From 28f5973e857d21f6ef3382e1d5f81518ca4f9650 Mon Sep 17 00:00:00 2001
From: Tony Wasserka <neobrain@users.noreply.github.com>
Date: Fri, 8 Mar 2024 15:46:08 +0100
Subject: [PATCH] Add fs_common.cpp

---
 source/processes/fs_common.cpp | 136 +++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 source/processes/fs_common.cpp

diff --git a/source/processes/fs_common.cpp b/source/processes/fs_common.cpp
new file mode 100644
index 0000000..bca56c8
--- /dev/null
+++ b/source/processes/fs_common.cpp
@@ -0,0 +1,136 @@
+#include "fs_common.hpp"
+#include "pxi.hpp"
+
+#include <range/v3/algorithm/find.hpp>
+#include <range/v3/algorithm/generate_n.hpp>
+#include <range/v3/iterator/insert_iterators.hpp>
+
+namespace HLE {
+
+CommonPath CommonPath::FromUtf16(std::u16string_view utf16_data) {
+    while (!utf16_data.empty() && utf16_data.back() == 0) {
+        utf16_data.remove_suffix(1);
+    }
+    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>,char16_t> conversion;
+    return { Utf8PathType { conversion.to_bytes(utf16_data.begin(), utf16_data.end()) } };
+}
+
+CommonPath CommonPath::FromUtf16(std::basic_string_view<uint16_t> utf16_data) {
+    while (!utf16_data.empty() && utf16_data.back() == 0) {
+        utf16_data.remove_suffix(1);
+    }
+    std::vector<char16_t> char16_data(utf16_data.size());
+    std::copy(utf16_data.begin(), utf16_data.end(), char16_data.begin());
+    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>,char16_t> conversion;
+    return { Utf8PathType { conversion.to_bytes(&*char16_data.begin(), &*char16_data.end()) } };
+}
+
+CommonPath::CommonPath(OS::Thread& thread, uint32_t type, uint32_t num_bytes, const IPC::StaticBuffer& path)
+    : CommonPath(type, num_bytes, [&,offset=0]() mutable { return thread.ReadMemory(path.addr + offset++); }) {
+}
+
+CommonPath::CommonPath(OS::Thread& thread, uint32_t type, uint32_t num_bytes, const PXI::PXIBuffer& path)
+    : CommonPath(type, num_bytes, [&,offset=0]() mutable { return path.Read<uint8_t>(thread, offset++); }) {
+}
+
+template<typename ReadByte>
+CommonPath::CommonPath(uint32_t type, uint32_t num_bytes, ReadByte&& read) {
+    switch (type) {
+    case 1: // empty path
+    {
+        data = Utf8PathType { };
+        break;
+    }
+
+    case 2: // binary path
+    {
+        data = BinaryPathType { };
+        auto& path_data = std::get<BinaryPathType>(data);
+
+        if (num_bytes > max_length) {
+            throw std::runtime_error(fmt::format("Path length {} exceeded maximum {}", num_bytes, path_data.capacity()));
+        }
+
+        ranges::generate_n(ranges::back_inserter(path_data), num_bytes, read);
+        break;
+    }
+
+    case 3: // ASCII path
+    {
+        data = Utf8PathType { };
+        auto& path = std::get<Utf8PathType>(data);
+
+        path.reserve(num_bytes);
+        ranges::generate_n(ranges::back_inserter(path), num_bytes, read);
+
+        // Strip characters past the null terminator
+        path.erase(ranges::find(path, '\0'), path.end());
+        break;
+    }
+
+    case 4: // UTF-16 path
+    {
+        if (num_bytes % 2)
+            throw std::runtime_error("Expected path size for UTF16 to be a multiple of 2");
+
+        // Read in data as UTF-16 with host byte order
+        std::u16string utf16_data;
+        utf16_data.reserve(num_bytes / 2);
+        auto ReadFromAddr = [&]() -> char16_t {
+            uint16_t low = read();
+            uint32_t high = read();
+            return low | (high << uint16_t { 8 });
+        };
+        ranges::generate_n(ranges::back_inserter(utf16_data), num_bytes / 2, ReadFromAddr);
+
+        // Strip characters past the null terminator
+        utf16_data.erase(ranges::find(utf16_data, u'\0'), utf16_data.end());
+
+        *this = FromUtf16(utf16_data);
+
+        break;
+    }
+
+    default:
+        throw std::runtime_error(fmt::format("Unknown path type {}", type));
+    }
+}
+
+ValidatedHostPath PathValidator::ValidateAndGetSandboxedTreePath(const Utf8PathType& utf8_path) const {
+    auto path = utf8_path.to_std_path().lexically_normal();
+    auto path_elements = std::distance(path.begin(), path.end());
+    if (path_elements == 0 || *path.begin() != "/") {
+        test_mode ? throw IPC::IPCError { 0, 0xe0e046be } // TODO: Throw PathValidator errors instead
+                  : throw std::runtime_error("Path does not start with '/'");
+    }
+
+    if (path_elements > 1 && *std::next(path.begin()) == "..") {
+        test_mode ? throw IPC::IPCError { 0, 0xe0e046be }
+                  : throw std::runtime_error("Path escapes root directory");
+    }
+
+//        const uint32_t max_filename_length = 0x10; // TODO: Where does this come from? Seems overly short for HostArchives
+    const uint32_t max_filename_length = 0x100;
+    if (std::prev(path.end())->u8string().size() > max_filename_length) {
+        test_mode ? throw IPC::IPCError { 0, 0xe0e046c7 }
+                  : throw std::runtime_error("Filename too long");
+    }
+
+    // Append path to the sandbox root and double-check that we won't leak out of it
+    auto sandbox_root = GetSandboxHostRoot();
+    if (!sandbox_root.is_absolute()) {
+    // TODO: Required for cfg
+//            throw std::runtime_error("Sandbox root is not an absolute path: " + sandbox_root.string());
+    }
+    sandbox_root = canonical(sandbox_root);
+
+    auto new_path = sandbox_root;
+    new_path += utf8_path;
+    new_path = new_path.lexically_normal();
+    if (new_path.begin() != std::search(new_path.begin(), new_path.end(), sandbox_root.begin(), sandbox_root.end())) {
+        throw std::runtime_error(fmt::format("Requested path leaked out of sandbox: Got path {}, expected a child of {}", new_path, sandbox_root));
+    }
+    return ValidatedHostPath { std::move(new_path) };
+}
+
+}