BUF];
 
     /* Initialize all structures to blank state. */
-    for (i=0; i<SOCK_QUEUE; i++)
+    for (int i = 0; i < SOCK_QUEUE; i++)
         sks[i] = -1;
     initialize_if_data();
 
     lsock = get_listen();
 
+    epollfd = epoll_create1(0);
+    if (epollfd == -1)
+        suicide("epoll_create1 failed");
+    epoll_add(lsock);
+    epoll_add(signalFd);
+
     for (;;) {
-        FD_ZERO(&rfds);
+        int r = epoll_wait(epollfd, events, SOCK_QUEUE + 2, -1);
-        FD_SET(lsock, &rfds);
+        if (r == -1) {
-
+            if (errno == EINTR)
-        /* find highest fd */
+                continue;
-        for (i=0, highfd=0; i<SOCK_QUEUE; i++) {
+            else
-            if (sks[i] != -1) {
+                suicide("epoll_wait failed");
-                FD_SET(sks[i], &rfds);
-                if (sks[i] > highfd)
-                    highfd = sks[i];
-            }
         }
-        if (lsock > highfd)
+        for (int i = 0; i < r; ++i) {
-            highfd = lsock;
+            int fd = events[i].data.fd;
-
+            if (fd == lsock)
-        ret = select(highfd + 1, &rfds, NULL, NULL, NULL);
+                accept_conns(&lsock);
-        switch (ret) {
+            else if (fd == signalFd)
-            case 0:
+                signal_dispatch();
-                close_idle_sk();
+            else
-                break;
+                process_client_fd(fd);
-            case -1:
-                if (pending_exit == 1)
-                    return;
-                suicide("dispatch_work - select returned an error!");
-                break;
-        }
-
-        if (pending_exit == 1)
-            return;
-
-        /* handle pending connections */
-        if (FD_ISSET(lsock, &rfds))
-            accept_conns(&lsock);
-
-        /* Read in and process data on waiting connections */
-        for (i=0; i<SOCK_QUEUE; i++) {
-            if (sks[i] == -1)
-                continue;
-            if (!FD_ISSET(sks[i], &rfds))
-                continue;
-
-            idle_time[i] = time(NULL);
-            memset(buf, '\0', sizeof(buf));
-
-read_again:
-            ret = (int) read(sks[i], buf, MAX_BUF / 2 - 1);
-
-            /* Check to see if peer closed socket */
-            if (ret == 0) {
-                close(sks[i]);
-                new_sk(i, -1);
-                continue;
-            }
-
-            if (ret == -1) {
-                if (errno == EINTR)
-                    goto read_again;
-                log_line("dispatch_work: read returned %s.\n", strerror(errno));
-                close(sks[i]);
-                new_sk(i, -1);
-                continue;
-            }
-
-            /* Discard everything and close connection if we risk overflow.
-             * This approach is maximally conservative... worst case is that
-             * some client requests will get dropped. */
-            index = strlen(ibuf[i]);
-            if (index + strlen(buf) > MAX_BUF - 2) {
-                close(sks[i]);
-                new_sk(i, -1);
-                continue;
-            }
-
-            /* Append new stream input avoiding overflow. */
-            strlcpy(ibuf[i] + index, buf, sizeof(ibuf[i]) - index);
-
-            /* Decompose ibuf contents onto strlist. */
-            index = stream_onto_list(i);
-
-            /* Remove everything that we've parsed into the list. */
-            strlcpy(buf, ibuf[i] + index, sizeof(buf));
-            strlcpy(ibuf[i], buf, sizeof(ibuf[i]));
-
-            /* Now we have a strlist of commands and arguments.
-             * Decompose and execute it. */
-            if (!head[i])
-                continue;
-            curl[i] = head[i];
-            execute_list(i);
         }
         close_idle_sk();
     }
@@ -875,7 +918,7 @@ int main(int argc, char** argv) {
     write_pid(pidfile);
 
     umask(077);
-    fix_signals();
+    setup_signals();
 
     /* If we are requested to update resolv.conf, preopen the fd before
      * we drop root privileges, making sure that if we create