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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2020 Denis Corbin
//
// 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 program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author : http://dar.linux.free.fr/email.html
/*********************************************************************/
#include "../my_config.h"
#include "escape.hpp"
#include "tools.hpp"
extern "C"
{
#ifdef HAVE_STRIN_H
#include <string.h>
#endif
} // extern "C"
using namespace std;
extern "C"
{
#if HAVE_STRING_H
#include <string.h>
#endif
#if HAVE_STRINGS_H
#include <strings.h>
#endif
#if STDC_HEADERS
# include <string.h>
#else
# if !HAVE_STRCHR
# define strchr index
# define strrchr rindex
# endif
char *strchr (), *strrchr ();
# if !HAVE_MEMCPY
# define memcpy(d, s, n) bcopy ((s), (d), (n))
# define memmove(d, s, n) bcopy ((s), (d), (n))
# endif
#endif
} // end extern "C"
namespace libdar
{
//-- class static variable (well constant to be correct)
// escape sequence structure
//
// fixed pattern (5 bytes) + escape sequence type (1 byte) = total length: 6 bytes
// 0xAD 0xFD 0xEA 0x77 0x21 + { 'X' | 'H' | 'F' | 'E' | 'C' | ... }
//
// the fixed pattern may have its first byte (which default value is 0xAD) modified if necessary to
// avoid escaping of escape sequences when using two escape objects, one writing its data to a second one.
const unsigned char escape::usual_fixed_sequence[ESCAPE_SEQUENCE_LENGTH] = { ESCAPE_FIXED_SEQUENCE_NORMAL, 0xFD, 0xEA, 0x77, 0x21, 0x00 };
const infinint escape::READ_BUFFER_SIZE_INFININT = MAX_BUFFER_SIZE;
//-- class routines
escape::escape(generic_file *below, const set<sequence_type> & x_unjumpable) : generic_file(below->get_mode())
{
x_below = below;
if(below == nullptr)
throw SRC_BUG;
write_buffer_size = 0;
read_buffer_size = 0;
read_eof = false;
already_read = 0;
escape_seq_offset_in_buffer = 0;
escaped_data_count_since_last_skip = 0;
below_position = x_below->get_position();
unjumpable = x_unjumpable;
for(U_I i = 0 ; i < ESCAPE_SEQUENCE_LENGTH; ++i)
fixed_sequence[i] = usual_fixed_sequence[i];
}
escape::~escape()
{
try
{
terminate();
}
catch(...)
{
// ignore all exceptions
}
}
escape & escape::operator = (const escape & ref)
{
generic_file *me = this;
const generic_file *you = &ref;
if(is_terminated())
throw SRC_BUG;
*me = *you; // copying the generic_file data
copy_from(ref); // copying the escape specific data
return *this;
}
void escape::add_mark_at_current_position(sequence_type t)
{
// some necessary sanity checks
if(is_terminated())
throw SRC_BUG;
if(get_mode() == gf_read_only)
throw SRC_BUG;
check_below();
// sanity checks done
if(t == seqt_not_a_sequence)
throw Erange("escape::add_mark_at_current_position", gettext("Adding an explicit escape sequence of type seqt_not_a_sequence is forbidden"));
flush_write();
escaped_data_count_since_last_skip = 0;
set_fixed_sequence_for(t);
x_below->write((const char*)fixed_sequence, ESCAPE_SEQUENCE_LENGTH);
below_position += ESCAPE_SEQUENCE_LENGTH;
}
bool escape::skip_to_next_mark(sequence_type t, bool jump)
{
bool found = false;
if(is_terminated())
throw SRC_BUG;
// check whether we are not in write mode !!!
