Add BPS patch utility functions and integrate into CLI handlers

src/util/bps.cc

@@ -0,0 +1,207 @@
+
+#include "bps.h"
+
+#include <zlib.h>
+
+#include <cstdint>
+#include <vector>
+
+namespace yaze {
+namespace util {
+
+namespace {
+
+uint32_t crc32(const std::vector<uint8_t> &data) {
+  uint32_t crc = ::crc32(0L, Z_NULL, 0);
+  return ::crc32(crc, data.data(), data.size());
+}
+
+void encode(uint64_t data, std::vector<uint8_t> &output) {
+  while (true) {
+    uint8_t x = data & 0x7f;
+    data >>= 7;
+    if (data == 0) {
+      output.push_back(0x80 | x);
+      break;
+    }
+    output.push_back(x);
+    data--;
+  }
+}
+
+uint64_t decode(const std::vector<uint8_t> &input, size_t &offset) {
+  uint64_t data = 0;
+  uint64_t shift = 1;
+  while (true) {
+    uint8_t x = input[offset++];
+    data += (x & 0x7f) * shift;
+    if (x & 0x80) break;
+    shift <<= 7;
+    data += shift;
+  }
+  return data;
+}
+
+}  // namespace
+
+void CreateBpsPatch(const std::vector<uint8_t> &source,
+                    const std::vector<uint8_t> &target,
+                    std::vector<uint8_t> &patch) {
+  patch.clear();
+  patch.insert(patch.end(), {'B', 'P', 'S', '1'});
+
+  encode(source.size(), patch);
+  encode(target.size(), patch);
+  encode(0, patch);  // No metadata
+
+  size_t source_offset = 0;
+  size_t target_offset = 0;
+  int64_t source_rel_offset = 0;
+  int64_t target_rel_offset = 0;
+
+  while (target_offset < target.size()) {
+    if (source_offset < source.size() &&
+        source[source_offset] == target[target_offset]) {
+      size_t length = 0;
+      while (source_offset + length < source.size() &&
+             target_offset + length < target.size() &&
+             source[source_offset + length] == target[target_offset + length]) {
+        length++;
+      }
+      encode((length - 1) << 2 | 0, patch);  // SourceRead
+      source_offset += length;
+      target_offset += length;
+    } else {
+      size_t length = 0;
+      while (
+          target_offset + length < target.size() &&
+          (source_offset + length >= source.size() ||
+           source[source_offset + length] != target[target_offset + length])) {
+        length++;
+      }
+      if (length > 0) {
+        encode((length - 1) << 2 | 1, patch);  // TargetRead
+        for (size_t i = 0; i < length; i++) {
+          patch.push_back(target[target_offset + i]);
+        }
+        target_offset += length;
+      }
+    }
+
+    // SourceCopy
+    if (source_offset < source.size()) {
+      size_t length = 0;
+      int64_t offset = source_offset - source_rel_offset;
+      while (source_offset + length < source.size() &&
+             target_offset + length < target.size() &&
+             source[source_offset + length] == target[target_offset + length]) {
+        length++;
+      }
+      if (length > 0) {
+        encode((length - 1) << 2 | 2, patch);
+        encode((offset < 0 ? 1 : 0) | (abs(offset) << 1), patch);
+        source_offset += length;
+        target_offset += length;
+        source_rel_offset = source_offset;
+      }
+    }
+
+    // TargetCopy
+    if (target_offset > 0) {
+      size_t length = 0;
+      int64_t offset = target_offset - target_rel_offset;
+      while (target_offset + length < target.size() &&
+             target[target_offset - 1] == target[target_offset + length]) {
+        length++;
+      }
+      if (length > 0) {
+        encode((length - 1) << 2 | 3, patch);
+        encode((offset < 0 ? 1 : 0) | (abs(offset) << 1), patch);
+        target_offset += length;
