Add per-repository eol normalization

Change the semantics of the "crlf" attribute so that it enables
end-of-line normalization when it is set, regardless of "core.autocrlf".

Add a new setting for "crlf": "auto", which enables end-of-line
conversion but does not override the automatic text file detection.

Add a new attribute "eol" with possible values "crlf" and "lf".  When
set, this attribute enables normalization and forces git to use CRLF or
LF line endings in the working directory, respectively.

The line ending style to be used for normalized text files in the
working directory is set using "core.autocrlf".  When it is set to
"true", CRLFs are used in the working directory; when set to "input" or
"false", LFs are used.

Signed-off-by: Eyvind Bernhardsen <eyvind.bernhardsen@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 113 insertions, 25 deletions

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index b396a871b3..f621b23b84 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -95,50 +95,138 @@ repository upon 'git add' and 'git commit'.
 `crlf`
 ^^^^^^
 
-This attribute controls the line-ending convention.
+This attribute enables and controls end-of-line normalization.  When a
+text file is normalized, its line endings are converted to LF in the
+repository.  To control what line ending style is used in the working
+directory, use the `eol` attribute for a single file and the
+`core.autocrlf` configuration variable for all text files.
 
 Set::
 
-	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.
+	Setting the `crlf` attribute on a path enables end-of-line
+	normalization and marks the path as a text file.  End-of-line
+	conversion takes place without guessing the content type.
 
 Unset::
 
 	Unsetting the `crlf` attribute on a path tells git not to
 	attempt any end-of-line conversion upon checkin or checkout.
 
+Set to string value "auto"::
+
+	When `crlf` is set to "auto", the path is marked for automatic
+	end-of-line normalization.  If git decides that the content is
+	text, its line endings are normalized to LF on checkin.
+
 Unspecified::
 
-	Unspecified `crlf` attribute tells git to apply the
-	`core.autocrlf` conversion when the file content looks
-	like text.
+	If the `crlf` attribute is unspecified, git uses the `eol`
+	attribute and the `core.autocrlf` configuration variable to
+	determine if the file should be converted.
 
-Set to string value "input"::
+Any other value causes git to act as if `crlf` has been left
+unspecified.
 
-	This 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.
+`eol`
+^^^^^
 
-Any other value set to `crlf` attribute is ignored and git acts
-as if the attribute is left unspecified.
+This attribute sets a specific line-ending style to be used in the
+working directory.  It enables end-of-line normalization without any
+content checks, similar to setting the `crlf` attribute.
 
+Set to string value "crlf"::
 
-The `core.autocrlf` conversion
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+	This setting forces git to normalize line endings on checkin
+	and convert them to CRLF when the file is checked out,
+	regardless of `crlf` and `core.autocrlf`.
+
+Set to string value "lf"::
+
+	This setting forces git to normalize line endings to LF on
+	checkin and prevents conversion to CRLF when the file is
+	checked out, regardless of `crlf` and `core.autocrlf`.
+	`crlf=input` is a backwards compatibility alias for `eol=lf`.
+
+End-of-line conversion
+^^^^^^^^^^^^^^^^^^^^^^
+
+While git normally leaves file contents alone, it can be configured to
+normalize line endings to LF in the repository and, optionally, to
+convert them to CRLF when files are checked out.
+
+Here is an example that will make git normalize .txt, .vcproj and .sh
+files, ensure that .vcproj files have CRLF and .sh files have LF in
+the working directory, and prevent .jpg files from being normalized
+regardless of their content.
+
+------------------------
+*.txt		crlf
+*.vcproj	eol=crlf
+*.sh		eol=lf
+*.jpg		-crlf
+------------------------
+
+Other source code management systems normalize all text files in their
+repositories, and there are two ways to enable similar automatic
+normalization in git.
+
+If you simply want to have CRLF line endings in your working directory
+regardless of the repository you are working with, you can set the
+config variable "core.autocrlf" without changing any attributes.
+
+------------------------
+[core]
+	autocrlf = true
+------------------------
+
+This does not force normalization of all text files, but does ensure
+that text files that you introduce to the repository have their line
+endings normalized to LF when they are added, and that files that are
+already normalized in the repository stay normalized.  You can also
+set `autocrlf` to "input" to have automatic normalization of new text
+files without conversion to CRLF in the working directory.
+
+If you want to interoperate with a source code management system that
+enforces end-of-line normalization, or you simply want all text files
+in your repository to be normalized, you should instead set the `crlf`
+attribute to "auto" for _all_ files.
+
+------------------------
+*	crlf=auto
+------------------------
+
+This ensures that all files that git considers to be text will have
+normalized (LF) line endings in the repository.
 
-If the configuration variable `core.autocrlf` is false, no
-conversion is done.
+NOTE: When `crlf=auto` normalization is enabled in an existing
+repository, any text files containing CRLFs should be normalized.  If
+they are not they will be normalized the next time someone tries to
+change them, causing unfortunate misattribution.  From a clean working
+directory:
 
-When `core.autocrlf` is true, it means that the platform wants
-CRLF line endings for files in the working tree, and you want to
-convert them back to the normal LF line endings when checking
-in to the repository.
+-------------------------------------------------
+$ echo "* crlf=auto" >>.gitattributes
+$ rm .git/index     # Remove the index to force git to
+$ git reset         # re-scan the working directory
+$ git status        # Show files that will be normalized
+$ git add -u
+$ git add .gitattributes
+$ git commit -m "Introduce end-of-line normalization"
+-------------------------------------------------
 
-When `core.autocrlf` is set to "input", line endings are
-converted to LF upon checkin, but there is no conversion done
-upon checkout.
+If any files that should not be normalized show up in 'git status',
+unset their `crlf` attribute before running 'git add -u'.
+
+------------------------
+manual.pdf	-crlf
+------------------------
+
+Conversely, text files that git does not detect can have normalization
+enabled manually.
+
+------------------------
+weirdchars.txt	crlf
+------------------------
 
 If `core.safecrlf` is set to "true" or "warn", git verifies if
 the conversion is reversible for the current setting of