diff --git a/librecomp/include/librecomp/patcher.hpp b/librecomp/include/librecomp/patcher.hpp new file mode 100644 index 0000000..c8db9e8 --- /dev/null +++ b/librecomp/include/librecomp/patcher.hpp @@ -0,0 +1,20 @@ +#ifndef __RECOMP_PATCHER_HPP__ +#define __RECOMP_PATCHER_HPP__ + +#include +#include +#include + +namespace recomp { + namespace patcher { + enum class PatcherResult { + Success, + InvalidPatchFile, + WrongRom, + }; + + PatcherResult patch_rom(std::span rom, std::span patch_data, std::vector& patched_rom_out); + } +} + +#endif diff --git a/librecomp/src/patcher.cpp b/librecomp/src/patcher.cpp new file mode 100644 index 0000000..31522e2 --- /dev/null +++ b/librecomp/src/patcher.cpp @@ -0,0 +1,276 @@ +#include "patcher.hpp" + +// BPS patcher based on the spec at https://github.com/blakesmith/rombp/blob/master/docs/bps_spec.md. + +bool read_number(std::span patch_data, size_t& offset, uint64_t& number_out) { + uint64_t data = 0; + uint64_t shift = 1; + while (true) { + if (offset >= patch_data.size()) { + return false; + } + uint8_t x = patch_data[offset++]; + data += (x & 0x7f) * shift; + if (x & 0x80) { + break; + } + shift <<= 7; + data += shift; + } + number_out = data; + return true; +} + +bool read_signed_number(std::span patch_data, size_t& offset, int64_t& number_out) { + uint64_t raw_number; + if (!read_number(patch_data, offset, raw_number)) { + return false; + } + + int64_t ret = raw_number >> 1; + if (raw_number & 1) { + ret = -ret; + } + number_out = ret; + return true; +} + +bool read_u32(std::span patch_data, size_t& offset, uint32_t& number_out) { + if (offset > patch_data.size() - sizeof(uint32_t)) { + return false; + } + + number_out = + (uint32_t(patch_data[offset++]) << 0) | + (uint32_t(patch_data[offset++]) << 8) | + (uint32_t(patch_data[offset++]) << 16) | + (uint32_t(patch_data[offset++]) << 24); + return true; +} + +enum class PatchActionType { + SourceRead, + TargetRead, + SourceCopy, + TargetCopy +}; + +bool do_source_read(std::span patch_data, std::span rom, std::vector& ret, size_t& patch_offset, uint64_t action_length) { + size_t output_offset = ret.size(); + size_t read_end = output_offset + action_length; + if (read_end > rom.size()) { + return false; + } + + ret.insert(ret.end(), rom.begin() + output_offset, rom.begin() + output_offset + action_length); + return true; +} + +bool do_target_read(std::span patch_data, std::span rom, std::vector& ret, size_t& patch_offset, uint64_t action_length) { + size_t read_end = patch_offset + action_length; + if (read_end > patch_data.size()) { + return false; + } + + ret.insert(ret.end(), patch_data.begin() + patch_offset, patch_data.begin() + patch_offset + action_length); + patch_offset += action_length; + return true; +} + +bool do_source_copy(std::span patch_data, std::span rom, std::vector& ret, size_t& patch_offset, size_t& source_offset, uint64_t action_length) { + int64_t copy_offset; + if (!read_signed_number(patch_data, patch_offset, copy_offset)) { + return false; + } + + source_offset += copy_offset; + size_t read_end = source_offset + action_length; + if (read_end > rom.size()) { + return false; + } + + ret.insert(ret.end(), rom.begin() + source_offset, rom.begin() + source_offset + action_length); + source_offset += action_length; + return true; +} + +bool do_target_copy(std::span patch_data, std::span rom, std::vector& ret, size_t& patch_offset, size_t& target_offset, uint64_t action_length) { + int64_t copy_offset; + if (!read_signed_number(patch_data, patch_offset, copy_offset)) { + return false; + } + + target_offset += copy_offset; + if (target_offset >= ret.size()) { + return false; + } + + // Copy one byte at a time to allow for overlap. + size_t output_start = ret.size(); + ret.resize(output_start + action_length); + for (size_t i = 0; i < action_length; i++) { + ret[output_start + i] = ret[target_offset++]; + } + + return true; +} + +static const uint32_t crc_table[256] = { + 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, + 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, + 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, + 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, + 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, + 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, + 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, + 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, + 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, + 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01, + 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, + 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, + 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, + 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, + 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, + 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, + 