RASCSI/cpp/rascsi/rascsi_image.cpp

442 lines
12 KiB
C++

//---------------------------------------------------------------------------
//
// SCSI Target Emulator RaSCSI Reloaded
// for Raspberry Pi
//
// Copyright (C) 2021-2022 Uwe Seimet
//
//---------------------------------------------------------------------------
#include "shared/log.h"
#include "shared/protobuf_util.h"
#include "devices/disk.h"
#include "command_context.h"
#include "rascsi_image.h"
#include <unistd.h>
#include <pwd.h>
#include <fstream>
#include <string>
#include <array>
#include <filesystem>
using namespace std;
using namespace filesystem;
using namespace rascsi_interface;
using namespace protobuf_util;
RascsiImage::RascsiImage()
{
// ~/images is the default folder for device image files, for the root user it is /home/pi/images
default_folder = GetHomeDir() + "/images";
}
bool RascsiImage::CheckDepth(string_view filename) const
{
return count(filename.begin(), filename.end(), '/') <= depth;
}
bool RascsiImage::CreateImageFolder(const CommandContext& context, const string& filename) const
{
if (const size_t filename_start = filename.rfind('/'); filename_start != string::npos) {
const auto folder = path(filename.substr(0, filename_start));
// Checking for existence first prevents an error if the top-level folder is a softlink
if (error_code error; exists(folder, error)) {
return true;
}
try {
create_directories(folder);
return ChangeOwner(context, folder, false);
}
catch(const filesystem_error& e) {
return context.ReturnStatus(false, "Can't create image folder '" + string(folder) + "': " + e.what());
}
}
return true;
}
string RascsiImage::SetDefaultFolder(const string& f)
{
if (f.empty()) {
return "Can't set default image folder: Missing folder name";
}
string folder = f;
// If a relative path is specified, the path is assumed to be relative to the user's home directory
if (folder[0] != '/') {
folder = GetHomeDir() + "/" + folder;
}
else {
if (folder.find("/home/") != 0) {
return "Default image folder must be located in '/home/'";
}
}
// Resolve a potential symlink
auto p = path(folder);
if (error_code error; is_symlink(p, error)) {
p = read_symlink(p);
}
if (error_code error; !is_directory(p, error)) {
return "'" + string(p) + "' is not a valid folder";
}
default_folder = string(p);
LOGINFO("Default image folder set to '%s'", default_folder.c_str())
return "";
}
bool RascsiImage::CreateImage(const CommandContext& context, const PbCommand& command) const
{
const string filename = GetParam(command, "file");
if (filename.empty()) {
return context.ReturnStatus(false, "Can't create image file: Missing image filename");
}
if (!CheckDepth(filename)) {
return context.ReturnStatus(false, ("Invalid folder hierarchy depth '" + filename + "'").c_str());
}
const string full_filename = GetFullName(filename);
if (!IsValidDstFilename(full_filename)) {
return context.ReturnStatus(false, "Can't create image file: '" + full_filename + "': File already exists");
}
const string size = GetParam(command, "size");
if (size.empty()) {
return context.ReturnStatus(false, "Can't create image file '" + full_filename + "': Missing file size");
}
off_t len;
try {
len = stoull(size);
}
catch(const invalid_argument&) {
return context.ReturnStatus(false, "Can't create image file '" + full_filename + "': Invalid file size " + size);
}
catch(const out_of_range&) {
return context.ReturnStatus(false, "Can't create image file '" + full_filename + "': Invalid file size " + size);
}
if (len < 512 || (len & 0x1ff)) {
return context.ReturnStatus(false, "Invalid image file size " + to_string(len) + " (not a multiple of 512)");
}
if (!CreateImageFolder(context, full_filename)) {
return false;
}
const bool read_only = GetParam(command, "read_only") == "true";
error_code error;
path file(full_filename);
try {
ofstream s(file);
s.close();
if (!ChangeOwner(context, file, read_only)) {
