feat: add local access control and managed point clouds

server/pointcloudMetadata.ts

@@ -0,0 +1,153 @@
+import * as fs from "node:fs";
+import * as path from "node:path";
+import type {
+  PointAttribute,
+  PointcloudDataFormat,
+  PointcloudMetadataValues,
+} from "../shared/pointcloudMetadata";
+
+export const MAX_PLY_HEADER_BYTES = 16 * 1024;
+
+type ScalarType = { type: string; bytes: number };
+
+const PLY_SCALAR_TYPES: Record<string, ScalarType> = {
+  char: { type: "int8", bytes: 1 },
+  int8: { type: "int8", bytes: 1 },
+  uchar: { type: "uint8", bytes: 1 },
+  uint8: { type: "uint8", bytes: 1 },
+  short: { type: "int16", bytes: 2 },
+  int16: { type: "int16", bytes: 2 },
+  ushort: { type: "uint16", bytes: 2 },
+  uint16: { type: "uint16", bytes: 2 },
+  int: { type: "int32", bytes: 4 },
+  int32: { type: "int32", bytes: 4 },
+  uint: { type: "uint32", bytes: 4 },
+  uint32: { type: "uint32", bytes: 4 },
+  float: { type: "float32", bytes: 4 },
+  float32: { type: "float32", bytes: 4 },
+  double: { type: "float64", bytes: 8 },
+  float64: { type: "float64", bytes: 8 },
+};
+
+export class PointcloudMetadataParseError extends Error {}
+
+export type ParsedPlyMetadata = {
+  pointCount: number;
+  pointAttributes: PointAttribute[];
+  pointDataFormat: PointcloudDataFormat;
+  bytesPerPoint: number;
+};
+
+/** 解析内存中的 PLY 文件头。调用方应保证输入不超过 MAX_PLY_HEADER_BYTES。 */
+export function parsePlyHeader(buffer: Buffer): ParsedPlyMetadata {
+  const text = buffer.toString("latin1");
+  const endMatch = /(?:^|\r?\n)end_header(?:\r?\n|$)/.exec(text);
+  if (!endMatch) {
+    throw new PointcloudMetadataParseError("未在 16KB 内找到 PLY 文件头结束标记");
+  }
+
+  const headerEnd = endMatch.index + endMatch[0].length;
+  const lines = text.slice(0, headerEnd).split(/\r?\n/).map((line) => line.trim());
+  if (lines[0] !== "ply") {
+    throw new PointcloudMetadataParseError("不是有效的 PLY 文件");
+  }
+
+  let pointDataFormat: PointcloudDataFormat | null = null;
+  let pointCount: number | null = null;
+  let currentElement: string | null = null;
+  const pointAttributes: PointAttribute[] = [];
+
+  for (const line of lines.slice(1)) {
+    if (!line || line === "end_header" || line.startsWith("comment ") || line.startsWith("obj_info ")) {
+      continue;
+    }
+
+    const tokens = line.split(/\s+/);
+    if (tokens[0] === "format") {
+      const value = tokens[1];
+      if (value !== "ascii" && value !== "binary_little_endian" && value !== "binary_big_endian") {
+        throw new PointcloudMetadataParseError("不支持的 PLY 编码");
+      }
+      pointDataFormat = value;
+      continue;
+    }
+
+    if (tokens[0] === "element") {
+      currentElement = tokens[1] ?? null;
+      if (currentElement === "vertex") {
+        const count = Number(tokens[2]);
+        if (!Number.isSafeInteger(count) || count < 0) {
+          throw new PointcloudMetadataParseError("PLY 顶点数无效");
+        }
+        pointCount = count;
+      }
+      continue;
+    }
+
+    if (tokens[0] === "property" && currentElement === "vertex") {
+      if (tokens[1] === "list") {
+        throw new PointcloudMetadataParseError("暂不支持列表型顶点属性");
+      }
+      const scalar = PLY_SCALAR_TYPES[tokens[1]];
+      const name = tokens[2];
+      if (!scalar || !name) {
+        throw new PointcloudMetadataParseError("PLY 包含未知的顶点属性类型");
+      }
+      pointAttributes.push({ name, type: scalar.type, bytes: scalar.bytes });
+    }
+  }
+
+  if (!pointDataFormat) {
+    throw new PointcloudMetadataParseError("PLY 文件头缺少编码信息");
+  }
+  if (pointCount === null) {
+    throw new PointcloudMetadataParseError("PLY 文件头缺少顶点数量");
+  }
+  if (pointAttributes.length === 0) {
+    throw new PointcloudMetadataParseError("PLY 文件头缺少顶点属性");
+  }
+
+  return {
+    pointCount,
+    pointAttributes,
+    pointDataFormat,
+    bytesPerPoint: pointAttributes.reduce((sum, attribute) => sum + attribute.bytes, 0),
+  };
+}
+
+export function inspectPointcloudMetadata(filePath: string, displayName = filePath): PointcloudMetadataValues {
+  const extension = path.extname(displayName || filePath).toLowerCase();
+  if (extension !== ".ply") {
+    return {
+      metadataStatus: "unsupported",
+      pointCount: null,
+      pointAttributes: null,
+      pointDataFormat: null,
+      bytesPerPoint: null,
+      metadataError: null,
+    };
+  }
+
+  try {
+    const fd = fs.openSync(filePath, "r");
+    try {
+      const buffer = Buffer.allocUnsafe(MAX_PLY_HEADER_BYTES);
+      const bytesRead = fs.readSync(fd, buffer, 0, buffer.length, 0);
+      const parsed = parsePlyHeader(buffer.subarray(0, bytesRead));
+      return { metadataStatus: "ready", ...parsed, metadataError: null };
+    } finally {
+      fs.closeSync(fd);
+    }
+  } catch (error) {
+    return {
+      metadataStatus: "error",
+      pointCount: null,
+      pointAttributes: null,
+      pointDataFormat: null,
+      bytesPerPoint: null,
+      metadataError: error instanceof PointcloudMetadataParseError
+        ? error.message
+        : "PLY 文件头解析失败",
+    };
+  }
+}