Leveraged the existing verification code by making it also check the
retrievalSecurityPolicy.
Also, prevented getViaTmp from running the download action at all when the
retrievalSecurityPolicy is going to prevent verifying and so storing it.
Added annex.security.allow-unverified-downloads. A per-remote version
would be nice to have too, but would need more plumbing, so KISS.
(Bill the Cat reference not too over the top I hope. The point is to
make this something the user reads the documentation for before using.)
A few calls to verifyKeyContent and getViaTmp, that don't
involve downloads from remotes, have RetrievalAllKeysSecure hard-coded.
It was also hard-coded for P2P.Annex and Command.RecvKey,
to match the values of the corresponding remotes.
A few things use retrieveKeyFile/retrieveKeyFileCheap without going
through getViaTmp.
* Command.Fsck when downloading content from a remote to verify it.
That content does not get into the annex, so this is ok.
* Command.AddUrl when using a remote to download an url; this is new
content being added, so this is ok.
This commit was sponsored by Fernando Jimenez on Patreon.
Security fix! Allowing any schemes, particularly file: and
possibly others like scp: allowed file exfiltration by anyone who had
write access to the git repository, since they could add an annexed file
using such an url, or using an url that redirected to such an url,
and wait for the victim to get it into their repository and send them a copy.
* Added annex.security.allowed-url-schemes setting, which defaults
to only allowing http and https URLs. Note especially that file:/
is no longer enabled by default.
* Removed annex.web-download-command, since its interface does not allow
supporting annex.security.allowed-url-schemes across redirects.
If you used this setting, you may want to instead use annex.web-options
to pass options to curl.
With annex.web-download-command removed, nearly all url accesses in
git-annex are made via Utility.Url via http-client or curl. http-client
only supports http and https, so no problem there.
(Disabling one and not the other is not implemented.)
Used curl --proto to limit the allowed url schemes.
Note that this will cause git annex fsck --from web to mark files using
a disallowed url scheme as not being present in the web. That seems
acceptable; fsck --from web also does that when a web server is not available.
youtube-dl already disabled file: itself (probably for similar
reasons). The scheme check was also added to youtube-dl urls for
completeness, although that check won't catch any redirects it might
follow. But youtube-dl goes off and does its own thing with other
protocols anyway, so that's fine.
Special remotes that support other domain-specific url schemes are not
affected by this change. In the bittorrent remote, aria2c can still
download magnet: links. The download of the .torrent file is
otherwise now limited by annex.security.allowed-url-schemes.
This does not address any external special remotes that might download
an url themselves. Current thinking is all external special remotes will
need to be audited for this problem, although many of them will use
http libraries that only support http and not curl's menagarie.
The related problem of accessing private localhost and LAN urls is not
addressed by this commit.
This commit was sponsored by Brett Eisenberg on Patreon.
* For url downloads, git-annex now defaults to using a http library,
rather than wget or curl. But, if annex.web-options is set, it will
use curl. To use the .netrc file, run:
git config annex.web-options --netrc
* git-annex no longer uses wget (and wget is no longer shipped with
git-annex builds).
Note that curl is always run in silent mode, since the new API for
download has a MeterUpdate and doesn't make way for curl progress
output. It might be worth writing a parser for curl's progress output
to update the meter when using it, but I didn't bother with this edge
case for now.
This commit was supported by the NSF-funded DataLad project.
Enable HTTP connection reuse across multiple files, when git-annex
uses http-conduit. Before, a new Manager was created each time
Utility.Url used it. Now, a single Manager gets created the first time,
so connections are reused.
Doesn't help when external programs are used for url download,
but does speed up addurl --fast, fsck --from web, etc.
Testing fsck --fast --from web with 3 files, over high-latency
satellite internet, it sped up from 19.37s to 14.96s.
This commit was supported by the NSF-funded DataLad project.
When resuming a download and not using a rolling checksummer like rsync,
the partial file we start with might contain garbage, in the case where a
file changed as it was being downloaded. So, disabling verification on
resumes risked a bad object being put into the annex.
Even downloads with rsync are currently affected. It didn't seem worth the
added complexity to special case those to prevent verification, especially
since git-annex is using rsync less often now.
This commit was sponsored by Brock Spratlen on Patreon.
P2P protocol version 1 adds VALID|INVALID after DATA; INVALID means the
file was detected to change content while it was being sent and so we
may not have received the valid content of the file.