if(get_mode() != gf_read_only)
throw SRC_BUG; // escape implementation does not support this mode
read_eof = false; // may be have been set because we reached a mark while reading data, so we now need to unset it
escaped_data_count_since_last_skip = 0;
do
{
// looking at data currently in the buffer
if(escape_seq_offset_in_buffer < read_buffer_size) // amorce found in buffer
{
already_read = escape_seq_offset_in_buffer; // dropping data before that start of escape sequence
// at that time, this may be just the start of what seems to be an escape mark,
// so we need more data, which may turn out to show that this is not an escape mark
if(!mini_read_buffer())
{
read_eof = true; // not enough data available, thus
clean_read();
}
else // we could get more data to determine whether we have a mark in the buffer or not
{
if(escape_seq_offset_in_buffer + ESCAPE_SEQUENCE_LENGTH - 1 < read_buffer_size)
{
sequence_type found_type = char2type(read_buffer[escape_seq_offset_in_buffer + ESCAPE_SEQUENCE_LENGTH - 1]);
if(found_type == seqt_not_a_sequence)
{
// this is just escaped data, so we skip it
already_read = escape_seq_offset_in_buffer + ESCAPE_SEQUENCE_LENGTH;
// moving the marker to the next possible escape sequence
escape_seq_offset_in_buffer = already_read + trouve_amorce(read_buffer + already_read, read_buffer_size - already_read, fixed_sequence);
}
else // real mark found
if(found_type == t) // found the expected type of mark
{
found = true;
already_read = escape_seq_offset_in_buffer + ESCAPE_SEQUENCE_LENGTH;
escape_seq_offset_in_buffer = already_read + trouve_amorce(read_buffer + already_read, read_buffer_size - already_read, fixed_sequence);
}
else
if(jump && unjumpable.find(found_type) == unjumpable.end()) // not an unjumpable mark or jump allowed for any mark
{
already_read = escape_seq_offset_in_buffer + ESCAPE_SEQUENCE_LENGTH;
escape_seq_offset_in_buffer = already_read + trouve_amorce(read_buffer + already_read, read_buffer_size - already_read, fixed_sequence);
}
else // not an unjumpable mark
read_eof = true;
}
else // what seemed to be the start of a mark is not a mark
already_read = escape_seq_offset_in_buffer;
}
}
else // no mark in current data
{
// dropping all data in read_buffer, and filling it again with some new data
read_buffer_size = x_below->read(read_buffer, READ_BUFFER_SIZE);
below_position += read_buffer_size;
if(read_buffer_size == 0)
read_eof = true;
already_read = 0;
escape_seq_offset_in_buffer = trouve_amorce(read_buffer, read_buffer_size, fixed_sequence);
}
}
while(!found && !read_eof);
return found;
}
bool escape::next_to_read_is_mark(sequence_type t)
{
sequence_type toberead;
if(is_terminated())
throw SRC_BUG;
if(next_to_read_is_which_mark(toberead))
return t == toberead;
else
return false;
}
void escape::remove_unjumpable_mark(sequence_type t)
{
set<sequence_type>::iterator it = unjumpable.find(t);
if(is_terminated())
throw SRC_BUG;
if(it != unjumpable.end())
unjumpable.erase(it);
}
bool escape::next_to_read_is_which_mark(sequence_type & t)
{
if(is_terminated())
throw SRC_BUG;
check_below();
if(get_mode() != gf_read_only)
throw SRC_BUG;
if(escape_seq_offset_in_buffer > already_read) //no next to read mark
return false;
// if read_buffer size is less than ESCAPE_SEQUENCE MARK, then read some data for that
if(mini_read_buffer())
{
if(read_buffer_size - already_read < ESCAPE_SEQUENCE_LENGTH)
throw SRC_BUG;
// check the data in the read_buffer
if(escape_seq_offset_in_buffer == already_read)
{
t = char2type(read_buffer[already_read + ESCAPE_SEQUENCE_LENGTH - 1]);
if(t == seqt_not_a_sequence)
throw SRC_BUG; // mini_read_buffer did not made its job properly!
