Merge branch 'jc/attr'

* 'jc/attr': (28 commits)
  lockfile: record the primary process.
  convert.c: restructure the attribute checking part.
  Fix bogus linked-list management for user defined merge drivers.
  Simplify calling of CR/LF conversion routines
  Document gitattributes(5)
  Update 'crlf' attribute semantics.
  Documentation: support manual section (5) - file formats.
  Simplify code to find recursive merge driver.
  Counto-fix in merge-recursive
  Fix funny types used in attribute value representation
  Allow low-level driver to specify different behaviour during internal merge.
  Custom low-level merge driver: change the configuration scheme.
  Allow the default low-level merge driver to be configured.
  Custom low-level merge driver support.
  Add a demonstration/test of customized merge.
  Allow specifying specialized merge-backend per path.
  merge-recursive: separate out xdl_merge() interface.
  Allow more than true/false to attributes.
  Document git-check-attr
  Change attribute negation marker from '!' to '-'.
  ...

22 files changed, 1816 insertions, 134 deletions

diff --git a/.gitignore b/.gitignore
index fa7ac93594..4dc0c395fa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,7 @@ git-blame
 git-branch
 git-bundle
 git-cat-file
+git-check-attr
 git-check-ref-format
 git-checkout
 git-checkout-index
diff --git a/Documentation/Makefile b/Documentation/Makefile
index a637d8d559..8d3617db97 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -2,9 +2,10 @@ MAN1_TXT= \
 	$(filter-out $(addsuffix .txt, $(ARTICLES) $(SP_ARTICLES)), \
 		$(wildcard git-*.txt)) \
 	gitk.txt
+MAN5_TXT=gitattributes.txt
 MAN7_TXT=git.txt
 
-DOC_HTML=$(patsubst %.txt,%.html,$(MAN1_TXT) $(MAN7_TXT))
+DOC_HTML=$(patsubst %.txt,%.html,$(MAN1_TXT) $(MAN5_TXT) $(MAN7_TXT))
 
 ARTICLES = tutorial
 ARTICLES += tutorial-2
@@ -23,12 +24,14 @@ SP_ARTICLES = howto/revert-branch-rebase user-manual
 DOC_HTML += $(patsubst %,%.html,$(ARTICLES) $(SP_ARTICLES))
 
 DOC_MAN1=$(patsubst %.txt,%.1,$(MAN1_TXT))
+DOC_MAN5=$(patsubst %.txt,%.5,$(MAN1_TXT))
 DOC_MAN7=$(patsubst %.txt,%.7,$(MAN7_TXT))
 
 prefix?=$(HOME)
 bindir?=$(prefix)/bin
 mandir?=$(prefix)/man
 man1dir=$(mandir)/man1
+man5dir=$(mandir)/man5
 man7dir=$(mandir)/man7
 # DESTDIR=
 
@@ -53,15 +56,19 @@ all: html man
 
 html: $(DOC_HTML)
 
-$(DOC_HTML) $(DOC_MAN1) $(DOC_MAN7): asciidoc.conf
+$(DOC_HTML) $(DOC_MAN1) $(DOC_MAN5) $(DOC_MAN7): asciidoc.conf
 
-man: man1 man7
+man: man1 man5 man7
 man1: $(DOC_MAN1)
+man5: $(DOC_MAN5)
 man7: $(DOC_MAN7)
 
 install: man
-	$(INSTALL) -d -m755 $(DESTDIR)$(man1dir) $(DESTDIR)$(man7dir)
+	$(INSTALL) -d -m755 $(DESTDIR)$(man1dir)
+	$(INSTALL) -d -m755 $(DESTDIR)$(man5dir)
+	$(INSTALL) -d -m755 $(DESTDIR)$(man7dir)
 	$(INSTALL) -m644 $(DOC_MAN1) $(DESTDIR)$(man1dir)
+	$(INSTALL) -m644 $(DOC_MAN5) $(DESTDIR)$(man5dir)
 	$(INSTALL) -m644 $(DOC_MAN7) $(DESTDIR)$(man7dir)
 
 
@@ -99,7 +106,7 @@ cmd-list.made: cmd-list.perl $(MAN1_TXT)
 git.7 git.html: git.txt core-intro.txt
 
 clean:
-	rm -f *.xml *.xml+ *.html *.html+ *.1 *.7 howto-index.txt howto/*.html doc.dep
+	rm -f *.xml *.xml+ *.html *.html+ *.1 *.5 *.7 howto-index.txt howto/*.html doc.dep
 	rm -f $(cmds_txt) *.made
 
 %.html : %.txt
@@ -109,7 +116,7 @@ clean:
 		sed -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' >$@+
 	mv $@+ $@
 
-%.1 %.7 : %.xml
+%.1 %.5 %.7 : %.xml
 	xmlto -m callouts.xsl man $<
 
 %.xml : %.txt
diff --git a/Documentation/cmd-list.perl b/Documentation/cmd-list.perl
index 0381590d38..443802a9a3 100755
--- a/Documentation/cmd-list.perl
+++ b/Documentation/cmd-list.perl
@@ -84,6 +84,7 @@ git-bundle                              mainporcelain
 git-cat-file                            plumbinginterrogators
 git-checkout-index                      plumbingmanipulators
 git-checkout                            mainporcelain
+git-check-attr                          purehelpers
 git-check-ref-format                    purehelpers
 git-cherry                              ancillaryinterrogators
 git-cherry-pick                         mainporcelain
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 2c0a666323..b13ff3a1bb 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -525,6 +525,19 @@ merge.verbosity::
 	conflicts, 2 outputs conflicts and file changes.  Level 5 and
 	above outputs debugging information.  The default is level 2.
 