Added new MustVerify constructor for Verification, which forces
verification even when annex.verify=false etc. This is used when INVALID
and in protocol version 0.
As well as changing git-annex-shell p2psdio, this makes git-annex tor
remotes always force verification, since they don't yet use protocol
version 1. Previously, annex.verify=false could skip verification when
using tor remotes, and let bad data into the repository.
This commit was sponsored by Jack Hill on Patreon.
lockContentShared had a screwy caveat that it didn't verify that the content
was present when locking it, but in the most common case, eg indirect mode,
it failed to lock when the content is not present.
That led to a few callers forgetting to check inAnnex when using it,
but the potential data loss was unlikely to be noticed because it only
affected direct mode I think.
Fix data loss bug when the local repository uses direct mode, and a
locally modified file is dropped from a remote repsitory. The bug
caused the modified file to be counted as a copy of the original file.
(This is not a severe bug because in such a situation, dropping
from the remote and then modifying the file is allowed and has the same
end result.)
And, in content locking over tor, when the remote repository is
in direct mode, it neglected to check that the content was actually
present when locking it. This could cause git annex drop to remove
the only copy of a file when it thought the tor remote had a copy.
So, make lockContentShared do its own inAnnex check. This could perhaps
be optimised for direct mode, to avoid the check then, since locking
the content necessarily verifies it exists there, but I have not bothered
with that.
This commit was sponsored by Jeff Goeke-Smith on Patreon.
Better to make it not be surprising and slow, than surprising and fast.
--raw can be used when it needs to be really fast.
Implemented adding a youtube-dl supported url to an existing file.
This commit was sponsored by andrea rota.
Including resuming and cleanup of incomplete downloads.
Still todo: --fast, --relaxed, importfeed, disk reserve checking,
quvi code cleanup.
This commit was sponsored by Anthony DeRobertis on Patreon.
Needed to run youtube-dl in, but could also be useful for other stuff.
The tricky part of this was making the workdir be cleaned up whenever the
tmp object file is cleaned up.
This commit was sponsored by Ole-Morten Duesund on Patreon.
Needs ghc 7.6.1, so minimum base version increased slightly. All builds
are well above this version of ghc, and debian oldstable is as well.
Code that could use lambdacase can be found by running:
git grep -B 1 'case ' | less
and searching in less for "<-"
This commit was sponsored by andrea rota.
That version has my patches for the problems that Utility.PosixFiles
was working around, so am able to get rid of that module now.
This will later allow bringing back the custom-setup stanza in the cabal
file. It will need to depend on unix-compat 0.5 on all OS's, which I'm
not ready to do yet.
This commit was sponsored by Nick Daly on Patreon.
Don't allow "exporttree=yes" to be set when the special remote
does not support exports. That would be confusing since the user would
set up a special remote for exports, but `git annex export` to it would
later fail.
This commit was supported by the NSF-funded DataLad project.
Straightforward enough, except for the needed belt-and-suspenders sanity
checks to avoid foot shooting due to exports not being key/value stores.
* Even when annex.verify=false, always verify from exports.
* Only get files from exports that use a backend that supports
checksum verification.
* Never trust exports, even if the user says to, because then
`git annex drop` would drop content if the export seemed to contain
a copy.
This commit was supported by the NSF-funded DataLad project.
Cryptographically secure hashes can be forced to be used in a repository,
by setting annex.securehashesonly. This does not prevent the git repository
from containing files with insecure hashes, but it does prevent the content
of such files from being pulled into .git/annex/objects from another
repository.
We want to make sure that at no point does git-annex accept content into
.git/annex/objects that is hashed with an insecure key. Here's how it
was done:
* .git/annex/objects/xx/yy/KEY/ is kept frozen, so nothing can be
written to it normally
* So every place that writes content must call, thawContent or modifyContent.
We can audit for these, and be sure we've considered all cases.
* The main functions are moveAnnex, and linkToAnnex; these were made to
check annex.securehashesonly, and are the main security boundary
for annex.securehashesonly.
* Most other calls to modifyContent deal with other files in the KEY
directory (inode cache etc). The other ones that mess with the content
are:
- Annex.Direct.toDirectGen, in which content already in the
annex directory is moved to the direct mode file, so not relevant.
