casaroli commented on code in PR #20583:
URL: https://github.com/apache/nuttx/pull/20583#discussion_r4263661995
##########
libs/libc/environ/env_dup.c:
##########
@@ -132,9 +133,42 @@ int env_dup(FAR struct task_info_s *info, FAR char * const
*envcp)
}
}
+ /* libc allocated each string: record it as owned */
+
+ if (envp != NULL)
+ {
+ own = env_malloc(info, sizeof(*own) * info->ta_envpc);
Review Comment:
The two blocks have different lives. The array is replaced when setenv()
needs more entries: env_reserve() allocates a new one and frees the old one.
The strings stay until exit, because a pointer that getenv() returned must stay
valid. In one block, the array could not be freed alone.
##########
libs/libc/environ/env_sync.c:
##########
@@ -0,0 +1,153 @@
+/****************************************************************************
+ * libs/libc/environ/env_sync.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership. The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <errno.h>
+#include <stdbool.h>
+
+#include <nuttx/tls.h>
+
+#include "environ/environ.h"
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: env_isowned
+ *
+ * Description:
+ * Return true if libc allocated the string str and still owns it.
+ *
+ ****************************************************************************/
+
+static bool env_isowned(FAR struct task_info_s *info, FAR const char *str)
+{
+ ssize_t i;
+
+ if (info->ta_envown == NULL || str == NULL)
+ {
+ return false;
+ }
+
+ for (i = 0; i < info->ta_envpc; i++)
+ {
+ if (info->ta_envown[i] == str)
+ {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: env_sync
+ ****************************************************************************/
+
+int env_sync(FAR struct task_info_s *info)
Review Comment:
Done
##########
include/nuttx/tls.h:
##########
@@ -153,7 +153,11 @@ struct task_info_s
#ifndef CONFIG_DISABLE_ENVIRON
/* Environment variables **************************************************/
- FAR char **ta_envp; /* Allocated environment strings */
+ FAR char **ta_envp; /* The array that environ names */
Review Comment:
A program can replace one variable many times, and each old string must stay
valid until exit, because a pointer that getenv() returned may still be in use.
So the number of strings to keep has no limit.
A second half of ta_envp keeps one old string per entry, but not the strings
of the earlier replacements. ta_envmem is a list of every block that libc
allocated, so it holds any number of them, and they are all freed at exit.
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