ppsspp/Core/PSPLoaders.cpp

// Copyright (C) 2012 PPSSPP Project

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0 or later versions.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official git repository and contact information can be found at
// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.

#include <algorithm>
#include <iterator>
#include <thread>

#include "Core/Core.h"
#include "Common/Thread/ThreadUtil.h"
#include "Common/System/Request.h"

#include "Common/File/AndroidContentURI.h"
#include "Common/File/FileUtil.h"
#include "Common/StringUtils.h"
#ifdef _WIN32
#include "Common/CommonWindows.h"
#endif
#include "Common/Data/Text/I18n.h"
#include "Common/System/OSD.h"

#include "Core/ELF/ParamSFO.h"
#include "Core/ELF/PBPReader.h"
#include "Core/ELF/PrxDecrypter.h"

#include "Core/FileSystems/BlockDevices.h"
#include "Core/FileSystems/BlobFileSystem.h"
#include "Core/FileSystems/DirectoryFileSystem.h"
#include "Core/FileSystems/ISOFileSystem.h"
#include "Core/FileSystems/MetaFileSystem.h"
#include "Core/FileSystems/VirtualDiscFileSystem.h"

#include "Core/Loaders.h"
#include "Core/MemMap.h"
#include "Core/HDRemaster.h"
#include "Core/Util/PathUtil.h"
#include "Core/MIPS/MIPS.h"

#include "Core/Config.h"
#include "Core/ConfigValues.h"
#include "Core/System.h"
#include "Core/PSPLoaders.h"
#include "Core/HLE/sceKernelModule.h"
#include "Core/HLE/PopsBoot.h"

static void UseLargeMem(int memsize) {
	if (memsize != 1) {
		// Nothing requested.
		return;
	}

	if (Memory::g_PSPModel != PSP_MODEL_FAT) {
		INFO_LOG(Log::Loader, "Game requested full PSP-2000 memory access");
		Memory::g_MemorySize = Memory::RAM_DOUBLE_SIZE;
	} else {
		WARN_LOG(Log::Loader, "Game requested full PSP-2000 memory access, ignoring in PSP-1000 mode");
	}
}

void DumpBlockDeviceAsync(std::shared_ptr<BlockDevice> bd, Path destPath, std::string title) {
	NPDRMDemoBlockDevice *npdrmDemoBD = dynamic_cast<NPDRMDemoBlockDevice *>(bd.get());
	if (npdrmDemoBD) {
		INFO_LOG(Log::System, "Dumping NPDRM demo ISO... (%s)", destPath.c_str());
		std::thread dumpThread([bd, title, destPath]() {
			SetCurrentThreadName("DumpBlockDevice");
			AndroidJNIThreadContext jniContext;  // destPath can be a content URI.
			File::CreateFullPath(destPath.NavigateUp());
			if (File::Exists(destPath)) {
				INFO_LOG(Log::System, "Dump file already exists, skipping: %s", destPath.c_str());
				return;
			}
			FILE *dest = File::OpenCFile(destPath, "wb");
			if (!dest) {
				ERROR_LOG(Log::System, "Failed to open destination for NPDRM demo ISO dump: %s", destPath.c_str());
				return;
			}
			g_OSD.SetProgressBar("npdrm_dump", title, 0.0f, 1.0f, 0.0f, 0.0f);
			int blocks = bd->GetNumBlocks();
			std::vector<u8> blockBuf(bd->GetBlockSize());
			for (int i = 0; i < blocks; i++) {
				bd->ReadBlock(i, blockBuf.data());
				fwrite(blockBuf.data(), 1, blockBuf.size(), dest);
				g_OSD.SetProgressBar("npdrm_dump", title, 0.0f, 1.0f, (float)(i + 1) / blocks, 0.0f);
			}
			fclose(dest);
			g_OSD.RemoveProgressBar("npdrm_dump", true, 1.0f);
			g_OSD.Show(OSDType::MESSAGE_SUCCESS, title, GetFriendlyPath(destPath), 5.0f, "npdrm_finished");
			if (System_GetPropertyBool(SYSPROP_CAN_SHOW_FILE)) {
				g_OSD.SetClickCallback("npdrm_finished", [destPath]() {
					System_ShowFileInFolder(destPath);
				});
			}
			INFO_LOG(Log::System, "Finished dumping NPDRM demo ISO... (%s)", title.c_str());
		});
		dumpThread.detach();
	}
}