return true;
}
else
return false; // no escape sequence found next to be read
}
else // not enough data available in x_below to form a escape sequence mark (eof reached)
return false;
}
bool escape::skippable(skippability direction, const infinint & amount)
{
infinint new_amount = amount;
switch(get_mode())
{
case gf_read_only:
return x_below->skippable(direction, new_amount);
case gf_write_only:
case gf_read_write:
switch(direction)
{
case skip_backward:
new_amount += ESCAPE_SEQUENCE_LENGTH;
// we read some bytes before to check fo escape sequence
break;
case skip_forward:
break;
default:
throw SRC_BUG;
}
if(direction == skip_forward)
return false;
else
return x_below->skippable(direction, new_amount);
default:
throw SRC_BUG;
}
}
bool escape::skip(const infinint & pos)
{
bool ret = true;
if(is_terminated())
throw SRC_BUG;
check_below();
escaped_data_count_since_last_skip = 0;
if(get_position() == pos)
return true;
switch(get_mode())
{
case gf_read_only:
if(pos >= below_position - read_buffer_size
&&
pos < below_position)
{
// requested position is in read_buffer
infinint delta = below_position - pos;
already_read = 0;
delta.unstack(already_read);
if(!delta.is_zero())
throw SRC_BUG;
already_read = read_buffer_size - already_read;
// this leads to the following:
// alread_read = read_buffer_size - (below_position - pos);
escape_seq_offset_in_buffer = already_read + trouve_amorce(read_buffer + already_read, read_buffer_size - already_read, fixed_sequence);
escaped_data_count_since_last_skip = 0;
read_eof = false;
}
else
{
// requested position is out of read_buffer
read_eof = false;
flush_or_clean();
ret = x_below->skip(pos);
if(ret)
below_position = pos;
else
below_position = x_below->get_position();
}
break;
case gf_write_only:
if(get_position() != pos)
throw Efeature("Skipping on write_only escape object");
else
ret = true;
break;
case gf_read_write:
// only backward skipping is allowed in that mode
if(get_position() < pos)
throw Efeature("Skipping forward not implemented in write mode for escape class");
else
{
char tmp_buffer[WRITE_BUFFER_SIZE];
infinint cur_below = below_position;
U_I trouve;
try
{
if(pos >= ESCAPE_SEQUENCE_LENGTH)
{
U_I lu = 0;
below_position = pos - ESCAPE_SEQUENCE_LENGTH;
ret = x_below->skip(below_position);
if(ret)
{
lu = x_below->read(tmp_buffer, ESCAPE_SEQUENCE_LENGTH);
below_position += lu;
write_buffer_size = lu;
}
else
below_position = x_below->get_position();
}
else // skipping very close after the start of file, no escape mark can take place there
{
U_I width = 0;
U_I lu = 0;
infinint tmp = pos;
tmp.unstack(width);
if(tmp != 0)
throw SRC_BUG;
width = ESCAPE_SEQUENCE_LENGTH - width;
if(!x_below->skip(0))
throw SRC_BUG; // should succeed or throw an exception in that situation (backward skipping)
below_position = 0;
lu = x_below->read(tmp_buffer, width); // may throw exception
write_buffer_size = lu;
below_position += lu;
ret = true;
}
}
catch(...)
{
x_below->skip(cur_below);
below_position = cur_below;
throw;
}
(void)memcpy(write_buffer, tmp_buffer, write_buffer_size);
trouve = trouve_amorce(write_buffer, write_buffer_size, fixed_sequence);
if(trouve == 0) // we read a whole escape sequence
write_buffer_size = 0; // so we know that we can restart the lookup process here from scratch
else if(trouve == write_buffer_size) // no start of escape sequence found
write_buffer_size = 0; // so we know that we can restart the lookup process here from scratch
else // partial escape sequence found, moving at the beginning of the write_buffer for further lookup
{
(void)memmove(write_buffer, write_buffer + trouve, write_buffer_size - trouve);
write_buffer_size -= trouve;
}
}
break;
default:
throw SRC_BUG; // this mode is not allowed
}
return ret;
}
bool escape::skip_to_eof()
{
bool ret;
if(is_terminated())
throw SRC_BUG;
check_below();
if(get_mode() != gf_read_only)
throw Efeature("Skipping not implemented in write mode for escape class");
// if the buffer is neither empty not full, we cannot know what to do with this date
// either place it asis in the below file, or escape it in the below file.
