libmocha/source/devoptab/devoptab_fsa_seek.cpp

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#include "devoptab_fs.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;
__fsa_file_t *file;
if (!fd) {
r->_errno = EINVAL;
return -1;
}
file = (__fsa_file_t *) fd;
auto *deviceData = (FSADeviceData *) r->deviceData;
std::lock_guard<FastLockWrapper> lock(deviceData->mutex);
status = FSAGetStatFile(deviceData->clientHandle, file->fd, &fsStat);
if (status < 0) {
DEBUG_FUNCTION_LINE_ERR("FSAGetStatFile(0x%08X, 0x%08X, 0x%08X) failed: %s", deviceData->clientHandle, file->fd, &fsStat, FSAGetStatusStr(status));
r->_errno = __fsa_translate_error(status);
return -1;
}
// Find the offset to see from
switch (whence) {
// Set absolute position; start offset is 0
case SEEK_SET:
offset = 0;
break;
// Set position relative to the current position
case SEEK_CUR:
offset = file->offset;
break;
// Set position relative to the end of the file
case SEEK_END:
offset = fsStat.size;
break;
// An invalid option was provided
default:
r->_errno = EINVAL;
return -1;
}
// TODO: A better check that prevents overflow.
if (pos < 0 && (off_t) offset < -pos) {
// Don't allow seek to before the beginning of the file
r->_errno = EINVAL;
return -1;
}
uint32_t old_pos = file->offset;
file->offset = offset + pos;
status = FSASetPosFile(deviceData->clientHandle, file->fd, file->offset);
if (status < 0) {
file->offset = old_pos;
DEBUG_FUNCTION_LINE_ERR("FSASetPosFile(0x%08X, 0x%08X, 0x%08X) failed: %s", deviceData->clientHandle, file->fd, file->offset, FSAGetStatusStr(status));
r->_errno = __fsa_translate_error(status);
return -1;
}
return file->offset;
}