- fix and lock, which don't add new content
- Command.ReKey.linkKey, which manually unlocks it to make a
copy.
* All other calls to thawContent appear safe.
Made moveAnnex return a Bool, so checked all callsites and made them
deal with a failure in appropriate ways.
linkToAnnex simply returns LinkAnnexFailed; all callsites already deal
with it failing in appropriate ways.
This commit was sponsored by Riku Voipio.
Where before the "name" of a key and a backend was a string, this makes
it a concrete data type.
This is groundwork for allowing some varieties of keys to be disabled
in file2key, so git-annex won't use them at all.
Benchmarks ran in my big repo:
old git-annex info:
real 0m3.338s
user 0m3.124s
sys 0m0.244s
new git-annex info:
real 0m3.216s
user 0m3.024s
sys 0m0.220s
new git-annex find:
real 0m7.138s
user 0m6.924s
sys 0m0.252s
old git-annex find:
real 0m7.433s
user 0m7.240s
sys 0m0.232s
Surprising result; I'd have expected it to be slower since it now parses
all the key varieties. But, the parser is very simple and perhaps
sharing KeyVarieties uses less memory or something like that.
This commit was supported by the NSF-funded DataLad project.
ghc 8 added backtraces on uncaught errors. This is great, but git-annex was
using error in many places for a error message targeted at the user, in
some known problem case. A backtrace only confuses such a message, so omit it.
Notably, commands like git annex drop that failed due to eg, numcopies,
used to use error, so had a backtrace.
This commit was sponsored by Ethan Aubin.
Note that get --from foo --failed will get things that a previous get --from bar
tried and failed to get, etc. I considered making --failed only retry
transfers from the same remote, but it was easier, and seems more useful,
to not have the same remote requirement.
Noisy due to some refactoring into Types/
When annex.thin is set, adding an object will add the execute bits to the
work tree file, and this does mean that the annex object file ends up
executable.
This doesn't add any complexity that wasn't already present, because git
annex add of an executable file has always ingested it so that the annex
object ends up executable.
But, since an annex object file can be executable or not, when populating
an unlocked file from one, the executable bit is always added or removed
to match the mode of the pointer file.
Fixes several bugs with updates of pointer files. When eg, running
git annex drop --from localremote
it was updating the pointer file in the local repository, not the remote.
Also, fixes drop ../foo when run in a subdir, and probably lots of other
problems. Test suite drops from ~30 to 11 failures now.
TopFilePath is used to force thinking about what the filepath is relative
to.
The data stored in the sqlite db is still just a plain string, and
TopFilePath is a newtype, so there's no overhead involved in using it in
DataBase.Keys.
Since the file was present and locked, its annex object was not in the
inode cache. So, despite not needing to update the annex object when the
clean filter is run on the content by git merge, it does need to record the
inode cache of the annex object. Otherwise, the annex object will be
assumed to be bad, since its inode is not cached.
Decided it's too scary to make v6 unlocked files have 1 copy by default,
but that should be available to those who need it. This is consistent with
git-annex not dropping unused content without --force, etc.
* Added annex.thin setting, which makes unlocked files in v6 repositories
be hard linked to their content, instead of a copy. This saves disk
space but means any modification of an unlocked file will lose the local
(and possibly only) copy of the old version.
* Enable annex.thin by default on upgrade from direct mode to v6, since
direct mode made the same tradeoff.
* fix: Adjusts unlocked files as configured by annex.thin.
This can happen when ingesting a new file in either locked or unlocked
mode, when some unlocked files in the repo use the same key, and the
content was not locally available before.
This fixes a race where the modified file ended up in annex/objects, and
the InodeCache stored in the database was for the modified version, so
git-annex didn't know it had gotten modified.
The race could occur when the smudge filter was running; now it gets the
InodeCache before generating the Key, which avoids the race.
This covers the case where multiple files have the same content and are
added with git add. Previously only the one that was linked to the annex
got its inode cached; now both are.
When a v6 unlocked files is removed from the work tree,
unused doesn't show it. When it gets removed from the index,
unused does show it. This is the same as a locked file.
If multiple files point to the same annex object, the user may want to
modify them independently, so don't use a hard link.
Also, check diskreserve when copying.
This avoids querying the database when the content file doen't exist
(or otherwise fails the provided check). However, it does add overhead of
querying the database, and will certianly impact performance.
