Commit | Line | Data |
---|---|---|
45413064 MW |
1 | This patch is needed in order to build Guix on a Btrfs file system. |
2 | ||
3 | ||
4 | From da922703282b0d3b8837a99a9c7fdd32f1d20d49 Mon Sep 17 00:00:00 2001 | |
5 | From: Mark H Weaver <mhw@netris.org> | |
6 | Date: Tue, 9 Jan 2018 20:16:14 -0500 | |
7 | Subject: [PATCH] Remove nonportable check for files containing only zeroes. | |
8 | ||
9 | This check benefitted only one unlikely case (large files containing | |
10 | only zeroes, on systems that do not support SEEK_HOLE) and was based | |
11 | on an assumption about file system behavior that is not mandated by | |
12 | POSIX and no longer holds in practice, namely that for sufficiently | |
13 | large files, (st_blocks == 0) implies that the file contains only | |
14 | zeroes. Examples of file systems that violate this assumption include | |
15 | Linux's /proc file system and Btrfs. | |
16 | ||
17 | * src/sparse.c (sparse_scan_file_wholesparse): Remove this function. | |
18 | (sparse_scan_file_seek): Remove the initial check for files containing | |
19 | only zeroes. | |
20 | --- | |
21 | src/sparse.c | 24 ------------------------ | |
22 | 1 file changed, 24 deletions(-) | |
23 | ||
24 | diff --git a/src/sparse.c b/src/sparse.c | |
25 | index d41c0ea..3de6560 100644 | |
26 | --- a/src/sparse.c | |
27 | +++ b/src/sparse.c | |
28 | @@ -261,26 +261,6 @@ sparse_scan_file_raw (struct tar_sparse_file *file) | |
29 | return tar_sparse_scan (file, scan_end, NULL); | |
30 | } | |
31 | ||
32 | -static bool | |
33 | -sparse_scan_file_wholesparse (struct tar_sparse_file *file) | |
34 | -{ | |
35 | - struct tar_stat_info *st = file->stat_info; | |
36 | - struct sp_array sp = {0, 0}; | |
37 | - | |
38 | - /* Note that this function is called only for truly sparse files of size >= 1 | |
39 | - block size (checked via ST_IS_SPARSE before). See the thread | |
40 | - http://www.mail-archive.com/bug-tar@gnu.org/msg04209.html for more info */ | |
41 | - if (ST_NBLOCKS (st->stat) == 0) | |
42 | - { | |
43 | - st->archive_file_size = 0; | |
44 | - sp.offset = st->stat.st_size; | |
45 | - sparse_add_map (st, &sp); | |
46 | - return true; | |
47 | - } | |
48 | - | |
49 | - return false; | |
50 | -} | |
51 | - | |
52 | #ifdef SEEK_HOLE | |
53 | /* Try to engage SEEK_HOLE/SEEK_DATA feature. */ | |
54 | static bool | |
55 | @@ -343,10 +323,6 @@ sparse_scan_file_seek (struct tar_sparse_file *file) | |
56 | static bool | |
57 | sparse_scan_file (struct tar_sparse_file *file) | |
58 | { | |
59 | - /* always check for completely sparse files */ | |
60 | - if (sparse_scan_file_wholesparse (file)) | |
61 | - return true; | |
62 | - | |
63 | switch (hole_detection) | |
64 | { | |
65 | case HOLE_DETECTION_DEFAULT: | |
66 | -- | |
67 | 2.15.1 | |
68 |