flashparams: fix memory leak when saving parameters

A large buffer on the heap was not deallocated when parameters were saved,
but there were no changes to the parameters. In that case
parameter_flashfs_write() was not called, which was previously responsible
for freeing the buffer.

This patch moves the responsibility of freeing the buffer to the calling
side, which already explicitly allocates the buffer.

src/modules/systemlib/flashparams/flashfs.c

@@ -132,12 +132,12 @@ const flash_file_token_t parameters_token = {
  * Name: parameter_flashfs_free
  *
  * Description:
- *   Frees  dynamicaly allocated memory
+ *   Frees  dynamically allocated memory
  *
  *
  ****************************************************************************/
 
-static void parameter_flashfs_free(void)
+void parameter_flashfs_free(void)
 {
 	if (!working_buffer_static && working_buffer != NULL) {
 		free(working_buffer);
@@ -769,7 +769,7 @@ int parameter_flashfs_read(flash_file_token_t token, uint8_t **buffer, size_t
  *   token      - File Token File to read
  *   buffer      - A pointer to a buffer with buf_size bytes to be written
  *                 to the flash. This buffer must be allocated
- *                 with a previous call to flash_alloc_buffer
+ *                 with a previous call to parameter_flashfs_alloc
  *   buf_size    - Number of bytes to write
  *
  * Returned value:
@@ -806,7 +806,6 @@ parameter_flashfs_write(flash_file_token_t token, uint8_t *buffer, size_t buf_si
 			/* No Space */
 
 			if (pf == 0) {
-				parameter_flashfs_free();
 				return -ENOSPC;
 			}
 
@@ -829,7 +828,6 @@ parameter_flashfs_write(flash_file_token_t token, uint8_t *buffer, size_t buf_si
 				rv = erase_entry(pf);
 
 				if (rv < 0) {
-					parameter_flashfs_free();
 					return rv;
 				}
 
@@ -848,7 +846,6 @@ parameter_flashfs_write(flash_file_token_t token, uint8_t *buffer, size_t buf_si
 				/* Will the data fit */
 
 				if (current_sector->size < total_size) {
-					parameter_flashfs_free();
 					return -ENOSPC;
 				}
 
@@ -861,7 +858,6 @@ parameter_flashfs_write(flash_file_token_t token, uint8_t *buffer, size_t buf_si
 				rv = erase_entry(pf);
 
 				if (rv < 0) {
-					parameter_flashfs_free();
 					return rv;
 				}
 
@@ -892,7 +888,6 @@ parameter_flashfs_write(flash_file_token_t token, uint8_t *buffer, size_t buf_si
 		}
 	}
 
-	parameter_flashfs_free();
 	return rv;
 }
 
@@ -903,6 +898,7 @@ parameter_flashfs_write(flash_file_token_t token, uint8_t *buffer, size_t buf_si
  *   This function is called to get a buffer to use in a subsequent call
  *   to parameter_flashfs_write. The address returned is advanced into the
  *   buffer to reserve space for the flash entry header.
+ *   The caller is responsible to call parameter_flashfs_free after usage.
  *
  * Input Parameters:
  *   token      - File Token File to read (not used)
@@ -1003,9 +999,9 @@ int parameter_flashfs_erase(void)
  *                  space is reserved in the front for the
  *                  flash_entry_header_t.
  *                  If this is passes as NULL. The buffer will be
- *                  allocated from the heap on callse to
- *                  parameter_flashfs_alloc and fread on calls calls
- *                  to parameter_flashfs_write
+ *                  allocated from the heap on calls to
+ *                  parameter_flashfs_alloc and fread on calls
+ *                  to parameter_flashfs_free
  *
  *   size         - The size of the buffer in bytes. Should be be 0 if buffer
  *                  is NULL
@@ -1091,6 +1087,7 @@ __EXPORT void test(void)
 		buf_size = a;
 		written = parameter_flashfs_write(parameters_token, fbuffer, buf_size);
 		read = parameter_flashfs_read(parameters_token, &fbuffer, &buf_size);
+		parameter_flashfs_free();
 
 		if (read != written) {
 			static volatile int j;
@@ -1106,6 +1103,7 @@ __EXPORT void test(void)
 		buf_size = block;
 		written = parameter_flashfs_write(parameters_token, fbuffer, buf_size);
 		read = parameter_flashfs_read(parameters_token, &fbuffer, &buf_size);
+		parameter_flashfs_free();
 
 		if (read != written) {
 			static volatile int j;

src/modules/systemlib/flashparams/flashfs.h

@@ -119,9 +119,9 @@ typedef struct sector_descriptor_t {
  *                  space is reserved in the front for the
  *                  flash_entry_header_t.
  *                  If this is passes as NULL. The buffer will be
- *                  allocated from the heap on callse to
- *                  parameter_flashfs_alloc and fread on calls calls
- *                  to parameter_flashfs_write
+ *                  allocated from the heap on calls to
+ *                  parameter_flashfs_alloc and fread on calls
+ *                  to parameter_flashfs_free
  *
  *   size         - The size of the buffer in bytes. Should be be 0 if buffer
  *                  is NULL
@@ -167,13 +167,11 @@ __EXPORT int parameter_flashfs_read(flash_file_token_t ft, uint8_t **buffer, siz
  *   token      - File Token File to read
  *   buffer      - A pointer to a buffer with buf_size bytes to be written
  *                 to the flash. This buffer must be allocated
- *                 with a previous call to flash_alloc_buffer
+ *                 with a previous call to parameter_flashfs_alloc
  *   buf_size    - Number of bytes to write
  *
  * Returned value:
  *   On success the number of bytes written On Error a negative value of errno
- *   If static buffer was not provided to parameter_flashfs_init the
- *   buffer will be freed.
  *
  ****************************************************************************/
 
@@ -216,5 +214,18 @@ __EXPORT int parameter_flashfs_erase(void);
  ****************************************************************************/
 
 __EXPORT int parameter_flashfs_alloc(flash_file_token_t ft, uint8_t **buffer, size_t *buf_size);
+
+
+/****************************************************************************
+ * Name: parameter_flashfs_free
+ *
+ * Description:
+ *   Frees  dynamically allocated memory
+ *
+ *
+ ****************************************************************************/
+
+__EXPORT void parameter_flashfs_free(void);
+
 __END_DECLS
 #endif /* _SYSTEMLIB_FLASHPARAMS_NUTTX_PARAM_H */

src/modules/systemlib/flashparams/flashparams.c

@@ -202,6 +202,7 @@ out:
 			}
 
 			free(enc_buff);
+			parameter_flashfs_free();
 		}
 	}