return false;
}
resize_file(file, len);
}
catch(const filesystem_error& e) {
remove(file, error);
return context.ReturnStatus(false, "Can't create image file '" + full_filename + "': " + e.what());
}
LOGINFO("%s", string("Created " + string(read_only ? "read-only " : "") + "image file '" + full_filename +
"' with a size of " + to_string(len) + " bytes").c_str())
return context.ReturnStatus();
}
bool RascsiImage::DeleteImage(const CommandContext& context, const PbCommand& command) const
{
const string filename = GetParam(command, "file");
if (filename.empty()) {
return context.ReturnStatus(false, "Missing image filename");
}
if (!CheckDepth(filename)) {
return context.ReturnStatus(false, ("Invalid folder hierarchy depth '" + filename + "'").c_str());
}
const auto full_filename = path(GetFullName(filename));
if (!exists(full_filename)) {
return context.ReturnStatus(false, "Image file '" + string(full_filename) + "' does not exist");
}
const auto [id, lun] = StorageDevice::GetIdsForReservedFile(full_filename);
if (id != -1 || lun != -1) {
return context.ReturnStatus(false, "Can't delete image file '" + string(full_filename) +
"', it is currently being used by device ID " + to_string(id) + ", LUN " + to_string(lun));
}
if (error_code error; !remove(full_filename, error)) {
return context.ReturnStatus(false, "Can't delete image file '" + string(full_filename) + "'");
}
// Delete empty subfolders
size_t last_slash = filename.rfind('/');
while (last_slash != string::npos) {
const string folder = filename.substr(0, last_slash);
const auto full_folder = path(GetFullName(folder));
if (error_code error; !filesystem::is_empty(full_folder, error) || error) {
break;
}
if (error_code error; !remove(full_folder)) {
return context.ReturnStatus(false, "Can't delete empty image folder '" + string(full_folder) + "'");
}
last_slash = folder.rfind('/');
}
LOGINFO("Deleted image file '%s'", full_filename.c_str())
return context.ReturnStatus();
}
bool RascsiImage::RenameImage(const CommandContext& context, const PbCommand& command) const
{
string from;
string to;
if (!ValidateParams(context, command, "rename/move", from, to)) {
return false;
}
const auto [id, lun] = StorageDevice::GetIdsForReservedFile(from);
if (id != -1 || lun != -1) {
return context.ReturnStatus(false, "Can't rename/move image file '" + from +
"', it is currently being used by device ID " + to_string(id) + ", LUN " + to_string(lun));
}
if (!CreateImageFolder(context, to)) {
return false;
}
try {
rename(path(from), path(to));
}
catch(const filesystem_error& e) {
return context.ReturnStatus(false, "Can't rename/move image file '" + from + "' to '" + to + "': " + e.what());
}
LOGINFO("Renamed/Moved image file '%s' to '%s'", from.c_str(), to.c_str())
return context.ReturnStatus();
}
bool RascsiImage::CopyImage(const CommandContext& context, const PbCommand& command) const
{
string from;
string to;
if (!ValidateParams(context, command, "copy", from, to)) {
return false;
}
if (access(from.c_str(), R_OK)) {
return context.ReturnStatus(false, "Can't read source image file '" + from + "'");
}
const auto [id, lun] = StorageDevice::GetIdsForReservedFile(from);
if (id != -1 || lun != -1) {
return context.ReturnStatus(false, "Can't copy image file '" + from +
"', it is currently being used by device ID " + to_string(id) + ", LUN " + to_string(lun));
}
if (!CreateImageFolder(context, to)) {
return false;
}
path f(from);
path t(to);
// Symbolic links need a special handling
if (error_code error; is_symlink(f, error)) {
try {
copy_symlink(f, t);
}
catch(const filesystem_error& e) {
return context.ReturnStatus(false, "Can't copy image file symlink '" + from + "': " + e.what());
}
LOGINFO("Copied image file symlink '%s' to '%s'", from.c_str(), to.c_str())
return context.ReturnStatus();
}
try {
copy_file(f, t);
permissions(t, GetParam(command, "read_only") == "true" ?