flush_or_clean();
read_eof = true;
escaped_data_count_since_last_skip = 0;
ret = x_below->skip_to_eof();
below_position = x_below->get_position();
return ret;
}
bool escape::skip_relative(S_I x)
{
bool ret;
if(is_terminated())
throw SRC_BUG;
if(x == 0)
return true;
check_below();
read_eof = false;
escaped_data_count_since_last_skip = 0;
if(get_mode() != gf_read_only)
throw Efeature("Skipping not implemented in write mode for escape class");
// if the buffer is neither empty not full, we cannot know what to do with this date
// either place it asis in the below file, or escape it in the below file.
flush_or_clean();
ret = x_below->skip_relative(x);
if(ret) // skipping succeeded
{
if(x >= 0)
below_position += x;
else // x is negative
{
if(below_position < -x)
below_position = 0;
else
below_position -= -x; // trick used, because infinint cannot be negative
}
}
else // skipping failed, need to consult x_below to know where we are now
below_position = x_below->get_position();
return ret;
}
infinint escape::get_position() const
{
if(is_terminated())
throw SRC_BUG;
check_below();
if(get_mode() == gf_read_only)
return below_position - read_buffer_size + already_read - escaped_data_count_since_last_skip;
else
return below_position + write_buffer_size - escaped_data_count_since_last_skip;
}
void escape::inherited_read_ahead(const infinint & amount)
{
if(is_terminated())
throw SRC_BUG;
check_below();
if(!read_eof)
{
U_I avail = read_buffer_size - already_read;
infinint i_avail = avail;
if(i_avail < amount)
x_below->read_ahead(amount - i_avail);
}
}
U_I escape::inherited_read(char *a, U_I size)
{
U_I returned = 0;
// ############# if EOF -> stop
if(read_eof && already_read == read_buffer_size)
return 0; // eof reached. (real eof or next to read is a real mark)
// ############# if read_buffer not empty (we copy as needed and available data from the buffer into "a") up to the first mark
bool loop = true;
do
{
if(escape_seq_offset_in_buffer < already_read)
throw SRC_BUG;
U_I avail = escape_seq_offset_in_buffer - already_read;
if(avail > 0)
{
U_I needed = size - returned;
U_I min_cp = avail > needed ? needed : avail;
(void)memcpy(a + returned, read_buffer + already_read, min_cp);
returned += min_cp;
already_read += min_cp;
}
if(already_read == read_buffer_size)
{
already_read = read_buffer_size = 0;
escape_seq_offset_in_buffer = 0;
}
if(returned == size)
return returned;
if(returned > size)
throw SRC_BUG;
if(already_read != read_buffer_size)
{
// some data remains in the buffer (either more than requested, or due to a real or data mark found in it)
if(already_read != escape_seq_offset_in_buffer)
throw SRC_BUG; // more data was requested but could not be delivered, while no mark is next to be read from read_buffer!?
if(mini_read_buffer()) // se we complete it and eventually unescape data from data mark : mini_read_buffer() does this
{
// there is now enough data in buffer_size to tell that this is a real completed mark
if(escape_seq_offset_in_buffer == already_read) // there is a real mark next to be read in the buffer
{
// no more real data to be read
read_eof = true;
loop = false;
}
else
{
// the real mark is not the next to be read, some data have been unescaped before it
loop = true;
}
}
else // data in buffer is not a mark, just a truncated mark at an EOF so we can take it as pure data
{
escape_seq_offset_in_buffer = read_buffer_size;
loop = true;
}
}
else
loop = false;
}
while(loop);
// ############# OK, now, read_buffer is empty, no eof/mark met and still more data needed.