+merge.<driver>.name::
+	Defines a human readable name for a custom low-level
+	merge driver.  See gitlink:gitattributes[5] for details.
+
+merge.<driver>.driver::
+	Defines the command that implements a custom low-level
+	merge driver.  See gitlink:gitattributes[5] for details.
+
+merge.<driver>.recursive::
+	Names a low-level merge driver to be used when
+	performing an internal merge between common ancestors.
+	See gitlink:gitattributes[5] for details.
+
 pack.window::
 	The size of the window used by gitlink:git-pack-objects[1] when no
 	window size is given on the command line. Defaults to 10.
diff --git a/Documentation/git-check-attr.txt b/Documentation/git-check-attr.txt
new file mode 100644
index 0000000000..ceb51959b1
--- /dev/null
+++ b/Documentation/git-check-attr.txt
@@ -0,0 +1,37 @@
+git-check-attr(1)
+=================
+
+NAME
+----
+git-check-attr - Display gitattributes information.
+
+
+SYNOPSIS
+--------
+'git-check-attr' attr... [--] pathname...
+
+DESCRIPTION
+-----------
+For every pathname, this command will list if each attr is 'unspecified',
+'set', or 'unset' as a gitattribute on that pathname.
+
+OPTIONS
+-------
+\--::
+	Interpret all preceding arguments as attributes, and all following
+	arguments as path names. If not supplied, only the first argument will
+	be treated as an attribute.
+
+
+Author
+------
+Written by Junio C Hamano <junkio@cox.net>
+
+Documentation
+--------------
+Documentation by James Bowes.
+
+GIT
+---
+Part of the gitlink:git[7] suite
+
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
new file mode 100644
index 0000000000..ece58abee2
--- /dev/null
+++ b/Documentation/gitattributes.txt
@@ -0,0 +1,285 @@
+gitattributes(5)
+================
+
+NAME
+----
+gitattributes - defining attributes per path
+
+SYNOPSIS
+--------
+.gitattributes
+
+
+DESCRIPTION
+-----------
+
+A `gitattributes` file is a simple text file that gives
+`attributes` to pathnames.
+
+Each line in `gitattributes` file is of form:
+
+	glob	attr1 attr2 ...
+
+That is, a glob pattern followed by an attributes list,
+separated by whitespaces.  When the glob pattern matches the
+path in question, the attributes listed on the line are given to
+the path.
+
+Each attribute can be in one of these states for a given path:
+
+Set::
+
+	The path has the attribute with special value "true";
+	this is specified by listing only the name of the
+	attribute in the attribute list.
+
+Unset::
+
+	The path has the attribute with special value "false";
+	this is specified by listing the name of the attribute
+	prefixed with a dash `-` in the attribute list.
+
+Set to a value::
+
+	The path has the attribute with specified string value;
+	this is specified by listing the name of the attribute
+	followed by an equal sign `=` and its value in the
+	attribute list.
+
+Unspecified::
+
+	No glob pattern matches the path, and nothing says if
+	the path has or does not have the attribute.
+
+When more than one glob pattern matches the path, a later line
+overrides an earlier line.
+
+When deciding what attributes are assigned to a path, git
+consults `$GIT_DIR/info/attributes` file (which has the highest
+precedence), `.gitattributes` file in the same directory as the
+path in question, and its parent directories (the further the
+directory that contains `.gitattributes` is from the path in
+question, the lower its precedence).
+
+Sometimes you would need to override an setting of an attribute
+for a path to `unspecified` state.  This can be done by listing
+the name of the attribute prefixed with an exclamation point `!`.
+
+
+EFFECTS
+-------
+
+Certain operations by git can be influenced by assigning
+particular attributes to a path.  Currently, three operations
+are attributes-aware.
+
+Checking-out and checking-in
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The attribute `crlf` affects how the contents stored in the
+repository are copied to the working tree files when commands
+such as `git checkout` and `git merge` run.  It also affects how
+git stores the contents you prepare in the working tree in the
+repository upon `git add` and `git commit`.
+
+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.
+
+Unset::
+
+	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::
+
+	Unspecified `crlf` attribute tells git to apply the
+	`core.autocrlf` conversion when the file content looks
+	like text.
+
+Set to string value "input"::
+
+	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.
+
+Any other value set to `crlf` attribute is ignored and git acts
+as if the attribute is left unspecified.
+
+
+The `core.autocrlf` conversion
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If the configuration variable `core.autocrlf` is false, no
+conversion is done.
+
+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.
+
+When `core.autocrlf` is set to "input", line endings are
+converted to LF upon checkin, but there is no conversion done
+upon checkout.
+
+
+Generating diff text
+~~~~~~~~~~~~~~~~~~~~
+
+The attribute `diff` affects if `git diff` generates textual
+patch for the path or just says `Binary files differ`.
+
+Set::
+
+	A path to which the `diff` attribute is set is treated
+	as text, even when they contain byte values that
+	normally never appear in text files, such as NUL.
+
+Unset::
+
+	A path to which the `diff` attribute is unset will
+	generate `Binary files differ`.
+
+Unspecified::
+
+	A path to which the `diff` attribute is unspecified
+	first gets its contents inspected, and if it looks like
+	text, it is treated as text.  Otherwise it would
+	generate `Binary files differ`.
+
+Any other value set to `diff` attribute is ignored and git acts
+as if the attribute is left unspecified.
+
+
+Performing a three-way merge
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The attribute `merge` affects how three versions of a file is
+merged when a file-level merge is necessary during `git merge`,
+and other programs such as `git revert` and `git cherry-pick`.
+
+Set::
+
+	Built-in 3-way merge driver is used to merge the
+	contents in a way similar to `merge` command of `RCS`
+	suite.  This is suitable for ordinary text files.
+
+Unset::
+
+	Take the version from the current branch as the
+	tentative merge result, and declare that the merge has
+	conflicts.  This is suitable for binary files that does
+	not have a well-defined merge semantics.
+
+Unspecified::
+
+	By default, this uses the same built-in 3-way merge
+	driver as is the case the `merge` attribute is set.
+	However, `merge.default` configuration variable can name
+	different merge driver to be used for paths to which the
+	`merge` attribute is unspecified.
+
+Any other string value::
+
+	3-way merge is performed using the specified custom
+	merge driver.  The built-in 3-way merge driver can be
+	explicitly specified by asking for "text" driver; the
+	built-in "take the current branch" driver can be
+	requested by "binary".
+
+
+Defining a custom merge driver
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The definition of a merge driver is done in `gitconfig` not
+`gitattributes` file, so strictly speaking this manual page is a
+wrong place to talk about it.  However...
+
+To define a custom merge driver `filfre`, add a section to your
+`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
+
+----------------------------------------------------------------
+[merge "filfre"]
+	name = feel-free merge driver
+	driver = filfre %O %A %B
+	recursive = binary
+----------------------------------------------------------------
+
+The `merge.*.name` variable gives the driver a human-readable
+name.
+
+The `merge.*.driver` variable's value is used to construct a
+command to run to merge ancestor's version (`%O`), current
+version (`%A`) and the other branches' version (`%B`).  These
+three tokens are replaced with the names of temporary files that
+hold the contents of these versions when the command line is
+built.
+
+The merge driver is expected to leave the result of the merge in
+the file named with `%A` by overwriting it, and exit with zero
+status if it managed to merge them cleanly, or non-zero if there
+were conflicts.
+
+The `merge.*.recursive` variable specifies what other merge
+driver to use when the merge driver is called for an internal
+merge between common ancestors, when there are more than one.
+When left unspecified, the driver itself is used for both
+internal merge and the final merge.
+
+
+EXAMPLE
+-------
+
+If you have these three `gitattributes` file:
+
+----------------------------------------------------------------
+(in $GIT_DIR/info/attributes)
+
+a*	foo !bar -baz
+
+(in .gitattributes)
+abc	foo bar baz
+
+(in t/.gitattributes)
+ab*	merge=filfre
+abc	-foo -bar
+*.c	frotz
+----------------------------------------------------------------
+
+the attributes given to path `t/abc` are computed as follows:
+
+1. By examining `t/.gitattributes` (which is in the same
+   diretory as the path in question), git finds that the first
+   line matches.  `merge` attribute is set.  It also finds that
+   the second line matches, and attributes `foo` and `bar`
+   are unset.
+
+2. Then it examines `.gitattributes` (which is in the parent
+   directory), and finds that the first line matches, but
+   `t/.gitattributes` file already decided how `merge`, `foo`
+   and `bar` attributes should be given to this path, so it
+   leaves `foo` and `bar` unset.  Attribute `baz` is set.
+
+3. Finally it examines `$GIT_DIR/info/gitattributes`.  This file
+   is used to override the in-tree settings.  The first line is
+   a match, and `foo` is set, `bar` is reverted to unspecified
+   state, and `baz` is unset.
+
+As the result, the attributes assignement to `t/abc` becomes:
+
+----------------------------------------------------------------
+foo	set to true
+bar	unspecified
+baz	set to false
+merge	set to string value "filfre"
+frotz	unspecified
+----------------------------------------------------------------
+
+
+GIT
+---
+Part of the gitlink:git[7] suite
diff --git a/Makefile b/Makefile
index 173c8b68c0..c9c2a5fb66 100644
--- a/Makefile
+++ b/Makefile
@@ -283,7 +283,7 @@ LIB_H = \
 	diff.h object.h pack.h pkt-line.h quote.h refs.h list-objects.h sideband.h \
 	run-command.h strbuf.h tag.h tree.h git-compat-util.h revision.h \
 	tree-walk.h log-tree.h dir.h path-list.h unpack-trees.h builtin.h \
-	utf8.h reflog-walk.h patch-ids.h decorate.h
+	utf8.h reflog-walk.h patch-ids.h attr.h decorate.h
 
 DIFF_OBJS = \
 	diff.o diff-lib.o diffcore-break.o diffcore-order.o \
@@ -305,7 +305,7 @@ LIB_OBJS = \
 	write_or_die.o trace.o list-objects.o grep.o match-trees.o \
 	alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS) \
 	color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \
-	convert.o decorate.o
+	convert.o attr.o decorate.o
 
