CRLF conversion bears a slight chance of corrupting data.
autocrlf=true will convert CRLF to LF during commit and LF to
CRLF during checkout. A file that contains a mixture of LF and
CRLF before the commit cannot be recreated by git. For text
files this is the right thing to do: it corrects line endings
such that we have only LF line endings in the repository.
But for binary files that are accidentally classified as text the
conversion can corrupt data.
If you recognize such corruption early you can easily fix it by
setting the conversion type explicitly in .gitattributes. Right
after committing you still have the original file in your work
tree and this file is not yet corrupted. You can explicitly tell
git that this file is binary and git will handle the file
appropriately.
Unfortunately, the desired effect of cleaning up text files with
mixed line endings and the undesired effect of corrupting binary
files cannot be distinguished. In both cases CRLFs are removed
in an irreversible way. For text files this is the right thing
to do because CRLFs are line endings, while for binary files
converting CRLFs corrupts data.
This patch adds a mechanism that can either warn the user about
an irreversible conversion or can even refuse to convert. The
mechanism is controlled by the variable core.safecrlf, with the
following values:
- false: disable safecrlf mechanism
- warn: warn about irreversible conversions
- true: refuse irreversible conversions
The default is to warn. Users are only affected by this default
if core.autocrlf is set. But the current default of git is to
leave core.autocrlf unset, so users will not see warnings unless
they deliberately chose to activate the autocrlf mechanism.
The safecrlf mechanism's details depend on the git command. The
general principles when safecrlf is active (not false) are:
- we warn/error out if files in the work tree can modified in an
irreversible way without giving the user a chance to backup the
original file.
- for read-only operations that do not modify files in the work tree
we do not not print annoying warnings.
There are exceptions. Even though...
- "git add" itself does not touch the files in the work tree, the
next checkout would, so the safety triggers;
- "git apply" to update a text file with a patch does touch the files
in the work tree, but the operation is about text files and CRLF
conversion is about fixing the line ending inconsistencies, so the
safety does not trigger;
- "git diff" itself does not touch the files in the work tree, it is
often run to inspect the changes you intend to next "git add". To
catch potential problems early, safety triggers.
The concept of a safety check was originally proposed in a similar
way by Linus Torvalds. Thanks to Dimitry Potapov for insisting
on getting the naked LF/autocrlf=true case right.
Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Some versions of 'tr' only accept octal codes if entered with three digits,
and therefor misinterpret the '\0' in the test suite.
Some versions of 'tr' reject the (needless) use of character classes.
Signed-off-by: H.Merijn Brand <h.m.brand@xs4all.nl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git may segfault if gitattributes contains an invalid
entry. A test is added to t0020 that triggers the segfault.
The parsing code is fixed to avoid the crash.
Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This makes .gitattributes files to be read from the index when
they are not checked out to the work tree. This is in line with
the way we always allowed low-level tools to operate in sparsely
checked out work tree in a reasonable way.
It swaps the order of new file creation and converting the blob
to work tree representation; otherwise when we are in the middle
of checking out .gitattributes we would notice an empty but
unwritten .gitattributes file in the work tree and will ignore
the copy in the index.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This updates the semantics of 'crlf' so that .gitattributes file
can say "this is text, even though it may look funny".
Setting the `crlf` attribute on a path is meant to mark the path
as a "text" file. 'core.autocrlf' conversion takes place
without guessing the content type by inspection.
Unsetting the `crlf` attribute on a path is meant to mark the
path as a "binary" file. The path never goes through line
endings conversion upon checkin/checkout.
Unspecified `crlf` attribute tells git to apply the
`core.autocrlf` conversion when the file content looks like
text.
Setting the `crlf` attribut to string value "input" is similar
to setting the attribute to `true`, but also forces git to act
as if `core.autocrlf` is set to `input` for the path.
Signed-off-by: Junio C Hamano <junkio@cox.net>
At the same time, we do not want to allow arbitrary strings for
attribute names, as we are likely to want to extend the syntax
later. Allow only alnum, dash, underscore and dot for now.
Signed-off-by: Junio C Hamano <junkio@cox.net>
This defines the semantics of 'crlf' attribute as an example.
When a path has this attribute unset (i.e. '!crlf'), autocrlf
line-end conversion is not applied.
Eventually we would want to let users to build a pipeline of
processing to munge blob data to filesystem format (and in the
other direction) based on combination of attributes, and at that
point the mechanism in convert_to_{git,working_tree}() that
looks at 'crlf' attribute needs to be enhanced. Perhaps the
existing 'crlf' would become the first step in the input chain,
and the last step in the output chain.
Signed-off-by: Junio C Hamano <junkio@cox.net>
This teaches git-apply that the data read from and written to
the filesystem might need to get converted to adjust for local
line-ending convention.
Signed-off-by: Junio C Hamano <junkio@cox.net>
This tests lowlevel of update/checkout codepaths and some patch
application. Currently, variants of "git apply" that look at
the working tree files does not work, so it does not test the
patch application without parameter and with --index parameter
when autocrlf is set to produce CRLF files.
We should add test for diff generation too.
Signed-off-by: Junio C Hamano <junkio@cox.net>