bool MountGameISO(FileLoader *fileLoader, std::string *errorString) {
	std::shared_ptr<IFileSystem> fileSystem;
	std::shared_ptr<IFileSystem> blockSystem;

	if (fileLoader->IsDirectory()) {
		fileSystem = std::make_shared<VirtualDiscFileSystem>(&pspFileSystem, fileLoader->GetPath());
		blockSystem = fileSystem;
	} else {
		std::shared_ptr<BlockDevice> bd(ConstructBlockDevice(fileLoader, errorString));
		if (!bd) {
			// Can only fail if the ISO is bad.
			return false;
		}

		auto iso = std::make_shared<ISOFileSystem>(&pspFileSystem, bd);
		fileSystem = iso;
		blockSystem = std::make_shared<ISOBlockSystem>(iso);
	}

	pspFileSystem.Mount("umd0:", blockSystem);
	pspFileSystem.Mount("umd1:", blockSystem);
	pspFileSystem.Mount("umd:", blockSystem);
	pspFileSystem.Mount("disc0:", fileSystem);
	return true;
}

bool LoadParamSFOFromDisc() {
	std::string sfoPath("disc0:/PSP_GAME/PARAM.SFO");
	PSPFileInfo fileInfo = pspFileSystem.GetFileInfo(sfoPath.c_str());
	if (fileInfo.exists) {
		std::vector<u8> paramsfo;
		pspFileSystem.ReadEntireFile(sfoPath, paramsfo);
		if (g_paramSFO.ReadSFO(paramsfo)) {
			g_paramSFORaw = g_paramSFO;
			return true;
		}
	}
	return false;
}

// We gather the game info before actually loading/booting the ISO
// to determine if the emulator should enable extra memory and
// double-sized texture coordinates.
void InitMemorySizeForGame() {
	std::string gameID;
	std::string umdData;

	if (g_paramSFO.IsValid()) {
		UseLargeMem(g_paramSFO.GetValueInt("MEMSIZE"));
		gameID = g_paramSFO.GetValueString("DISC_ID");
	}

	for (size_t i = 0; i < g_HDRemastersCount; i++) {
		const auto &entry = g_HDRemasters[i];
		if (entry.gameID != gameID) {
			continue;
		}

		if (umdData.empty()) {
			// A real UMD_DATA.BIN is a few dozen bytes - it's just the disc ID line matched below.
			// Check the size first: this comes off the disc image, which is not something we trust,
			// and ReadEntireFile has no limit of its own - it would resize a vector to whatever the
			// image claims, and the string copy after it doubles that.
			const s64 MAX_UMD_DATA_SIZE = 4096;
			const PSPFileInfo info = pspFileSystem.GetFileInfo("disc0:/UMD_DATA.BIN");
			if (info.exists && info.size > MAX_UMD_DATA_SIZE) {
				WARN_LOG(Log::Loader, "Ignoring implausibly large UMD_DATA.BIN (%lld bytes)", (long long)info.size);
			} else if (info.exists) {
				std::vector<u8> umdDataBin;
				// .data() rather than &umdDataBin[0] - the file can legitimately be empty, and
				// indexing an empty vector is undefined.
				if (pspFileSystem.ReadEntireFile("disc0:/UMD_DATA.BIN", umdDataBin) >= 0) {
					umdData = std::string((const char *)umdDataBin.data(), umdDataBin.size());
				}
			}
		}

		if (entry.umdDataValue && umdData.find(entry.umdDataValue) == umdData.npos) {
			continue;
		}

		g_RemasterMode = true;
		Memory::g_MemorySize = entry.memorySize;
		g_DoubleTextureCoordinates = entry.doubleTextureCoordinates;
		break;
	}
	if (g_RemasterMode) {
		INFO_LOG(Log::Loader, "HDRemaster found, using increased memory");
	}
}

bool LoadParamSFOFromPBP(FileLoader *fileLoader) {
	PBPReader pbp(fileLoader);
	if (pbp.IsValid() && !pbp.IsELF()) {
		std::vector<u8> sfoData;
		if (pbp.GetSubFile(PBP_PARAM_SFO, &sfoData)) {
			// Carefully parse param SFO for PBP files.
			ParamSFOData paramSFO;
			if (paramSFO.ReadSFO(sfoData)) {
				g_paramSFORaw = paramSFO;
				std::string title = paramSFO.GetValueString("TITLE");
				if (g_paramSFO.GetValueString("TITLE").empty() && !title.empty()) {
					g_paramSFO.SetValue("TITLE", title, (int)title.size());
				}