 BUILTIN_OBJS = \
 	builtin-add.o \
@@ -316,6 +316,7 @@ BUILTIN_OBJS = \
 	builtin-branch.o \
 	builtin-bundle.o \
 	builtin-cat-file.o \
+	builtin-check-attr.o \
 	builtin-checkout-index.o \
 	builtin-check-ref-format.o \
 	builtin-commit-tree.o \
@@ -1032,9 +1033,10 @@ dist-doc:
 	gzip -n -9 -f $(htmldocs).tar
 	:
 	rm -fr .doc-tmp-dir
-	mkdir .doc-tmp-dir .doc-tmp-dir/man1 .doc-tmp-dir/man7
+	mkdir -p .doc-tmp-dir/man1 .doc-tmp-dir/man5 .doc-tmp-dir/man7
 	$(MAKE) -C Documentation DESTDIR=./ \
 		man1dir=../.doc-tmp-dir/man1 \
+		man5dir=../.doc-tmp-dir/man5 \
 		man7dir=../.doc-tmp-dir/man7 \
 		install
 	cd .doc-tmp-dir && $(TAR) cf ../$(manpages).tar .
diff --git a/attr.c b/attr.c
new file mode 100644
index 0000000000..285e689e5a
--- /dev/null
+++ b/attr.c
@@ -0,0 +1,563 @@
+#include "cache.h"
+#include "attr.h"
+
+const char git_attr__true[] = "(builtin)true";
+const char git_attr__false[] = "\0(builtin)false";
+static const char git_attr__unknown[] = "(builtin)unknown";
+#define ATTR__TRUE git_attr__true
+#define ATTR__FALSE git_attr__false
+#define ATTR__UNSET NULL
+#define ATTR__UNKNOWN git_attr__unknown
+
+/*
+ * The basic design decision here is that we are not going to have
+ * insanely large number of attributes.
+ *
+ * This is a randomly chosen prime.
+ */
+#define HASHSIZE 257
+
+#ifndef DEBUG_ATTR
+#define DEBUG_ATTR 0
+#endif
+
+struct git_attr {
+	struct git_attr *next;
+	unsigned h;
+	int attr_nr;
+	char name[FLEX_ARRAY];
+};
+static int attr_nr;
+
+static struct git_attr_check *check_all_attr;
+static struct git_attr *(git_attr_hash[HASHSIZE]);
+
+static unsigned hash_name(const char *name, int namelen)
+{
+	unsigned val = 0;
+	unsigned char c;
+
+	while (namelen--) {
+		c = *name++;
+		val = ((val << 7) | (val >> 22)) ^ c;
+	}
+	return val;
+}
+
+static int invalid_attr_name(const char *name, int namelen)
+{
+	/*
+	 * Attribute name cannot begin with '-' and from
+	 * [-A-Za-z0-9_.].  We'd specifically exclude '=' for now,
+	 * as we might later want to allow non-binary value for
+	 * attributes, e.g. "*.svg	merge=special-merge-program-for-svg"
+	 */
+	if (*name == '-')
+		return -1;
+	while (namelen--) {
+		char ch = *name++;
+		if (! (ch == '-' || ch == '.' || ch == '_' ||
+		       ('0' <= ch && ch <= '9') ||
+		       ('a' <= ch && ch <= 'z') ||
+		       ('A' <= ch && ch <= 'Z')) )
+			return -1;
+	}
+	return 0;
+}
+
+struct git_attr *git_attr(const char *name, int len)
+{
+	unsigned hval = hash_name(name, len);
+	unsigned pos = hval % HASHSIZE;
+	struct git_attr *a;
+
+	for (a = git_attr_hash[pos]; a; a = a->next) {
+		if (a->h == hval &&
+		    !memcmp(a->name, name, len) && !a->name[len])
+			return a;
+	}
+
+	if (invalid_attr_name(name, len))
+		return NULL;
+
+	a = xmalloc(sizeof(*a) + len + 1);
+	memcpy(a->name, name, len);
+	a->name[len] = 0;
+	a->h = hval;
+	a->next = git_attr_hash[pos];
+	a->attr_nr = attr_nr++;
+	git_attr_hash[pos] = a;
+
+	check_all_attr = xrealloc(check_all_attr,
+				  sizeof(*check_all_attr) * attr_nr);
+	check_all_attr[a->attr_nr].attr = a;
+	check_all_attr[a->attr_nr].value = ATTR__UNKNOWN;
+	return a;
+}
+
+/*
+ * .gitattributes file is one line per record, each of which is
+ *
+ * (1) glob pattern.
+ * (2) whitespace
+ * (3) whitespace separated list of attribute names, each of which
+ *     could be prefixed with '-' to mean "set to false", '!' to mean
+ *     "unset".
+ */
+
+/* What does a matched pattern decide? */
+struct attr_state {
+	struct git_attr *attr;
+	const char *setto;
+};
+
+struct match_attr {
+	union {
+		char *pattern;
+		struct git_attr *attr;
+	} u;
+	char is_macro;
+	unsigned num_attr;
+	struct attr_state state[FLEX_ARRAY];
+};
+
+static const char blank[] = " \t\r\n";
+
+static const char *parse_attr(const char *src, int lineno, const char *cp,
+			      int *num_attr, struct match_attr *res)
+{
+	const char *ep, *equals;
+	int len;
+
+	ep = cp + strcspn(cp, blank);
+	equals = strchr(cp, '=');
+	if (equals && ep < equals)
+		equals = NULL;
+	if (equals)
+		len = equals - cp;
+	else
+		len = ep - cp;
+	if (!res) {
+		if (*cp == '-' || *cp == '!') {
+			cp++;
+			len--;
+		}
+		if (invalid_attr_name(cp, len)) {
+			fprintf(stderr,
+				"%.*s is not a valid attribute name: %s:%d\n",
+				len, cp, src, lineno);
+			return NULL;
+		}
+	} else {
+		struct attr_state *e;
+
+		e = &(res->state[*num_attr]);
+		if (*cp == '-' || *cp == '!') {
+			e->setto = (*cp == '-') ? ATTR__FALSE : ATTR__UNSET;
+			cp++;
+			len--;
+		}
+		else if (!equals)
+			e->setto = ATTR__TRUE;
+		else {
+			char *value;
+			int vallen = ep - equals;
+			value = xmalloc(vallen);
+			memcpy(value, equals+1, vallen-1);
+			value[vallen-1] = 0;
+			e->setto = value;
+		}
+		e->attr = git_attr(cp, len);
+	}
+	(*num_attr)++;
+	return ep + strspn(ep, blank);
+}
+
+static struct match_attr *parse_attr_line(const char *line, const char *src,
+					  int lineno, int macro_ok)
+{
+	int namelen;
+	int num_attr;
+	const char *cp, *name;
+	struct match_attr *res = NULL;
+	int pass;
+	int is_macro;
+
+	cp = line + strspn(line, blank);
+	if (!*cp || *cp == '#')
+		return NULL;
+	name = cp;
+	namelen = strcspn(name, blank);
+	if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
+	    !prefixcmp(name, ATTRIBUTE_MACRO_PREFIX)) {
+		if (!macro_ok) {
+			fprintf(stderr, "%s not allowed: %s:%d\n",
+				name, src, lineno);
+			return NULL;
+		}
+		is_macro = 1;
+		name += strlen(ATTRIBUTE_MACRO_PREFIX);
+		name += strspn(name, blank);
+		namelen = strcspn(name, blank);
+		if (invalid_attr_name(name, namelen)) {
+			fprintf(stderr,
+				"%.*s is not a valid attribute name: %s:%d\n",
+				namelen, name, src, lineno);
+			return NULL;
+		}
+	}
+	else
+		is_macro = 0;
+
+	for (pass = 0; pass < 2; pass++) {
+		/* pass 0 counts and allocates, pass 1 fills */
+		num_attr = 0;
+		cp = name + namelen;
+		cp = cp + strspn(cp, blank);
+		while (*cp)
+			cp = parse_attr(src, lineno, cp, &num_attr, res);
+		if (pass)
+			break;
+		res = xcalloc(1,
+			      sizeof(*res) +
+			      sizeof(struct attr_state) * num_attr +
+			      (is_macro ? 0 : namelen + 1));
+		if (is_macro)
+			res->u.attr = git_attr(name, namelen);
+		else {
+			res->u.pattern = (char*)&(res->state[num_attr]);
+			memcpy(res->u.pattern, name, namelen);
+			res->u.pattern[namelen] = 0;
+		}
+		res->is_macro = is_macro;
+		res->num_attr = num_attr;
+	}
+	return res;
+}
+
+/*
+ * Like info/exclude and .gitignore, the attribute information can
+ * come from many places.
+ *
+ * (1) .gitattribute file of the same directory;
+ * (2) .gitattribute file of the parent directory if (1) does not have
+ *      any match; this goes recursively upwards, just like .gitignore.
+ * (3) $GIT_DIR/info/attributes, which overrides both of the above.
+ *
+ * In the same file, later entries override the earlier match, so in the
+ * global list, we would have entries from info/attributes the earliest
+ * (reading the file from top to bottom), .gitattribute of the root
+ * directory (again, reading the file from top to bottom) down to the
+ * current directory, and then scan the list backwards to find the first match.
+ * This is exactly the same as what excluded() does in dir.c to deal with
+ * .gitignore
+ */
+
+static struct attr_stack {
+	struct attr_stack *prev;
+	char *origin;
+	unsigned num_matches;
+	struct match_attr **attrs;
+} *attr_stack;
+
+static void free_attr_elem(struct attr_stack *e)
+{
+	int i;
+	free(e->origin);
+	for (i = 0; i < e->num_matches; i++) {
+		struct match_attr *a = e->attrs[i];
+		int j;
+		for (j = 0; j < a->num_attr; j++) {
+			const char *setto = a->state[j].setto;
+			if (setto == ATTR__TRUE ||
+			    setto == ATTR__FALSE ||
+			    setto == ATTR__UNSET ||
+			    setto == ATTR__UNKNOWN)
+				;
+			else
+				free((char*) setto);
+		}
+		free(a);
+	}
+	free(e);
+}
+
+static const char *builtin_attr[] = {
+	"[attr]binary -diff -crlf",
+	NULL,
+};
+
+static struct attr_stack *read_attr_from_array(const char **list)
+{
+	struct attr_stack *res;
+	const char *line;
+	int lineno = 0;
+
+	res = xcalloc(1, sizeof(*res));
+	while ((line = *(list++)) != NULL) {
+		struct match_attr *a;
+
+		a = parse_attr_line(line, "[builtin]", ++lineno, 1);
+		if (!a)
+			continue;
+		res->attrs = xrealloc(res->attrs, res->num_matches + 1);
+		res->attrs[res->num_matches++] = a;
+	}
+	return res;
+}
+
+static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
+{
+	FILE *fp;
+	struct attr_stack *res;
+	char buf[2048];
+	int lineno = 0;
+
+	res = xcalloc(1, sizeof(*res));
+	fp = fopen(path, "r");
+	if (!fp)
+		return res;
+
+	while (fgets(buf, sizeof(buf), fp)) {
+		struct match_attr *a;
+
+		a = parse_attr_line(buf, path, ++lineno, macro_ok);
+		if (!a)
+			continue;
+		res->attrs = xrealloc(res->attrs, res->num_matches + 1);
+		res->attrs[res->num_matches++] = a;
+	}
+	fclose(fp);
+	return res;
+}
+
+#if DEBUG_ATTR
+static void debug_info(const char *what, struct attr_stack *elem)
+{
+	fprintf(stderr, "%s: %s\n", what, elem->origin ? elem->origin : "()");
+}
+static void debug_set(const char *what, const char *match, struct git_attr *attr, void *v)
+{
+	const char *value = v;
+
+	if (ATTR_TRUE(value))
+		value = "set";
+	else if (ATTR_FALSE(value))
+		value = "unset";
+	else if (ATTR_UNSET(value))
+		value = "unspecified";
+
+	fprintf(stderr, "%s: %s => %s (%s)\n",
+		what, attr->name, (char *) value, match);
+}
+#define debug_push(a) debug_info("push", (a))
+#define debug_pop(a) debug_info("pop", (a))
+#else
+#define debug_push(a) do { ; } while (0)
+#define debug_pop(a) do { ; } while (0)
+#define debug_set(a,b,c,d) do { ; } while (0)
+#endif
+
+static void bootstrap_attr_stack(void)
+{
+	if (!attr_stack) {
+		struct attr_stack *elem;
+
+		elem = read_attr_from_array(builtin_attr);
+		elem->origin = NULL;
+		elem->prev = attr_stack;
+		attr_stack = elem;
+
+		elem = read_attr_from_file(GITATTRIBUTES_FILE, 1);
+		elem->origin = strdup("");
+		elem->prev = attr_stack;
+		attr_stack = elem;
+		debug_push(elem);
+
+		elem = read_attr_from_file(git_path(INFOATTRIBUTES_FILE), 1);
+		elem->origin = NULL;
+		elem->prev = attr_stack;
+		attr_stack = elem;
+	}
+}
+
+static void prepare_attr_stack(const char *path, int dirlen)
+{
+	struct attr_stack *elem, *info;
+	int len;
+	char pathbuf[PATH_MAX];
+
+	/*
+	 * At the bottom of the attribute stack is the built-in
+	 * set of attribute definitions.  Then, contents from
+	 * .gitattribute files from directories closer to the
+	 * root to the ones in deeper directories are pushed
+	 * to the stack.  Finally, at the very top of the stack
+	 * we always keep the contents of $GIT_DIR/info/attributes.
+	 *
+	 * When checking, we use entries from near the top of the
+	 * stack, preferring $GIT_DIR/info/attributes, then
+	 * .gitattributes in deeper directories to shallower ones,
+	 * and finally use the built-in set as the default.
+	 */
+	if (!attr_stack)
+		bootstrap_attr_stack();
+
+	/*
+	 * Pop the "info" one that is always at the top of the stack.
+	 */
+	info = attr_stack;
+	attr_stack = info->prev;
+
+	/*
+	 * Pop the ones from directories that are not the prefix of
+	 * the path we are checking.
+	 */
+	while (attr_stack && attr_stack->origin) {
+		int namelen = strlen(attr_stack->origin);
+
+		elem = attr_stack;
+		if (namelen <= dirlen &&
+		    !strncmp(elem->origin, path, namelen))
+			break;
+
+		debug_pop(elem);
+		attr_stack = elem->prev;
+		free_attr_elem(elem);
+	}
+
+	/*
+	 * Read from parent directories and push them down
+	 */
+	while (1) {
+		char *cp;
+
+		len = strlen(attr_stack->origin);
+		if (dirlen <= len)
+			break;
+		memcpy(pathbuf, path, dirlen);
+		memcpy(pathbuf + dirlen, "/", 2);
+		cp = strchr(pathbuf + len + 1, '/');
+		strcpy(cp + 1, GITATTRIBUTES_FILE);
+		elem = read_attr_from_file(pathbuf, 0);
+		*cp = '\0';
+		elem->origin = strdup(pathbuf);
+		elem->prev = attr_stack;
+		attr_stack = elem;
+		debug_push(elem);
+	}
+
+	/*
+	 * Finally push the "info" one at the top of the stack.
+	 */
+	info->prev = attr_stack;
+	attr_stack = info;
+}
+
+static int path_matches(const char *pathname, int pathlen,
+			const char *pattern,
+			const char *base, int baselen)
+{
+	if (!strchr(pattern, '/')) {
+		/* match basename */
+		const char *basename = strrchr(pathname, '/');
+		basename = basename ? basename + 1 : pathname;
+		return (fnmatch(pattern, basename, 0) == 0);
+	}
+	/*
+	 * match with FNM_PATHNAME; the pattern has base implicitly
+	 * in front of it.
+	 */
+	if (*pattern == '/')
+		pattern++;
+	if (pathlen < baselen ||
+	    (baselen && pathname[baselen - 1] != '/') ||
+	    strncmp(pathname, base, baselen))
+		return 0;
+	return fnmatch(pattern, pathname + baselen, FNM_PATHNAME) == 0;
+}
+
+static int fill_one(const char *what, struct match_attr *a, int rem)
+{
+	struct git_attr_check *check = check_all_attr;
+	int i;
+
+	for (i = 0; 0 < rem && i < a->num_attr; i++) {
+		struct git_attr *attr = a->state[i].attr;
+		const char **n = &(check[attr->attr_nr].value);
+		const char *v = a->state[i].setto;
+
+		if (*n == ATTR__UNKNOWN) {
+			debug_set(what, a->u.pattern, attr, v);
+			*n = v;
+			rem--;
+		}
+	}
+	return rem;
+}
+
+static int fill(const char *path, int pathlen, struct attr_stack *stk, int rem)
+{
+	int i;
+	const char *base = stk->origin ? stk->origin : "";
+
+	for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
+		struct match_attr *a = stk->attrs[i];
+		if (a->is_macro)
+			continue;
+		if (path_matches(path, pathlen,
+				 a->u.pattern, base, strlen(base)))
+			rem = fill_one("fill", a, rem);
+	}
+	return rem;
+}
+
+static int macroexpand(struct attr_stack *stk, int rem)
+{
+	int i;
+	struct git_attr_check *check = check_all_attr;
+
+	for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
+		struct match_attr *a = stk->attrs[i];
+		if (!a->is_macro)
+			continue;
+		if (check[a->u.attr->attr_nr].value != ATTR__TRUE)
+			continue;
+		rem = fill_one("expand", a, rem);
+	}
+	return rem;
+}
+
+int git_checkattr(const char *path, int num, struct git_attr_check *check)
+{
+	struct attr_stack *stk;
+	const char *cp;
+	int dirlen, pathlen, i, rem;
+
+	bootstrap_attr_stack();
+	for (i = 0; i < attr_nr; i++)
+		check_all_attr[i].value = ATTR__UNKNOWN;
+
+	pathlen = strlen(path);
+	cp = strrchr(path, '/');
+	if (!cp)
+		dirlen = 0;
+	else
+		dirlen = cp - path;
+	prepare_attr_stack(path, dirlen);
+	rem = attr_nr;
+	for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
+		rem = fill(path, pathlen, stk, rem);
+
+	for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
+		rem = macroexpand(stk, rem);
+
+	for (i = 0; i < num; i++) {
+		const char *value = check_all_attr[check[i].attr->attr_nr].value;
+		if (value == ATTR__UNKNOWN)
+			value = ATTR__UNSET;
+		check[i].value = value;
+	}
+
+	return 0;
+}
diff --git a/attr.h b/attr.h
new file mode 100644
index 0000000000..f1c2038b09
--- /dev/null
+++ b/attr.h
@@ -0,0 +1,34 @@
+#ifndef ATTR_H
+#define ATTR_H
+
+/* An attribute is a pointer to this opaque structure */
+struct git_attr;
+
+/*
+ * Given a string, return the gitattribute object that
+ * corresponds to it.
+ */
+struct git_attr *git_attr(const char *, int);
+
+/* Internal use */
+extern const char git_attr__true[];
+extern const char git_attr__false[];
+
+/* For public to check git_attr_check results */
+#define ATTR_TRUE(v) ((v) == git_attr__true)
+#define ATTR_FALSE(v) ((v) == git_attr__false)
+#define ATTR_UNSET(v) ((v) == NULL)
+
+/*
+ * Send one or more git_attr_check to git_checkattr(), and
+ * each 'value' member tells what its value is.
+ * Unset one is returned as NULL.
+ */
+struct git_attr_check {
+	struct git_attr *attr;
+	const char *value;
+};
+
+int git_checkattr(const char *path, int, struct git_attr_check *);
+
+#endif /* ATTR_H */
diff --git a/builtin-apply.c b/builtin-apply.c
index 94311e7af4..f94d0dbf48 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -1475,8 +1475,8 @@ static int read_old_data(struct stat *st, const char *path, char **buf_p, unsign
 		}
 		close(fd);
 		nsize = got;
-		nbuf = buf;
-		if (convert_to_git(path, &nbuf, &nsize)) {
+		nbuf = convert_to_git(path, buf, &nsize);
+		if (nbuf) {
 			free(buf);
 			*buf_p = nbuf;
 			*alloc_p = nsize;
@@ -2355,9 +2355,8 @@ static void add_index_file(const char *path, unsigned mode, void *buf, unsigned
 
