+++ /dev/null
-/*****************************************************************************\
-* *
-* Name : huge_file *
-* Author : Chris Koeritz *
-* *
-*******************************************************************************
-* Copyright (c) 2007-$now By Author. This program is free software; you can *
-* redistribute it and/or modify it under the terms of the GNU General Public *
-* License as published by the Free Software Foundation; either version 2 of *
-* the License or (at your option) any later version. This is online at: *
-* http://www.fsf.org/copyleft/gpl.html *
-* Please send any updates to: fred@gruntose.com *
-\*****************************************************************************/
-
-#include "byte_filer.h"
-#include "huge_file.h"
-
-#include <basis/byte_array.h>
-#include <basis/functions.h>
-#include <basis/guards.h>
-
-#include <stdio.h>
-
-#undef LOG
-#define LOG(to_print) printf("%s::%s: %s\n", static_class_name(), func, astring(to_print).s())
-
-//#define DEBUG_HUGE_FILE
- // uncomment for noisy version.
-
-using namespace basis;
-
-namespace filesystem {
-
-huge_file::huge_file(const astring &filename, const astring &permissions)
-: _real_file(new byte_filer(filename, permissions)),
- _file_pointer(0)
-{
-}
-
-huge_file::~huge_file()
-{
- WHACK(_real_file);
-}
-
-void huge_file::flush() { _real_file->flush(); }
-
-bool huge_file::truncate() { return _real_file->truncate(); }
-
-double huge_file::length()
-{
- FUNCDEF("length");
-
-//trying to read to see if we're past endpoint.
-// if this approach works, length may want to close and reopen file for
-// reading, since we can't add any bytes to it for writing just to find
-// the length out.
-
-
- double save_posn = _file_pointer;
- // skip to the beginning of the file so we can try to find the end.
- _file_pointer = 0;
- _real_file->seek(0, byte_filer::FROM_START);
- size_t naive_size = _real_file->length();
- if (naive_size < _real_file->file_size_limit()) {
- // lucked out; we are within normal file size limitations.
- seek(save_posn, byte_filer::FROM_START);
- return double(naive_size);
- }
-
- double best_highest = 0.0; // the maximum we've safely seeked to.
-
- size_t big_jump = byte_filer::file_size_limit();
- // try with the largest possible seek at first.
-
- while (true) {
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf("best highest=%.0f", best_highest));
-#endif
- // iterate until we reach our exit condition, which seems like it must
- // always occur eventually unless the file is being monkeyed with.
- bool seek_ret = _real_file->seek(int(big_jump), byte_filer::FROM_CURRENT);
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" seek ret=%d", int(seek_ret)));
-#endif
- byte_array temp_bytes;
- int bytes_read = _real_file->read(temp_bytes, 1);
- if (bytes_read < 1)
- seek_ret = false;
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" read %d bytes", bytes_read));
-#endif
- bool at_eof = _real_file->eof();
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" at_eof=%d", int(at_eof)));
-#endif
- if (seek_ret && !at_eof) {
-#ifdef DEBUG_HUGE_FILE
- LOG("seek worked, incrementing best highest and trying same jump again");
-#endif
- // the seek worked, so we'll just jump forward again.
- best_highest += double(big_jump);
- _file_pointer += double(big_jump);
- continue;
- } else if (seek_ret && at_eof) {
-#ifdef DEBUG_HUGE_FILE
- LOG("seek worked but found eof exactly.");
-#endif
- // the seek did worked, but apparently we've also found the end point.
- best_highest += double(big_jump);
- _file_pointer += double(big_jump);
- break;
- } else {
- // that seek was too large, so we need to back down and try a smaller
- // seek size.
-#ifdef DEBUG_HUGE_FILE
- LOG("seek failed, going back to best highest and trying same jump again");
-#endif
- _file_pointer = 0;
- _real_file->seek(0, byte_filer::FROM_START);
- outcome worked = seek(best_highest, byte_filer::FROM_START);
- // this uses our version to position at large sizes.
- if (worked != OKAY) {
- // this is a bad failure; it says that the file size changed or
- // something malfunctioned. we should always be able to get back to
- // the last good size we found if the file is static.
- LOG(a_sprintf("failed to seek back to best highest %.0f on ",
- best_highest) + _real_file->filename());
- // try to repair our ideas about the file by starting the process
- // over.
-//hmmm: count the number of times restarted and bail after N.
- seek_ret = _real_file->seek(0, byte_filer::FROM_START);
- _file_pointer = 0;
- if (!seek_ret) {
- // the heck with this. we can't even go back to the start. this
- // file seems to be screwed up now.