				// Copy over the MEMSIZE flag for later inspection.
				if (paramSFO.HasKey("MEMSIZE")) {
					g_paramSFO.SetValue("MEMSIZE", paramSFO.GetValueInt("MEMSIZE"), 4);
				}

				std::string discID = paramSFO.GetValueString("DISC_ID");
				std::string systemVer = paramSFO.GetValueString("PSP_SYSTEM_VER");
				// Homebrew typically always leave this zero.
				bool discTotalCheck = paramSFO.GetValueInt("DISC_TOTAL") != 0;
				// A lot of homebrew reuse real game disc IDs - avoid.
				bool formatCheck = discID.substr(0, 2) != "NP" && discID.substr(0, 2) != "UL" && discID.substr(0, 2) != "UC";
				char region = discID.size() > 3 ? discID[2] : '\0';
				bool regionCheck = region != 'A' && region != 'E' && region != 'H' && region != 'I' && region != 'J' && region != 'K' && region != 'U' && region != 'X';
				bool systemVerCheck = !systemVer.empty() && systemVer[0] >= '5';
				if ((formatCheck || regionCheck || discTotalCheck || systemVerCheck) && !discID.empty()) {
					// This is NOT a homebrew, so we set the ID. Otherwise it'll later be generated
					// on the first access. This is kinda backwards and weird.
					g_paramSFO.SetValue("DISC_ID", discID, (int)discID.size());
					std::string ver = paramSFO.GetValueString("DISC_VERSION");
					if (ver.empty())
						ver = "1.00";
					g_paramSFO.SetValue("DISC_VERSION", ver, (int)ver.size());
				}
				return true;
			}
		}
	}
	return false;
}


// Chinese translators like to rename EBOOT.BIN and replace it with some kind of stub
// that probably loads a plugin and then launches the actual game. These stubs don't work in PPSSPP.
// No idea why they are doing this, but it works to just bypass it. They could stop
// inventing new filenames though...
static const char * const altBootNames[] = {
	"disc0:/PSP_GAME/SYSDIR/EBOOT.OLD",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.DAT",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.BI",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.LLD",
	//"disc0:/PSP_GAME/SYSDIR/OLD_EBOOT.BIN", //Utawareru Mono Chinese version
	"disc0:/PSP_GAME/SYSDIR/EBOOT.123",
	//"disc0:/PSP_GAME/SYSDIR/EBOOT_LRC_CH.BIN", // Hatsune Miku Project Diva Extend chinese version
	"disc0:/PSP_GAME/SYSDIR/BOOT0.OLD",
	"disc0:/PSP_GAME/SYSDIR/BOOT1.OLD",
	"disc0:/PSP_GAME/SYSDIR/BINOT.BIN",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.FRY",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.Z.Y",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.LEI",
	"disc0:/PSP_GAME/SYSDIR/EBOOT.DNR",
	"disc0:/PSP_GAME/SYSDIR/DBZ2.BIN",
	//"disc0:/PSP_GAME/SYSDIR/ss.RAW",//Code Geass: Lost Colors chinese version
};

// A game update installed from a .pkg (see Core/Util/PkgUnpack.h) lands in PSP/GAME/<DISC_ID>/,
// with the patched executable as PBOOT.PBP. The PSP boots that instead of the disc's own EBOOT,
// leaving the disc mounted - so the update overrides the files it ships and the disc supplies
// everything else.