// reading data from "below" directly into "a" after already placed data (if there is enough place to detect marks)
loop = !read_eof;
// if all data could be read, we already returned from this function, so we do not reach this statement,
// if data remains in read_buffer, this is thus because we need more, but either the buffer is empty
// or we met a real mark, so we reached "eof" and must not continue the reading in the following loop.
while(loop)
{
U_I needed = size - returned;
U_I read;
if(needed > ESCAPE_SEQUENCE_LENGTH)
{
U_I delta;
// filling missing data in "a" from x_below
read = x_below->read(a + returned, needed);
below_position += read;
if(read < needed)
read_eof = true;
// analyse the new data, unescape data sequences, (skip left for each escaped data) and stop at the first non data escape sequence
// we temporarily use the variable escape_seq_offset_in_buffer to point in "a" instead of "read_buffer"
escape_seq_offset_in_buffer = remove_data_marks_and_stop_at_first_real_mark(a + returned, read, delta, fixed_sequence);
escaped_data_count_since_last_skip += delta;
read -= delta;
if(escape_seq_offset_in_buffer > read)
throw SRC_BUG;
returned += escape_seq_offset_in_buffer;
if(escape_seq_offset_in_buffer < read)
{
// mark found in data
// copy back the remaining data to read_buffer
if(READ_BUFFER_SIZE < read - escape_seq_offset_in_buffer)
throw SRC_BUG; // read_buffer too small to store all in-transit data
read_buffer_size = read - escape_seq_offset_in_buffer;
escape_seq_offset_in_buffer = 0;
already_read = 0;
// not setting yet read_eof, as it could be a false mark (starting like a mark, but not enough data to determin the real nature of the sequence)
(void)memcpy(read_buffer, a + returned, read_buffer_size);
read_eof = false; // because we moved out data from the one ready to be returned
// eithet this was not the eof, and thus this call does not change anything
// or it was EOF because data "read" was less than "needed"
// but here some data will still be in read_buffer so EOF must be cleaned
// be sure the mark is completed and return as much as requested data if not a complet mark
needed = size - returned;
if(needed > 0)
{
read = escape::inherited_read(a + returned, needed); // recursive call <!>
returned += read;
}
loop = false;
}
else // no mark found in data, all that got read is pure data and is directly sent to the upper layer
{
escape_seq_offset_in_buffer = read_buffer_size; // both should be equal to zero now
loop = returned < size && !read_eof;
}
}
else // too short space in "a" to put data and be sure there is not any mark in it, so we use read_buffer again
{
(void)mini_read_buffer(); // filling the read_buffer
if(escape_seq_offset_in_buffer > 0) // some more data available in read_buffer
returned += escape::inherited_read(a + returned, needed); // recursive call <!>
else
read_eof = true;
loop = false;
}
}
// return the amount of data put into "a"
return returned;
}
void escape::inherited_write(const char *a, U_I size)
{
U_I written = 0;
U_I trouve;
if(size == 0)
return; // nothing to do
try
{
if(write_buffer_size > 0) // some data are pending in transit
{
U_I initial_buffer_size = write_buffer_size;
if(write_buffer_size >= ESCAPE_SEQUENCE_LENGTH - 1)
throw SRC_BUG;
// filling the buffer
U_I delta = WRITE_BUFFER_SIZE - write_buffer_size; // available room in write_buffer
delta = delta > size ? size : delta;
(void)memcpy(write_buffer + write_buffer_size, a, delta);
write_buffer_size += delta;
written += delta;
// checking for escape sequence in write_buffer
trouve = trouve_amorce(write_buffer, write_buffer_size, fixed_sequence);
if(trouve == write_buffer_size) // no escape sequence found
{
x_below->write(write_buffer, write_buffer_size);
below_position += write_buffer_size;
write_buffer_size = 0;
}
else // start of escape sequence found
{
if(trouve + ESCAPE_SEQUENCE_LENGTH - 1 <= write_buffer_size) // no doubt, we have a full escape sequence in data, we need to protect this data
{
x_below->write(write_buffer, trouve);
below_position += trouve;
set_fixed_sequence_for(seqt_not_a_sequence);
x_below->write((const char *)fixed_sequence, ESCAPE_SEQUENCE_LENGTH);
below_position += ESCAPE_SEQUENCE_LENGTH;
// still remains valid data not yet written in write_buffer at offset 'trouve + ESCAPE_SEQUENCE_LENGTH - 1'
// however this data is also in the input write_buffer (a, size)
written = (trouve + ESCAPE_SEQUENCE_LENGTH - 1) - initial_buffer_size;
// this way, we do not have to copy back to "a" the not yet written data
++escaped_data_count_since_last_skip;
write_buffer_size = 0; // dropping all supplementary data added
// it will be treated from the "a" buffer where they had been copied from
}
else // the escape sequence found is not complete
{
U_I yet_in_a = size - written;
U_I missing_for_sequence = trouve + (ESCAPE_SEQUENCE_LENGTH - 1) - write_buffer_size;
if(write_buffer_size < WRITE_BUFFER_SIZE && yet_in_a > 0)
throw SRC_BUG; // write_buffer_size not filled while remains available data in "a" !
