fds: Make many fds nonblocking

[secnet.git] / secnet.c

diff --git a/secnet.c b/secnet.c
index 465a93fc260404cad1eb2070bf8df446013e87a9..111a1b0886f0c1e11a0d8a367a6aec75136689f9 100644 (file)
--- a/secnet.c
+++ b/secnet.c
@@ -36,16 +36,19 @@ static pid_t secnet_pid;
 
 /* Structures dealing with poll() call */
 struct poll_interest {
-    beforepoll_fn *before;
+    beforepoll_fn *before; /* 0 if deregistered and waiting to be deleted */
     afterpoll_fn *after;
     void *state;
-    int32_t max_nfds;
     int32_t nfds;
     cstring_t desc;
-    struct poll_interest *next;
+    LIST_ENTRY(poll_interest) entry;
 };
-static struct poll_interest *reg=NULL;
-static int32_t total_nfds=10;
+static LIST_HEAD(, poll_interest) reg = LIST_HEAD_INITIALIZER(&reg);
+
+static bool_t interest_isregistered(const struct poll_interest *i)
+{
+    return !!i->before;
+}
 
 static bool_t finished=False;
 
@@ -227,8 +230,8 @@ static void setup(dict_t *config)
     }
 }
 
-void register_for_poll(void *st, beforepoll_fn *before,
-                      afterpoll_fn *after, int32_t max_nfds, cstring_t desc)
+struct poll_interest *register_for_poll(void *st, beforepoll_fn *before,
+                      afterpoll_fn *after, cstring_t desc)
 {
     struct poll_interest *i;
 
@@ -236,14 +239,18 @@ void register_for_poll(void *st, beforepoll_fn *before,
     i->before=before;
     i->after=after;
     i->state=st;
-    i->max_nfds=max_nfds;
     i->nfds=0;
     i->desc=desc;
-    assert(total_nfds < INT_MAX - max_nfds);
-    total_nfds+=max_nfds;
-    i->next=reg;
-    reg=i;
-    return;
+    LIST_INSERT_HEAD(&reg, i, entry);
+    return i;
+}
+
+void deregister_for_poll(struct poll_interest *i)
+{
+    /* We cannot simply throw this away because we're reentrantly
+     * inside the main loop, which needs to remember which range of
+     * fds corresponds to this now-obsolete interest */
+    i->before=0;
 }
 
 static void system_phase_hook(void *sst, uint32_t newphase)
@@ -294,12 +301,11 @@ uint64_t now_global;
 
 static void run(void)
 {
-    struct poll_interest *i;
-    int rv, nfds, remain, idx;
+    struct poll_interest *i, *itmp;
+    int rv, nfds, idx;
     int timeout;
-    struct pollfd *fds;
-
-    fds=safe_malloc(sizeof(*fds)*total_nfds, "run");
+    struct pollfd *fds=0;
+    int allocdfds=0, shortfall=0;
 
     Message(M_NOTICE,"%s [%d]: starting\n",version,secnet_pid);
 
@@ -310,32 +316,54 @@ static void run(void)
        now_global=((uint64_t)tv_now_global.tv_sec*(uint64_t)1000)+
                   ((uint64_t)tv_now_global.tv_usec/(uint64_t)1000);
        idx=0;
-       for (i=reg; i; i=i->next) {
+       LIST_FOREACH(i, &reg, entry) {
            int check;
-           for (check=0; check<i->nfds; check++) {
-               if(fds[idx+check].revents & POLLNVAL) {
-                   fatal("run: poll (%s#%d) set POLLNVAL", i->desc, check);
+           if (interest_isregistered(i)) {
+               for (check=0; check<i->nfds; check++) {
+                   if(fds[idx+check].revents & POLLNVAL) {
+                       fatal("run: poll (%s#%d) set POLLNVAL", i->desc, check);
+                   }
                }
+               i->after(i->state, fds+idx, i->nfds);
            }
-           i->after(i->state, fds+idx, i->nfds);
            idx+=i->nfds;
        }
-       remain=total_nfds;
+       if (shortfall) {
+           allocdfds *= 2;
+           allocdfds += shortfall;
+           fds=safe_realloc_ary(fds,sizeof(*fds),allocdfds, "run");
+       }
+       shortfall=0;
        idx=0;
        timeout=-1;
-       for (i=reg; i; i=i->next) {
+       LIST_FOREACH_SAFE(i, &reg, entry, itmp) {
+           int remain=allocdfds-idx;
            nfds=remain;
-           rv=i->before(i->state, fds+idx, &nfds, &timeout);
-           if (rv!=0) {
-               /* XXX we need to handle this properly: increase the
-                  nfds available */
-               fatal("run: beforepoll_fn (%s) returns %d",i->desc,rv);
+           if (interest_isregistered(i)) {
+               rv=i->before(i->state, fds+idx, &nfds, &timeout);
+               if (rv!=0) {
+                   if (rv!=ERANGE)
+                       fatal("run: beforepoll_fn (%s) returns %d",i->desc,rv);
+                   assert(nfds < INT_MAX/4 - shortfall);
+                   shortfall += nfds-remain;
+                   nfds=0;
+                   timeout=0;
+               }
+           } else {
+               nfds=0;
            }
            if (timeout<-1) {
-               fatal("run: beforepoll_fn (%s) set timeout to %d",timeout);
+               fatal("run: beforepoll_fn (%s) set timeout to %d",
+                     i->desc,timeout);
+           }
+           if (!interest_isregistered(i)) {
+               /* check this here, rather than earlier, so that we
+                  handle the case where i->before() calls deregister */
+               LIST_REMOVE(i, entry);
+               free(i);
+               continue;
            }
            idx+=nfds;
-           remain-=nfds;
            i->nfds=nfds;
        }
        do {
@@ -402,9 +430,7 @@ static void become_daemon(void)
     }
     if (secnet_is_daemon) {
        /* stderr etc are redirected to the system/log facility */
-       if (pipe(errfds)!=0) {
-           fatal_perror("can't create pipe for stderr");
-       }
+       pipe_cloexec(errfds);
        if (dup2(errfds[1],0) < 0
            || dup2(errfds[1],1) < 0
            || dup2(errfds[1],2) < 0)