 static int try_create_file(const char *path, unsigned int mode, const char *buf, unsigned long size)
 {
-	int fd, converted;
+	int fd;
 	char *nbuf;
-	unsigned long nsize;
 
 	if (has_symlinks && S_ISLNK(mode))
 		/* Although buf:size is counted string, it also is NUL
@@ -2369,13 +2368,10 @@ static int try_create_file(const char *path, unsigned int mode, const char *buf,
 	if (fd < 0)
 		return -1;
 
-	nsize = size;
-	nbuf = (char *) buf;
-	converted = convert_to_working_tree(path, &nbuf, &nsize);
-	if (converted) {
+	nbuf = convert_to_working_tree(path, buf, &size);
+	if (nbuf)
 		buf = nbuf;
-		size = nsize;
-	}
+
 	while (size) {
 		int written = xwrite(fd, buf, size);
 		if (written < 0)
@@ -2387,7 +2383,7 @@ static int try_create_file(const char *path, unsigned int mode, const char *buf,
 	}
 	if (close(fd) < 0)
 		die("closing file %s: %s", path, strerror(errno));
-	if (converted)
+	if (nbuf)
 		free(nbuf);
 	return 0;
 }
diff --git a/builtin-check-attr.c b/builtin-check-attr.c
new file mode 100644
index 0000000000..9d77f76ff1
--- /dev/null
+++ b/builtin-check-attr.c
@@ -0,0 +1,59 @@
+#include "builtin.h"
+#include "attr.h"
+#include "quote.h"
+
+static const char check_attr_usage[] =
+"git-check-attr attr... [--] pathname...";
+
+int cmd_check_attr(int argc, const char **argv, const char *prefix)
+{
+	struct git_attr_check *check;
+	int cnt, i, doubledash;
+
+	doubledash = -1;
+	for (i = 1; doubledash < 0 && i < argc; i++) {
+		if (!strcmp(argv[i], "--"))
+			doubledash = i;
+	}
+
+	/* If there is no double dash, we handle only one attribute */
+	if (doubledash < 0) {
+		cnt = 1;
+		doubledash = 1;
+	} else
+		cnt = doubledash - 1;
+	doubledash++;
+
+	if (cnt <= 0 || argc < doubledash)
+		usage(check_attr_usage);
+	check = xcalloc(cnt, sizeof(*check));
+	for (i = 0; i < cnt; i++) {
+		const char *name;
+		struct git_attr *a;
+		name = argv[i + 1];
+		a = git_attr(name, strlen(name));
+		if (!a)
+			return error("%s: not a valid attribute name", name);
+		check[i].attr = a;
+	}
+
+	for (i = doubledash; i < argc; i++) {
+		int j;
+		if (git_checkattr(argv[i], cnt, check))
+			die("git_checkattr died");
+		for (j = 0; j < cnt; j++) {
+			const char *value = check[j].value;
+
+			if (ATTR_TRUE(value))
+				value = "set";
+			else if (ATTR_FALSE(value))
+				value = "unset";
+			else if (ATTR_UNSET(value))
+				value = "unspecified";
+
+			write_name_quoted("", 0, argv[i], 1, stdout);
+			printf(": %s: %s\n", argv[j+1], value);
+		}
+	}
+	return 0;
+}
diff --git a/builtin.h b/builtin.h
index af203e9e36..d3f3a7496e 100644
--- a/builtin.h
+++ b/builtin.h
@@ -22,6 +22,7 @@ extern int cmd_branch(int argc, const char **argv, const char *prefix);
 extern int cmd_bundle(int argc, const char **argv, const char *prefix);
 extern int cmd_cat_file(int argc, const char **argv, const char *prefix);
 extern int cmd_checkout_index(int argc, const char **argv, const char *prefix);
+extern int cmd_check_attr(int argc, const char **argv, const char *prefix);
 extern int cmd_check_ref_format(int argc, const char **argv, const char *prefix);
 extern int cmd_cherry(int argc, const char **argv, const char *prefix);
 extern int cmd_cherry_pick(int argc, const char **argv, const char *prefix);
diff --git a/cache.h b/cache.h
index 8747d01c60..05f188558b 100644
--- a/cache.h
+++ b/cache.h
@@ -169,6 +169,9 @@ enum object_type {
 #define CONFIG_ENVIRONMENT "GIT_CONFIG"
 #define CONFIG_LOCAL_ENVIRONMENT "GIT_CONFIG_LOCAL"
 #define EXEC_PATH_ENVIRONMENT "GIT_EXEC_PATH"
+#define GITATTRIBUTES_FILE ".gitattributes"
+#define INFOATTRIBUTES_FILE "info/attributes"
+#define ATTRIBUTE_MACRO_PREFIX "[attr]"
 
