RASCSI/cpp/piscsi/piscsi_image.cpp
Uwe Seimet 8bd06ea5cd
Improve how commands are internally executed (#1247)
* Improve how commands are internally executed
* Use const CommandContext for execution
* Update error handling
* Fix SonarQube issues
* Remove duplicate code
* Use mutex instead of atomic_bool
* Add hasher
* Add param_map
* Do not log unknown operations as an error for backward/foward compatibility
2023-10-30 13:57:46 +01:00

426 lines
12 KiB
C++

//---------------------------------------------------------------------------
//
// SCSI Target Emulator PiSCSI
// for Raspberry Pi
//
// Copyright (C) 2021-2023 Uwe Seimet
//
//---------------------------------------------------------------------------
#include "devices/disk.h"
#include "piscsi_image.h"
#include "shared/protobuf_util.h"
#include <spdlog/spdlog.h>
#include <unistd.h>
#include <pwd.h>
#include <fstream>
#include <array>
using namespace std;
using namespace filesystem;
using namespace piscsi_interface;
using namespace protobuf_util;
PiscsiImage::PiscsiImage()
{
// ~/images is the default folder for device image files, for the root user it is /home/pi/images
default_folder = GetHomeDir() + "/images";
}
bool PiscsiImage::CheckDepth(string_view filename) const
{
return ranges::count(filename, '/') <= depth;
}
bool PiscsiImage::CreateImageFolder(const CommandContext& context, string_view filename) const
{
if (const auto folder = path(filename).parent_path(); !folder.string().empty()) {
// 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.ReturnErrorStatus("Can't create image folder '" + folder.string() + "': " + e.what());
}
}
return true;
}
string PiscsiImage::SetDefaultFolder(string_view f)
{
if (f.empty()) {
return "Can't set default image folder: Missing folder name";
}
// If a relative path is specified, the path is assumed to be relative to the user's home directory
path folder(f);
if (folder.is_relative()) {
folder = path(GetHomeDir() + "/" + folder.string());
}
if (path home_root = path(GetHomeDir()).parent_path(); !folder.string().starts_with(home_root.string())) {
return "Default image folder must be located in '" + home_root.string() + "'";
}
// Resolve a potential symlink
if (error_code error; is_symlink(folder, error)) {
folder = read_symlink(folder);
}
if (error_code error; !is_directory(folder)) {
return string("'") + folder.string() + "' is not a valid image folder";
}
default_folder = folder.string();
spdlog::info("Default image folder set to '" + default_folder + "'");
return "";
}
bool PiscsiImage::CreateImage(const CommandContext& context) const
{
const string filename = GetParam(context.GetCommand(), "file");
if (filename.empty()) {
return context.ReturnErrorStatus("Missing image filename");
}
if (!CheckDepth(filename)) {
return context.ReturnErrorStatus(("Invalid folder hierarchy depth '" + filename + "'").c_str());
}
const string full_filename = GetFullName(filename);
if (!IsValidDstFilename(full_filename)) {
return context.ReturnErrorStatus("Can't create image file: '" + full_filename + "': File already exists");
}
const string size = GetParam(context.GetCommand(), "size");
if (size.empty()) {
return context.ReturnErrorStatus("Can't create image file '" + full_filename + "': Missing file size");
}
off_t len;
try {
len = stoull(size);
}
catch(const invalid_argument&) {
return context.ReturnErrorStatus("Can't create image file '" + full_filename + "': Invalid file size " + size);
}
catch(const out_of_range&) {
return context.ReturnErrorStatus("Can't create image file '" + full_filename + "': Invalid file size " + size);
}
if (len < 512 || (len & 0x1ff)) {
return context.ReturnErrorStatus("Invalid image file size " + to_string(len) + " (not a multiple of 512)");
}
if (!CreateImageFolder(context, full_filename)) {
return false;
}
const bool read_only = GetParam(context.GetCommand(), "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.ReturnErrorStatus("Can't create image file '" + full_filename + "': " + e.what());
}
spdlog::info("Created " + string(read_only ? "read-only " : "") + "image file '" + full_filename +
"' with a size of " + to_string(len) + " bytes");
return context.ReturnSuccessStatus();
}
bool PiscsiImage::DeleteImage(const CommandContext& context) const
{
const string filename = GetParam(context.GetCommand(), "file");
if (filename.empty()) {
return context.ReturnErrorStatus("Missing image filename");
}
if (!CheckDepth(filename)) {
return context.ReturnErrorStatus("Invalid folder hierarchy depth '" + filename + "'");
}
const auto full_filename = path(GetFullName(filename));
if (!exists(full_filename)) {
return context.ReturnErrorStatus("Image file '" + full_filename.string() + "' does not exist");
}
if (!IsReservedFile(context, full_filename, "delete")) {
return false;
}
if (error_code error; !remove(full_filename, error)) {
