Prevent memory leak

```
for (int i = 0; i < arg->family_size; i++) {
    arg->getaddrinfo_entries[i] = allocate_fast_fallback_getaddrinfo_entry();
    if (!(arg->getaddrinfo_entries[i])) rb_syserr_fail(errno, "calloc(3)");
```

If the allocation fails in the second interation, the memory allocated
in the first iteration would be leaked.

This change prevents the memory leak by allocating the memory in
advance.
(The struct name `fast_fallback_getaddrinfo_shared` might no longer be
good.)

Author: mame

ext/socket/ipsocket.c

@@ -235,31 +235,18 @@ struct fast_fallback_inetsock_arg
 };
 
 static struct fast_fallback_getaddrinfo_shared *
-allocate_fast_fallback_getaddrinfo_shared(void)
+allocate_fast_fallback_getaddrinfo_shared(int family_size)
 {
     struct fast_fallback_getaddrinfo_shared *shared;
 
     shared = (struct fast_fallback_getaddrinfo_shared *)calloc(
         1,
-        sizeof(struct fast_fallback_getaddrinfo_shared)
+        sizeof(struct fast_fallback_getaddrinfo_shared) + (family_size == 1 ? 0 : 2) * sizeof(struct fast_fallback_getaddrinfo_entry)
     );
 
     return shared;
 }
 
-static struct fast_fallback_getaddrinfo_entry *
-allocate_fast_fallback_getaddrinfo_entry(void)
-{
-    struct fast_fallback_getaddrinfo_entry *entry;
-
-    entry = (struct fast_fallback_getaddrinfo_entry *)calloc(
-        1,
-        sizeof(struct fast_fallback_getaddrinfo_entry)
-    );
-
-    return entry;
-}
-
 static void
 allocate_fast_fallback_getaddrinfo_hints(struct addrinfo *hints, int family, int remote_addrinfo_hints, int additional_flags)
 {
@@ -604,7 +591,7 @@ init_fast_fallback_inetsock_internal(VALUE v)
     hostname_resolution_notifier = pipefd[1];
     wait_arg.readfds = &readfds;
 
-    arg->getaddrinfo_shared = allocate_fast_fallback_getaddrinfo_shared();
+    arg->getaddrinfo_shared = allocate_fast_fallback_getaddrinfo_shared(arg->family_size);
     if (!arg->getaddrinfo_shared) rb_syserr_fail(errno, "calloc(3)");
 
     arg->getaddrinfo_shared->lock = calloc(1, sizeof(rb_nativethread_lock_t));
@@ -659,8 +646,7 @@ init_fast_fallback_inetsock_internal(VALUE v)
         arg->getaddrinfo_shared->refcount = arg->family_size + 1;
 
         for (int i = 0; i < arg->family_size; i++) {
-            arg->getaddrinfo_entries[i] = allocate_fast_fallback_getaddrinfo_entry();
-            if (!(arg->getaddrinfo_entries[i])) rb_syserr_fail(errno, "calloc(3)");
+            arg->getaddrinfo_entries[i] = &arg->getaddrinfo_shared->getaddrinfo_entries[i];
             arg->getaddrinfo_entries[i]->shared = arg->getaddrinfo_shared;
 
             struct addrinfo getaddrinfo_hints[arg->family_size];

ext/socket/raddrinfo.c

@@ -3047,7 +3047,6 @@ free_fast_fallback_getaddrinfo_entry(struct fast_fallback_getaddrinfo_entry **en
         freeaddrinfo((*entry)->ai);
         (*entry)->ai = NULL;
     }
-    free(*entry);
     *entry = NULL;
 }
 

ext/socket/rubysocket.h

@@ -138,6 +138,7 @@
 
 #include "internal.h"
 #include "internal/array.h"
+#include "internal/compilers.h"
 #include "internal/error.h"
 #include "internal/gc.h"
 #include "internal/io.h"
@@ -426,15 +427,6 @@ char *port_str(VALUE port, char *pbuf, size_t pbuflen, int *flags_ptr);
 #    define IPV4_HOSTNAME_RESOLVED '2'
 #    define SELECT_CANCELLED '3'
 
-struct fast_fallback_getaddrinfo_shared
-{
-    int wait, notify, refcount, connection_attempt_fds_size;
-    int cancelled;
-    int *connection_attempt_fds;
-    char *node, *service;
-    rb_nativethread_lock_t *lock;
-};
-
 struct fast_fallback_getaddrinfo_entry
 {
     int family, err, refcount;
@@ -446,6 +438,16 @@ struct fast_fallback_getaddrinfo_entry
     int test_ecode;
 };
 
+struct fast_fallback_getaddrinfo_shared
+{
+    int wait, notify, refcount, connection_attempt_fds_size;
+    int cancelled;
+    int *connection_attempt_fds;
+    char *node, *service;
+    rb_nativethread_lock_t *lock;
+    struct fast_fallback_getaddrinfo_entry getaddrinfo_entries[FLEX_ARY_LEN];
+};
+
 int raddrinfo_pthread_create(pthread_t *th, void *(*start_routine) (void *), void *arg);
 void *do_fast_fallback_getaddrinfo(void *ptr);
 void free_fast_fallback_getaddrinfo_entry(struct fast_fallback_getaddrinfo_entry **entry);