static bool ReadPBPParamSFO(const std::string &path, ParamSFOData *sfo) {
	const int fd = pspFileSystem.OpenFile(path, FILEACCESS_READ);
	if (fd < 0) {
		return false;
	}

	bool success = false;
	// A PBP starts with its magic, a version, and eight little-endian subfile offsets. PARAM.SFO
	// is the first subfile, so it runs from its own offset to ICON0.PNG's.
	u8 header[0x28];
	if (pspFileSystem.ReadFile(fd, header, sizeof(header)) == sizeof(header) && !memcmp(header, "\0PBP", 4)) {
		u32_le sfoOffset, iconOffset;
		memcpy(&sfoOffset, header + 0x08, sizeof(sfoOffset));
		memcpy(&iconOffset, header + 0x0C, sizeof(iconOffset));
		const u32 sfoSize = iconOffset - sfoOffset;
		if (sfoOffset >= sizeof(header) && iconOffset > sfoOffset && sfoSize <= 64 * 1024) {
			std::vector<u8> sfoData(sfoSize);
			if (pspFileSystem.SeekFile(fd, sfoOffset, FILEMOVE_BEGIN) >= 0 &&
				pspFileSystem.ReadFile(fd, sfoData.data(), sfoSize) == sfoSize) {
				success = sfo->ReadSFO(sfoData);
			}
		}
	}
	pspFileSystem.CloseFile(fd);
	return success;
}

// Returns the path of the update to boot, or an empty string to boot the disc normally.
static std::string FindGameUpdatePBOOT(const std::string &discId, const std::string &discVersion) {
	if (discId.empty()) {
		return std::string();
	}
	const std::string path = "ms0:/PSP/GAME/" + discId + "/PBOOT.PBP";
	if (!pspFileSystem.GetFileInfo(path).exists) {
		return std::string();
	}

	// Check what the update claims to patch before handing it the boot.
	ParamSFOData sfo;
	if (!ReadPBPParamSFO(path, &sfo)) {
		WARN_LOG(Log::Loader, "Ignoring '%s': couldn't read its PARAM.SFO", path.c_str());
		return std::string();
	}

	const std::string updateDiscId = sfo.GetValueString("DISC_ID");
	if (updateDiscId != discId) {
		WARN_LOG(Log::Loader, "Ignoring '%s': it's an update for %s, not %s", path.c_str(), updateDiscId.c_str(), discId.c_str());
		return std::string();
	}

	// The disc version is advisory here. An update is built against one specific revision of a
	// disc, but refusing to run one on a slightly different dump is a worse failure than letting
	// the user find out - they went and installed it on purpose.
	const std::string updateDiscVersion = sfo.GetValueString("DISC_VERSION");
	if (!updateDiscVersion.empty() && !discVersion.empty() && updateDiscVersion != discVersion) {
		WARN_LOG(Log::Loader, "Game update '%s' is for disc version %s, but this disc is %s. Booting it anyway.",
			path.c_str(), updateDiscVersion.c_str(), discVersion.c_str());
	}

	NOTICE_LOG(Log::Loader, "Booting game update '%s' (app version %s) instead of the disc's executable",
		path.c_str(), sfo.GetValueString("APP_VER").c_str());
	return path;
}

// A game patch download that was meant to be installed by the PSP's install utility (a DRM BB install
// package, see pspReadDrmBBPackage) sits in PSP/GAME/<DISC_ID>/ as an EBOOT.PBP the XMB won't start.
// The game's boot program installs it, but only when started with -i, which the game did itself after
// its online download and nothing does any more. So install it here, the way psheet does: the files
// it holds go next to it, and its own EBOOT.PBP replaces it. The .PRX modules are written as the
// package has them rather than tied to a console, so this only happens when we can decrypt them.
// Only a few games had such downloads. These are the ones whose modules g_kirk2Results in
// PrxDecrypter.cpp covers; add a game here along with its entries there.
static const char * const drmBBPackageGames[] = {
	"UCES00279",  // Killzone: Liberation (EU)
	"UCUS98646",  // Killzone: Liberation (US)
};

static void InstallDrmBBPackage(const std::string &discId) {
	if (std::find(std::begin(drmBBPackageGames), std::end(drmBBPackageGames), discId) == std::end(drmBBPackageGames)) {
		return;
	}
	const std::string dir = "ms0:/PSP/GAME/" + discId + "/";
	// The boot program's check: anything smaller is the EBOOT.PBP an install leaves behind.
	const PSPFileInfo info = pspFileSystem.GetFileInfo(dir + "EBOOT.PBP");
	if (!info.exists || info.size <= 0x100000) {
		return;
	}

	const char *osdId = "drmbbinstall";
	auto di = GetI18NCategory(I18NCat::DIALOG);
	g_OSD.SetProgressBar(osdId, di->T("Installing..."), 0.0f, 0.0f, 0.0f, 0.0f);

