notify:add path tmp buffer

Signed-off-by: guohao15 <guohao15@xiaomi.com>

include/nuttx/lib/lib.h

@@ -116,6 +116,11 @@ FAR struct file_struct *lib_get_stream(int fd);
 
 unsigned long nrand(unsigned long limit);
 
+/* Functions defined in lib_pathbuffer.c ************************************/
+
+FAR char *lib_get_pathbuffer(void);
+void lib_put_pathbuffer(FAR char *buffer);
+
 #undef EXTERN
 #ifdef __cplusplus
 }

libs/libc/misc/CMakeLists.txt

@@ -43,7 +43,8 @@ list(
   lib_mkdirat.c
   lib_utimensat.c
   lib_memoryregion.c
-  lib_getnprocs.c)
+  lib_getnprocs.c
+  lib_pathbuffer.c)
 
 # Support for platforms that do not have long long types
 

libs/libc/misc/Kconfig

@@ -112,3 +112,11 @@ config LIBC_MEM_FD_VFS_PATH
 	depends on !LIBC_MEMFD_ERROR
 	---help---
 		The relative path to where memfd will exist in the tmpfs namespace.
+
+config LIBC_MAX_PATHBUFFER
+	int "Maximum size of a temporary file path buffer array"
+	range 0 32
+	default 2
+	---help---
+		This value is the maximum size of the buffer that will hold the full
+		file path.

libs/libc/misc/Make.defs

@@ -25,7 +25,7 @@ CSRCS += lib_xorshift128.c lib_tea_encrypt.c lib_tea_decrypt.c
 CSRCS += lib_cxx_initialize.c lib_impure.c lib_memfd.c lib_mutex.c
 CSRCS += lib_fchmodat.c lib_fstatat.c lib_getfullpath.c lib_openat.c
 CSRCS += lib_mkdirat.c lib_utimensat.c lib_mallopt.c lib_memoryregion.c
-CSRCS += lib_idr.c lib_getnprocs.c
+CSRCS += lib_idr.c lib_getnprocs.c lib_pathbuffer.c
 
 # Support for platforms that do not have long long types
 

libs/libc/misc/lib_pathbuffer.c

@@ -0,0 +1,138 @@
+/****************************************************************************
+ * libs/libc/misc/lib_pathbuffer.c
+ *
+ * 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 <nuttx/mutex.h>
+#include <nuttx/lib/lib.h>
+
+#include <stdlib.h>
+#include <string.h>
+
+/****************************************************************************
+ * Pre-processor definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct pathbuffer_s
+{
+  mutex_t lock;         /* Lock for the buffer */
+  int free_bitmap;      /* Bitmap of free buffer */
+  char buffer[CONFIG_LIBC_MAX_PATHBUFFER][PATH_MAX];
+};
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct pathbuffer_s g_pathbuffer =
+{
+  NXMUTEX_INITIALIZER,
+  (1u << CONFIG_LIBC_MAX_PATHBUFFER) - 1,
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_get_pathbuffer
+ *
+ * Description:
+ *   The lib_get_pathbuffer() function returns a pointer to a temporary
+ *   buffer.  The buffer is allocated from a pool of pre-allocated buffers
+ *   and if the pool is exhausted, a new buffer is allocated through
+ *   kmm_malloc(). The size of the buffer is PATH_MAX, and must freed by
+ *   calling lib_put_pathbuffer().
+ *
+ * Returned Value:
+ *   On success, lib_get_pathbuffer() returns a pointer to a temporary
+ *   buffer.  On failure, NULL is returned.
+ *
+ ****************************************************************************/
+
+FAR char *lib_get_pathbuffer(void)
+{
+  int index;
+
+  /* Try to find a free buffer */
+
+  nxmutex_lock(&g_pathbuffer.lock);
+  index = ffs(g_pathbuffer.free_bitmap) - 1;
+  if (index >= 0 && index < CONFIG_LIBC_MAX_PATHBUFFER)
+    {
+      g_pathbuffer.free_bitmap &= ~(1u << index);
+      nxmutex_unlock(&g_pathbuffer.lock);
+      return g_pathbuffer.buffer[index];
+    }
+
+  nxmutex_unlock(&g_pathbuffer.lock);
+
+  /* If no free buffer is found, allocate a new one */
+
+  return lib_malloc(PATH_MAX);
+}
+
+/****************************************************************************
+ * Name: lib_put_pathbuffer
+ *
+ * Description:
+ *   The lib_put_pathbuffer() function frees a temporary buffer that was
+ *   allocated by lib_get_pathbuffer(). If the buffer was allocated
+ *   dynamically, it is freed by calling kmm_free(). Otherwise, the buffer
+ *   is marked as free in the pool of pre-allocated buffers.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void lib_put_pathbuffer(FAR char *buffer)
+{
+  int index;
+
+  nxmutex_lock(&g_pathbuffer.lock);
+  index = (buffer - &g_pathbuffer.buffer[0][0]) / PATH_MAX;
+
+  if (index >= 0 && index < CONFIG_LIBC_MAX_PATHBUFFER)
+    {
+      /* Mark the corresponding bit as free */
+
+      g_pathbuffer.free_bitmap |= 1u << index;
+      nxmutex_unlock(&g_pathbuffer.lock);
+      return;
+    }
+
+  nxmutex_unlock(&g_pathbuffer.lock);
+
+  /* Free the buffer if it was dynamically allocated */
+
+  lib_free(buffer);
+}