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core: add structures for handling fingerprints

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This just adds the basic structures and the accessor functions needed to
manage a table of fingerprint data. The table is indexed by the hash of
the model name and binary serial number as created by libdivcecomputer.
This way the data is accessible when libdivecomputer fist accesses a
dive computer (which is the point in time when we need to use the
fingerprint.

The table also contains the corresponding device id and dive id so we
can verify that the current dive table still contains that dive.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
This commit is contained in:
Dirk Hohndel 2021-10-30 09:54:18 -07:00
parent 95192bdf83
commit fa250906c9
2 changed files with 77 additions and 0 deletions
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55
core/device.cpp
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@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include "ssrf.h"
#include "dive.h"
#include "divelist.h"
#include "subsurface-string.h"
#include "device.h"
#include "errorhelper.h" // for verbose flag
@ -9,6 +10,7 @@
#include <QString> // for QString::number
struct device_table device_table;
struct fingerprint_table fingerprint_table;
bool device::operator==(const device &a) const
{
@ -197,3 +199,56 @@ extern "C" void free_device_table(struct device_table *devices)
{
delete devices;
}
// managing fingerprint data
bool fingerprint_record::operator<(const fingerprint_record &a) const
{
if (model == a.model)
return serial < a.serial;
return model < a.model;
}
// annoyingly, the Cressi Edy doesn't support a serial number (it's always 0), but still uses fingerprints
// so we can't bail on the serial number being 0
extern "C" unsigned int get_fingerprint_data(const struct fingerprint_table *table, uint32_t model, uint32_t serial, const unsigned char **fp_out)
{
if (model == 0 || fp_out == nullptr)
return 0;
struct fingerprint_record fpr = { model, serial };
auto it = std::lower_bound(table->fingerprints.begin(), table->fingerprints.end(), fpr);
if (it != table->fingerprints.end() && it->model == model && it->serial == serial) {
// std::lower_bound gets us the first element that isn't smaller than what we are looking
// for - so if one is found, we still need to check for equality
if (has_dive(it->fdeviceid, it->fdiveid)) {
*fp_out = it->raw_data;
return it->fsize;
}
}
return 0;
}
extern "C" void create_fingerprint_node(struct fingerprint_table *table, uint32_t model, uint32_t serial,
const unsigned char *raw_data_in, unsigned int fsize, uint32_t fdeviceid, uint32_t fdiveid)
{
// since raw data can contain \0 we copy this manually, not as string
unsigned char *raw_data = (unsigned char *)malloc(fsize);
if (!raw_data)
return;
memcpy(raw_data, raw_data_in, fsize);
struct fingerprint_record fpr = { model, serial, raw_data, fsize, fdeviceid, fdiveid };
auto it = std::lower_bound(table->fingerprints.begin(), table->fingerprints.end(), fpr);
if (it != table->fingerprints.end() && it->model == model && it->serial == serial) {
// std::lower_bound gets us the first element that isn't smaller than what we are looking
// for - so if one is found, we still need to check for equality - and then we
// can update the existing entry; first we free the memory for the stored raw data
free(it->raw_data);
it->fdeviceid = fdeviceid;
it->fdiveid = fdiveid;
it->raw_data = raw_data;
it->fsize = fsize;
} else {
// insert a new one
table->fingerprints.insert(it, fpr);
}
}