165 lines
6.2 KiB
Diff
165 lines
6.2 KiB
Diff
From 7819e9ce26a6331f7a347c59cebfd5c6a8902ea3 Mon Sep 17 00:00:00 2001
|
||
From: Lukas Nykryn <lnykryn@redhat.com>
|
||
Date: Thu, 15 Aug 2024 14:19:58 +0200
|
||
Subject: [PATCH] =?UTF-8?q?Warn=20=E2=80=9Cfile=20changed=20as=20we=20read?=
|
||
=?UTF-8?q?=20it=E2=80=9D=20less=20often?=
|
||
MIME-Version: 1.0
|
||
Content-Type: text/plain; charset=UTF-8
|
||
Content-Transfer-Encoding: 8bit
|
||
|
||
* src/create.c (dump_file0): Remove an fstatat call that is
|
||
unnecessary because the file wasn’t read so we can treat the first
|
||
fstatat as atomic. Warn “file changed” when the file’s size,
|
||
mtime, user ID, group ID, or mode changes, instead of when the
|
||
file’s size or ctime changes. Also, when such a change happens,
|
||
do not change exit status if --ignore-failed-read. Finally, don’t
|
||
attempt to change atime back if it didn’t change.
|
||
---
|
||
doc/tar.texi | 10 ++++++----
|
||
src/create.c | 54 ++++++++++++++++++++++++++++++++++++----------------
|
||
2 files changed, 44 insertions(+), 20 deletions(-)
|
||
|
||
diff --git a/doc/tar.texi b/doc/tar.texi
|
||
index b66b163..dd5a272 100644
|
||
--- a/doc/tar.texi
|
||
+++ b/doc/tar.texi
|
||
@@ -2854,7 +2854,7 @@ Ignore exit codes of subprocesses. @xref{Writing to an External Program}.
|
||
@opsummary{ignore-failed-read}
|
||
@item --ignore-failed-read
|
||
|
||
-Do not exit unsuccessfully merely because an unreadable file was encountered.
|
||
+Do not exit unsuccessfully merely because reading failed.
|
||
@xref{Ignore Failed Read}.
|
||
|
||
@opsummary{ignore-zeros}
|
||
@@ -4638,7 +4638,8 @@ Disable all warning messages.
|
||
@item file-changed
|
||
@samp{%s: file changed as we read it}
|
||
@item failed-read
|
||
-Suppresses warnings about unreadable files or directories. This
|
||
+Suppresses warnings about read failures, which can occur if files
|
||
+or directories are unreadable, or if they change while being read. This
|
||
keyword applies only if used together with the @option{--ignore-failed-read}
|
||
option. @xref{Ignore Failed Read}.
|
||
@end table
|
||
@@ -5761,11 +5762,12 @@ Disable SELinux context support.
|
||
@table @option
|
||
@item --ignore-failed-read
|
||
@opindex ignore-failed-read
|
||
-Do not exit with nonzero on unreadable files or directories.
|
||
+Do not exit with nonzero if there are mild problems while reading.
|
||
@end table
|
||
|
||
This option has effect only during creation. It instructs tar to
|
||
-treat as mild conditions any missing or unreadable files (directories).
|
||
+treat as mild conditions any missing or unreadable files (directories),
|
||
+or files that change while reading.
|
||
Such failures don't affect the program exit code, and the
|
||
corresponding diagnostic messages are marked as warnings, not errors.
