Quality RTOS & Embedded Software

LIBRARIES

ff_findnext()

[FreeRTOS+FAT Standard API Reference]

ff_stdio.h
int ff_findnext( FF_FindData_t *pxFindData );
		

Finds the next file or directory within an embedded FAT file system directory. ff_findnext() can only be called after first calling ff_findfirst(). ff_findfirst() finds the first file in the directory, ff_findnext() then finds all subsequent files in the directory.

The same instance of the FF_FindData_t object must be passed into ff_findnext() as was passed into ff_findfirst().

FF_FindData_t contains the fields shown in the table below:

Field
Description
pcFileName The name of the file
ulFileSize The length of the file in bytes
ucAttributes The file’s attributes, which is a bitwise OR of the following bit definitions:
  • FF_FAT_ATTR_READONLY
  • FF_FAT_ATTR_HIDDEN
  • FF_FAT_ATTR_SYSTEM
  • FF_FAT_ATTR_DIR (directory)

Parameters:

pxFindData   A pointer to a structure that is used to store information required to scan a directory, and to pass out details of the files contained in the directory.
Returns:

If a file or directory was found then 0 is returned. If an error occurs a non-zero value is returned.

Example usage:


void DIRCommand( const char *pcDirectoryToScan )
{
FF_FindData_t *pxFindStruct;
const char *pcAttrib;
*pcWritableFile = “writable file”,
*pcReadOnlyFile = “read only file”,
*pcDirectory = “directory”;

/* FF_FindData_t can be large, so it is best to allocate the structure
dynamically, rather than declare it as a stack variable. */

pxFindStruct = ( FF_FindData_t * ) pvPortMalloc( sizeof( FF_FindData_t ) );

/* FF_FindData_t must be cleared to 0. */
memset( pxFindStruct, 0x00, sizeof( FF_FindData_t ) );

/* The first parameter to ff_findfist() is the directory being searched. Do
not add wildcards to the end of the directory name. */

if( ff_findfirst( pcDirectoryToScan, pxFindStruct ) == 0 )
{
do
{
/* Point pcAttrib to a string that describes the file. */
if( ( pxFindStruct->ucAttributes & FF_FAT_ATTR_DIR ) != 0 )
{
pcAttrib = pcDirectory;
}
else if( pxFindStruct->ucAttributes & FF_FAT_ATTR_READONLY )
{
pcAttrib = pcReadOnlyFile;
}
else
{
pcAttrib = pcWritableFile;
}

/* Print the files name, size, and attribute string. */
FreeRTOS_printf( ( “%s [%s] [size=%d]”, pxFindStruct->pcFileName,
pcAttrib,
pxFindStruct->ulFileSize ) );

} while( ff_findnext( pxFindStruct ) == 0 );
}

/* Free the allocated FF_FindData_t structure. */
vPortFree( pxFindStruct );
}

Example use of the ff_findfirst() API function create a directory listing


Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.