thodg/libgit2

diff --git a/include/git2.h b/include/git2.h
index 4016748..805044a 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -41,6 +41,7 @@
 #include "git2/checkout.h"
 
 #include "git2/attr.h"
+#include "git2/ignore.h"
 #include "git2/branch.h"
 #include "git2/refspec.h"
 #include "git2/net.h"
diff --git a/include/git2/ignore.h b/include/git2/ignore.h
new file mode 100644
index 0000000..f7e04e8
--- /dev/null
+++ b/include/git2/ignore.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_ignore_h__
+#define INCLUDE_git_ignore_h__
+
+#include "common.h"
+#include "types.h"
+
+GIT_BEGIN_DECL
+
+/**
+ * Add ignore rules for a repository.
+ *
+ * Excludesfile rules (i.e. .gitignore rules) are generally read from
+ * .gitignore files in the repository tree or from a shared system file
+ * only if a "core.excludesfile" config value is set.  The library also
+ * keeps a set of per-repository internal ignores that can be configured
+ * in-memory and will not persist.  This function allows you to add to
+ * that internal rules list.
+ *
+ * Example usage:
+ *
+ *     error = git_ignore_add(myrepo, "*.c\ndir/\nFile with space\n");
+ *
+ * This would add three rules to the ignores.
+ *
+ * @param repo The repository to add ignore rules to.
+ * @param rules Text of rules, a la the contents of a .gitignore file.
+ *              It is okay to have multiple rules in the text; if so,
+ *              each rule should be terminated with a newline.
+ * @return 0 on success
+ */
+GIT_EXTERN(int) git_ignore_add_rule(
+	git_repository *repo,
+	const char *rules);
+
+/**
+ * Clear ignore rules that were explicitly added.
+ *
+ * Clears the internal ignore rules that have been set up.  This will not
+ * turn off the rules in .gitignore files that actually exist in the
+ * filesystem.
+ *
+ * @param repo The repository to remove ignore rules from.
+ * @return 0 on success
+ */
+GIT_EXTERN(int) git_ignore_clear_internal_rules(
+	git_repository *repo);
+
+/**
+ * Test if the ignore rules apply to a given path.
+ *
+ * This function simply checks the ignore rules to see if they would apply
+ * to the given file.  This indicates if the file would be ignored regardless
+ * of whether the file is already in the index or commited to the repository.
+ *
+ * @param ignored boolean returning 0 if the file is not ignored, 1 if it is
+ * @param repo a repository object
+ * @param path the file to check ignores for, relative to the repo's workdir.
+ * @return 0 if ignore rules could be processed for the file (regardless
+ *         of whether it exists or not), or an error < 0 if they could not.
+ */
+GIT_EXTERN(int) git_ignore_path_is_ignored(
+	int *ignored,
+	git_repository *repo,
+	const char *path);
+
+GIT_END_DECL
+
+#endif
diff --git a/src/attr.c b/src/attr.c
index de714a6..8a7ff28 100644
--- a/src/attr.c
+++ b/src/attr.c
@@ -612,6 +612,16 @@ int git_attr_cache__init(git_repository *repo)
 	if (ret < 0 && ret != GIT_ENOTFOUND)
 		return ret;
 
+	if (ret == GIT_ENOTFOUND) {
+		git_buf dflt = GIT_BUF_INIT;
+
+		ret = git_futils_find_global_file(&dflt, GIT_IGNORE_CONFIG_DEFAULT);
+		if (!ret)
+			cache->cfg_excl_file = git_buf_detach(&dflt);
+
+		git_buf_free(&dflt);
+	}
+
 	giterr_clear();
 
 	/* allocate hashtable for attribute and ignore file contents */
diff --git a/src/attr.h b/src/attr.h
index a35b116..78cfb57 100644
--- a/src/attr.h
+++ b/src/attr.h
@@ -12,6 +12,7 @@
 
 #define GIT_ATTR_CONFIG   "core.attributesfile"
 #define GIT_IGNORE_CONFIG "core.excludesfile"
+#define GIT_IGNORE_CONFIG_DEFAULT ".config/git/ignore"
 
 typedef struct {
 	int initialized;
diff --git a/src/ignore.c b/src/ignore.c
index 93d979f..1ac8afd 100644
--- a/src/ignore.c
+++ b/src/ignore.c
@@ -1,3 +1,4 @@
+#include "git2/ignore.h"
 #include "ignore.h"
 #include "path.h"
 