	std::vector<u8> pbp;
	std::vector<DrmBBFile> files;
	u8 secureId[16];
	if (pspFileSystem.ReadEntireFile(dir + "EBOOT.PBP", pbp) < 0 || !pspReadDrmBBPackage(pbp, nullptr, files, secureId)) {
		g_OSD.RemoveProgressBar(osdId, false, 0.0f);
		return;
	}

	bool hasEboot = false;
	for (const DrmBBFile &file : files) {
		if (file.name == "EBOOT.PBP") {
			hasEboot = true;
		} else if (endsWith(file.name, ".PRX")) {
			std::vector<u8> out(file.data.size());
			if (file.data.size() < 0x150 || pspDecryptPRX(file.data.data(), out.data(), (u32)file.data.size(), secureId) <= 0) {
				WARN_LOG(Log::Loader, "Not installing %sEBOOT.PBP: can't decrypt its %s without installing it on a PSP", dir.c_str(), file.name.c_str());
				g_OSD.RemoveProgressBar(osdId, false, 0.0f);
				return;
			}
		} else {
			// The install re-encrypts other files for the console as PGDs. Nothing we know of has any.
			WARN_LOG(Log::Loader, "Not installing %sEBOOT.PBP: don't know what to do with its %s", dir.c_str(), file.name.c_str());
			g_OSD.RemoveProgressBar(osdId, false, 0.0f);
			return;
		}
	}
	// psheet fails the install without one.
	if (!hasEboot) {
		g_OSD.RemoveProgressBar(osdId, false, 0.0f);
		return;
	}

	auto writeFile = [](const std::string &path, const std::vector<u8> &data) {
		const int fd = pspFileSystem.OpenFile(path, (FileAccess)(FILEACCESS_WRITE | FILEACCESS_CREATE | FILEACCESS_TRUNCATE));
		if (fd < 0) {
			return false;
		}
		const bool ok = pspFileSystem.WriteFile(fd, data.data(), data.size()) == data.size();
		pspFileSystem.CloseFile(fd);
		return ok;
	};
	// Like psheet, the new EBOOT.PBP goes in as _TEMP.PBP and is renamed last.
	for (const DrmBBFile &file : files) {
		const std::string path = dir + (file.name == "EBOOT.PBP" ? "_TEMP.PBP" : file.name);
		if (!writeFile(path, file.data)) {
			ERROR_LOG(Log::Loader, "Couldn't write %s while installing %sEBOOT.PBP", path.c_str(), dir.c_str());
			g_OSD.RemoveProgressBar(osdId, false, 0.0f);
			return;
		}
	}
	pspFileSystem.RemoveFile(dir + "EBOOT.PBP");
	pspFileSystem.RenameFile(dir + "_TEMP.PBP", dir + "EBOOT.PBP");
	g_OSD.RemoveProgressBar(osdId, true, 0.0f);
	NOTICE_LOG(Log::Loader, "Installed the game patch in %s", dir.c_str());
}

bool Load_PSP_ISO(FileLoader *fileLoader, std::string *error_string) {
	const std::string id = g_paramSFO.GetValueString("DISC_ID");

	InstallDrmBBPackage(id);

	// An installed game update replaces the disc's executable - see FindGameUpdatePBOOT above.
	std::string bootpath = FindGameUpdatePBOOT(id, g_paramSFO.GetValueString("DISC_VERSION"));
	if (bootpath.empty()) {
		bootpath = "disc0:/PSP_GAME/SYSDIR/EBOOT.BIN";

		// Bypass Chinese translation patches, see comment above.
		for (size_t i = 0; i < ARRAY_SIZE(altBootNames); i++) {
			if (pspFileSystem.GetFileInfo(altBootNames[i]).exists) {
				WARN_LOG(Log::Boot, "Bypassing suspected translation patch. Booting '%s' instead of '%s'.", altBootNames[i], bootpath.c_str());
				bootpath = altBootNames[i];
				// break;  // should have a break here, but it would effectively reverse the evaluation order.
			}
		}

