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#include <euler/stream.hpp>
#include <cstring>
namespace euler {
file_stream::file_stream(
syscall::stream_handle handle, bool may_read,
uint64_t length, uint64_t position)
: handle(handle), may_read(may_read), buffer_loaded(false),
length(length), position(position) {}
syscall::stream_result file_stream::seek(
syscall::seek_from from, int64_t offset) {
int64_t new_position = offset +
(from == syscall::seek_from::beginning ? 0 :
from == syscall::seek_from::end ? length : position);
if (new_position < 0 || (uint64_t)new_position > length)
return syscall::stream_result::out_of_bounds;
position = new_position;
return syscall::stream_result::success;
}
std::pair<uint64_t, syscall::stream_result>
file_stream::read(uint64_t bytes, void *into) {
if (!may_read)
return {0, syscall::stream_result::not_readable};
uint64_t have_read = 0;
syscall::stream_result result = syscall::stream_result::success;
uint64_t end = position + bytes;
if (end > length) {
end = length;
result = syscall::stream_result::out_of_bounds;
}
uint64_t block_start = (position / 1024) * 1024;
while (position < end) {
uint64_t length_in_this_block =
std::min(end, block_start + 1024) - position;
if (buffer_loaded && buffer_start == block_start)
memcpy(into, buffer + position - block_start, length_in_this_block);
else if (length_in_this_block == 1024) {
syscall::stream_result seek_result =
syscall::seek_stream(
handle, syscall::seek_from::beginning, block_start);
if (seek_result != syscall::stream_result::success)
return {have_read, seek_result};
syscall::stream_result read_result =
syscall::read_from_stream(handle, 1024, into);
if (read_result != syscall::stream_result::success)
return {have_read, read_result};
}
else {
syscall::stream_result seek_result =
syscall::seek_stream(
handle, syscall::seek_from::beginning, block_start);
if (seek_result != syscall::stream_result::success)
return {have_read, seek_result};
uint64_t buffer_length = std::min(1024UL, length - block_start);
syscall::stream_result read_result =
syscall::read_from_stream(handle, buffer_length, buffer);
if (read_result != syscall::stream_result::success) {
buffer_loaded = false;
return {have_read, read_result};
}
buffer_loaded = true;
buffer_start = block_start;
memcpy(into, buffer + position - block_start, length_in_this_block);
}
into = (uint8_t *)into + length_in_this_block;
have_read += length_in_this_block;
position += length_in_this_block;
block_start += 1024;
}
return {have_read, result};
}
void file_stream::close() {
syscall::close_stream(handle);
}
}
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