- LOG(astring("failed to seek back to start of file! on ")
- + _real_file->filename());
- return 0;
- }
- // reset the rest of the positions for our failed attempt to return
- // to what we already thought was good.
- _file_pointer = 0;
- big_jump = byte_filer::file_size_limit();
- best_highest = 0;
- continue;
- }
- // okay, nothing bad happened when we went back to our last good point.
- if (big_jump <= 0) {
- // success in finding the smallest place that we can't seek between.
-#ifdef DEBUG_HUGE_FILE
- LOG("got down to smallest big jump, 0!");
-#endif
- break;
- }
- // formula expects that the maximum file size is a power of 2.
- big_jump /= 2;
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf("restraining big jump down to %u.", big_jump));
-#endif
- continue;
- }
- }
-
- // go back to where we started out.
- seek(0, byte_filer::FROM_START);
- seek(save_posn, byte_filer::FROM_CURRENT);
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf("saying file len is %.0f.", best_highest + 1.0));
-#endif
- return best_highest + 1.0;
-}
-
-bool huge_file::good() const { return _real_file->good(); }
-
-bool huge_file::eof() const { return _real_file->eof(); }
-
-outcome huge_file::move_to(double absolute_posn)
-{
-#ifdef DEBUG_HUGE_FILE
- FUNCDEF("move_to");
-#endif
- double difference = absolute_posn - _file_pointer;
- // calculate the size we want to offset.
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf("abs_pos=%.0f difference=%.0f old_filepoint=%.0f",
- absolute_posn, difference, _file_pointer));
-#endif
- // if we're at the same place, we don't have to do anything.
- if (difference < 0.000001) {
-#ifdef DEBUG_HUGE_FILE
- LOG("difference was minimal, saying we're done.");
-#endif
- return OKAY;
- }
- while (absolute_value(difference) > 0.000001) {
- double seek_size = minimum(double(byte_filer::file_size_limit() - 1),
- absolute_value(difference));
- if (difference < 0)
- seek_size *= -1.0; // flip sign of seek.
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" seeksize=%d", int(seek_size)));
-#endif
- bool seek_ret = _real_file->seek(int(seek_size),
- byte_filer::FROM_CURRENT);
- if (!seek_ret) {
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf("failed to seek %d from current", int(seek_size)));
-#endif
- return FAILURE; // seek failed somehow.
- }
- _file_pointer += seek_size;
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" now_filepoint=%.0f", _file_pointer));
-#endif
- difference = absolute_posn - _file_pointer;
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" now_difference=%.0f", difference));
-#endif
- }
- return OKAY;
-}
-
-outcome huge_file::seek(double new_position, byte_filer::origins origin)
-{
-#ifdef DEBUG_HUGE_FILE
- FUNCDEF("seek");
-#endif
- if (origin == byte_filer::FROM_CURRENT) {
- return move_to(_file_pointer + new_position);
- } else if (origin == byte_filer::FROM_START) {
- _file_pointer = 0;
- if (!_real_file->seek(0, byte_filer::FROM_START))
- return FAILURE;
- return move_to(new_position);
- } else if (origin == byte_filer::FROM_END) {
-#ifdef DEBUG_HUGE_FILE
- LOG("into precarious FROM_END case.");
-#endif
- double file_len = length(); // could take a scary long time possibly.
-#ifdef DEBUG_HUGE_FILE
- LOG(a_sprintf(" FROM_END got len %.0f.", file_len));
-#endif
- _file_pointer = file_len;
- // it's safe, although not efficient, for us to call the length()
- // method here. our current version of length() uses the byte_filer's
- // seek method directly and only FROM_CURRENT and FROM_START from this
- // class's seek method.
- _real_file->seek(0, byte_filer::FROM_END);
- return move_to(_file_pointer - new_position);
- }
- // unknown origin.
- return BAD_INPUT;
-}
-
-outcome huge_file::read(byte_array &to_fill, int desired_size, int &size_read)
-{
-// FUNCDEF("read");
- size_read = 0;
- int ret = _real_file->read(to_fill, desired_size);
- if (ret < 0)
- return FAILURE; // couldn't read the bytes.
- _file_pointer += double(size_read);
- size_read = ret;
- return OKAY;
-}
-
-outcome huge_file::write(const byte_array &to_write, int &size_written)
-{
-// FUNCDEF("write");
- size_written = 0;
- int ret = _real_file->write(to_write);
- if (ret < 0)
- return FAILURE; // couldn't write the bytes.
- _file_pointer += double(size_written);
- size_written = ret;
- return OKAY;
-}
-
-} //namespace.
-
projects / feisty_meow.git / blobdiff