return context.ReturnErrorStatus("Can't delete image file '" + full_filename.string() + "'");
}
// 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.ReturnErrorStatus("Can't delete empty image folder '" + full_folder.string() + "'");
}
last_slash = folder.rfind('/');
}
spdlog::info("Deleted image file '" + full_filename.string() + "'");
return context.ReturnSuccessStatus();
}
bool PiscsiImage::RenameImage(const CommandContext& context) const
{
string from;
string to;
if (!ValidateParams(context, "rename/move", from, to)) {
return false;
}
try {
rename(path(from), path(to));
}
catch(const filesystem_error& e) {
return context.ReturnErrorStatus("Can't rename/move image file '" + from + "': " + e.what());
}
spdlog::info("Renamed/Moved image file '" + from + "' to '" + to + "'");
return context.ReturnSuccessStatus();
}
bool PiscsiImage::CopyImage(const CommandContext& context) const
{
string from;
string to;
if (!ValidateParams(context, "copy", from, 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.ReturnErrorStatus("Can't copy image file symlink '" + from + "': " + e.what());
}
spdlog::info("Copied image file symlink '" + from + "' to '" + to + "'");
return context.ReturnSuccessStatus();
}
try {
copy_file(f, t);
permissions(t, GetParam(context.GetCommand(), "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.ReturnErrorStatus("Can't copy image file '" + from + "': " + e.what());
}
spdlog::info("Copied image file '" + from + "' to '" + to + "'");
return context.ReturnSuccessStatus();
}
bool PiscsiImage::SetImagePermissions(const CommandContext& context) const
{
const string filename = GetParam(context.GetCommand(), "file");
if (filename.empty()) {
return context.ReturnErrorStatus("Missing image filename");
}
if (!CheckDepth(filename)) {
return context.ReturnErrorStatus("Invalid folder hierarchy depth '" + filename + "'");
}
const string full_filename = GetFullName(filename);
if (!IsValidSrcFilename(full_filename)) {
return context.ReturnErrorStatus("Can't modify image file '" + full_filename + "': Invalid name or type");
}
const bool protect = context.GetCommand().operation() == PROTECT_IMAGE;
if (protect && !IsReservedFile(context, full_filename, "protect")) {
return false;
}
try {
permissions(path(full_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.ReturnErrorStatus("Can't " + string(protect ? "protect" : "unprotect") + " image file '" +
full_filename + "': " + e.what());
}
spdlog::info((protect ? "Protected" : "Unprotected") + string(" image file '") + full_filename + "'");
return context.ReturnSuccessStatus();
}
bool PiscsiImage::IsReservedFile(const CommandContext& context, const string& file, const string& op)
{
const auto [id, lun] = StorageDevice::GetIdsForReservedFile(file);
if (id != -1) {
return context.ReturnErrorStatus("Can't " + op + " image file '" + file +
"', it is currently being used by device " + to_string(id) + ":" + to_string(lun));
}
return true;
}
bool PiscsiImage::ValidateParams(const CommandContext& context, const string& op, string& from, string& to) const
{
from = GetParam(context.GetCommand(), "from");
if (from.empty()) {
return context.ReturnErrorStatus("Can't " + op + " image file: Missing source filename");
}
if (!CheckDepth(from)) {
return context.ReturnErrorStatus("Invalid folder hierarchy depth '" + from + "'");
}
to = GetParam(context.GetCommand(), "to");
if (to.empty()) {
return context.ReturnErrorStatus("Can't " + op + " image file '" + from + "': Missing destination filename");
}
if (!CheckDepth(to)) {
return context.ReturnErrorStatus("Invalid folder hierarchy depth '" + to + "'");
}
from = GetFullName(from);
if (!IsValidSrcFilename(from)) {
return context.ReturnErrorStatus("Can't " + op + " image file: '" + from + "': Invalid name or type");
}
to = GetFullName(to);
if (!IsValidDstFilename(to)) {
return context.ReturnErrorStatus("Can't " + op + " image file '" + from + "' to '" + to + "': File already exists");
}
if (!IsReservedFile(context, from, op)) {
return false;
}
if (!CreateImageFolder(context, to)) {
return false;
}
return true;
}
bool PiscsiImage::IsValidSrcFilename(string_view filename)
{
// Source file must exist and must be a regular file or a symlink
path file(filename);
error_code error;
return is_regular_file(file, error) || is_symlink(file, error);
}
bool PiscsiImage::IsValidDstFilename(string_view filename)
{
// Destination file must not yet exist
try {
return !exists(path(filename));
}
catch(const filesystem_error&) {
return false;
}
}
bool PiscsiImage::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.ReturnErrorStatus("Can't change ownership of '" + filename.string() + "': " + 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 PiscsiImage::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> PiscsiImage::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 { uid, gid };
}