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, + 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, + 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, + 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, + 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, + 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, + 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, + 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, + 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, + 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, + 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, + 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, + 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, + 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, + 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF, + 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D +}; + +uint32_t calculate_crc32(std::span data) { + uint32_t crc; + + crc = 0xFFFFFFFF; + for (size_t i = 0; i < data.size(); i++) { + crc = (crc >> 8) ^ crc_table[ (crc ^ data[i]) & 0xFF ]; + } + return crc ^ 0xFFFFFFFF; +} + +recomp::patcher::PatcherResult recomp::patcher::patch_rom(std::span rom, std::span patch_data, std::vector& patched_rom_out) { + constexpr size_t footer_size = 3 * sizeof(uint32_t); + if (patch_data.size() < 4) { + return PatcherResult::InvalidPatchFile; + } + + if (patch_data[0] != 'B' || patch_data[1] != 'P' || patch_data[2] != 'S' || patch_data[3] != '1') { + return PatcherResult::InvalidPatchFile; + } + + size_t patch_offset = 4; + size_t source_offset = 0; + size_t target_offset = 0; + + // Read the header fields. + uint64_t source_size; + uint64_t target_size; + uint64_t metadata_size; + if (!read_number(patch_data, patch_offset, source_size)) { + return PatcherResult::InvalidPatchFile; + } + if (!read_number(patch_data, patch_offset, target_size)) { + return PatcherResult::InvalidPatchFile; + } + if (!read_number(patch_data, patch_offset, metadata_size)) { + return PatcherResult::InvalidPatchFile; + } + + // Skip the metadata. + patch_offset += metadata_size; + if (patch_offset >= patch_data.size()) { + return PatcherResult::InvalidPatchFile; + } + + // Early phase validation to rule out very incorrect patch files. + if (source_size != rom.size()) { + return PatcherResult::WrongRom; + } + + std::vector ret; + ret.reserve(target_size); + + // Read and apply actions. + size_t actions_end = patch_data.size() - footer_size; + while (patch_offset < actions_end) { + uint64_t cur_action_number; + if (!read_number(patch_data, patch_offset, cur_action_number)) { + return PatcherResult::InvalidPatchFile; + } + uint64_t action_length = (cur_action_number >> 2) + 1; + PatchActionType action_type = static_cast(cur_action_number & 0b11); + switch (action_type) { + case PatchActionType::SourceRead: + if (!do_source_read(patch_data, rom, ret, patch_offset, action_length)) { + return PatcherResult::InvalidPatchFile; + } + break; + case PatchActionType::TargetRead: + if (!do_target_read(patch_data, rom, ret, patch_offset, action_length)) { + return PatcherResult::InvalidPatchFile; + } + break; + case PatchActionType::SourceCopy: + if (!do_source_copy(patch_data, rom, ret, patch_offset, source_offset, action_length)) { + return PatcherResult::InvalidPatchFile; + } + break; + case PatchActionType::TargetCopy: + if (!do_target_copy(patch_data, rom, ret, patch_offset, target_offset, action_length)) { + return PatcherResult::InvalidPatchFile; + } + break; + } + } + + // Read the checksums from the patch file. + uint32_t good_source_checksum; + uint32_t good_target_checksum; + uint32_t good_patch_checksum; + if (!read_u32(patch_data, patch_offset, good_source_checksum)) { + return PatcherResult::InvalidPatchFile; + } + if (!read_u32(patch_data, patch_offset, good_target_checksum)) { + return PatcherResult::InvalidPatchFile; + } + if (!read_u32(patch_data, patch_offset, good_patch_checksum)) { + return PatcherResult::InvalidPatchFile; + } + + // Make sure all the patch data was consumed. + if (patch_offset != patch_data.size()) { + return PatcherResult::InvalidPatchFile; + } + + // Checksums are skipped as these patches aren't applied by end users. Any issues with a patch included in a mod would be caught immediately in mod testing. + + // uint32_t source_checksum = calculate_crc32(rom); + // if (source_checksum != good_source_checksum) { + // return PatcherResult::WrongRom; + // } + + // uint32_t target_checksum = calculate_crc32(std::span{ ret }); + // if (target_checksum != good_target_checksum) { + // return PatcherResult::InvalidPatchFile; + // } + + // uint32_t patch_checksum = calculate_crc32(patch_data.subspan(0, patch_data.size() - 4)); + // if (patch_checksum != good_patch_checksum) { + // return PatcherResult::InvalidPatchFile; + // } + + patched_rom_out = std::move(ret); + return PatcherResult::Success; +}