|
||
These warnings can be suppressed using the
|
||
diff --git a/src/create.c b/src/create.c
|
||
index e2816fc..2b3001d 100644
|
||
--- a/src/create.c
|
||
+++ b/src/create.c
|
||
@@ -1650,8 +1650,6 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p)
|
||
{
|
||
union block *header;
|
||
char type;
|
||
- off_t original_size;
|
||
- struct timespec original_ctime;
|
||
off_t block_ordinal = -1;
|
||
int fd = 0;
|
||
bool is_dir;
|
||
@@ -1694,10 +1692,11 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p)
|
||
return;
|
||
}
|
||
|
||
- st->archive_file_size = original_size = st->stat.st_size;
|
||
+ struct stat st1 = st->stat;
|
||
+ st->archive_file_size = st->stat.st_size;
|
||
st->atime = get_stat_atime (&st->stat);
|
||
st->mtime = get_stat_mtime (&st->stat);
|
||
- st->ctime = original_ctime = get_stat_ctime (&st->stat);
|
||
+ st->ctime = get_stat_ctime (&st->stat);
|
||
|
||
#ifdef S_ISHIDDEN
|
||
if (S_ISHIDDEN (st->stat.st_mode))
|
||
@@ -1747,7 +1746,7 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p)
|
||
if (is_dir || S_ISREG (st->stat.st_mode) || S_ISCTG (st->stat.st_mode))
|
||
{
|
||
bool ok;
|
||
- struct stat final_stat;
|
||
+ struct stat st2;
|
||
|
||
xattrs_acls_get (parentfd, name, st, 0, !is_dir);
|
||
xattrs_selinux_get (parentfd, name, st, fd);
|
||
@@ -1815,31 +1814,54 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p)
|
||
errno = - parentfd;
|
||
ok = false;
|
||
}
|
||
- else
|
||
- ok = fstatat (parentfd, name, &final_stat, fstatat_flags) == 0;
|
||
}
|
||
else
|
||
- ok = fstat (fd, &final_stat) == 0;
|
||
+ ok = fstat (fd, &st2) == 0;
|
||
|
||
if (! ok)
|
||
file_removed_diag (p, top_level, stat_diag);
|
||
}
|
||
|
||
- if (ok)
|
||
+ if (ok && fd)
|
||
{
|
||
- if ((timespec_cmp (get_stat_ctime (&final_stat), original_ctime) != 0
|
||
- /* Original ctime will change if the file is a directory and
|
||
- --remove-files is given */
|
||
- && !(remove_files_option && is_dir))
|
||
- || original_size < final_stat.st_size)
|
||
+ /* Heuristically check whether the file is the same in all
|
||
+ attributes that tar cares about and can easily check.
|
||
+ Although the check is not perfect since it does not
|
||
+ consult file contents, it is typically good enough.
|
||
+ Do not check atime which is saved only to replace it later.
|
||
+ Do not check ctime where changes might be benign (e.g.,
|
||
+ another process creates a hard link to the file). */
|
||
+
|
||
+ /* If the file's user ID, group ID or mode changed, tar may
|
||
+ have output the wrong info for the file. */
|
||
+ ok &= st1.st_uid == st2.st_uid;
|
||
+ ok &= st1.st_gid == st2.st_gid;
|
||
+ ok &= st1.st_mode == st2.st_mode;
|
||
+
|
||
+ /* Likewise for the file's mtime, but skip this check if it
|
||
+ is a directory possibly updated by --remove-files. */
|
||
+ if (! (is_dir && remove_files_option))
|
||
+ ok &= ! timespec_cmp (get_stat_mtime (&st1),
|
||
+ get_stat_mtime (&st2));
|
||
+
|
||
+ /* Likewise for the file's size, but skip this check if it
|
||
+ is a directory as tar does not output directory sizes.
|
||
+ Although dump_regular_file caught regular file shrinkage,
|
||
+ it shouldn't hurt to check for shrinkage again now;
|
||
+ plus, the file may have grown. */
|
||
+ if (!is_dir)
|
||
+ ok &= st1.st_size == st2.st_size;
|
||
+
|
||
+ if (!ok)
|
||
{
|
||
WARNOPT (WARN_FILE_CHANGED,
|
||
(0, 0, _("%s: file changed as we read it"),
|
||
quotearg_colon (p)));
|
||
- set_exit_status (TAREXIT_DIFFERS);
|
||
+ if (! ignore_failed_read_option)
|
||
+ set_exit_status (TAREXIT_DIFFERS);
|
||
}
|
||
else if (atime_preserve_option == replace_atime_preserve
|
||
- && fd && (is_dir || original_size != 0)
|
||
+ && timespec_cmp (st->atime, get_stat_atime (&st2)) != 0
|
||
&& set_file_atime (fd, parentfd, name, st->atime) != 0
|
||
&& errno != EROFS )
|
||
utime_error (p);
|
||
--
|
||
2.45.2
|
||
|