poll: Make handling of fds array actually dynamic

Previously we relied on the max_fds argument to register_for_poll
being big enough and allocated an array at startup.  But we are going
to want to be more dynamic, so actually do the dynamic array resizing.

We now start with a zero-sized array and increase it as needed.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/secnet.c b/secnet.c
index 84aac21ea8d1f14a16c07ce55b01ea9bac5a11e2..7a9d3f009274176620f36f4b8cc5f807c7362278 100644 (file)
--- a/secnet.c
+++ b/secnet.c
@@ -45,7 +45,6 @@ struct poll_interest {
     LIST_ENTRY(poll_interest) entry;
 };
 static LIST_HEAD(, poll_interest) reg = LIST_HEAD_INITIALIZER(&reg);
-static int32_t total_nfds=10;
 
 static bool_t finished=False;
 
@@ -239,8 +238,6 @@ void register_for_poll(void *st, beforepoll_fn *before,
     i->max_nfds=max_nfds;
     i->nfds=0;
     i->desc=desc;
-    assert(total_nfds < INT_MAX - max_nfds);
-    total_nfds+=max_nfds;
     LIST_INSERT_HEAD(&reg, i, entry);
     return;
 }
@@ -296,9 +293,8 @@ static void run(void)
     struct poll_interest *i;
     int rv, nfds, remain, 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);
 
@@ -319,16 +315,25 @@ static void run(void)
            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");
+       }
+       remain=allocdfds;
+       shortfall=0;
        idx=0;
        timeout=-1;
        LIST_FOREACH(i, &reg, entry) {
            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 (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;
            }
            if (timeout<-1) {
                fatal("run: beforepoll_fn (%s) set timeout to %d",