Handle resize failures in the select backend better.

1 files changed, 14 insertions, 5 deletions

diff --git a/select.c b/select.c
index 993a4e60..8327518e 100644
--- a/select.c
+++ b/select.c
@@ -100,7 +100,9 @@ select_init(struct event_base *base)
 		return (NULL);
 
 	if (select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask))) {
-		mm_free(sop);
+		/* select_resize might have left this around. */
+		if (sop->event_readset_in)
+			mm_free(sop->event_readset_in);
 		return (NULL);
 	}
 
@@ -131,11 +133,14 @@ select_dispatch(struct event_base *base, struct timeval *tv)
 		size_t sz = sop->event_fdsz;
 		if (!(readset_out = mm_realloc(sop->event_readset_out, sz)))
 			return (-1);
+		sop->event_readset_out = readset_out;
 		if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) {
-			mm_free(readset_out);
+			/* We don't free readset_out here, since it was
+			 * already successfully reallocated. The next time
+			 * we call select_dispatch, the realloc will be a
+			 * no-op. */
 			return (-1);
 		}
-		sop->event_readset_out = readset_out;
 		sop->event_writeset_out = writeset_out;
 		sop->resize_out_sets = 0;
 	}
@@ -188,7 +193,6 @@ select_dispatch(struct event_base *base, struct timeval *tv)
 	return (0);
 }
 
-
 static int
 select_resize(struct selectop *sop, int fdsz)
 {
@@ -202,7 +206,12 @@ select_resize(struct selectop *sop, int fdsz)
 		goto error;
 	sop->event_readset_in = readset_in;
 	if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) {
-		mm_free(readset_in);
+		/* Note that this will leave event_readset_in expanded.
+		 * That's okay; we wouldn't want to free it, since that would
+		 * change the semantics of select_resize from "expand the
+		 * readset_in and writeset_in, or return -1" to "expand the
+		 * *set_in members, or trash them and return -1."
+		 */
 		goto error;
 	}
 	sop->event_writeset_in = writeset_in;