/*************************************************************************/
/*  macho.cpp                                                            */
/*************************************************************************/
/*                         This file is part of:                         */
/*                          PANDEMONIUM ENGINE                           */
/*             https://github.com/Relintai/pandemonium_engine            */
/*************************************************************************/
/* Copyright (c) 2022-present Péter Magyar.                              */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/

#include "macho.h"

#include "modules/modules_enabled.gen.h" // For regex.

#ifdef MODULE_REGEX_ENABLED

uint32_t MachO::seg_align(uint64_t p_vmaddr, uint32_t p_min, uint32_t p_max) {
	uint32_t align = p_max;
	if (p_vmaddr != 0) {
		uint64_t seg_align = 1;
		align = 0;
		while ((seg_align & p_vmaddr) == 0) {
			seg_align = seg_align << 1;
			align++;
		}
		align = CLAMP(align, p_min, p_max);
	}
	return align;
}

bool MachO::alloc_signature(uint64_t p_size) {
	ERR_FAIL_COND_V_MSG(!fa, false, "MachO: File not opened.");
	if (signature_offset != 0) {
		// Nothing to do, already have signature load command.
		return true;
	}
	if (lc_limit == 0 || lc_limit + 16 > exe_base) {
		ERR_FAIL_V_MSG(false, "MachO: Can't allocate signature load command, please use \"codesign_allocate\" utility first.");
	} else {
		// Add signature load command.
		signature_offset = lc_limit;

		fa->seek(lc_limit);
		LoadCommandHeader lc;
		lc.cmd = LC_CODE_SIGNATURE;
		lc.cmdsize = 16;
		if (swap) {
			lc.cmdsize = BSWAP32(lc.cmdsize);
		}
		fa->store_buffer((const uint8_t *)&lc, sizeof(LoadCommandHeader));

		uint32_t lc_offset = fa->get_len() + PAD(fa->get_len(), 16);
		uint32_t lc_size = 0;
		if (swap) {
			lc_offset = BSWAP32(lc_offset);
			lc_size = BSWAP32(lc_size);
		}
		fa->store_32(lc_offset);
		fa->store_32(lc_size);

		// Write new command number.
		fa->seek(0x10);
		uint32_t ncmds = fa->get_32();
		uint32_t cmdssize = fa->get_32();
		if (swap) {
			ncmds = BSWAP32(ncmds);
			cmdssize = BSWAP32(cmdssize);
		}
		ncmds += 1;
		cmdssize += 16;
		if (swap) {
			ncmds = BSWAP32(ncmds);
			cmdssize = BSWAP32(cmdssize);
		}
		fa->seek(0x10);
		fa->store_32(ncmds);
		fa->store_32(cmdssize);

		lc_limit = lc_limit + sizeof(LoadCommandHeader) + 8;

		return true;
	}
}

bool MachO::is_macho(const String &p_path) {
	FileAccessRef fb = FileAccess::open(p_path, FileAccess::READ);
	ERR_FAIL_COND_V_MSG(!fb, false, vformat("MachO: Can't open file: \"%s\".", p_path));
	uint32_t magic = fb->get_32();
	return (magic == 0xcefaedfe || magic == 0xfeedface || magic == 0xcffaedfe || magic == 0xfeedfacf);
}

bool MachO::open_file(const String &p_path) {
	fa = FileAccess::open(p_path, FileAccess::READ_WRITE);
	ERR_FAIL_COND_V_MSG(!fa, false, vformat("MachO: Can't open file: \"%s\".", p_path));
	uint32_t magic = fa->get_32();
	MachHeader mach_header;

