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Modified WinterMute's seek then write fix for elegance, removed

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resetPosition
This commit is contained in:
Michael Chisholm 2008-05-12 09:35:18 +00:00
parent 02d3e47079
commit 8d36ebe061
1 changed files with 29 additions and 24 deletions
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53
source/fatfile.c
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@ -52,6 +52,10 @@
2007-11-04 - Chishm
* file_extend_r renamed to _FAT_file_extend_r
* A cluster is only allocated for a file when data is written, instead of when the file is opened
2008-05-12 - Chishm
* Modified WinterMute's seek then write fix for elegance
* Removed resetPosition
*/
@ -68,20 +72,6 @@
#include "bit_ops.h"
#include "filetime.h"
static void _FAT_file_resetPosition (FILE_STRUCT* file) {
PARTITION* partition = file->partition;
if ( file->currentPosition < partition->bytesPerCluster ) {
file->rwPosition.cluster = file->startCluster;
file->rwPosition.sector = (file->currentPosition % partition->bytesPerCluster) / BYTES_PER_READ;
file->rwPosition.byte = file->currentPosition % BYTES_PER_READ;
}
file->appendPosition.cluster = _FAT_fat_lastCluster (partition, file->startCluster);
file->appendPosition.sector = (file->filesize % partition->bytesPerCluster) / BYTES_PER_READ;
file->appendPosition.byte = file->filesize % BYTES_PER_READ;
}
int _FAT_open_r (struct _reent *r, void *fileStruct, const char *path, int flags, int mode) {
PARTITION* partition = NULL;
bool fileExists;
@ -218,7 +208,7 @@ int _FAT_open_r (struct _reent *r, void *fileStruct, const char *path, int flags
// Truncate the file if requested
if ((flags & O_TRUNC) && file->write && (file->startCluster != 0)) {
_FAT_fat_clearLinks (partition, file->startCluster);
file->startCluster = 0;
file->startCluster = CLUSTER_FREE;
file->filesize = 0;
}
@ -226,8 +216,14 @@ int _FAT_open_r (struct _reent *r, void *fileStruct, const char *path, int flags
file->dirEntryStart = dirEntry.dataStart; // Points to the start of the LFN entries of a file, or the alias for no LFN
file->dirEntryEnd = dirEntry.dataEnd;
// Reset read/write and append pointers
file->currentPosition = 0;
_FAT_file_resetPosition (file);
file->rwPosition.cluster = file->startCluster;
file->rwPosition.sector = 0;
file->rwPosition.byte = 0;
file->appendPosition.cluster = _FAT_fat_lastCluster (partition, file->startCluster);
file->appendPosition.sector = (file->filesize % partition->bytesPerCluster) / BYTES_PER_READ;
file->appendPosition.byte = file->filesize % BYTES_PER_READ;
// Check if the end of the file is on the end of a cluster
if ( (file->filesize > 0) && ((file->filesize % partition->bytesPerCluster)==0) ){
@ -312,12 +308,12 @@ int _FAT_read_r (struct _reent *r, int fd, char *ptr, int len) {
// Make sure we can actually read from the file
if ((file == NULL) || !file->inUse || !file->read) {
r->_errno = EBADF;
return 0;
return -1;
}
// Don't try to read if the read pointer is past the end of file
if (file->currentPosition >= file->filesize || file->startCluster == CLUSTER_FREE) {
return 0;
return -1;
}
// Don't read past end of file
@ -573,7 +569,7 @@ int _FAT_write_r (struct _reent *r,int fd, const char *ptr, int len) {
// Make sure we can actually write to the file
if ((file == NULL) || !file->inUse || !file->write) {
r->_errno = EBADF;
return 0;
return -1;
}
// Short circuit cases where len is 0 (or less)
@ -585,12 +581,21 @@ int _FAT_write_r (struct _reent *r,int fd, const char *ptr, int len) {
cache = file->partition->cache;
remain = len;
// Get a new cluster for the file if required
// Get a new cluster for the start of the file if required
if (file->startCluster == CLUSTER_FREE) {
file->startCluster = _FAT_fat_linkFreeCluster (partition, CLUSTER_FREE);
_FAT_file_resetPosition (file);
tempNextCluster = _FAT_fat_linkFreeCluster (partition, CLUSTER_FREE);
if (!_FAT_fat_isValidCluster(partition, tempNextCluster)) {
// Couldn't get a cluster, so abort immediately
r->_errno = ENOSPC;
return -1;
}
file->startCluster = tempNextCluster;
// Appending starts at the begining for a 0 byte file
file->appendPosition.cluster = file->startCluster;
file->appendPosition.sector = 0;
file->appendPosition.byte = 0;
}
if (file->append) {
position = file->appendPosition;
flagAppending = true;
@ -598,7 +603,7 @@ int _FAT_write_r (struct _reent *r,int fd, const char *ptr, int len) {
// If the write pointer is past the end of the file, extend the file to that size
if (file->currentPosition > file->filesize) {
if (!_FAT_file_extend_r (r, file)) {
return 0;
return -1;
}
}