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mark as deleted and zero content on deletion instead of shifting everything

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This commit is contained in:
Antoni Piasecki
2026-04-25 13:37:53 +02:00
parent 85541e1db4
commit 48fc35e16c
4 changed files with 43 additions and 58 deletions
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9
src/common.h
View File

@@ -2,7 +2,6 @@
#include <cstdint>
#include <iostream>
#include <string>
#define ASSERT(cond) \
do { \
@@ -25,11 +24,3 @@ static_assert(sizeof(float) * 8 == 32);
using f32 = float;
static_assert(sizeof(double) * 8 == 64);
using f64 = double;
template <typename T> constexpr char *to_char_ptr(T *ptr) noexcept {
return reinterpret_cast<char *>(ptr);
}
template <typename T> constexpr const char *to_char_ptr(const T *ptr) noexcept {
return reinterpret_cast<const char *>(ptr);
}

10
src/mainwindow.cc
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@@ -230,13 +230,15 @@ void MainWindow::file_context_menu(const QPoint &pos) {
QMenu menu(this);
QAction *preview_action = menu.addAction(
style()->standardIcon(QStyle::SP_FileDialogContentsView), "Preview");
QAction *preview_action =
menu.addAction(style()->standardIcon(QStyle::SP_FileDialogContentsView),
"Preview as text");
connect(preview_action, &QAction::triggered, this,
[this, item]() { preview_file(item->text(0).toStdString()); });
QAction *edit_action = menu.addAction(
style()->standardIcon(QStyle::SP_FileDialogDetailedView), "Edit");
QAction *edit_action =
menu.addAction(style()->standardIcon(QStyle::SP_FileDialogDetailedView),
"Edit in external app");
connect(edit_action, &QAction::triggered, this,
[this, item]() { edit_file(item->text(0).toStdString()); });

81
src/vault.cc
View File

@@ -2,7 +2,18 @@
#include "common.h"
#include "crypto.h"
#include <botan/auto_rng.h>
#include <filesystem>
namespace {
template <typename T> constexpr char *to_char_ptr(T *ptr) noexcept {
return reinterpret_cast<char *>(ptr);
}
template <typename T> constexpr const char *to_char_ptr(const T *ptr) noexcept {
return reinterpret_cast<const char *>(ptr);
}
} // namespace
Vault::Vault(std::string path, const std::string &password)
: m_path(std::move(path)) {
@@ -57,7 +68,9 @@ std::vector<FileHeader> Vault::read_file_headers() {
while (true) {
auto header = read_file_header();
if (header) {
headers.push_back(header.value());
if (!header->deleted) {
headers.push_back(header.value());
}
m_file.seekg(static_cast<i64>(header->content_ciphertext_size),
std::ios::cur);
} else {
@@ -78,7 +91,7 @@ std::optional<std::string> Vault::read_file(const std::string &filename) {
break;
}
if (header->name == filename) {
if (!header->deleted && header->name == filename) {
Botan::secure_vector<u8> ciphertext;
ciphertext.resize(header->content_ciphertext_size);
if (!m_file.read(to_char_ptr(ciphertext.data()),
@@ -110,6 +123,7 @@ void Vault::create_file(const std::string &filename,
auto ciphertext = Crypto::encrypt(m_key, content_sv);
u64 ciphertext_size = ciphertext.size();
ASSERT(m_file.write("\0", 1)); // deleted flag
ASSERT(m_file.write(to_char_ptr(&filename_ciphertext_size), sizeof(u64)));
ASSERT(m_file.write(to_char_ptr(filename_ciphertext.data()),
static_cast<i64>(filename_ciphertext_size)));
@@ -123,9 +137,6 @@ void Vault::delete_file(const std::string &filename) {
m_file.clear();
m_file.seekg(AFTER_HEADER_OFFSET, std::ios::beg);
i64 entry_start = -1;
u64 entry_total_size = 0;
while (true) {
i64 current_pos = m_file.tellg();
@@ -134,49 +145,21 @@ void Vault::delete_file(const std::string &filename) {
break;
}
if (header->name == filename) {
entry_start = current_pos;
entry_total_size = sizeof(u64) + header->name_ciphertext_size +
sizeof(u64) + header->content_ciphertext_size;
m_file.seekg(static_cast<i64>(header->content_ciphertext_size),
std::ios::cur);
if (!header->deleted && header->name == filename) {
// zero the ciphertext and mark as deleted
m_file.seekp(m_file.tellg());
for (size_t i = 0; i < header->content_ciphertext_size; i++) {
m_file.write(to_char_ptr("\0"), 1);
}
m_file.seekp(current_pos, std::ios::beg);
m_file.write(to_char_ptr("\1"), 1);
break;
}
m_file.seekg(static_cast<i64>(header->content_ciphertext_size),
std::ios::cur);
}
if (entry_start != -1) {
i64 entry_end = entry_start + static_cast<i64>(entry_total_size);
i64 read_pos = entry_end;
i64 write_pos = entry_start;
std::array<u8, 65536> buffer{};
while (true) {
m_file.clear();
m_file.seekg(read_pos);
m_file.read(to_char_ptr(buffer.data()), buffer.size());
auto bytes = m_file.gcount();
if (bytes == 0) {
break;
}
m_file.seekp(write_pos);
ASSERT(m_file.write(to_char_ptr(buffer.data()), bytes));
read_pos += bytes;
write_pos += bytes;
}
m_file.flush();
m_file.close();
std::filesystem::resize_file(m_path, write_pos);
m_file.open(m_path, std::ios::in | std::ios::out | std::ios::binary);
ASSERT(m_file.good());
}
}
void Vault::update_file(const std::string &filename,
@@ -188,6 +171,10 @@ void Vault::update_file(const std::string &filename,
std::optional<FileHeader> Vault::read_file_header() {
FileHeader header{};
if (!m_file.read(to_char_ptr(&header.deleted), 1)) {
return std::nullopt;
}
if (!m_file.read(to_char_ptr(&header.name_ciphertext_size), sizeof(u64))) {
return std::nullopt;
}
@@ -201,10 +188,14 @@ std::optional<FileHeader> Vault::read_file_header() {
return std::nullopt;
}
auto name = Crypto::decrypt(m_key, name_ciphertext);
header.name = std::string(name.begin(), name.end());
if (!header.deleted) {
auto name = Crypto::decrypt(m_key, name_ciphertext);
header.name = std::string(name.begin(), name.end());
}
if (!m_file.read(to_char_ptr(&header.content_ciphertext_size), sizeof(u64))) {
return std::nullopt;
}
return header;
}

1
src/vault.h
View File

@@ -10,6 +10,7 @@ constexpr u64 AFTER_HEADER_OFFSET = 68;
// !!! REMEMBER TO UPDATE entry_total_size IN Vault::delete_file
struct FileHeader {
bool deleted;
u64 name_ciphertext_size;
std::string name;
u64 content_ciphertext_size;