		// Bypass another more dangerous one where the file is in USRDIR - this could collide with files in some game.
		if (id == "NPJH50624" && pspFileSystem.GetFileInfo("disc0:/PSP_GAME/USRDIR/PAKFILE2.BIN").exists) {
			bootpath = "disc0:/PSP_GAME/USRDIR/PAKFILE2.BIN";
		}
		if (id == "NPJH00100" && pspFileSystem.GetFileInfo("disc0:/PSP_GAME/USRDIR/DATA/GIM/GBL").exists) {
			bootpath = "disc0:/PSP_GAME/USRDIR/DATA/GIM/GBL";
		}

		bool hasEncrypted = false;
		int fd;
		if ((fd = pspFileSystem.OpenFile(bootpath, FILEACCESS_READ)) >= 0) {
			u8 head[4]{};
			// A file shorter than the magic used to leave head partly uninitialized, and then decided
			// which boot file to use by comparing against it.
			if (pspFileSystem.ReadFile(fd, head, sizeof(head)) == sizeof(head)) {
				if (memcmp(head, "~PSP", 4) == 0 || memcmp(head, "\x7F""ELF", 4) == 0) {
					hasEncrypted = true;
				}
			}
			pspFileSystem.CloseFile(fd);
		}

		if (!hasEncrypted) {
			// try unencrypted Boot.BIN
			bootpath = "disc0:/PSP_GAME/SYSDIR/BOOT.BIN";
		}
	}

	// Fail early with a clearer message for some types of ISOs.
	if (!pspFileSystem.GetFileInfo(bootpath).exists) {
		// Can't tell for sure if it's PS1 or PS2, but doesn't much matter.
		if (pspFileSystem.GetFileInfo("disc0:/SYSTEM.CNF;1").exists || pspFileSystem.GetFileInfo("disc0:/PSX.EXE;1").exists) {
			*error_string = "PPSSPP plays PSP games, not PlayStation 1 or 2 games.";
		} else if (pspFileSystem.GetFileInfo("disc0:/UMD_VIDEO/PLAYLIST.UMD").exists) {
			*error_string = "PPSSPP doesn't support UMD Video.";
		} else if (pspFileSystem.GetFileInfo("disc0:/UMD_AUDIO/PLAYLIST.UMD").exists) {
			*error_string = "PPSSPP doesn't support UMD Music.";
		} else if (pspFileSystem.GetDirListing("disc0:/").empty()) {
			*error_string = "Not a valid disc image.";
		} else {
			*error_string = "A PSP game couldn't be found on the disc.";
		}
		return false;
	}

	// If there's a game-specific config, load it.
	g_Config.LoadGameConfig(id);

	System_PostUIMessage(UIMessage::CONFIG_LOADED);
	INFO_LOG(Log::Loader, "Loading %s...", bootpath.c_str());
	// TODO: We can't use the initial error_string pointer.
	return __KernelLoadExec(currentMIPS, bootpath.c_str(), 0, &PSP_CoreParameter().errorString);
}

// TODO: Move this to common. Merge with ResolvePath?
static Path NormalizePath(const Path &path) {
	if (path.Type() != PathType::NATIVE) {
		// Nothing to do - these can't be non-normalized.
		return path;
	}

#ifdef _WIN32
	const std::wstring wpath = path.ToWString();
	std::wstring buf;
	buf.resize(512);
	// On success GetFullPathName returns the length without the terminator; if the buffer is too
	// small it returns the required length *including* it, and on failure it returns 0. A zero used
	// to fall through both branches below and hand back 512 characters of uninitialized buffer.
	DWORD sz = GetFullPathName(wpath.c_str(), (DWORD)buf.size(), buf.data(), nullptr);
	if (sz >= buf.size()) {
		buf.resize(sz);
		sz = GetFullPathName(wpath.c_str(), (DWORD)buf.size(), buf.data(), nullptr);
	}
	if (sz == 0 || sz >= buf.size()) {
		WARN_LOG(Log::Loader, "GetFullPathName failed for '%s'", path.c_str());
		return Path();
	}
	// Truncates off the null terminator.
	buf.resize(sz);
	return Path(buf);
#else
	char buf[PATH_MAX + 1];
	if (!realpath(path.c_str(), buf))
		return Path();
	return Path(buf);
#endif
}