// either the escape sequence is entirely in "a" (and partially copied in write_buffer)
// or there is not enough data in "a" to determin whether this start of sequence is complete or not
// first, we can at least write down the data up to offset "trouve - 1" (that's "trouve" bytes).
x_below->write(write_buffer, trouve);
below_position += trouve;
if(yet_in_a >= missing_for_sequence) // sequence entirely available with remaining data in "a"
{
if(trouve < initial_buffer_size)
throw SRC_BUG; // some original data of write_buffer are part of the escape sequence !!!
written = trouve - initial_buffer_size;
write_buffer_size = 0;
}
else // missing data to determine the nature of the sequence
{
(void)memmove(write_buffer, write_buffer + trouve, write_buffer_size - trouve);
write_buffer_size -= trouve;
if(write_buffer_size >= ESCAPE_SEQUENCE_LENGTH - 1)
throw SRC_BUG; // should never seen this if() condition
if(write_buffer_size + yet_in_a > WRITE_BUFFER_SIZE)
throw SRC_BUG; // not possible to reach normally, because yet_in_a < missing_for_sequence < SEQUENCE_LENGTH
(void)memcpy(write_buffer + write_buffer_size, a+written, yet_in_a);
written = size;
write_buffer_size += yet_in_a;
}
}
}
}
// now that we have eventually treated the write_buffer, we get two possibilities
// either no escape sequence is pending in the write_buffer [write_buffer_size == 0] (escape sequence in "a" or non escape sequence found at all)
// or an potential escape sequence is pending in the write_buffer, which only occurs if "a" does not contain any more
// data to detemine the exact nature of this sequence [ written == size ]
if(written != size && write_buffer_size > 0)
throw SRC_BUG; // anormal situation, seen the previous comment.
while(written < size)
{
U_I remains = size - written;
trouve = trouve_amorce(a + written, remains, fixed_sequence);
if(trouve == remains)
{
x_below->write(a + written, remains);
below_position += remains;
written = size;
}
else
{
if(trouve > 0)
{
x_below->write(a + written, trouve);
below_position += trouve;
written += trouve;
}
if(trouve + ESCAPE_SEQUENCE_LENGTH - 1 <= remains) // full escape sequence
{
set_fixed_sequence_for(seqt_not_a_sequence);
x_below->write((const char *)fixed_sequence, ESCAPE_SEQUENCE_LENGTH);
below_position += ESCAPE_SEQUENCE_LENGTH;
written += ESCAPE_SEQUENCE_LENGTH - 1;
++escaped_data_count_since_last_skip;
}
else // not completed sequence
{
remains = size - written;
if(remains >= ESCAPE_SEQUENCE_LENGTH - 1)
throw SRC_BUG; // how possible is to not be able to fully determine the sequence ???