The Keys database can hold multiple inode caches for a given key. One for
the annex object, and one for each pointer file, which may not be hard
linked to it.
Inode caches for a key are recorded when its content is added to the annex,
but only if it has known pointer files. This is to avoid the overhead of
maintaining the database when not needed.
When the smudge filter outputs a file's content, the inode cache is not
updated, because git's smudge interface doesn't let us write the file. So,
dropping will fall back to doing an expensive verification then. Ideally,
git's interface would be improved, and then the inode cache could be
updated then too.
Renamed the db to keys, since it is various info about a Keys.
Dropping a key will update its pointer files, as long as their content can
be verified to be unmodified. This falls back to checksum verification, but
I want it to use an InodeCache of the key, for speed. But, I have not made
anything populate that cache yet.
When core.sharedRepository is set, annex object files are not made mode
444, since that prevents a user other than the file owner from locking
them. Instead, a mode such as 664 is used in this case.
There should be no behavior changes in this commit, it just adds a more
expressive data type and adjusts code that had been passing around a [UUID]
or sometimes a Maybe Remote to instead use [VerifiedCopy].
Although, since some functions were taking two different [UUID] lists,
there's some potential for me to have gotten it horribly wrong.
Also, rename lockContent to lockContentExclusive
inAnnexSafe should perhaps be eliminated, and instead use
`lockContentShared inAnnex`. However, I'm waiting on that, as there are
only 2 call sites for inAnnexSafe and it's fiddly.
In c6632ee5c8, it actually only handled
uploading objects to a shared repository. To avoid verification when
downloading objects from a shared repository, was a lot harder.
On the plus side, if the process of downloading a file from a remote
is able to verify its content on the side, the remote can indicate this
now, and avoid the extra post-download verification.
As of yet, I don't have any remotes (except Git) using this ability.
Some more work would be needed to support it in special remotes.
It would make sense for tahoe to implicitly verify things downloaded from it;
as long as you trust your tahoe server (which typically runs locally),
there's cryptographic integrity. OTOH, despite bup being based on shas,
a bup repo under an attacker's control could have the git ref used for an
object changed, and so a bup repo shouldn't implicitly verify. Indeed,
tahoe seems unique in being trustworthy enough to implicitly verify.
* When annex objects are received into git repositories, their checksums are
verified then too.
* To get the old, faster, behavior of not verifying checksums, set
annex.verify=false, or remote.<name>.annex-verify=false.
* setkey, rekey: These commands also now verify that the provided file
matches the key, unless annex.verify=false.
* reinject: Already verified content; this can now be disabled by
setting annex.verify=false.
recvkey and reinject already did verification, so removed now duplicate
code from them. fsck still does its own verification, which is ok since it
does not use getViaTmp, so verification doesn't happen twice when using fsck
--from.
The content file may not be owned by the user running git-annex, in which
case, setting the owner write bit was not enough to let lockContent
act on the file. However, with some core.sharedRepository configs, the file
should be writable by the user's group. So, the thing to do is to call
thawContent on it.
It was returning Just False in this situation, which differed from indirect
mode behavior. I don't think this led to any actual problems; things that
checked if the file being dropped was present just failed to fail, and
instead reported it wasn't present, possibly incorrectly.
Hmm, it's possible that this could have made git annex fsck --from remote
update the location log wrongly, if a remote was in direct mode, and was in
the middle of trying to drop a key, and the drop later failed.
Also cleaned up the code, avoiding creating a lock file if we're going to
open it for create later anyway.
And, if there's an exception while preparing to lock the file, but not at
the point of actually taking the lock, throw an exception, instead of
silently not locking and pretending to succeed.
And, on Windows, always use lock file, even if the repo somehow got into
indirect mode (maybe with cygwin git..)
The one exception is in Utility.Daemon. As long as a process only
daemonizes once, which seems reasonable, and as long as it avoids calling
checkDaemon once it's already running as a daemon, the fcntl locking
gotchas won't be a problem there.
Annex.LockFile has it's own separate lock pool layer, which has been
renamed to LockCache. This is a persistent cache of locks that persist
until closed.
This is not quite done; lockContent stil needs to be converted.
Came up with a generic way to filter out progress messages while keeping
errors, for commands that use stderr for both.
--json mode will disable command outputs too.