	// Read MachO header.
	swap = (magic == 0xcffaedfe || magic == 0xcefaedfe);
	if (magic == 0xcefaedfe || magic == 0xfeedface) {
		// Thin 32-bit binary.
		fa->get_buffer((uint8_t *)&mach_header, sizeof(MachHeader));
	} else if (magic == 0xcffaedfe || magic == 0xfeedfacf) {
		// Thin 64-bit binary.
		fa->get_buffer((uint8_t *)&mach_header, sizeof(MachHeader));
		fa->get_32(); // Skip extra reserved field.
	} else {
		ERR_FAIL_V_MSG(false, vformat("MachO: File is not a valid MachO binary: \"%s\".", p_path));
	}

	if (swap) {
		mach_header.ncmds = BSWAP32(mach_header.ncmds);
		mach_header.cpusubtype = BSWAP32(mach_header.cpusubtype);
		mach_header.cputype = BSWAP32(mach_header.cputype);
	}
	cpusubtype = mach_header.cpusubtype;
	cputype = mach_header.cputype;
	align = 0;
	exe_base = std::numeric_limits<uint64_t>::max();
	exe_limit = 0;
	lc_limit = 0;
	link_edit_offset = 0;
	signature_offset = 0;

	// Read load commands.
	for (uint32_t i = 0; i < mach_header.ncmds; i++) {
		LoadCommandHeader lc;
		fa->get_buffer((uint8_t *)&lc, sizeof(LoadCommandHeader));
		if (swap) {
			lc.cmd = BSWAP32(lc.cmd);
			lc.cmdsize = BSWAP32(lc.cmdsize);
		}
		uint64_t ps = fa->get_position();
		switch (lc.cmd) {
			case LC_SEGMENT: {
				LoadCommandSegment lc_seg;
				fa->get_buffer((uint8_t *)&lc_seg, sizeof(LoadCommandSegment));
				if (swap) {
					lc_seg.nsects = BSWAP32(lc_seg.nsects);
					lc_seg.vmaddr = BSWAP32(lc_seg.vmaddr);
					lc_seg.vmsize = BSWAP32(lc_seg.vmsize);
				}
				align = MAX(align, seg_align(lc_seg.vmaddr, 2, 15));
				if (String(lc_seg.segname) == "__TEXT") {
					exe_limit = MAX(exe_limit, lc_seg.vmsize);
					for (uint32_t j = 0; j < lc_seg.nsects; j++) {
						Section lc_sect;
						fa->get_buffer((uint8_t *)&lc_sect, sizeof(Section));
						if (String(lc_sect.sectname) == "__text") {
							if (swap) {
								exe_base = MIN(exe_base, BSWAP32(lc_sect.offset));
							} else {
								exe_base = MIN(exe_base, lc_sect.offset);
							}
						}
						if (swap) {
							align = MAX(align, BSWAP32(lc_sect.align));
						} else {
							align = MAX(align, lc_sect.align);
						}
					}
				} else if (String(lc_seg.segname) == "__LINKEDIT") {
					link_edit_offset = ps - 8;
				}
			} break;
			case LC_SEGMENT_64: {
				LoadCommandSegment64 lc_seg;
				fa->get_buffer((uint8_t *)&lc_seg, sizeof(LoadCommandSegment64));
				if (swap) {
					lc_seg.nsects = BSWAP32(lc_seg.nsects);
					lc_seg.vmaddr = BSWAP64(lc_seg.vmaddr);
					lc_seg.vmsize = BSWAP64(lc_seg.vmsize);
				}
				align = MAX(align, seg_align(lc_seg.vmaddr, 3, 15));
				if (String(lc_seg.segname) == "__TEXT") {
					exe_limit = MAX(exe_limit, lc_seg.vmsize);
					for (uint32_t j = 0; j < lc_seg.nsects; j++) {
						Section64 lc_sect;
						fa->get_buffer((uint8_t *)&lc_sect, sizeof(Section64));
						if (String(lc_sect.sectname) == "__text") {
							if (swap) {
								exe_base = MIN(exe_base, BSWAP32(lc_sect.offset));
							} else {
								exe_base = MIN(exe_base, lc_sect.offset);
							}
							if (swap) {
								align = MAX(align, BSWAP32(lc_sect.align));
							} else {
								align = MAX(align, lc_sect.align);
							}
						}
					}
				} else if (String(lc_seg.segname) == "__LINKEDIT") {
					link_edit_offset = ps - 8;
				}
			} break;
			case LC_CODE_SIGNATURE: {
				signature_offset = ps - 8;
			} break;
			default: {
			} break;
		}
		fa->seek(ps + lc.cmdsize - 8);
		lc_limit = ps + lc.cmdsize - 8;
	}