 extern int is_bare_repository_cfg;
 extern int is_bare_repository(void);
@@ -224,6 +227,7 @@ extern int refresh_cache(unsigned int flags);
 
 struct lock_file {
 	struct lock_file *next;
+	pid_t owner;
 	char on_list;
 	char filename[PATH_MAX];
 };
@@ -512,8 +516,8 @@ extern void trace_printf(const char *format, ...);
 extern void trace_argv_printf(const char **argv, int count, const char *format, ...);
 
 /* convert.c */
-extern int convert_to_git(const char *path, char **bufp, unsigned long *sizep);
-extern int convert_to_working_tree(const char *path, char **bufp, unsigned long *sizep);
+extern char *convert_to_git(const char *path, const char *src, unsigned long *sizep);
+extern char *convert_to_working_tree(const char *path, const char *src, unsigned long *sizep);
 
 /* match-trees.c */
 void shift_tree(const unsigned char *, const unsigned char *, unsigned char *, int);
diff --git a/convert.c b/convert.c
index 898bfe3eb2..37239ace83 100644
--- a/convert.c
+++ b/convert.c
@@ -1,4 +1,6 @@
 #include "cache.h"
+#include "attr.h"
+
 /*
  * convert.c - convert a file when checking it out and checking it in.
  *
@@ -8,6 +10,11 @@
  * translation when the "auto_crlf" option is set.
  */
 
+#define CRLF_GUESS	(-1)
+#define CRLF_BINARY	0
+#define CRLF_TEXT	1
+#define CRLF_INPUT	2
+
 struct text_stat {
 	/* CR, LF and CRLF counts */
 	unsigned cr, lf, crlf;
@@ -72,115 +79,171 @@ static int is_binary(unsigned long size, struct text_stat *stats)
 	return 0;
 }
 
-int convert_to_git(const char *path, char **bufp, unsigned long *sizep)
+static char *crlf_to_git(const char *path, const char *src, unsigned long *sizep, int action)
 {
-	char *buffer, *nbuf;
+	char *buffer, *dst;
 	unsigned long size, nsize;
 	struct text_stat stats;
 
-	/*
-	 * FIXME! Other pluggable conversions should go here,
-	 * based on filename patterns. Right now we just do the
-	 * stupid auto-CRLF one.
-	 */
-	if (!auto_crlf)
-		return 0;
+	if ((action == CRLF_BINARY) || (action == CRLF_GUESS && !auto_crlf))
+		return NULL;
 
 	size = *sizep;
 	if (!size)
-		return 0;
-	buffer = *bufp;
+		return NULL;
 
-	gather_stats(buffer, size, &stats);
+	gather_stats(src, size, &stats);
 
 	/* No CR? Nothing to convert, regardless. */
 	if (!stats.cr)
-		return 0;
-
-	/*
-	 * We're currently not going to even try to convert stuff
-	 * that has bare CR characters. Does anybody do that crazy
-	 * stuff?
-	 */
-	if (stats.cr != stats.crlf)
-		return 0;
-
-	/*
-	 * And add some heuristics for binary vs text, of course...
-	 */
-	if (is_binary(size, &stats))
-		return 0;
+		return NULL;
+
+	if (action == CRLF_GUESS) {
+		/*
+		 * We're currently not going to even try to convert stuff
+		 * that has bare CR characters. Does anybody do that crazy
+		 * stuff?
+		 */
+		if (stats.cr != stats.crlf)
+			return NULL;
+
+		/*
+		 * And add some heuristics for binary vs text, of course...
+		 */
+		if (is_binary(size, &stats))
+			return NULL;
+	}
 
 	/*
 	 * Ok, allocate a new buffer, fill it in, and return true
 	 * to let the caller know that we switched buffers on it.
 	 */
 	nsize = size - stats.crlf;
-	nbuf = xmalloc(nsize);
-	*bufp = nbuf;
+	buffer = xmalloc(nsize);
 	*sizep = nsize;
-	do {
-		unsigned char c = *buffer++;
-		if (c != '\r')
-			*nbuf++ = c;
-	} while (--size);
 
-	return 1;
+	dst = buffer;
+	if (action == CRLF_GUESS) {
+		/*
+		 * If we guessed, we already know we rejected a file with
+		 * lone CR, and we can strip a CR without looking at what
+		 * follow it.
+		 */
+		do {
+			unsigned char c = *src++;
+			if (c != '\r')
+				*dst++ = c;
+		} while (--size);
+	} else {
+		do {
+			unsigned char c = *src++;
+			if (! (c == '\r' && (1 < size && *buffer == '\n')))
+				*dst++ = c;
+		} while (--size);
+	}
+
+	return buffer;
 }
 
-int convert_to_working_tree(const char *path, char **bufp, unsigned long *sizep)
+static char *crlf_to_worktree(const char *path, const char *src, unsigned long *sizep, int action)
 {
-	char *buffer, *nbuf;
+	char *buffer, *dst;
 	unsigned long size, nsize;
 	struct text_stat stats;
 	unsigned char last;
 
-	/*
-	 * FIXME! Other pluggable conversions should go here,
-	 * based on filename patterns. Right now we just do the
-	 * stupid auto-CRLF one.
-	 */
-	if (auto_crlf <= 0)
-		return 0;
+	if ((action == CRLF_BINARY) || (action == CRLF_INPUT) ||
+	    (action == CRLF_GUESS && auto_crlf <= 0))
+		return NULL;
 
 	size = *sizep;
 	if (!size)
-		return 0;
-	buffer = *bufp;
+		return NULL;
 
-	gather_stats(buffer, size, &stats);
+	gather_stats(src, size, &stats);
 
 	/* No LF? Nothing to convert, regardless. */
 	if (!stats.lf)
-		return 0;
+		return NULL;
 
 	/* Was it already in CRLF format? */
 	if (stats.lf == stats.crlf)
-		return 0;
+		return NULL;
 
-	/* If we have any bare CR characters, we're not going to touch it */
-	if (stats.cr != stats.crlf)
-		return 0;
+	if (action == CRLF_GUESS) {
+		/* If we have any bare CR characters, we're not going to touch it */
+		if (stats.cr != stats.crlf)
+			return NULL;
 
-	if (is_binary(size, &stats))
-		return 0;
+		if (is_binary(size, &stats))
+			return NULL;
+	}
 
 	/*
 	 * Ok, allocate a new buffer, fill it in, and return true
 	 * to let the caller know that we switched buffers on it.
 	 */
 	nsize = size + stats.lf - stats.crlf;
-	nbuf = xmalloc(nsize);
-	*bufp = nbuf;
+	buffer = xmalloc(nsize);
 	*sizep = nsize;
 	last = 0;
+
+	dst = buffer;
 	do {
-		unsigned char c = *buffer++;
+		unsigned char c = *src++;
 		if (c == '\n' && last != '\r')
-			*nbuf++ = '\r';
-		*nbuf++ = c;
+			*dst++ = '\r';
+		*dst++ = c;
 		last = c;
 	} while (--size);
 
-	return 1;
+	return buffer;
+}
+
+static void setup_convert_check(struct git_attr_check *check)
+{
+	static struct git_attr *attr_crlf;
+
+	if (!attr_crlf)
+		attr_crlf = git_attr("crlf", 4);
+	check->attr = attr_crlf;
+}
+
+static int git_path_check_crlf(const char *path, struct git_attr_check *check)
+{
+	const char *value = check->value;
+
+	if (ATTR_TRUE(value))
+		return CRLF_TEXT;
+	else if (ATTR_FALSE(value))
+		return CRLF_BINARY;
+	else if (ATTR_UNSET(value))
+		;
+	else if (!strcmp(value, "input"))
+		return CRLF_INPUT;
+	return CRLF_GUESS;
+}
+
+char *convert_to_git(const char *path, const char *src, unsigned long *sizep)
+{
+	struct git_attr_check check[1];
+	int crlf = CRLF_GUESS;
+
+	setup_convert_check(check);
+	if (!git_checkattr(path, 1, check)) {
+		crlf = git_path_check_crlf(path, check);
+	}
+	return crlf_to_git(path, src, sizep, crlf);
+}
+
+char *convert_to_working_tree(const char *path, const char *src, unsigned long *sizep)
+{
+	struct git_attr_check check[1];
+	int crlf = CRLF_GUESS;
+
+	setup_convert_check(check);
+	if (!git_checkattr(path, 1, check)) {
+		crlf = git_path_check_crlf(path, check);
+	}
+	return crlf_to_worktree(path, src, sizep, crlf);
 }
diff --git a/diff.c b/diff.c
index 1e8e689be2..f516664968 100644
--- a/diff.c
+++ b/diff.c
@@ -8,6 +8,7 @@
 #include "delta.h"
 #include "xdiff-interface.h"
 #include "color.h"
+#include "attr.h"
 