* init: Repository tuning parameters can now be passed when initializing a
repository for the first time. For details, see
http://git-annex.branchable.com/tuning/
* merge: Refuse to merge changes from a git-annex branch of a repo
that has been tuned in incompatable ways.
Avoid using fileSize which maxes out at just 2 gb on Windows.
Instead, use hFileSize, which doesn't have a bounded size.
Fixes support for files > 2 gb on Windows.
Note that the InodeCache code only needs to compare a file size,
so it doesn't matter it the file size wraps. So it has been
left as-is. This was necessary both to avoid invalidating existing inode
caches, and because the code passed FileStatus around and would have become
more expensive if it called getFileSize.
This commit was sponsored by Christian Dietrich.
Reverts 965e106f24
Unfortunately, this caused breakage on Windows, and possibly elsewhere,
because parentDir and takeDirectory do not behave the same when there is a
trailing directory separator.
parentDir is less safe than takeDirectory, especially when working
with relative FilePaths. It's really only useful in loops that
want to terminate at /
This commit was sponsored by Audric SCHILTKNECHT.
This fixes all instances of " \t" in the code base. Most common case
seems to be after a "where" line; probably vim copied the two space layout
of that line.
Done as a background task while listening to episode 2 of the Type Theory
podcast.
* New annex.hardlink setting. Closes: #758593
* init: Automatically detect when a repository was cloned with --shared,
and set annex.hardlink=true, as well as marking the repository as
untrusted.
Had to reorganize Logs.Trust a bit to avoid a cycle between it and
Annex.Init.
This avoids cp -a overriding the default mode acls that the user might have
set in a git repository.
With GNU cp, this behavior change should not be a breaking change, because
git-anex also uses rsync sometimes in the same situation, and has only ever
preserved timestamps when using rsync.
Systems without GNU cp will no longer use cp -a, but instead just cp.
So, timestamps will no longer be preserved. Preserving timestamps when
copying between repos is not guaranteed anyway.
Closes: #729757
This fixed one bug where it needed to be and wasn't (in Assistant.Unused).
And also found one place where lockContent was used unnecessarily (by
drop --from remote).
A few other places like uninit probably don't really need to lockContent,
but it doesn't hurt to do call it anyway.
This commit was sponsored by David Wagner.
Also fixes a test suite failures introduced in recent commits, where
inAnnexSafe failed in indirect mode, since it tried to open the lock file
ReadWrite. This is why the new checkLocked opens it ReadOnly.
This commit was sponsored by Chad Horohoe.
The nice refactoring in ec7dd0446a
highlighted a bug in lockContent -- when the content is not present,
this incorrectly created an empty lock file, using the same filename
as the content file.
This seems like it could result in empty objects, which fsck would detect
and complain about. Both drop and move --to call lockContent, as does
Remote.Git.dropKey -- I think we got lucky and this bug didn't show up
because both all of those only operate on files that are present. So
this bug could only manifest if there was a race, and a file's content
was dropped at just the wrong time, just as another process was about to
drop it. (And then only if the other process's dropping failed, otherwise
it'd delete the empty object file.)
Hmm, move --from also called lockContent. Unnecessarily, since the content
is not being removed from the local annex. In this case, the combination of
the 2 bugs could result in an empty lock file being written, and then if
the download of the content failed, left in the object directory as the
content.
This commit also optimises lockContent, avoiding an unncessary
doesFileExist test and instead just catching the exception that's thrown
when the file doesn't exist.
This commit was sponsored by Justine Lam.
Added a convenience Utility.LockFile that is not a windows/posix
portability shim, but still manages to cut down on the boilerplate around
locking.
This commit was sponsored by Johan Herland.
(With the exception of daemon pid locking.)
This fixes at part of #758630. I reproduced the assistant locking eg, a
removable drive's annex journal lock file and forking a long-running
git-cat-file process that inherited that lock.
This did not affect Windows.
Considered doing a portable Utility.LockFile layer, but git-annex uses
posix locks in several special ways that have no direct Windows equivilant,
and it seems like it would mostly be a complication.
This commit was sponsored by Protonet.
Removed old extensible-exceptions, only needed for very old ghc.
Made webdav use Utility.Exception, to work after some changes in DAV's
exception handling.
Removed Annex.Exception. Mostly this was trivial, but note that
tryAnnex is replaced with tryNonAsync and catchAnnex replaced with
catchNonAsync. In theory that could be a behavior change, since the former
caught all exceptions, and the latter don't catch async exceptions.