	if (exe_limit == 0 || lc_limit == 0) {
		ERR_FAIL_V_MSG(false, vformat("MachO: No load commands or executable code found: \"%s\".", p_path));
	}

	return true;
}

uint64_t MachO::get_exe_base() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	return exe_base;
}

uint64_t MachO::get_exe_limit() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	return exe_limit;
}

int32_t MachO::get_align() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	return align;
}

uint32_t MachO::get_cputype() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	return cputype;
}

uint32_t MachO::get_cpusubtype() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	return cpusubtype;
}

uint64_t MachO::get_size() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	return fa->get_len();
}

uint64_t MachO::get_signature_offset() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	ERR_FAIL_COND_V_MSG(signature_offset == 0, 0, "MachO: No signature load command.");

	fa->seek(signature_offset + 8);
	if (swap) {
		return BSWAP32(fa->get_32());
	} else {
		return fa->get_32();
	}
}

uint64_t MachO::get_code_limit() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");

	if (signature_offset == 0) {
		return fa->get_len() + PAD(fa->get_len(), 16);
	} else {
		return get_signature_offset();
	}
}

uint64_t MachO::get_signature_size() {
	ERR_FAIL_COND_V_MSG(!fa, 0, "MachO: File not opened.");
	ERR_FAIL_COND_V_MSG(signature_offset == 0, 0, "MachO: No signature load command.");

	fa->seek(signature_offset + 12);
	if (swap) {
		return BSWAP32(fa->get_32());
	} else {
		return fa->get_32();
	}
}

bool MachO::is_signed() {
	ERR_FAIL_COND_V_MSG(!fa, false, "MachO: File not opened.");
	if (signature_offset == 0) {
		return false;
	}

	fa->seek(get_signature_offset());
	uint32_t magic = BSWAP32(fa->get_32());
	if (magic != 0xfade0cc0) {
		return false; // No SuperBlob found.
	}
	fa->get_32(); // Skip size field, unused.
	uint32_t count = BSWAP32(fa->get_32());
	for (uint32_t i = 0; i < count; i++) {
		uint32_t index_type = BSWAP32(fa->get_32());
		uint32_t offset = BSWAP32(fa->get_32());
		if (index_type == 0x00000000) { // CodeDirectory index type.
			fa->seek(get_signature_offset() + offset + 12);
			uint32_t flags = BSWAP32(fa->get_32());
			if (flags & 0x20000) {
				return false; // Found CD, linker-signed.
			} else {
				return true; // Found CD, not linker-signed.
			}
		}
	}
	return false; // No CD found.
}

PoolByteArray MachO::get_cdhash_sha1() {
	ERR_FAIL_COND_V_MSG(!fa, PoolByteArray(), "MachO: File not opened.");
	if (signature_offset == 0) {
		return PoolByteArray();
	}

	fa->seek(get_signature_offset());
	uint32_t magic = BSWAP32(fa->get_32());
	if (magic != 0xfade0cc0) {
		return PoolByteArray(); // No SuperBlob found.
	}
	fa->get_32(); // Skip size field, unused.
	uint32_t count = BSWAP32(fa->get_32());
	for (uint32_t i = 0; i < count; i++) {
		fa->get_32(); // Index type, skip.
		uint32_t offset = BSWAP32(fa->get_32());
		uint64_t pos = fa->get_position();

		fa->seek(get_signature_offset() + offset);
		uint32_t cdmagic = BSWAP32(fa->get_32());
		uint32_t cdsize = BSWAP32(fa->get_32());
		if (cdmagic == 0xfade0c02) { // CodeDirectory.
			fa->seek(get_signature_offset() + offset + 36);
			uint8_t hash_size = fa->get_8();
			uint8_t hash_type = fa->get_8();
			if (hash_size == 0x14 && hash_type == 0x01) { /* SHA-1 */
				PoolByteArray hash;
				hash.resize(0x14);

				fa->seek(get_signature_offset() + offset);
				PoolByteArray blob;
				blob.resize(cdsize);
				fa->get_buffer(blob.write().ptr(), cdsize);