 #ifdef NO_FAST_WORKING_DIRECTORY
 #define FAST_WORKING_DIRECTORY 0
@@ -1051,13 +1052,44 @@ static void emit_binary_diff(mmfile_t *one, mmfile_t *two)
 	emit_binary_diff_body(two, one);
 }
 
+static void setup_diff_attr_check(struct git_attr_check *check)
+{
+	static struct git_attr *attr_diff;
+
+	if (!attr_diff)
+		attr_diff = git_attr("diff", 4);
+	check->attr = attr_diff;
+}
+
 #define FIRST_FEW_BYTES 8000
-static int mmfile_is_binary(mmfile_t *mf)
+static int file_is_binary(struct diff_filespec *one)
 {
-	long sz = mf->size;
+	unsigned long sz;
+	struct git_attr_check attr_diff_check;
+
+	setup_diff_attr_check(&attr_diff_check);
+	if (!git_checkattr(one->path, 1, &attr_diff_check)) {
+		const char *value = attr_diff_check.value;
+		if (ATTR_TRUE(value))
+			return 0;
+		else if (ATTR_FALSE(value))
+			return 1;
+		else if (ATTR_UNSET(value))
+			;
+		else
+			die("unknown value %s given to 'diff' attribute",
+			    value);
+	}
+
+	if (!one->data) {
+		if (!DIFF_FILE_VALID(one))
+			return 0;
+		diff_populate_filespec(one, 0);
+	}
+	sz = one->size;
 	if (FIRST_FEW_BYTES < sz)
 		sz = FIRST_FEW_BYTES;
-	return !!memchr(mf->ptr, 0, sz);
+	return !!memchr(one->data, 0, sz);
 }
 
 static void builtin_diff(const char *name_a,
@@ -1114,7 +1146,7 @@ static void builtin_diff(const char *name_a,
 	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
 		die("unable to read files to diff");
 
-	if (!o->text && (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))) {
+	if (!o->text && (file_is_binary(one) || file_is_binary(two))) {
 		/* Quite common confusing case */
 		if (mf1.size == mf2.size &&
 		    !memcmp(mf1.ptr, mf2.ptr, mf1.size))
@@ -1190,7 +1222,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
 	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
 		die("unable to read files to diff");
 
-	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2)) {
+	if (file_is_binary(one) || file_is_binary(two)) {
 		data->is_binary = 1;
 		data->added = mf2.size;
 		data->deleted = mf1.size;
@@ -1228,7 +1260,7 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
 	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
 		die("unable to read files to diff");
 
-	if (mmfile_is_binary(&mf2))
+	if (file_is_binary(two))
 		return;
 	else {
 		/* Crazy xdl interfaces.. */
@@ -1481,9 +1513,9 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
 		/*
 		 * Convert from working tree format to canonical git format
 		 */
-		buf = s->data;
 		size = s->size;
-		if (convert_to_git(s->path, &buf, &size)) {
+		buf = convert_to_git(s->path, s->data, &size);
+		if (buf) {
 			munmap(s->data, s->size);
 			s->should_munmap = 0;
 			s->data = buf;
@@ -1825,8 +1857,8 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
 
 		if (o->binary) {
 			mmfile_t mf;
-			if ((!fill_mmfile(&mf, one) && mmfile_is_binary(&mf)) ||
-			    (!fill_mmfile(&mf, two) && mmfile_is_binary(&mf)))
+			if ((!fill_mmfile(&mf, one) && file_is_binary(one)) ||
+			    (!fill_mmfile(&mf, two) && file_is_binary(two)))
 				abbrev = 40;
 		}
 		len += snprintf(msg + len, sizeof(msg) - len,
@@ -2721,7 +2753,7 @@ static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
 			return error("unable to read files to diff");
 
 		/* Maybe hash p->two? into the patch id? */
-		if (mmfile_is_binary(&mf2))
+		if (file_is_binary(p->two))
 			continue;
 
 		len1 = remove_space(p->one->path, strlen(p->one->path));
diff --git a/entry.c b/entry.c
index 50ffae40c7..84f78025ff 100644
--- a/entry.c
+++ b/entry.c
@@ -82,7 +82,7 @@ static int write_entry(struct cache_entry *ce, char *path, struct checkout *stat
 
 	switch (ntohl(ce->ce_mode) & S_IFMT) {
 		char *buf, *new;
-		unsigned long size, nsize;
+		unsigned long size;
 
 	case S_IFREG:
 		new = read_blob_entry(ce, path, &size);
@@ -103,12 +103,10 @@ static int write_entry(struct cache_entry *ce, char *path, struct checkout *stat
 		/*
 		 * Convert from git internal format to working tree format
 		 */
-		buf = new;
-		nsize = size;
-		if (convert_to_working_tree(ce->name, &buf, &nsize)) {
+		buf = convert_to_working_tree(ce->name, new, &size);
+		if (buf) {
 			free(new);
 			new = buf;
-			size = nsize;
 		}
 
 		wrote = write_in_full(fd, new, size);
diff --git a/git.c b/git.c
index 7def319e60..f20090721a 100644
--- a/git.c
+++ b/git.c
@@ -234,6 +234,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "cat-file", cmd_cat_file, RUN_SETUP },
 		{ "checkout-index", cmd_checkout_index, RUN_SETUP },
 		{ "check-ref-format", cmd_check_ref_format },
+		{ "check-attr", cmd_check_attr, RUN_SETUP | NOT_BARE },
 		{ "cherry", cmd_cherry, RUN_SETUP },
 		{ "cherry-pick", cmd_cherry_pick, RUN_SETUP | NOT_BARE },
 		{ "commit-tree", cmd_commit_tree, RUN_SETUP },
diff --git a/lockfile.c b/lockfile.c
index bed6b21daf..23db35aff2 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -8,8 +8,11 @@ static const char *alternate_index_output;
 
 static void remove_lock_file(void)
 {
+	pid_t me = getpid();
+
 	while (lock_file_list) {
-		if (lock_file_list->filename[0])
+		if (lock_file_list->owner == me &&
+		    lock_file_list->filename[0])
 			unlink(lock_file_list->filename);
 		lock_file_list = lock_file_list->next;
 	}
@@ -28,6 +31,7 @@ static int lock_file(struct lock_file *lk, const char *path)
 	sprintf(lk->filename, "%s.lock", path);
 	fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
 	if (0 <= fd) {
+		lk->owner = getpid();
 		if (!lk->on_list) {
 			lk->next = lock_file_list;
 			lock_file_list = lk;
diff --git a/merge-recursive.c b/merge-recursive.c
index 31e66e5ca3..403a4c8bca 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -15,6 +15,8 @@
 #include "unpack-trees.h"
 #include "path-list.h"
 #include "xdiff-interface.h"
+#include "interpolate.h"
+#include "attr.h"
 
 static int subtree_merge;
 
@@ -645,6 +647,384 @@ static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 	mm->size = size;
 }
 