bool Load_PSP_ELF_PBP(FileLoader *fileLoader, std::string_view discId, bool loadGameConfigs, std::string *error_string) {
	// This is really just for headless, might need tweaking later.
	if (PSP_CoreParameter().mountIsoLoader != nullptr) {
		std::shared_ptr<BlockDevice> bd(ConstructBlockDevice(PSP_CoreParameter().mountIsoLoader, error_string));
		if (bd) {
			auto umd2 = std::make_shared<ISOFileSystem>(&pspFileSystem, bd);
			auto blockSystem = std::make_shared<ISOBlockSystem>(umd2);

			pspFileSystem.Mount("umd1:", blockSystem);
			pspFileSystem.Mount("disc0:", umd2);
			pspFileSystem.Mount("umd:", blockSystem);
		} else {
			ERROR_LOG(Log::Loader, "mountIso failed: %s", error_string->c_str());
		}
	}

	Path full_path = fileLoader->GetPath();
	std::string path = full_path.GetDirectory();
	std::string file = full_path.GetFilename();

	if (full_path.Type() == PathType::CONTENT_URI) {
		path = AndroidContentURI(full_path.GetDirectory()).FilePath();
	}

	// TODO: More robust check.
	size_t pos = path.find("PSP/GAME/");
	std::string ms_path;
	if (pos != std::string::npos) {
		ms_path = "ms0:/" + path.substr(pos) + "/";
	} else {
		// We map host0: to the containing directory, see below. This will also be set as the current dir
		ms_path = "host0:/";
	}

	Path host0Dir;
	if (!PSP_CoreParameter().mountRoot.empty()) {
		// We don't want to worry about .. and cwd and such.
		const Path rootNorm = NormalizePath(PSP_CoreParameter().mountRoot);
		Path pathNorm = NormalizePath(Path(path));

		if (full_path.Type() == PathType::CONTENT_URI) {
			pathNorm = full_path.NavigateUp();
		}

		// Path::StartsWith() returns true for an empty argument, so an unresolvable mountRoot would
		// make the containment check below pass for any path at all.
		if (rootNorm.empty() || pathNorm.empty()) {
			*error_string = "Cannot boot ELF - couldn't resolve its path or mountRoot.";
			return false;
		}

		// If root is not a subpath of path, we can't boot the game.
		if (!pathNorm.StartsWith(rootNorm)) {
			*error_string = "Cannot boot ELF located outside mountRoot.";
			return false;
		}

		std::string filepath;
		if (full_path.Type() == PathType::CONTENT_URI) {
			const std::string rootFilePath = AndroidContentURI(rootNorm.c_str()).FilePath();
			const std::string pathFilePath = AndroidContentURI(pathNorm.c_str()).FilePath();
			// StartsWith above compared the URIs. That doesn't mean the decoded file paths have the
			// same prefix relationship, and substr() throws when they don't.
			if (!startsWith(pathFilePath, rootFilePath)) {
				*error_string = "Cannot boot ELF located outside mountRoot.";
				return false;
			}
			filepath = pathFilePath.substr(rootFilePath.size());
		} else {
			filepath = ReplaceAll(pathNorm.ToString().substr(rootNorm.ToString().size()), "\\", "/");
		}

		file = filepath + "/" + file;
		path = rootNorm.ToString();
		pspFileSystem.SetStartingDirectory(filepath);
		host0Dir = Path(path);
	} else {
		pspFileSystem.SetStartingDirectory(ms_path);
		host0Dir = full_path.NavigateUp();
	}

	auto fs = std::make_shared<DirectoryFileSystem>(&pspFileSystem, host0Dir, FileSystemFlags::SIMULATE_FAT32 | FileSystemFlags::CARD);
	pspFileSystem.Mount("host0:", fs);

	std::string finalName = ms_path + file;

	std::string homebrewName = PSP_CoreParameter().fileToStart.ToVisualString();
	std::size_t lslash = homebrewName.find_last_of('/');
	std::size_t rslash = homebrewName.find_last_of('\\');
	if (lslash != homebrewName.npos) {
		homebrewName = homebrewName.substr(lslash + 1);
	}
	if (rslash != homebrewName.npos) {
		homebrewName = homebrewName.substr(rslash + 1);
	}
	std::string discID = g_paramSFO.GetDiscID();
	std::string discVersion = g_paramSFO.GetValueString("DISC_VERSION");
	std::string madeUpID = g_paramSFO.GenerateFakeID(Path());