				CryptoCore::SHA1Context ctx;
				ctx.start();
				ctx.update(blob.read().ptr(), blob.size());
				ctx.finish(hash.write().ptr());

				return hash;
			}
		}
		fa->seek(pos);
	}
	return PoolByteArray();
}

PoolByteArray MachO::get_cdhash_sha256() {
	ERR_FAIL_COND_V_MSG(!fa, PoolByteArray(), "MachO: File not opened.");
	if (signature_offset == 0) {
		return PoolByteArray();
	}

	fa->seek(get_signature_offset());
	uint32_t magic = BSWAP32(fa->get_32());
	if (magic != 0xfade0cc0) {
		return PoolByteArray(); // No SuperBlob found.
	}
	fa->get_32(); // Skip size field, unused.
	uint32_t count = BSWAP32(fa->get_32());
	for (uint32_t i = 0; i < count; i++) {
		fa->get_32(); // Index type, skip.
		uint32_t offset = BSWAP32(fa->get_32());
		uint64_t pos = fa->get_position();

		fa->seek(get_signature_offset() + offset);
		uint32_t cdmagic = BSWAP32(fa->get_32());
		uint32_t cdsize = BSWAP32(fa->get_32());
		if (cdmagic == 0xfade0c02) { // CodeDirectory.
			fa->seek(get_signature_offset() + offset + 36);
			uint8_t hash_size = fa->get_8();
			uint8_t hash_type = fa->get_8();
			if (hash_size == 0x20 && hash_type == 0x02) { /* SHA-256 */
				PoolByteArray hash;
				hash.resize(0x20);

				fa->seek(get_signature_offset() + offset);
				PoolByteArray blob;
				blob.resize(cdsize);
				fa->get_buffer(blob.write().ptr(), cdsize);

				CryptoCore::SHA256Context ctx;
				ctx.start();
				ctx.update(blob.read().ptr(), blob.size());
				ctx.finish(hash.write().ptr());

				return hash;
			}
		}
		fa->seek(pos);
	}
	return PoolByteArray();
}

PoolByteArray MachO::get_requirements() {
	ERR_FAIL_COND_V_MSG(!fa, PoolByteArray(), "MachO: File not opened.");
	if (signature_offset == 0) {
		return PoolByteArray();
	}

	fa->seek(get_signature_offset());
	uint32_t magic = BSWAP32(fa->get_32());
	if (magic != 0xfade0cc0) {
		return PoolByteArray(); // No SuperBlob found.
	}
	fa->get_32(); // Skip size field, unused.
	uint32_t count = BSWAP32(fa->get_32());
	for (uint32_t i = 0; i < count; i++) {
		fa->get_32(); // Index type, skip.
		uint32_t offset = BSWAP32(fa->get_32());
		uint64_t pos = fa->get_position();

		fa->seek(get_signature_offset() + offset);
		uint32_t rqmagic = BSWAP32(fa->get_32());
		uint32_t rqsize = BSWAP32(fa->get_32());
		if (rqmagic == 0xfade0c01) { // Requirements.
			PoolByteArray blob;
			fa->seek(get_signature_offset() + offset);
			blob.resize(rqsize);
			fa->get_buffer(blob.write().ptr(), rqsize);
			return blob;
		}
		fa->seek(pos);
	}
	return PoolByteArray();
}

const FileAccess *MachO::get_file() const {
	return fa;
}

FileAccess *MachO::get_file() {
	return fa;
}

bool MachO::set_signature_size(uint64_t p_size) {
	ERR_FAIL_COND_V_MSG(!fa, false, "MachO: File not opened.");