perms::owner_read | perms::group_read | perms::others_read :
perms::owner_read | perms::group_read | perms::others_read |
perms::owner_write | perms::group_write);
}
catch(const filesystem_error& e) {
return context.ReturnStatus(false, "Can't copy image file '" + from + "' to '" + to + "': " + e.what());
}
LOGINFO("Copied image file '%s' to '%s'", from.c_str(), to.c_str())
return context.ReturnStatus();
}
bool RascsiImage::SetImagePermissions(const CommandContext& context, const PbCommand& command) const
{
string filename = GetParam(command, "file");
if (filename.empty()) {
return context.ReturnStatus(false, "Missing image filename");
}
if (!CheckDepth(filename)) {
return context.ReturnStatus(false, ("Invalid folder hierarchy depth '" + filename + "'").c_str());
}
filename = GetFullName(filename);
if (!IsValidSrcFilename(filename)) {
return context.ReturnStatus(false, "Can't modify image file '" + filename + "': Invalid name or type");
}
const bool protect = command.operation() == PROTECT_IMAGE;
try {
permissions(path(filename), protect ?
perms::owner_read | perms::group_read | perms::others_read :
perms::owner_read | perms::group_read | perms::others_read |
perms::owner_write | perms::group_write);
}
catch(const filesystem_error& e) {
return context.ReturnStatus(false, "Can't " + string(protect ? "protect" : "unprotect") + " image file '" +
filename + "': " + e.what());
}
if (protect) {
LOGINFO("Protected image file '%s'", filename.c_str())
}
else {
LOGINFO("Unprotected image file '%s'", filename.c_str())
}
return context.ReturnStatus();
}
bool RascsiImage::ValidateParams(const CommandContext& context, const PbCommand& command, const string& operation,
string& from, string& to) const
{
from = GetParam(command, "from");
if (from.empty()) {
return context.ReturnStatus(false, "Can't " + operation + " image file: Missing source filename");
}
if (!CheckDepth(from)) {
return context.ReturnStatus(false, ("Invalid folder hierarchy depth '" + from + "'").c_str());
}
from = GetFullName(from);
if (!IsValidSrcFilename(from)) {
return context.ReturnStatus(false, "Can't " + operation + " image file: '" + from + "': Invalid name or type");
}
to = GetParam(command, "to");
if (to.empty()) {
return context.ReturnStatus(false, "Can't " + operation + " image file '" + from + "': Missing destination filename");
}
if (!CheckDepth(to)) {
return context.ReturnStatus(false, ("Invalid folder hierarchy depth '" + to + "'").c_str());
}
to = GetFullName(to);
if (!IsValidDstFilename(to)) {
return context.ReturnStatus(false, "Can't " + operation + " image file '" + from + "' to '" + to + "': File already exists");
}
return true;
}
bool RascsiImage::IsValidSrcFilename(const string& filename)
{
// Source file must exist and must be a regular file or a symlink
path file(filename);
return is_regular_file(file) || is_symlink(file);
}
bool RascsiImage::IsValidDstFilename(const string& filename)
{
// Destination file must not yet exist
try {
return !exists(path(filename));
}
catch(const filesystem_error&) {
return true;
}
}
bool RascsiImage::ChangeOwner(const CommandContext& context, const path& filename, bool read_only)
{
const auto [uid, gid] = GetUidAndGid();
if (chown(filename.c_str(), uid, gid)) {
// Remember the current error before the next filesystem operation
const int e = errno;
error_code error;
remove(filename, error);
return context.ReturnStatus(false, "Can't change ownership of '" + string(filename) + "': " + strerror(e));
}
permissions(filename, read_only ?
perms::owner_read | perms::group_read | perms::others_read :
perms::owner_read | perms::group_read | perms::others_read |
perms::owner_write | perms::group_write);
return true;
}
string RascsiImage::GetHomeDir()
{
const auto [uid, gid] = GetUidAndGid();
passwd pwd = {};
passwd *p_pwd;
array<char, 256> pwbuf;
if (uid && !getpwuid_r(uid, &pwd, pwbuf.data(), pwbuf.size(), &p_pwd)) {
return pwd.pw_dir;
}
else {
return "/home/pi";
}
}
pair<int, int> RascsiImage::GetUidAndGid()
{
int uid = getuid();
if (const char *sudo_user = getenv("SUDO_UID"); sudo_user != nullptr) {
uid = stoi(sudo_user);
}
passwd pwd = {};
passwd *p_pwd;
array<char, 256> pwbuf;
int gid = -1;
if (!getpwuid_r(uid, &pwd, pwbuf.data(), pwbuf.size(), &p_pwd)) {
gid = pwd.pw_gid;
}
return make_pair(uid, gid);
}