+        target_rel_offset = target_offset;
+      }
+    }
+  }
+
+  patch.resize(patch.size() + 12);  // Make space for the checksums
+  uint32_t source_checksum = crc32(source);
+  uint32_t target_checksum = crc32(target);
+  uint32_t patch_checksum = crc32(patch);
+
+  memcpy(patch.data() + patch.size() - 12, &source_checksum, sizeof(uint32_t));
+  memcpy(patch.data() + patch.size() - 8, &target_checksum, sizeof(uint32_t));
+  memcpy(patch.data() + patch.size() - 4, &patch_checksum, sizeof(uint32_t));
+}
+
+void ApplyBpsPatch(const std::vector<uint8_t> &source,
+                   const std::vector<uint8_t> &patch,
+                   std::vector<uint8_t> &target) {
+  if (patch.size() < 4 || patch[0] != 'B' || patch[1] != 'P' ||
+      patch[2] != 'S' || patch[3] != '1') {
+    throw std::runtime_error("Invalid patch format");
+  }
+
+  size_t patch_offset = 4;
+  uint64_t target_size = decode(patch, patch_offset);
+  uint64_t metadata_size = decode(patch, patch_offset);
+  patch_offset += metadata_size;
+
+  target.resize(target_size);
+  size_t source_offset = 0;
+  size_t target_offset = 0;
+  int64_t source_rel_offset = 0;
+  int64_t target_rel_offset = 0;
+
+  while (patch_offset < patch.size() - 12) {
+    uint64_t data = decode(patch, patch_offset);
+    uint64_t command = data & 3;
+    uint64_t length = (data >> 2) + 1;
+
+    switch (command) {
+      case 0:  // SourceRead
+        while (length--) {
+          target[target_offset++] = source[source_offset++];
+        }
+        break;
+      case 1:  // TargetRead
+        while (length--) {
+          target[target_offset++] = patch[patch_offset++];
+        }
+        break;
+      case 2:  // SourceCopy
+      {
+        int64_t offsetData = decode(patch, patch_offset);
+        source_rel_offset += (offsetData & 1 ? -1 : +1) * (offsetData >> 1);
+        while (length--) {
+          target[target_offset++] = source[source_rel_offset++];
+        }
+      } break;
+      case 3:  // TargetCopy
+      {
+        uint64_t offsetData = decode(patch, patch_offset);
+        target_rel_offset += (offsetData & 1 ? -1 : +1) * (offsetData >> 1);
+        while (length--) {
+          target[target_offset++] = target[target_rel_offset++];
+        }
+      }
+      default:
+        throw std::runtime_error("Invalid patch command");
+    }
+  }
+
+  uint32_t source_checksum;
+  uint32_t target_checksum;
+  uint32_t patch_checksum;
+  memcpy(&source_checksum, patch.data() + patch.size() - 12, sizeof(uint32_t));
+  memcpy(&target_checksum, patch.data() + patch.size() - 8, sizeof(uint32_t));
+  memcpy(&patch_checksum, patch.data() + patch.size() - 4, sizeof(uint32_t));
+
+  if (source_checksum != crc32(source) || target_checksum != crc32(target) ||
+      patch_checksum !=
+          crc32(std::vector<uint8_t>(patch.begin(), patch.end() - 4))) {
+    throw std::runtime_error("Checksum mismatch");
+  }
+}
+
+}  // namespace util
+}  // namespace yaze

src/util/bps.h

@@ -0,0 +1,21 @@
+#ifndef YAZE_UTIL_BPS_H
+#define YAZE_UTIL_BPS_H
+
+#include <cstdint>
+#include <vector>
+
+namespace yaze {
+namespace util {
+
+void CreateBpsPatch(const std::vector<uint8_t> &source,
+                    const std::vector<uint8_t> &target,
+                    std::vector<uint8_t> &patch);
+
+void ApplyBpsPatch(const std::vector<uint8_t> &source,
+                   const std::vector<uint8_t> &patch,
+                   std::vector<uint8_t> &target);
+
+}  // namespace util
+}  // namespace yaze
+
+#endif  // YAZE_UTIL_BPS_H