	// Ensure signature load command exists.
	ERR_FAIL_COND_V_MSG(link_edit_offset == 0, false, "MachO: No __LINKEDIT segment found.");
	ERR_FAIL_COND_V_MSG(!alloc_signature(p_size), false, "MachO: Can't allocate signature load command.");

	// Update signature load command.
	uint64_t old_size = get_signature_size();
	uint64_t new_size = p_size + PAD(p_size, 16384);

	if (new_size <= old_size) {
		fa->seek(get_signature_offset());
		for (uint64_t i = 0; i < old_size; i++) {
			fa->store_8(0x00);
		}
		return true;
	}

	fa->seek(signature_offset + 12);
	if (swap) {
		fa->store_32(BSWAP32(new_size));
	} else {
		fa->store_32(new_size);
	}

	uint64_t end = get_signature_offset() + new_size;

	// Update "__LINKEDIT" segment.
	LoadCommandHeader lc;
	fa->seek(link_edit_offset);
	fa->get_buffer((uint8_t *)&lc, sizeof(LoadCommandHeader));
	if (swap) {
		lc.cmd = BSWAP32(lc.cmd);
		lc.cmdsize = BSWAP32(lc.cmdsize);
	}
	switch (lc.cmd) {
		case LC_SEGMENT: {
			LoadCommandSegment lc_seg;
			fa->get_buffer((uint8_t *)&lc_seg, sizeof(LoadCommandSegment));
			if (swap) {
				lc_seg.vmsize = BSWAP32(lc_seg.vmsize);
				lc_seg.filesize = BSWAP32(lc_seg.filesize);
				lc_seg.fileoff = BSWAP32(lc_seg.fileoff);
			}

			lc_seg.vmsize = end - lc_seg.fileoff;
			lc_seg.vmsize += PAD(lc_seg.vmsize, 4096);
			lc_seg.filesize = end - lc_seg.fileoff;

			if (swap) {
				lc_seg.vmsize = BSWAP32(lc_seg.vmsize);
				lc_seg.filesize = BSWAP32(lc_seg.filesize);
			}
			fa->seek(link_edit_offset + 8);
			fa->store_buffer((const uint8_t *)&lc_seg, sizeof(LoadCommandSegment));
		} break;
		case LC_SEGMENT_64: {
			LoadCommandSegment64 lc_seg;
			fa->get_buffer((uint8_t *)&lc_seg, sizeof(LoadCommandSegment64));
			if (swap) {
				lc_seg.vmsize = BSWAP64(lc_seg.vmsize);
				lc_seg.filesize = BSWAP64(lc_seg.filesize);
				lc_seg.fileoff = BSWAP64(lc_seg.fileoff);
			}
			lc_seg.vmsize = end - lc_seg.fileoff;
			lc_seg.vmsize += PAD(lc_seg.vmsize, 4096);
			lc_seg.filesize = end - lc_seg.fileoff;
			if (swap) {
				lc_seg.vmsize = BSWAP64(lc_seg.vmsize);
				lc_seg.filesize = BSWAP64(lc_seg.filesize);
			}
			fa->seek(link_edit_offset + 8);
			fa->store_buffer((const uint8_t *)&lc_seg, sizeof(LoadCommandSegment64));
		} break;
		default: {
			ERR_FAIL_V_MSG(false, "MachO: Invalid __LINKEDIT segment type.");
		} break;
	}
	fa->seek(get_signature_offset());
	for (uint64_t i = 0; i < new_size; i++) {
		fa->store_8(0x00);
	}
	return true;
}

MachO::~MachO() {
	if (fa) {
		fa->close();
		memdelete(fa);
		fa = nullptr;
	}
}

#endif // MODULE_REGEX_ENABLED