[{"id":3672999,"web_url":"http://patchwork.ozlabs.org/comment/3672999/","msgid":"<87ldf4ilz4.fsf@gmail.com>","list_archive_url":null,"date":"2026-04-03T06:42:07","subject":"Re: [PATCH v5 2/2] io: Use gnulib fts implementation (BZ 22944, BZ\n 20331)","submitter":{"id":88687,"url":"http://patchwork.ozlabs.org/api/people/88687/","name":"Collin Funk","email":"collin.funk1@gmail.com"},"content":"Adhemerval Zanella writes:\n\n> This patch synchronizes the glibc fts implementation with the latest\n> version from gnulib (as of 2026-02-16).\n>\n> The primary motivation is to address limitations in the legacy glibc\n> implementation, most notably BZ 22944, where fts fails with an\n> ENAMETOOLONG error when traversing very long paths or deeply nested\n> directory trees. The gnulib implementation dynamically reallocates\n> path buffers and uses openat/fchdir optimizations, effectively\n> lifting the MAXPATHLEN limitation.\n>\n> The gnulib implementation also added extra features, which are\n> used by different GNU projects (coreutils, diffutils):\n>\n> * FTS_TIGHT_CYCLE_CHECK: used to enable a strict, immediate\n> cycle-detection algorithm during a file system traversal. This is\n> done internally using a hash table: every time the traversal enters\n> a directory, it records the directory's device and inode (dev/ino)\n> pair in the hash table, and before entering any directory, fts\n> checks the hash table.\n>\n> * FTS_CWDFD: instead of actually changing the process's current\n> working directory, it maintains a virtual current working directory\n> using file descriptors. The file descriptor is store at the\n> fts_cwd_fd field and all subsequent file operations are performed\n> relative to this file descriptor using *at functions.\n>\n> * FTS_DEFER_STAT: performance-oriented flag that instructs the file\n> tree traversal engine to delay fetching file metadata. When the\n> flag is used, fts skips the immediate stat call. Instead, it marks\n> the entry with a special internal state (FTS_NSOK and\n> FTS_STAT_REQUIRED). The actual stat call is pushed down the line\n> and executed by fts_read right before the application actually\n> accesses the entry.\n>\n> * FTS_VERBATIM: fts_open aaccept and use the path strings exactly as\n> they were provided in the arguments array without slash trimming.\n>\n> * FTS_MOUNT: it restrict the file tree walk to a single file system.\n>\n> Hopefully,it would allow some GNU projects to use the glibc\n> implementation instead of pulling the gnulib one.\n>\n> It requires some changes to keep compatibility, compared to gnulib:\n>\n> * The new required fields are added at the end of FTS structure, and\n> the new FTS flags are adjusted to avoid change FTS_NAMEONLY/FTS_STOP\n> (even though they are marked as private).\n>\n> * The FTSENT uses a flexible array (fts_name), so two adjustments are\n> required: the two new members (fts_fts and fts_dirp) are place\n> *before* the struct and the fts_statp is now always allocated and\n> accounted (the gnulib implementation uses a awalys allocated member).\n>\n> Checked on x86_64-linux-gnu and i686-linux-gnu.\n> --\n> Changes from v4:\n> * I_ring struct, typedef, and enum under the \"__*\".\n> ---\n\nThis looks good to me. Thanks again for working on this.\n\nReviewed-by: Collin Funk \n\nCollin","headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","libc-alpha@sourceware.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","libc-alpha@sourceware.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=lQ7955kd;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org\n (client-ip=38.145.34.32; helo=vm01.sourceware.org;\n envelope-from=libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org;\n receiver=patchwork.ozlabs.org)","sourceware.org;\n\tdkim=pass (2048-bit key,\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=lQ7955kd","sourceware.org;\n dmarc=pass (p=none dis=none) header.from=gmail.com","sourceware.org; spf=pass smtp.mailfrom=gmail.com","server2.sourceware.org;\n arc=none smtp.remote-ip=2607:f8b0:4864:20::42b"],"Received":["from vm01.sourceware.org (vm01.sourceware.org [38.145.34.32])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fn8Kk2FQjz1yD3\n\tfor ; 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