	// TODO: This was long enough ago that I think this can be safely removed.
	// Migrate old save states from old versions of fake game IDs.
	// Ugh, this might actually be slow on Android.
	// The strings here are attacker-controlled (from PARAM.SFO / filenames), so
	// if any of them contain a path separator, skip the migration to avoid
	// building traversal paths.
	const bool anyPathSeparator =
		HasPathTraversal(discID) || HasPathTraversal(discVersion) ||
		HasPathTraversal(homebrewName) || HasPathTraversal(madeUpID);
	const Path savestateDir = GetSysDirectory(DIRECTORY_SAVESTATE);
	for (int i = 0; i < 5 && !anyPathSeparator; ++i) {
		Path newPrefix = savestateDir / StringFromFormat("%s_%s_%d", discID.c_str(), discVersion.c_str(), i);
		Path oldNamePrefix = savestateDir / StringFromFormat("%s_%d", homebrewName.c_str(), i);
		Path oldIDPrefix = savestateDir / StringFromFormat("%s_1.00_%d", madeUpID.c_str(), i);

		if (oldIDPrefix != newPrefix && File::Exists(oldIDPrefix.WithExtraExtension(".ppst")))
			File::Rename(oldIDPrefix.WithExtraExtension(".ppst"), newPrefix.WithExtraExtension(".ppst"));
		else if (File::Exists(oldNamePrefix.WithExtraExtension(".ppst")))
			File::Rename(oldNamePrefix.WithExtraExtension(".ppst"), newPrefix.WithExtraExtension(".ppst"));
		if (oldIDPrefix != newPrefix && File::Exists(oldIDPrefix.WithExtraExtension(".jpg")))
			File::Rename(oldIDPrefix.WithExtraExtension(".jpg"), newPrefix.WithExtraExtension(".jpg"));
		else if (File::Exists(oldNamePrefix.WithExtraExtension(".jpg")))
			File::Rename(oldNamePrefix.WithExtraExtension(".jpg"), newPrefix.WithExtraExtension(".jpg"));
	}

	if (loadGameConfigs) {
		g_Config.LoadGameConfig(discID);
	}

	return __KernelLoadExec(currentMIPS, finalName.c_str(), 0, error_string);
}

// A PS1 EBOOT, run by the firmware's POPS manager, which loads its PS1 emulator for the game.
bool Load_PSP_POPS(FileLoader *fileLoader, std::string *error_string) {
	static const char *const popsmanPath = "flash0:/kd/popsman.prx";
	if (!pspFileSystem.GetFileInfo(popsmanPath).exists) {
		auto er = GetI18NCategory(I18NCat::ERRORS);
		*error_string = er->T("PS1NoFirmware", "PS1 games need the PS1 emulator in the PSP's firmware, and no firmware is installed. Install firmware 6.30 to 6.61 from an official PSP update file in Settings > Tools > PSP Firmware. Starting a PSP game whose disc has an updater on it also installs its firmware.");
		return false;
	}

	// Its directory as host0:, as for a homebrew EBOOT.
	const Path fullPath = fileLoader->GetPath();
	auto fs = std::make_shared<DirectoryFileSystem>(&pspFileSystem, fullPath.NavigateUp(), FileSystemFlags::SIMULATE_FAT32 | FileSystemFlags::CARD);
	pspFileSystem.Mount("host0:", fs);
	pspFileSystem.SetStartingDirectory("host0:/");

	__PopsBootInit();
	const std::string gamePath = "host0:/" + fullPath.GetFilename();
	INFO_LOG(Log::Loader, "POPS: booting %s through %s", gamePath.c_str(), popsmanPath);
	if (!__KernelLoadExec(currentMIPS, popsmanPath, 0, error_string)) {
		return false;
	}
	__PopsBootLoadModules();
	if (!__PopsBootStartInit(fileLoader, gamePath, error_string)) {
		return false;
	}
	return true;
}

bool Load_PSP_GE_Dump(FileLoader *fileLoader, std::string *error_string) {
	auto umd = std::make_shared<BlobFileSystem>(&pspFileSystem, fileLoader, "data.ppdmp");
	pspFileSystem.Mount("disc0:", umd);

	return __KernelLoadGEDump(currentMIPS, "disc0:/data.ppdmp", &PSP_CoreParameter().errorString);
}