@@ -203,3 +204,51 @@ cleanup:
 	git_attr_path__free(&path);
 	return 0;
 }
+
+int git_ignore_add_rule(
+	git_repository *repo,
+	const char *rules)
+{
+	int error;
+	git_attr_file *ign_internal;
+
+	error = git_attr_cache__internal_file(
+		repo, GIT_IGNORE_INTERNAL, &ign_internal);
+
+	if (!error && ign_internal != NULL)
+		error = parse_ignore_file(repo, rules, ign_internal);
+
+	return error;
+}
+
+int git_ignore_clear_internal_rules(
+	git_repository *repo)
+{
+	int error;
+	git_attr_file *ign_internal;
+
+	error = git_attr_cache__internal_file(
+		repo, GIT_IGNORE_INTERNAL, &ign_internal);
+
+	if (!error && ign_internal != NULL)
+		git_attr_file__clear_rules(ign_internal);
+
+	return error;
+}
+
+int git_ignore_path_is_ignored(
+	int *ignored,
+	git_repository *repo,
+	const char *path)
+{
+	int error;
+	git_ignores ignores;
+
+	if (git_ignore__for_path(repo, path, &ignores) < 0)
+		return -1;
+
+	error = git_ignore__lookup(&ignores, path, ignored);
+	git_ignore__free(&ignores);
+	return error;
+}
+
diff --git a/src/status.c b/src/status.c
index 8e46255..3d3d15d 100644
--- a/src/status.c
+++ b/src/status.c
@@ -243,14 +243,6 @@ int git_status_should_ignore(
 	git_repository *repo,
 	const char *path)
 {
-	int error;
-	git_ignores ignores;
-
-	if (git_ignore__for_path(repo, path, &ignores) < 0)
-		return -1;
-
-	error = git_ignore__lookup(&ignores, path, ignored);
-	git_ignore__free(&ignores);
-	return error;
+	return git_ignore_path_is_ignored(ignored, repo, path);
 }
 
diff --git a/tests-clar/status/ignore.c b/tests-clar/status/ignore.c
index 0384306..9c6d7ee 100644
--- a/tests-clar/status/ignore.c
+++ b/tests-clar/status/ignore.c
@@ -139,9 +139,63 @@ void test_status_ignore__ignore_pattern_contains_space(void)
 	g_repo = cl_git_sandbox_init("empty_standard_repo");
 	cl_git_rewritefile("empty_standard_repo/.gitignore", "foo bar.txt\n");
 
+	cl_git_mkfile(
+		"empty_standard_repo/foo bar.txt", "I'm going to be ignored!");
+
+	cl_git_pass(git_status_file(&flags, g_repo, "foo bar.txt"));
+	cl_assert(flags == GIT_STATUS_IGNORED);
+
 	cl_git_pass(git_futils_mkdir_r("empty_standard_repo/foo", NULL, mode));
 	cl_git_mkfile("empty_standard_repo/foo/look-ma.txt", "I'm not going to be ignored!");
 
 	cl_git_pass(git_status_file(&flags, g_repo, "foo/look-ma.txt"));
 	cl_assert(flags == GIT_STATUS_WT_NEW);
 }
+
+void test_status_ignore__adding_internal_ignores(void)
+{
+	int ignored;
+
+	g_repo = cl_git_sandbox_init("empty_standard_repo");
+
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "one.txt"));
+	cl_assert(!ignored);
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "two.bar"));
+	cl_assert(!ignored);
+
+	cl_git_pass(git_ignore_add_rule(g_repo, "*.nomatch\n"));
+
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "one.txt"));
+	cl_assert(!ignored);
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "two.bar"));
+	cl_assert(!ignored);
+
+	cl_git_pass(git_ignore_add_rule(g_repo, "*.txt\n"));
+
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "one.txt"));
+	cl_assert(ignored);
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "two.bar"));
+	cl_assert(!ignored);
+
+	cl_git_pass(git_ignore_add_rule(g_repo, "*.bar\n"));
+
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "one.txt"));
+	cl_assert(ignored);
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "two.bar"));
+	cl_assert(ignored);
+
+	cl_git_pass(git_ignore_clear_internal_rules(g_repo));
+
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "one.txt"));
+	cl_assert(!ignored);
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "two.bar"));
+	cl_assert(!ignored);
+
+	cl_git_pass(git_ignore_add_rule(
+		g_repo, "multiple\n*.rules\n# comment line\n*.bar\n"));
+
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "one.txt"));
+	cl_assert(!ignored);
+	cl_git_pass(git_status_should_ignore(&ignored, g_repo, "two.bar"));
+	cl_assert(ignored);
+}