AuroraRuntime/Source/IO/FS/Resources.cpp

/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: Resources.cpp
    Date: 2021-6-16
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "FS.hpp"
#include "Resources.hpp"

#if defined(AURORA_PLATFORM_LINUX)
    #include <sys/types.h>
    #include <pwd.h>
    #include <unistd.h>
#elif defined(AURORA_PLATFORM_WIN32)
    #include <ShlObj_core.h>
    #include <accctrl.h>
    #include <aclapi.h>
#endif 

namespace Aurora::IO::FS
{
    #if defined(AURORA_PLATFORM_WIN32)
        static void Win32FixGlobalAppDataAcl(const AuString &path);
    #endif
        
    static AuString gHomeDirectory;
    static AuString gUserHomeDirectory;
    static AuString gUserWritableAppData;
    static AuString gGlobalWritableAppDirectory;
    static AuString gAdminWritableAppDirectory;
    static AuString gProgramsFolder;
    static AuString gApplicationData;
    static AuOptional<AuString> gSystemLibPath;
    static AuOptional<AuString> gSystemLibPath2;
    static AuOptional<AuString> gUserLibPath;
    static AuOptional<AuString> gUserLibPath2;
    // Should the following be /opt? Probably, if it were a direct replacement for Windows' appdata on Linux for global software packages outside of our ecosystem, sure; however, this is strictly a fallback for when there is no home
    // We don't support initially-undefined global application configurations across users on Unix targets. We can therefore conclue the application running is a service whose user is without a home, and should be subject to the same rules as an application deployed by a real package manager
    // For internal packages, in our own ecosystem of tools, I think this follows the UNIX spec, not that I care what arcahic C-with-vendor-packages-as-an-OS specification says.
    // The only way you can break this assumption is if you argue for users who will be outside of our deployment pipeline, wanting global configs, and don't have write permission on a relevant global directory.
    // They can shove it. Superuser should install software for all users.
    // XDG (falling back to home) for non-root installs; for root installs, installing a service package, use /var; for root installs of an application whose system configs should be shared amongst all users, unsupported, idc, it's sandboxed per user
    static const AuString kUnixAppData {"/var"};

    AUKN_SYM bool GetSystemDomain(AuString &path)
    {
        path = gApplicationData;
        return true;
    }

    AUKN_SYM bool GetProfileDomain(AuString &path)
    {
        path = gHomeDirectory;
        return true;
    }

    AUKN_SYM bool GetSystemResourcePath(const AuString &fileName, AuString &path)
    {
        path.clear();

        if (fileName.find("..") != AuString::npos)
        {
            AuLogWarn("Exploit Attempt? A system resource path may not contain relative directory move tokens: {}", fileName);
            return false;
        }

        {
            AuString tempPath;
            if (Process::GetWorkingDirectory(tempPath))
            {
                tempPath += "/" + fileName;
                if (FileExists(tempPath))
                {
                    path = tempPath;
                    return true;
                }
            }
        }

        {
            AuString tempPath;
            if (Process::GetProcDirectory(tempPath))
            {
                tempPath += "/" + fileName;
                if (FileExists(tempPath))
                {
                    path = tempPath;
                    return true;
                }
            }
        }
        
        {
            auto systemPath = gHomeDirectory + fileName;
            if (FileExists(systemPath))
            {
                path = systemPath;
                return true;
            }
        }
        
        {
            auto systemPath = gApplicationData + fileName;
            if (FileExists(systemPath))
            {
                path = systemPath;
                return true;
            }
        }

        return false;
    }

#if defined(AURORA_PLATFORM_WIN32) 

    static AuString GetSpecialDir(REFKNOWNFOLDERID rfid)
    {
        PWSTR directory;
        if (SHGetKnownFolderPath(rfid, KF_FLAG_DEFAULT, NULL, &directory) != S_OK)
        {
            SysPanic("Couldn't get known special directory path of [MS:{}-{}-{}-{}{}{}{}{}{}{}{}] with a NULL access token",
                     rfid.Data1, rfid.Data2, rfid.Data3, rfid.Data4[0], rfid.Data4[1], rfid.Data4[2], rfid.Data4[3], rfid.Data4[4], rfid.Data4[5], rfid.Data4[6], rfid.Data4[7]);
        }
        return Locale::ConvertFromWChar(directory);
    }

    static void SetNamespaceDirectories()
    {
        gHomeDirectory   = GetSpecialDir(FOLDERID_RoamingAppData);
        gApplicationData = GetSpecialDir(FOLDERID_ProgramData);
        gSystemLibPath   = GetSpecialDir(FOLDERID_System);
        gUserHomeDirectory = GetSpecialDir(FOLDERID_Profile);
        gAdminWritableAppDirectory = gApplicationData;
        gUserWritableAppData = gHomeDirectory;
        gProgramsFolder = GetSpecialDir(FOLDERID_UserProgramFiles);
    }

