unix,fs: fix realpath calls that use the system allocator

Make sure we allocate the memory with uv__malloc so it's in turn freed
with uv__free.

Fixes: libuv#4329

src/unix/fs.c

@@ -691,14 +691,23 @@ static ssize_t uv__fs_readlink(uv_fs_t* req) {
 
 static ssize_t uv__fs_realpath(uv_fs_t* req) {
   char* buf;
+  char* tmp;
 
 #if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L
-  buf = realpath(req->path, NULL);
-  if (buf == NULL)
+  tmp = realpath(req->path, NULL);
+  if (tmp == NULL)
     return -1;
+  buf = uv__strdup(tmp);
+  free(tmp); /* _Not_ uv__free. */
+  if (buf == NULL) {
+    errno = ENOMEM;
+    return -1;
+  }
 #else
   ssize_t len;
 
+  (void)tmp;
+
   len = uv__fs_pathmax_size(req->path);
   buf = uv__malloc(len + 1);
 

src/unix/fsevents.c

@@ -793,6 +793,7 @@ int uv__cf_loop_signal(uv_loop_t* loop,
 
 /* Runs in UV loop to initialize handle */
 int uv__fsevents_init(uv_fs_event_t* handle) {
+  char* buf;
   int err;
   uv__cf_loop_state_t* state;
 
@@ -801,9 +802,13 @@ int uv__fsevents_init(uv_fs_event_t* handle) {
     return err;
 
   /* Get absolute path to file */
-  handle->realpath = realpath(handle->path, NULL);
-  if (handle->realpath == NULL)
+  buf = realpath(handle->path, NULL);
+  if (buf == NULL)
     return UV__ERR(errno);
+  handle->realpath = uv__strdup(buf);
+  free(buf); /* _Not_ uv__free. */
+  if (handle->realpath == NULL)
+    return UV_ENOMEM;
   handle->realpath_len = strlen(handle->realpath);
 
   /* Initialize event queue */