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A cluster is only allocated for a file when data is written, instead of when the file is opened
file_extend_r renamed to _FAT_file_extend_r
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@ -48,6 +48,10 @@
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2007-04-12 - Chishm
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* Fixed seek to end of file when reading
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2007-11-04 - Chishm
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* file_extend_r renamed to _FAT_file_extend_r
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* A cluster is only allocated for a file when data is written, instead of when the file is opened
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*/
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@ -64,6 +68,20 @@
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#include "bit_ops.h"
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#include "filetime.h"
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static void _FAT_file_resetPosition (FILE_STRUCT* file) {
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PARTITION* partition = file->partition;
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file->currentPosition = 0;
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file->rwPosition.cluster = file->startCluster;
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file->rwPosition.sector = 0;
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file->rwPosition.byte = 0;
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file->appendPosition.cluster = _FAT_fat_lastCluster (partition, file->startCluster);
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file->appendPosition.sector = (file->filesize % partition->bytesPerCluster) / BYTES_PER_READ;
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file->appendPosition.byte = file->filesize % BYTES_PER_READ;
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}
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int _FAT_open_r (struct _reent *r, void *fileStruct, const char *path, int flags, int mode) {
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PARTITION* partition = NULL;
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bool fileExists;
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@ -204,25 +222,12 @@ int _FAT_open_r (struct _reent *r, void *fileStruct, const char *path, int flags
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file->filesize = 0;
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}
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// Get a new cluster for the file if required
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if (file->startCluster == 0) {
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file->startCluster = _FAT_fat_linkFreeCluster (partition, CLUSTER_FREE);
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}
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// Remember the position of this file's directory entry
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file->dirEntryStart = dirEntry.dataStart; // Points to the start of the LFN entries of a file, or the alias for no LFN
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file->dirEntryEnd = dirEntry.dataEnd;
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file->currentPosition = 0;
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file->rwPosition.cluster = file->startCluster;
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file->rwPosition.sector = 0;
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file->rwPosition.byte = 0;
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file->appendPosition.cluster = _FAT_fat_lastCluster (partition, file->startCluster);
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file->appendPosition.sector = (file->filesize % partition->bytesPerCluster) / BYTES_PER_READ;
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file->appendPosition.byte = file->filesize % BYTES_PER_READ;
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_FAT_file_resetPosition (file);
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// Check if the end of the file is on the end of a cluster
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if ( (file->filesize > 0) && ((file->filesize % partition->bytesPerCluster)==0) ){
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// Set flag to allocate a new cluster
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@ -310,7 +315,7 @@ int _FAT_read_r (struct _reent *r, int fd, char *ptr, int len) {
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}
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// Don't try to read if the read pointer is past the end of file
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if (file->currentPosition >= file->filesize) {
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if (file->currentPosition >= file->filesize || file->startCluster == CLUSTER_FREE) {
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return 0;
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}
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@ -319,6 +324,11 @@ int _FAT_read_r (struct _reent *r, int fd, char *ptr, int len) {
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r->_errno = EOVERFLOW;
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len = file->filesize - file->currentPosition;
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}
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// Short circuit cases where len is 0 (or less)
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if (len <= 0) {
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return 0;
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}
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remain = len;
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@ -446,7 +456,7 @@ int _FAT_read_r (struct _reent *r, int fd, char *ptr, int len) {
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/*
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Extend a file so that the size is the same as the rwPosition
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*/
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static bool file_extend_r (struct _reent *r, FILE_STRUCT* file) {
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static bool _FAT_file_extend_r (struct _reent *r, FILE_STRUCT* file) {
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PARTITION* partition = file->partition;
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CACHE* cache = file->partition->cache;
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@ -460,6 +470,8 @@ static bool file_extend_r (struct _reent *r, FILE_STRUCT* file) {
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position.byte = file->filesize % BYTES_PER_READ;
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position.sector = (file->filesize % partition->bytesPerCluster) / BYTES_PER_READ;
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// It is assumed that there is always a startCluster
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// This will be true when _FAT_file_extend_r is called from _FAT_write_r
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position.cluster = _FAT_fat_lastCluster (partition, file->startCluster);
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remain = file->currentPosition - file->filesize;
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@ -563,17 +575,28 @@ int _FAT_write_r (struct _reent *r,int fd, const char *ptr, int len) {
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return 0;
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}
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// Short circuit cases where len is 0 (or less)
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if (len <= 0) {
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return 0;
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}
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partition = file->partition;
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cache = file->partition->cache;
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remain = len;
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// Get a new cluster for the file if required
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if (file->startCluster == CLUSTER_FREE) {
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file->startCluster = _FAT_fat_linkFreeCluster (partition, CLUSTER_FREE);
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_FAT_file_resetPosition (file);
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}
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if (file->append) {
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position = file->appendPosition;
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flagAppending = true;
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} else {
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// If the write pointer is past the end of the file, extend the file to that size
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if (file->currentPosition > file->filesize) {
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if (!file_extend_r (r, file)) {
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if (!_FAT_file_extend_r (r, file)) {
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return 0;
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}
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}
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@ -788,7 +811,7 @@ int _FAT_seek_r (struct _reent *r, int fd, int pos, int dir) {
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// Only change the read/write position if it is within the bounds of the current filesize,
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// or at the very edge of the file
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if (file->filesize >= position) {
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if (position <= file->filesize && file->startCluster != CLUSTER_FREE) {
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// Calculate the sector and byte of the current position,
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// and store them
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file->rwPosition.sector = (position % partition->bytesPerCluster) / BYTES_PER_READ;
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