(void)memcpy(write_buffer, a + written, remains);
write_buffer_size = remains;
written = size;
}
}
}
}
catch(Ethread_cancel & e)
{
below_position = x_below->get_position();
throw;
}
}
char escape::type2char(sequence_type x)
{
switch(x)
{
case seqt_not_a_sequence:
return 'X';
case seqt_file:
return 'F';
case seqt_ea:
return 'E';
case seqt_catalogue:
return 'C';
case seqt_data_name:
return 'D';
case seqt_file_crc:
return 'R';
case seqt_ea_crc:
return 'r';
case seqt_changed:
return 'W';
case seqt_dirty:
return 'I';
case seqt_failed_backup:
return '!';
case seqt_fsa:
return 'S';
case seqt_fsa_crc:
return 's';
case seqt_delta_sig:
return 'd';
default:
throw SRC_BUG;
}
}
escape::sequence_type escape::char2type(char x)
{
switch(x)
{
case 'X':
return seqt_not_a_sequence;
case 'F':
return seqt_file;
case 'E':
return seqt_ea;
case 'C':
return seqt_catalogue;
case 'D':
return seqt_data_name;
case 'R':
return seqt_file_crc;
case 'r':
return seqt_ea_crc;
case 'W':
return seqt_changed;
case 'I':
return seqt_dirty;
case '!':
return seqt_failed_backup;
case 'S':
return seqt_fsa;
case 's':
return seqt_fsa_crc;
case 'd':
return seqt_delta_sig;
default:
throw Erange("escape::char2type", gettext("Unknown escape sequence type"));
}
}
void escape::clean_read()
{
read_buffer_size = already_read = escape_seq_offset_in_buffer = 0;
read_eof = false;
escaped_data_count_since_last_skip = 0;
}
void escape::flush_write()
{
check_below();
if(write_buffer_size > 0)
{
x_below->write(write_buffer, write_buffer_size);
below_position += write_buffer_size;
write_buffer_size = 0;
}
}
void escape::copy_from(const escape & ref)
{
x_below = ref.x_below;
write_buffer_size = ref.write_buffer_size;
if(write_buffer_size > WRITE_BUFFER_SIZE)
throw SRC_BUG;
(void)memcpy(write_buffer, ref.write_buffer, write_buffer_size);
read_buffer_size = ref.read_buffer_size;
if(read_buffer_size > READ_BUFFER_SIZE)
throw SRC_BUG;
(void)memcpy(read_buffer, ref.read_buffer, read_buffer_size);
already_read = ref.already_read;
read_eof = ref.read_eof;
escaped_data_count_since_last_skip = ref.escaped_data_count_since_last_skip;
below_position = ref.below_position;
unjumpable = ref.unjumpable;
(void)memcpy(fixed_sequence, ref.fixed_sequence, ESCAPE_SEQUENCE_LENGTH);
}
void escape::move_from(escape && ref) noexcept
{
swap(x_below, ref.x_below);
write_buffer_size = move(ref.write_buffer_size);
swap(write_buffer, ref.write_buffer);
read_buffer_size = move(ref.read_buffer_size);
already_read = move(ref.already_read);
read_eof = move(ref.read_eof);
escape_seq_offset_in_buffer = move(ref.escape_seq_offset_in_buffer);
swap(read_buffer, ref.read_buffer);
unjumpable = move(ref.unjumpable);
swap(fixed_sequence, ref.fixed_sequence);
escaped_data_count_since_last_skip = move(ref.escaped_data_count_since_last_skip);
below_position = move(ref.below_position);
}
bool escape::mini_read_buffer()
{
U_I avail = read_buffer_size - already_read;
if(avail < ESCAPE_SEQUENCE_LENGTH)
{
// we need more data
if(already_read + ESCAPE_SEQUENCE_LENGTH >= READ_BUFFER_SIZE)
{
// we need room to place more data, so we skip data at the beginning of the read_buffer
if(already_read < ESCAPE_SEQUENCE_LENGTH)
throw SRC_BUG; // READ_BUFFER_SIZE is expected to be (much) larger than twice the escape sequence length,
// so now, we never have to use memmove in place of memcpy:
(void)memcpy(read_buffer, read_buffer + already_read, avail);
if(escape_seq_offset_in_buffer < already_read)
throw SRC_BUG; // escape_seq_offset_in_buffer, has not been updated sometime before
escape_seq_offset_in_buffer -= already_read;
already_read = 0;
read_buffer_size = avail;
}
// recording up to what point data had been unescaped