#elif defined(AURORA_PLATFORM_LINUX) || defined(AURORA_PLATFORM_BSD)

    static void SetUnixPaths(AuOptional<AuString> &primary, AuOptional<AuString> &secondary, const AuString &base)
    {
        primary = base;

        if (Aurora::Build::IsPlatformX32())
        {
            secondary = base + "32";
        }
        else
        {
            secondary = base + "64";
        }
        
        if (DirExists(*secondary))
        {
            std::swap(secondary, primary);
        }
        else
        {
            secondary.reset();
        }
        
        if (!DirExists(*primary))
        {
            primary.reset();
        }
    }

    static void SetXdg(AuString &out, const char *envvar, const char *home, const char *defaultHomeExt, const char *fallback)
    {
        auto value = getenv(envvar);

        if (value)
        {
            out  = value;
        }
        else if (home)
        {
            out = AuString(home) + defaultHomeExt;
        }
        else
        {
            out = fallback;
        }
    }

    static void SetNamespaceDirectories()
    {
        const char *homedir;

        homedir = getenv("HOME");
        if (!homedir)
        {
            homedir = getpwuid(getuid())->pw_dir;
        }

        gUserHomeDirectory = homedir;

        // XDG Base Directory Specification
        // $XDG_CONFIG_HOME defines the base directory relative to which user-specific configuration files should be stored. If $XDG_CONFIG_HOME is either not set or empty, a default equal to $HOME/.config should be used.
        // $XDG_DATA_HOME defines the base directory relative to which user-specific data files should be stored
        SetXdg(gApplicationData, "XDG_CONFIG_HOME", homedir, "/.config", kUnixAppData);
        SetXdg(gHomeDirectory, "XDG_DATA_HOME", homedir, "/.local/share", ".");

        // https://www.freedesktop.org/wiki/Software/systemd/TheCaseForTheUsrMerge/
        // Arch 2012: https://archlinux.org/news/the-lib-directory-becomes-a-symlink/
        // Ubuntu 2018 (mandatory 2021+): https://lists.ubuntu.com/archives/ubuntu-devel-announce/2018-November/001253.html https://wiki.debian.org/UsrMerge
        // Fedora (2011?): https://fedoraproject.org/wiki/Features/UsrMove
        SetUnixPaths(gUserLibPath, gUserLibPath2, "/usr/local/lib");
        SetUnixPaths(gSystemLibPath, gSystemLibPath2, "/usr/lib");

        gProgramsFolder = "/opt";
        gGlobalWritableAppDirectory = "/opt";
        gAdminWritableAppDirectory = kUnixAppData;
        gUserWritableAppData = gApplicationData;
    }

#else

    static void SetNamespaceDirectories()
    {
        gHomeDirectory   = ".";
        gApplicationData = ".";
    }

#endif

    AuOptional<AuString> GetSystemLibPath()
    {
        return gSystemLibPath;
    }

    AuOptional<AuString> GetUserLibPath()
    {
        return gUserLibPath;
    }

    AuOptional<AuString> GetSystemLibPath2()
    {
        return gSystemLibPath2;
    }

    AuOptional<AuString> GetUserLibPath2()
    {
        return gUserLibPath2;
    }

    static void ChangeDir()
    {
    #if !defined(AU_NO_AU_HOME_BRANDING)
        if (gRuntimeConfig.fio.defaultBrand.size())
        {
            gApplicationData += "/" + gRuntimeConfig.fio.defaultBrand;
            gHomeDirectory   += "/" + gRuntimeConfig.fio.defaultBrand;
            gProgramsFolder  += "/" + gRuntimeConfig.fio.defaultBrand;
        }
    #endif

    #if defined(AURORA_PLATFORM_WIN32)
        
        if (gRuntimeConfig.fio.defaultBrand.empty())
        {
            gApplicationData += "/AllUsers";
        }

        if (!FS::DirExists(gApplicationData))
        {
            if (FS::DirMk(gApplicationData))
            {
                Win32FixGlobalAppDataAcl(gApplicationData);
            }
        }
    #endif

        NormalizePath(gApplicationData);
        NormalizePath(gProgramsFolder);
        NormalizePath(gHomeDirectory);

        if ((gApplicationData == gHomeDirectory) || (gApplicationData == gProgramsFolder))
        {
            gApplicationData += kPathSplitter;
            gHomeDirectory   += kPathSplitter;
            gApplicationData += "System";
            gHomeDirectory   += "Profile";
        }
        
