Jared Lundell filed bug report #1604956

(http://curl.haxx.se/bug/view.cgi?id=1604956) which identified setting
CURLOPT_MAXCONNECTS to zero caused libcurl to SIGSEGV. Starting now, libcurl
will always internally use no less than 1 entry in the connection cache.

4 files changed, 22 insertions, 6 deletions

diff --git a/lib/easy.c b/lib/easy.c
index 7436017c0..73e145213 100644
--- a/lib/easy.c
+++ b/lib/easy.c
@@ -471,7 +471,7 @@ CURLcode curl_easy_perform(CURL *curl)
 
   if(!data->state.connc) {
     /* oops, no connection cache, make one up */
-    data->state.connc = Curl_mk_connc(CONNCACHE_PRIVATE);
+    data->state.connc = Curl_mk_connc(CONNCACHE_PRIVATE, -1);
     if(!data->state.connc)
       return CURLE_OUT_OF_MEMORY;
   }
@@ -561,7 +561,7 @@ CURL *curl_easy_duphandle(CURL *incurl)
     if(data->state.used_interface == Curl_if_multi)
       outcurl->state.connc = data->state.connc;
     else
-      outcurl->state.connc = Curl_mk_connc(CONNCACHE_PRIVATE);
+      outcurl->state.connc = Curl_mk_connc(CONNCACHE_PRIVATE, -1);
 
     if(!outcurl->state.connc)
       break;
diff --git a/lib/multi.c b/lib/multi.c
index a7cc25562..0411cc908 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -347,7 +347,7 @@ CURLM *curl_multi_init(void)
     return NULL;
   }
 
-  multi->connc = Curl_mk_connc(CONNCACHE_MULTI);
+  multi->connc = Curl_mk_connc(CONNCACHE_MULTI, -1);
   if(!multi->connc) {
     Curl_hash_destroy(multi->hostcache);
     free(multi);
diff --git a/lib/url.c b/lib/url.c
index 71463164a..4f9969dcf 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -377,11 +377,13 @@ CURLcode Curl_close(struct SessionHandle *data)
 }
 
 /* create a connection cache of a private or multi type */
-struct conncache *Curl_mk_connc(int type)
+struct conncache *Curl_mk_connc(int type,
+                                int amount) /* set -1 to use default */
 {
   /* It is subject for debate how many default connections to have for a multi
      connection cache... */
-  int default_amount = (type == CONNCACHE_PRIVATE)?5:10;
+  int default_amount = amount == -1?
+    ((type == CONNCACHE_PRIVATE)?5:10):amount;
   struct conncache *c;
 
   c= calloc(sizeof(struct conncache), 1);
@@ -407,6 +409,20 @@ CURLcode Curl_ch_connc(struct SessionHandle *data,
   long i;
   struct connectdata **newptr;
 
+  if(newamount < 1)
+    newamount = 1; /* we better have at least one entry */
+
+  if(!c) {
+    /* we get a NULL pointer passed in as connection cache, which means that
+       there is no cache created for this SessionHandle just yet, we create a
+       brand new with the requested size.
+    */
+    data->state.connc = Curl_mk_connc(CONNCACHE_PRIVATE, newamount);
+    if(!data->state.connc)
+      return CURLE_OUT_OF_MEMORY;
+    return CURLE_OK;
+  }
+
   if(newamount < c->num) {
     /* Since this number is *decreased* from the existing number, we must
        close the possibly open connections that live on the indexes that
diff --git a/lib/url.h b/lib/url.h
index 83706fd73..b92467350 100644
--- a/lib/url.h
+++ b/lib/url.h
@@ -47,7 +47,7 @@ CURLcode Curl_protocol_doing(struct connectdata *conn, bool *done);
 void Curl_safefree(void *ptr);
 
 /* create a connection cache */
-struct conncache *Curl_mk_connc(int type);
+struct conncache *Curl_mk_connc(int type, int amount);
 /* free a connection cache */
 void Curl_rm_connc(struct conncache *c);
 /* Change number of entries of a connection cache */