+/*
+ * Customizable low-level merge drivers support.
+ */
+
+struct ll_merge_driver;
+typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
+			   const char *path,
+			   mmfile_t *orig,
+			   mmfile_t *src1, const char *name1,
+			   mmfile_t *src2, const char *name2,
+			   mmbuffer_t *result);
+
+struct ll_merge_driver {
+	const char *name;
+	const char *description;
+	ll_merge_fn fn;
+	const char *recursive;
+	struct ll_merge_driver *next;
+	char *cmdline;
+};
+
+/*
+ * Built-in low-levels
+ */
+static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
+			const char *path_unused,
+			mmfile_t *orig,
+			mmfile_t *src1, const char *name1,
+			mmfile_t *src2, const char *name2,
+			mmbuffer_t *result)
+{
+	xpparam_t xpp;
+
+	memset(&xpp, 0, sizeof(xpp));
+	return xdl_merge(orig,
+			 src1, name1,
+			 src2, name2,
+			 &xpp, XDL_MERGE_ZEALOUS,
+			 result);
+}
+
+static int ll_union_merge(const struct ll_merge_driver *drv_unused,
+			  const char *path_unused,
+			  mmfile_t *orig,
+			  mmfile_t *src1, const char *name1,
+			  mmfile_t *src2, const char *name2,
+			  mmbuffer_t *result)
+{
+	char *src, *dst;
+	long size;
+	const int marker_size = 7;
+
+	int status = ll_xdl_merge(drv_unused, path_unused,
+				  orig, src1, NULL, src2, NULL, result);
+	if (status <= 0)
+		return status;
+	size = result->size;
+	src = dst = result->ptr;
+	while (size) {
+		char ch;
+		if ((marker_size < size) &&
+		    (*src == '<' || *src == '=' || *src == '>')) {
+			int i;
+			ch = *src;
+			for (i = 0; i < marker_size; i++)
+				if (src[i] != ch)
+					goto not_a_marker;
+			if (src[marker_size] != '\n')
+				goto not_a_marker;
+			src += marker_size + 1;
+			size -= marker_size + 1;
+			continue;
+		}
+	not_a_marker:
+		do {
+			ch = *src++;
+			*dst++ = ch;
+			size--;
+		} while (ch != '\n' && size);
+	}
+	result->size = dst - result->ptr;
+	return 0;
+}
+
+static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
+			   const char *path_unused,
+			   mmfile_t *orig,
+			   mmfile_t *src1, const char *name1,
+			   mmfile_t *src2, const char *name2,
+			   mmbuffer_t *result)
+{
+	/*
+	 * The tentative merge result is "ours" for the final round,
+	 * or common ancestor for an internal merge.  Still return
+	 * "conflicted merge" status.
+	 */
+	mmfile_t *stolen = index_only ? orig : src1;
+
+	result->ptr = stolen->ptr;
+	result->size = stolen->size;
+	stolen->ptr = NULL;
+	return 1;
+}
+
+#define LL_BINARY_MERGE 0
+#define LL_TEXT_MERGE 1
+#define LL_UNION_MERGE 2
+static struct ll_merge_driver ll_merge_drv[] = {
+	{ "binary", "built-in binary merge", ll_binary_merge },
+	{ "text", "built-in 3-way text merge", ll_xdl_merge },
+	{ "union", "built-in union merge", ll_union_merge },
+};
+
+static void create_temp(mmfile_t *src, char *path)
+{
+	int fd;
+
+	strcpy(path, ".merge_file_XXXXXX");
+	fd = mkstemp(path);
+	if (fd < 0)
+		die("unable to create temp-file");
+	if (write_in_full(fd, src->ptr, src->size) != src->size)
+		die("unable to write temp-file");
+	close(fd);
+}
+
+/*
+ * User defined low-level merge driver support.
+ */
+static int ll_ext_merge(const struct ll_merge_driver *fn,
+			const char *path,
+			mmfile_t *orig,
+			mmfile_t *src1, const char *name1,
+			mmfile_t *src2, const char *name2,
+			mmbuffer_t *result)
+{
+	char temp[3][50];
+	char cmdbuf[2048];
+	struct interp table[] = {
+		{ "%O" },
+		{ "%A" },
+		{ "%B" },
+	};
+	struct child_process child;
+	const char *args[20];
+	int status, fd, i;
+	struct stat st;
+
+	if (fn->cmdline == NULL)
+		die("custom merge driver %s lacks command line.", fn->name);
+
+	result->ptr = NULL;
+	result->size = 0;
+	create_temp(orig, temp[0]);
+	create_temp(src1, temp[1]);
+	create_temp(src2, temp[2]);
+
+	interp_set_entry(table, 0, temp[0]);
+	interp_set_entry(table, 1, temp[1]);
+	interp_set_entry(table, 2, temp[2]);
+
+	output(1, "merging %s using %s", path,
+	       fn->description ? fn->description : fn->name);
+
+	interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
+
+	memset(&child, 0, sizeof(child));
+	child.argv = args;
+	args[0] = "sh";
+	args[1] = "-c";
+	args[2] = cmdbuf;
+	args[3] = NULL;
+
+	status = run_command(&child);
+	if (status < -ERR_RUN_COMMAND_FORK)
+		; /* failure in run-command */
+	else
+		status = -status;
+	fd = open(temp[1], O_RDONLY);
+	if (fd < 0)
+		goto bad;
+	if (fstat(fd, &st))
+		goto close_bad;
+	result->size = st.st_size;
+	result->ptr = xmalloc(result->size + 1);
+	if (read_in_full(fd, result->ptr, result->size) != result->size) {
+		free(result->ptr);
+		result->ptr = NULL;
+		result->size = 0;
+	}
+ close_bad:
+	close(fd);
+ bad:
+	for (i = 0; i < 3; i++)
+		unlink(temp[i]);
+	return status;
+}
+
+/*
+ * merge.default and merge.driver configuration items
+ */
+static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
+static const char *default_ll_merge;
+
+static int read_merge_config(const char *var, const char *value)
+{
+	struct ll_merge_driver *fn;
+	const char *ep, *name;
+	int namelen;
+
+	if (!strcmp(var, "merge.default")) {
+		if (value)
+			default_ll_merge = strdup(value);
+		return 0;
+	}
+
+	/*
+	 * We are not interested in anything but "merge.<name>.variable";
+	 * especially, we do not want to look at variables such as
+	 * "merge.summary", "merge.tool", and "merge.verbosity".
+	 */
+	if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
+		return 0;
+
+	/*
+	 * Find existing one as we might be processing merge.<name>.var2
+	 * after seeing merge.<name>.var1.
+	 */
+	name = var + 6;
+	namelen = ep - name;
+	for (fn = ll_user_merge; fn; fn = fn->next)
+		if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
+			break;
+	if (!fn) {
+		char *namebuf;
+		fn = xcalloc(1, sizeof(struct ll_merge_driver));
+		namebuf = xmalloc(namelen + 1);
+		memcpy(namebuf, name, namelen);
+		namebuf[namelen] = 0;
+		fn->name = namebuf;
+		fn->fn = ll_ext_merge;
+		fn->next = NULL;
+		*ll_user_merge_tail = fn;
+		ll_user_merge_tail = &(fn->next);
+	}
+
+	ep++;
+
+	if (!strcmp("name", ep)) {
+		if (!value)
+			return error("%s: lacks value", var);
+		fn->description = strdup(value);
+		return 0;
+	}
+
+	if (!strcmp("driver", ep)) {
+		if (!value)
+			return error("%s: lacks value", var);
+		/*
+		 * merge.<name>.driver specifies the command line:
+		 *
+		 *	command-line
+		 *
+		 * The command-line will be interpolated with the following
+		 * tokens and is given to the shell:
+		 *
+		 *    %O - temporary file name for the merge base.
+		 *    %A - temporary file name for our version.
+		 *    %B - temporary file name for the other branches' version.
+		 *
+		 * The external merge driver should write the results in the
+		 * file named by %A, and signal that it has done with zero exit
+		 * status.
+		 */
+		fn->cmdline = strdup(value);
+		return 0;
+	}
+
+	if (!strcmp("recursive", ep)) {
+		if (!value)
+			return error("%s: lacks value", var);
+		fn->recursive = strdup(value);
+		return 0;
+	}
+
+	return 0;
+}
+
+static void initialize_ll_merge(void)
+{
+	if (ll_user_merge_tail)
+		return;
+	ll_user_merge_tail = &ll_user_merge;
+	git_config(read_merge_config);
+}
+
+static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
+{
+	struct ll_merge_driver *fn;
+	const char *name;
+	int i;
+
+	initialize_ll_merge();
+
+	if (ATTR_TRUE(merge_attr))
+		return &ll_merge_drv[LL_TEXT_MERGE];
+	else if (ATTR_FALSE(merge_attr))
+		return &ll_merge_drv[LL_BINARY_MERGE];
+	else if (ATTR_UNSET(merge_attr)) {
+		if (!default_ll_merge)
+			return &ll_merge_drv[LL_TEXT_MERGE];
+		else
+			name = default_ll_merge;
+	}
+	else
+		name = merge_attr;
+
+	for (fn = ll_user_merge; fn; fn = fn->next)
+		if (!strcmp(fn->name, name))
+			return fn;
+
+	for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
+		if (!strcmp(ll_merge_drv[i].name, name))
+			return &ll_merge_drv[i];
+
+	/* default to the 3-way */
+	return &ll_merge_drv[LL_TEXT_MERGE];
+}
+
+static const char *git_path_check_merge(const char *path)
+{
+	static struct git_attr_check attr_merge_check;
+
+	if (!attr_merge_check.attr)
+		attr_merge_check.attr = git_attr("merge", 5);
+
+	if (git_checkattr(path, 1, &attr_merge_check))
+		return NULL;
+	return attr_merge_check.value;
+}
+
+static int ll_merge(mmbuffer_t *result_buf,
+		    struct diff_filespec *o,
+		    struct diff_filespec *a,
+		    struct diff_filespec *b,
+		    const char *branch1,
+		    const char *branch2)
+{
+	mmfile_t orig, src1, src2;
+	char *name1, *name2;
+	int merge_status;
+	const char *ll_driver_name;
+	const struct ll_merge_driver *driver;
+
+	name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
+	name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
+
+	fill_mm(o->sha1, &orig);
+	fill_mm(a->sha1, &src1);
+	fill_mm(b->sha1, &src2);
+
+	ll_driver_name = git_path_check_merge(a->path);
+	driver = find_ll_merge_driver(ll_driver_name);
+
+	if (index_only && driver->recursive)
+		driver = find_ll_merge_driver(driver->recursive);
+	merge_status = driver->fn(driver, a->path,
+				  &orig, &src1, name1, &src2, name2,
+				  result_buf);
+
+	free(name1);
+	free(name2);
+	free(orig.ptr);
+	free(src1.ptr);
+	free(src2.ptr);
+	return merge_status;
+}
+
 static struct merge_file_info merge_file(struct diff_filespec *o,
 		struct diff_filespec *a, struct diff_filespec *b,
 		const char *branch1, const char *branch2)
@@ -673,30 +1053,11 @@ static struct merge_file_info merge_file(struct diff_filespec *o,
 		else if (sha_eq(b->sha1, o->sha1))
 			hashcpy(result.sha, a->sha1);
 		else if (S_ISREG(a->mode)) {
-			mmfile_t orig, src1, src2;
 			mmbuffer_t result_buf;
-			xpparam_t xpp;
-			char *name1, *name2;
 			int merge_status;
 