        // Noting we append a path splitter to prevent hair pulling over missing path delimiters
        // Eg: GetHome() + "myAwesomeApp/Config" = %HOME%/Aurora/ProfilemyAwsomeApp/Config
        gApplicationData += kPathSplitter;
        gHomeDirectory   += kPathSplitter;
        gProgramsFolder  += kPathSplitter;
    }

    void InitResources()
    {
        SetNamespaceDirectories();
        ChangeDir();
    }

    AUKN_SYM bool GetAppData(AuString &path)
    {
        path.clear();
        if (gUserWritableAppData.empty())
        {
            return false;
        }
        path = gUserWritableAppData;
        return true;
    }

    AUKN_SYM bool GetUserHome(AuString &path)
    {
        path.clear();
        if (gUserHomeDirectory.empty())
        {
            return false;
        }
        path = gUserHomeDirectory;
        return true;
    }

    AUKN_SYM bool GetPackagePath(AuString &path)
    {
        // TODO: iOS/mac OS -> CFBundleCopyResourcesDirectoryURL
        return Process::GetProcDirectory(path);
    }

    AUKN_SYM bool GetWritableAppdata(AuString &path)
    {
        path.clear();
        if (gGlobalWritableAppDirectory.empty())
        {
            return false;
        }
        path = gGlobalWritableAppDirectory;
        return true;
    }

    AUKN_SYM bool GetRootAppdata(AuString &path)
    {
        path.clear();
        if (gAdminWritableAppDirectory.empty())
        {
            return false;
        }
        path = gAdminWritableAppDirectory;
        return true;
    }

    AUKN_SYM bool GetUserProgramsFolder(AuString &path)
    {
        path.clear();
        if (gProgramsFolder.empty())
        {
            return false;
        }
        path = gProgramsFolder;
        return true;
    }

#if defined(AURORA_PLATFORM_WIN32)
    static void Win32FixGlobalAppDataAcl(const AuString &path)
    {
        BOOL bRetval = FALSE;

        HANDLE hToken = NULL; 
        PSID pSIDEveryone = NULL;
        PACL pACL = NULL;
        SID_IDENTIFIER_AUTHORITY SIDAuthWorld =
                SECURITY_WORLD_SID_AUTHORITY;
        const int NUM_ACES  = 1;
        EXPLICIT_ACCESS ea[NUM_ACES];
        DWORD dwRes;

        // Specify the DACL to use.
        // Create a SID for the Everyone group.
        if (!AllocateAndInitializeSid(&SIDAuthWorld, 1,
                         SECURITY_WORLD_RID,
                         0,
                         0, 0, 0, 0, 0, 0,
                         &pSIDEveryone)) 
        {
            SysPushErrorFIO("AllocateAndInitializeSid (Everyone) error");
            goto Cleanup;
        }

        ZeroMemory(&ea, NUM_ACES * sizeof(EXPLICIT_ACCESS));

        // Set read access for Everyone.
        ea[0].grfAccessPermissions = GENERIC_ALL;
        ea[0].grfAccessMode = SET_ACCESS;
        ea[0].grfInheritance = SUB_CONTAINERS_AND_OBJECTS_INHERIT;
        ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
        ea[0].Trustee.TrusteeType = TRUSTEE_IS_WELL_KNOWN_GROUP;
        ea[0].Trustee.ptstrName = (LPTSTR) pSIDEveryone;

        if (ERROR_SUCCESS != SetEntriesInAcl(NUM_ACES,
                                             ea,
                                             NULL,
                                             &pACL))
        {
            SysPushErrorFIO("Failed SetEntriesInAcl");
            goto Cleanup;
        }

        // Try to modify the object's DACL.
        dwRes = SetNamedSecurityInfoW(
            Locale::ConvertFromUTF8(FS::NormalizePathRet(path)).data(), // name of the object
            SE_FILE_OBJECT,              // type of object
            DACL_SECURITY_INFORMATION,   // change only the object's DACL
            NULL, NULL,                  // do not change owner or group
            pACL,                        // DACL specified
            NULL);                       // do not change SACL

        if (ERROR_SUCCESS == dwRes) 
        {
            bRetval = TRUE;
            // No more processing needed.
            goto Cleanup;
        }
        if (dwRes != ERROR_ACCESS_DENIED)
        {
            SysPushErrorFIO("First SetNamedSecurityInfo call failed: {}", dwRes); 
            goto Cleanup;
        }

    Cleanup:
  
        if (pSIDEveryone)
        {
            FreeSid(pSIDEveryone); 
        }

        if (pACL)
        {
            LocalFree(pACL);
        }

        if (hToken)
        {
            CloseHandle(hToken);
        }

        if (!bRetval)
        {
            AuLogError("Couldn't grant ownership to EVERYONE; System wide configuration directory {} will be inaccessible to other users", path);
        }
    }
#endif
}