However, in practice, nothing in the Annex monad uses async exceptions.
Grepping for throwTo and killThread only find stuff in the assistant,
which does not seem related.
Command.Add.undo is changed to accept a SomeException, and things
that use it for rollback now catch non-async exceptions, rather than
only IOExceptions.
Putting a callback in the Retriever type allows for the callback to
remove the retrieved file when it's done with it.
I did not really want to make Retriever be fixed to Annex Bool,
but when I tried to use Annex a, I got into some type of type mess.
Needed for eg, Remote.External.
Generally, any Retriever that stores content in a file is responsible for
updating the meter, while ones that procude a lazy bytestring cannot update
the meter, so are not asked to.
When annex.genmetadata is set, metadata from the feed is added to files
that are imported from it.
Reused the same feedtitle and itemtitle, feedauthor, itemauthor, etc names
that are used in --template.
Also added title and author, which are the item title/author if available,
falling back to the feed title/author. These are more likely to be common
metadata fields.
(There is a small bit of dupication here, but once git gets
around to packing the object, it will compress it away.)
The itempubdate field is not included in the metadata as a string; instead
it is used to generate year and month fields, same as is done when adding
files with annex.genmetadata set.
This commit was sponsored by Amitai Schlair, who cooincidentially
is responsible for ikiwiki generating nice feed metadata!
unused: In direct mode, files that are deleted from the work tree are no longer incorrectly detected as unused.
Direct mode `git annex info` slows down a bit due to more stringent
checking, but not by a lot.
This allows eg, putting .git/annex/tmp on a ram disk, if the disk IO
of temp object files is too annoying (and if you don't want to keep
partially transferred objects across reboots).
.git/annex/misctmp must be on the same filesystem as the git work tree,
since files are moved to there in a way that will not work cross-device,
as well as symlinked into there.
I first wanted to put the tmp objects in .git/annex/objects/tmp, but
that would pose transition problems on upgrade when partially transferred
objects existed.
git annex info does not currently show the size of .git/annex/misctemp,
since it should stay small. It would also be ok to make something clean it
out, periodically.
ef24751922 described a bug moving between
remotes in direct mode; I can no longer reproduce it with this strange
workaround removed. Also test suite still passes. Hope the broken code just
got fixed in the meantime.
Seems that locking of annexed objects when they're being dropped was broken
in direct mode:
* When taking the lock before dropping, it created the .git/annex/objects
file, as an empty file. It seems that the dropping code deleted that,
but that is not right, and for all I know could in some situation cause
a corrupted object to leak out.
* When the lock was checked, it actually tried to open each direct mode
file, and checked if it was locked. Not the same lock used above, and
could also fail if some consumer of the file locked it.
Fixed this, and added windows support by switching direct mode to lock a
.lck file.
This adds a http HEAD before the download is done. That was already the
case when the assistant was running, and it seems worth it to avoid filling
up the whole disk, like happened to my server today.
Because that allowed writing to symlinks of files that are not present,
which followed the link and put bad content in an object location.
fsck: Fix up .git/annex/object directory permissions.
This commit was sponsored by an anonymous bitcoin donor.
Overridable with --user-agent option.
Not yet done for S3 or WebDAV due to limitations of libraries used --
nether allows a user-agent header to be specified.
This commit sponsored by Michael Zehrer.
Made fromDirect check that a file in the tree has good content (and is not
a broken symlink either) before copying it to another file that has the
same key.
Made replaceFile clean up the temp file if the action that creates it, or
the file replacement action fails.
Before, if a direct mode repo had one or more associated files that
were modifed, moving the object into it would overwrite the associated
files with the pristine object.
Now, modified associated files are left unchanged. To ensure that,
when an object is moved into a direct mode repo, it's not thrown away,
it gets stored in indirect mode.
This fixes a bug with git annex add in direct mode. If some files already
existed in the tree pointing at the same key as a file that was just added,
and their content was not present, add neglected to copy the content to
those files.
I also changed the behavior of moveAnnex slightly: When content is moved
into the annex in direct mode, it does not overwrite any content already
present in direct mode files. That content may be modified after all.
A content directory can be frozen in direct mode. One way this can happen
is if the content is transferred before direct mode has a mapping for it,
so it's stored in the content directory.
So, we need to thaw the content directory before doing things with it.