-			name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
-			name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
-
-			fill_mm(o->sha1, &orig);
-			fill_mm(a->sha1, &src1);
-			fill_mm(b->sha1, &src2);
-
-			memset(&xpp, 0, sizeof(xpp));
-			merge_status = xdl_merge(&orig,
-						 &src1, name1,
-						 &src2, name2,
-						 &xpp, XDL_MERGE_ZEALOUS,
-						 &result_buf);
-			free(name1);
-			free(name2);
-			free(orig.ptr);
-			free(src1.ptr);
-			free(src2.ptr);
+			merge_status = ll_merge(&result_buf, o, a, b,
+						branch1, branch2);
 
 			if ((merge_status < 0) || !result_buf.ptr)
 				die("Failed to execute internal merge");
diff --git a/sha1_file.c b/sha1_file.c
index 0c0fcc597d..06426640ea 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2338,10 +2338,9 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
 	 */
 	if ((type == OBJ_BLOB) && S_ISREG(st->st_mode)) {
 		unsigned long nsize = size;
-		char *nbuf = buf;
-		if (convert_to_git(path, &nbuf, &nsize)) {
-			if (size)
-				munmap(buf, size);
+		char *nbuf = convert_to_git(path, buf, &nsize);
+		if (nbuf) {
+			munmap(buf, size);
 			size = nsize;
 			buf = nbuf;
 			re_allocated = 1;
diff --git a/t/t0020-crlf.sh b/t/t0020-crlf.sh
index 723b29ad17..fe1dfd08a0 100755
--- a/t/t0020-crlf.sh
+++ b/t/t0020-crlf.sh
@@ -4,6 +4,10 @@ test_description='CRLF conversion'
 
 . ./test-lib.sh
 
+q_to_nul () {
+	tr Q '\0'
+}
+
 append_cr () {
 	sed -e 's/$/Q/' | tr Q '\015'
 }
@@ -20,6 +24,7 @@ test_expect_success setup '
 	for w in Hello world how are you; do echo $w; done >one &&
 	mkdir dir &&
 	for w in I am very very fine thank you; do echo $w; done >dir/two &&
+	for w in Oh here is NULQin text here; do echo $w; done | q_to_nul >three &&
 	git add . &&
 
 	git commit -m initial &&
@@ -27,6 +32,7 @@ test_expect_success setup '
 	one=`git rev-parse HEAD:one` &&
 	dir=`git rev-parse HEAD:dir` &&
 	two=`git rev-parse HEAD:dir/two` &&
+	three=`git rev-parse HEAD:three` &&
 
 	for w in Some extra lines here; do echo $w; done >>one &&
 	git diff >patch.file &&
@@ -38,7 +44,7 @@ test_expect_success setup '
 
 test_expect_success 'update with autocrlf=input' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git read-tree --reset -u HEAD &&
 	git repo-config core.autocrlf input &&
 
@@ -62,7 +68,7 @@ test_expect_success 'update with autocrlf=input' '
 
 test_expect_success 'update with autocrlf=true' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git read-tree --reset -u HEAD &&
 	git repo-config core.autocrlf true &&
 
@@ -86,7 +92,7 @@ test_expect_success 'update with autocrlf=true' '
 
 test_expect_success 'checkout with autocrlf=true' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf true &&
 	git read-tree --reset -u HEAD &&
 
@@ -110,7 +116,7 @@ test_expect_success 'checkout with autocrlf=true' '
 
 test_expect_success 'checkout with autocrlf=input' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf input &&
 	git read-tree --reset -u HEAD &&
 
@@ -136,7 +142,7 @@ test_expect_success 'checkout with autocrlf=input' '
 
 test_expect_success 'apply patch (autocrlf=input)' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf input &&
 	git read-tree --reset -u HEAD &&
 
@@ -149,7 +155,7 @@ test_expect_success 'apply patch (autocrlf=input)' '
 
 test_expect_success 'apply patch --cached (autocrlf=input)' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf input &&
 	git read-tree --reset -u HEAD &&
 
@@ -162,7 +168,7 @@ test_expect_success 'apply patch --cached (autocrlf=input)' '
 
 test_expect_success 'apply patch --index (autocrlf=input)' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf input &&
 	git read-tree --reset -u HEAD &&
 
@@ -176,7 +182,7 @@ test_expect_success 'apply patch --index (autocrlf=input)' '
 
 test_expect_success 'apply patch (autocrlf=true)' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf true &&
 	git read-tree --reset -u HEAD &&
 
@@ -189,7 +195,7 @@ test_expect_success 'apply patch (autocrlf=true)' '
 
 test_expect_success 'apply patch --cached (autocrlf=true)' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf true &&
 	git read-tree --reset -u HEAD &&
 
@@ -202,7 +208,7 @@ test_expect_success 'apply patch --cached (autocrlf=true)' '
 
 test_expect_success 'apply patch --index (autocrlf=true)' '
 
-	rm -f tmp one dir/two &&
+	rm -f tmp one dir/two three &&
 	git repo-config core.autocrlf true &&
 	git read-tree --reset -u HEAD &&
 
@@ -214,4 +220,74 @@ test_expect_success 'apply patch --index (autocrlf=true)' '
 	}
 '
 
+test_expect_success '.gitattributes says two is binary' '
+
+	rm -f tmp one dir/two three &&
+	echo "two -crlf" >.gitattributes &&
+	git repo-config core.autocrlf true &&
+	git read-tree --reset -u HEAD &&
+
+	if remove_cr dir/two >/dev/null
+	then
+		echo "Huh?"
+		false
+	else
+		: happy
+	fi &&
+
+	if remove_cr one >/dev/null
+	then
+		: happy
+	else
+		echo "Huh?"
+		false
+	fi &&
+
+	if remove_cr three >/dev/null
+	then
+		echo "Huh?"
+		false
+	else
+		: happy
+	fi
+'
+
+test_expect_success '.gitattributes says two is input' '
+
+	rm -f tmp one dir/two three &&
+	echo "two crlf=input" >.gitattributes &&
+	git read-tree --reset -u HEAD &&
+
+	if remove_cr dir/two >/dev/null
+	then
+		echo "Huh?"
+		false
+	else
+		: happy
+	fi
+'
+
+test_expect_success '.gitattributes says two and three are text' '
+
+	rm -f tmp one dir/two three &&
+	echo "t* crlf" >.gitattributes &&
+	git read-tree --reset -u HEAD &&
+
+	if remove_cr dir/two >/dev/null
+	then
+		: happy
+	else
+		echo "Huh?"
+		false
+	fi &&
+
+	if remove_cr three >/dev/null
+	then
+		: happy
+	else
+		echo "Huh?"
+		false
+	fi
+'
+
 test_done
diff --git a/t/t6026-merge-attr.sh b/t/t6026-merge-attr.sh
new file mode 100755
index 0000000000..56fc341768
--- /dev/null
+++ b/t/t6026-merge-attr.sh
@@ -0,0 +1,145 @@
+#!/bin/sh
+#
+# Copyright (c) 2007 Junio C Hamano
+#
+
+test_description='per path merge controlled by merge attribute'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+
+	for f in text binary union
+	do
+		echo Initial >$f && git add $f || break
+	done &&
+	test_tick &&
+	git commit -m Initial &&
+
+	git branch side &&
+	for f in text binary union
+	do
+		echo Master >>$f && git add $f || break
+	done &&
+	test_tick &&
+	git commit -m Master &&
+
+	git checkout side &&
+	for f in text binary union
+	do
+		echo Side >>$f && git add $f || break
+	done &&
+	test_tick &&
+	git commit -m Side &&
+
+	git tag anchor
+'
+
+test_expect_success merge '
+
+	{
+		echo "binary -merge"
+		echo "union merge=union"
+	} >.gitattributes &&
+
+	if git merge master
+	then
+		echo Gaah, should have conflicted
+		false
+	else
+		echo Ok, conflicted.
+	fi
+'
+
+test_expect_success 'check merge result in index' '
+
+	git ls-files -u | grep binary &&
+	git ls-files -u | grep text &&
+	! (git ls-files -u | grep union)
+
+'
+
+test_expect_success 'check merge result in working tree' '
+
+	git cat-file -p HEAD:binary >binary-orig &&
+	grep "<<<<<<<" text &&
+	cmp binary-orig binary &&
+	! grep "<<<<<<<" union &&
+	grep Master union &&
+	grep Side union
+
+'
+
+cat >./custom-merge <<\EOF
+#!/bin/sh
+
+orig="$1" ours="$2" theirs="$3" exit="$4"
+(
+	echo "orig is $orig"
+	echo "ours is $ours"
+	echo "theirs is $theirs"
+	echo "=== orig ==="
+	cat "$orig"
+	echo "=== ours ==="
+	cat "$ours"
+	echo "=== theirs ==="
+	cat "$theirs"
+) >"$ours+"
+cat "$ours+" >"$ours"
+rm -f "$ours+"
+exit "$exit"
+EOF
+chmod +x ./custom-merge
+
+test_expect_success 'custom merge backend' '
+
+	echo "* merge=union" >.gitattributes &&
+	echo "text merge=custom" >>.gitattributes &&
+
+	git reset --hard anchor &&
+	git config --replace-all \
+	merge.custom.driver "./custom-merge %O %A %B 0" &&
+	git config --replace-all \
+	merge.custom.name "custom merge driver for testing" &&
+
+	git merge master &&
+
+	cmp binary union &&
+	sed -e 1,3d text >check-1 &&
+	o=$(git-unpack-file master^:text) &&
+	a=$(git-unpack-file side^:text) &&
+	b=$(git-unpack-file master:text) &&
+	sh -c "./custom-merge $o $a $b 0" &&
+	sed -e 1,3d $a >check-2 &&
+	cmp check-1 check-2 &&
+	rm -f $o $a $b
+'
+
+test_expect_success 'custom merge backend' '
+
+	git reset --hard anchor &&
+	git config --replace-all \
+	merge.custom.driver "./custom-merge %O %A %B 1" &&
+	git config --replace-all \
+	merge.custom.name "custom merge driver for testing" &&
+
+	if git merge master
+	then
+		echo "Eh? should have conflicted"
+		false
+	else
+		echo "Ok, conflicted"
+	fi &&
+
+	cmp binary union &&
+	sed -e 1,3d text >check-1 &&
+	o=$(git-unpack-file master^:text) &&
+	a=$(git-unpack-file anchor:text) &&
+	b=$(git-unpack-file master:text) &&
+	sh -c "./custom-merge $o $a $b 0" &&
+	sed -e 1,3d $a >check-2 &&
+	cmp check-1 check-2 &&
+	rm -f $o $a $b
+'
+
+test_done