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/*
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 *  This file is part of CoCalc: Copyright © 2020 Sagemath, Inc.
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 *  License: MS-RSL – see LICENSE.md for details
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 */
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/*
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Server directory listing through the HTTP server and Websocket API.
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{files:[..., {size:?,name:?,mtime:?,isdir:?}]}
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where mtime is integer SECONDS since epoch, size is in bytes, and isdir
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is only there if true.
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Obviously we should probably use POST instead of GET, due to the
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result being a function of time... but POST is so complicated.
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Use ?random= or ?time= if you're worried about cacheing.
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Browser client code only uses this through the websocket anyways.
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*/
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import { reuseInFlight } from "@cocalc/util/reuse-in-flight";
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import type { Dirent, Stats } from "node:fs";
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import { lstat, opendir, readdir, readlink, stat } from "node:fs/promises";
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import { getLogger } from "./logger";
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import { DirectoryListingEntry } from "@cocalc/util/types";
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import { join } from "path";
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const logger = getLogger("backend:directory-listing");
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// SMC_LOCAL_HUB_HOME is used for developing cocalc inside cocalc...
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const HOME = process.env.SMC_LOCAL_HUB_HOME ?? process.env.HOME ?? "";
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const getListing = reuseInFlight(
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  async (
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    path: string, // assumed in home directory!
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    hidden: boolean = false,
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    { home = HOME, limit }: { home?: string; limit?: number } = {},
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  ): Promise<DirectoryListingEntry[]> => {
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    const dir = join(home, path);
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    logger.debug(dir);
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    const files: DirectoryListingEntry[] = [];
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    let file: Dirent;
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    for await (file of await opendir(dir)) {
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      if (limit && files.length >= limit) {
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        break;
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      }
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      if (!hidden && file.name[0] === ".") {
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        continue;
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      }
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      let entry: DirectoryListingEntry;
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      try {
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        // I don't actually know if file.name can fail to be JSON-able with node.js -- is there
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        // even a string in Node.js that cannot be dumped to JSON?  With python
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        // this definitely was a problem, but I can't find the examples now.  Users
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        // sometimes create "insane" file names via bugs in C programs...
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        JSON.stringify(file.name);
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        entry = { name: file.name };
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      } catch (err) {
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        entry = { name: "????", error: "Cannot display bad binary filename. " };
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      }
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      try {
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        let stats: Stats;
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        if (file.isSymbolicLink()) {
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          // Optimization: don't explicitly set issymlink if it is false
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          entry.issymlink = true;
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        }
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        if (entry.issymlink) {
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          // at least right now we only use this symlink stuff to display
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          // information to the user in a listing, and nothing else.
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          try {
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            entry.link_target = await readlink(dir + "/" + entry.name);
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          } catch (err) {
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            // If we don't know the link target for some reason; just ignore this.
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          }
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        }
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        try {
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          stats = await stat(dir + "/" + entry.name);
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        } catch (err) {
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          // don't have access to target of link (or it is a broken link).
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          stats = await lstat(dir + "/" + entry.name);
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        }
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        entry.mtime = stats.mtime.valueOf() / 1000;
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        if (stats.isDirectory()) {
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          entry.isdir = true;
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          const v = await readdir(dir + "/" + entry.name);
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          if (hidden) {
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            entry.size = v.length;
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          } else {
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            // only count non-hidden files
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            entry.size = 0;
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            for (const x of v) {
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              if (x[0] != ".") {
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                entry.size += 1;
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              }
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            }
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          }
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        } else {
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          entry.size = stats.size;
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        }
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      } catch (err) {
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        entry.error = `${entry.error ? entry.error : ""}${err}`;
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      }
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      files.push(entry);
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    }
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    return files;
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  },
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);
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export default getListing;
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