if(escape_seq_offset_in_buffer > read_buffer_size)
throw SRC_BUG; // should not be greater than read_buffer_size
else
{
U_I delta; // will receive the amount of byte to reduce the buffer (one byte for each data mark found)
U_I delta_size; // will holds the size of the data to unescape
U_I offset_in_buffer;
U_I short_read;
// adding some data at the end of the buffer
short_read = x_below->read(read_buffer + read_buffer_size, ESCAPE_SEQUENCE_LENGTH - avail);
read_buffer_size += short_read;
below_position += short_read;
avail = read_buffer_size - already_read;
// we can continue unescaping the new data
// but only what has not yet been unescaped, thus no data before escape_seq_offset_in_buffer
delta_size = read_buffer_size - escape_seq_offset_in_buffer;
offset_in_buffer = remove_data_marks_and_stop_at_first_real_mark(read_buffer + escape_seq_offset_in_buffer, delta_size, delta, fixed_sequence);
delta_size -= delta;
escaped_data_count_since_last_skip += delta;
read_buffer_size = escape_seq_offset_in_buffer + delta_size;
escape_seq_offset_in_buffer += offset_in_buffer;
}
}
else // enough data, but removing any data mark found in the beginning of the read_buffer
{
if(escape_seq_offset_in_buffer == already_read
&& char2type(read_buffer[escape_seq_offset_in_buffer + ESCAPE_SEQUENCE_LENGTH - 1]) == seqt_not_a_sequence)
{
// next to read is a data mark, we must un-escape data
U_I delta = 0;
escape_seq_offset_in_buffer = already_read + remove_data_marks_and_stop_at_first_real_mark(read_buffer + already_read,
read_buffer_size - already_read,
delta,
fixed_sequence);
escaped_data_count_since_last_skip += delta;
read_buffer_size -= delta;
}
}
if(avail < ESCAPE_SEQUENCE_LENGTH)
{
read_eof = true;
return false;
}
else
return true;
}
U_I escape::trouve_amorce(const char *a, U_I size, const unsigned char escape_sequence[ESCAPE_SEQUENCE_LENGTH])
{
U_I ret = 0; // points to the start of the escape sequence
U_I curs = 0; // points to current byte considered
U_I amorce = 0; // points to the byte to compare in the fixed sequence
U_I found = ESCAPE_SEQUENCE_LENGTH - 1; // maximum number of byte to compare in fixed sequence
while(curs < size && amorce < found)
{
if((unsigned char)a[curs] == escape_sequence[amorce])
{
if(amorce == 0)
ret = curs;
++amorce;
}
else
if(amorce > 0)
{
curs -= amorce;
amorce = 0;
}
++curs;
}
if(curs >= size) // reached the end of the field
if(amorce == 0) // and no start of escape sequence could be found
ret = size;
// else we return the start of the escape sequence found (or partial escape sequence if found at the end of the "a" buffer
return ret;
}
U_I escape::remove_data_marks_and_stop_at_first_real_mark(char *a, U_I size, U_I & delta, const unsigned char escape_sequence[ESCAPE_SEQUENCE_LENGTH])
{
bool loop = false;
U_I ret = 0;
delta = 0;
do
{
ret += trouve_amorce(a + ret, size - ret, escape_sequence);
if(ret < size) // start of escape sequence found
if(ret + ESCAPE_SEQUENCE_LENGTH <= size) // we can determin the nature of the escape sequence
if(char2type(a[ret + ESCAPE_SEQUENCE_LENGTH - 1]) == seqt_not_a_sequence)
{
(void)memmove(a + ret + ESCAPE_SEQUENCE_LENGTH - 1, a + ret + ESCAPE_SEQUENCE_LENGTH, size - ret - ESCAPE_SEQUENCE_LENGTH);
++delta;
--size; // this modification is local to this method.
loop = true;
ret += ESCAPE_SEQUENCE_LENGTH - 1; // skipping one byte, as this is the escape data byte of which we just removed the protection
}
else
loop = false; // real mark found
else
loop = false; // cannot know whether this is a real mark or just escaped data
else
loop = false; // no mark found
}
while(loop);
return ret;
}
} // end of namespace
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