69 lines
2.2 KiB
Diff
69 lines
2.2 KiB
Diff
This patch is needed in order to build Guix on a Btrfs file system.
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From da922703282b0d3b8837a99a9c7fdd32f1d20d49 Mon Sep 17 00:00:00 2001
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From: Mark H Weaver <mhw@netris.org>
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Date: Tue, 9 Jan 2018 20:16:14 -0500
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Subject: [PATCH] Remove nonportable check for files containing only zeroes.
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This check benefitted only one unlikely case (large files containing
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only zeroes, on systems that do not support SEEK_HOLE) and was based
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on an assumption about file system behavior that is not mandated by
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POSIX and no longer holds in practice, namely that for sufficiently
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large files, (st_blocks == 0) implies that the file contains only
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zeroes. Examples of file systems that violate this assumption include
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Linux's /proc file system and Btrfs.
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* src/sparse.c (sparse_scan_file_wholesparse): Remove this function.
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(sparse_scan_file_seek): Remove the initial check for files containing
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only zeroes.
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---
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src/sparse.c | 24 ------------------------
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1 file changed, 24 deletions(-)
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diff --git a/src/sparse.c b/src/sparse.c
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index d41c0ea..3de6560 100644
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--- a/src/sparse.c
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+++ b/src/sparse.c
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@@ -261,26 +261,6 @@ sparse_scan_file_raw (struct tar_sparse_file *file)
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return tar_sparse_scan (file, scan_end, NULL);
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}
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-static bool
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-sparse_scan_file_wholesparse (struct tar_sparse_file *file)
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-{
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- struct tar_stat_info *st = file->stat_info;
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- struct sp_array sp = {0, 0};
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-
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- /* Note that this function is called only for truly sparse files of size >= 1
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- block size (checked via ST_IS_SPARSE before). See the thread
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- http://www.mail-archive.com/bug-tar@gnu.org/msg04209.html for more info */
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- if (ST_NBLOCKS (st->stat) == 0)
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- {
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- st->archive_file_size = 0;
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- sp.offset = st->stat.st_size;
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- sparse_add_map (st, &sp);
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- return true;
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- }
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-
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- return false;
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-}
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-
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#ifdef SEEK_HOLE
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/* Try to engage SEEK_HOLE/SEEK_DATA feature. */
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static bool
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@@ -343,10 +323,6 @@ sparse_scan_file_seek (struct tar_sparse_file *file)
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static bool
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sparse_scan_file (struct tar_sparse_file *file)
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{
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- /* always check for completely sparse files */
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- if (sparse_scan_file_wholesparse (file))
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- return true;
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-
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switch (hole_detection)
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{
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case HOLE_DETECTION_DEFAULT:
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--
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2.15.1
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