libmocha/source/devoptab/devoptab_fsa_seek.cpp

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#include "devoptab_fsa.h"
#include "logger.h"
#include <mutex>
off_t __fsa_seek(struct _reent *r,
void *fd,
off_t pos,
int whence) {
FSError status;
FSAStat fsStat;
uint64_t offset;
if (!fd) {
r->_errno = EINVAL;
return -1;
}
auto *file = (__fsa_file_t *) fd;
auto *deviceData = (FSADeviceData *) r->deviceData;
std::lock_guard<MutexWrapper> lock(file->mutex);
// Find the offset to see from
switch (whence) {
case SEEK_SET: { // Set absolute position; start offset is 0
offset = 0;
break;
}
case SEEK_CUR: { // Set position relative to the current position
offset = file->offset;
break;
}
case SEEK_END: { // Set position relative to the end of the file
status = FSAGetStatFile(deviceData->clientHandle, file->fd, &fsStat);
if (status < 0) {
DEBUG_FUNCTION_LINE_ERR("FSAGetStatFile(0x%08X, 0x%08X, 0x%08X) (%s) failed: %s",
deviceData->clientHandle, file->fd, &fsStat, file->fullPath, FSAGetStatusStr(status));
r->_errno = __fsa_translate_error(status);
return -1;
}
offset = fsStat.size;
break;
}
default: { // An invalid option was provided
r->_errno = EINVAL;
return -1;
}
}
if (pos < 0 && (off_t) offset < -pos) {
// Don't allow seek to before the beginning of the file
r->_errno = EINVAL;
return -1;
} else if (offset + pos > UINT32_MAX) {
// Check for overflow
r->_errno = EINVAL;
return -1;
}
if ((uint32_t) (offset + pos) == file->offset) {
return file->offset;
}
uint32_t old_pos = file->offset;
file->offset = offset + pos;
status = FSASetPosFile(deviceData->clientHandle, file->fd, file->offset);
if (status < 0) {
DEBUG_FUNCTION_LINE_ERR("FSASetPosFile(0x%08X, 0x%08X, 0x%08X) (%s) failed: %s",
deviceData->clientHandle, file->fd, file->offset, file->fullPath, FSAGetStatusStr(status));
file->offset = old_pos;
r->_errno = __fsa_translate_error(status);
return -1;
}
return file->offset;
}