Fix core.excludesfile named .gitignore

Ignore rules with slashes in them are matched using FNM_PATHNAME
and use the path to the .gitignore file from the root of the
repository along with the path fragment (including slashes) in
the ignore file itself.  Unfortunately, the relative path to the
.gitignore file was being applied to the global core.excludesfile
if that was also named ".gitignore".

This fixes that with more precise matching and includes test for
ignore rules with leading slashes (which were the primary example
of this being broken in the real world).

This also backports an improvement to the file context logic from
the threadsafe-iterators branch where we don't rely on mutating
the key of the attribute file name to generate the context path.

src/attr_file.c

@@ -61,8 +61,7 @@ int git_attr_file__parse_buffer(
 	git_repository *repo, void *parsedata, const char *buffer, git_attr_file *attrs)
 {
 	int error = 0;
-	const char *scan = NULL;
-	char *context = NULL;
+	const char *scan = NULL, *context = NULL;
 	git_attr_rule *rule = NULL;
 
 	GIT_UNUSED(parsedata);
@@ -72,10 +71,10 @@ int git_attr_file__parse_buffer(
 	scan = buffer;
 
 	/* if subdir file path, convert context for file paths */
-	if (attrs->key && git__suffixcmp(attrs->key, "/" GIT_ATTR_FILE) == 0) {
+	if (attrs->key &&
+		git_path_root(attrs->key + 2) < 0 &&
+		git__suffixcmp(attrs->key, "/" GIT_ATTR_FILE) == 0)
 		context = attrs->key + 2;
-		context[strlen(context) - strlen(GIT_ATTR_FILE)] = '\0';
-	}
 
 	while (!error && *scan) {
 		/* allocate rule if needed */
@@ -115,10 +114,6 @@ int git_attr_file__parse_buffer(
 
 	git_attr_rule__free(rule);
 
-	/* restore file path used for context */
-	if (context)
-		context[strlen(context)] = '.'; /* first char of GIT_ATTR_FILE */
-
 	return error;
 }
 
@@ -414,7 +409,10 @@ int git_attr_fnmatch__parse(
 	if ((spec->flags & GIT_ATTR_FNMATCH_FULLPATH) != 0 &&
 		source != NULL && git_path_root(pattern) < 0)
 	{
-		size_t sourcelen = strlen(source);
+        /* use context path minus the trailing filename */
+        char *slash = strrchr(source, '/');
+        size_t sourcelen = slash ? slash - source + 1 : 0;
+
 		/* given an unrooted fullpath match from a file inside a repo,
 		 * prefix the pattern with the relative directory of the source file
 		 */

src/ignore.c

@@ -14,8 +14,7 @@ static int parse_ignore_file(
 {
 	int error = 0;
 	git_attr_fnmatch *match = NULL;
-	const char *scan = NULL;
-	char *context = NULL;
+	const char *scan = NULL, *context = NULL;
 	int ignore_case = false;
 
 	/* Prefer to have the caller pass in a git_ignores as the parsedata
@@ -25,10 +24,10 @@ static int parse_ignore_file(
 	else if (git_repository__cvar(&ignore_case, repo, GIT_CVAR_IGNORECASE) < 0)
 		return error;
 
-	if (ignores->key && git__suffixcmp(ignores->key, "/" GIT_IGNORE_FILE) == 0) {
+	if (ignores->key &&
+		git_path_root(ignores->key + 2) < 0 &&
+		git__suffixcmp(ignores->key, "/" GIT_IGNORE_FILE) == 0)
 		context = ignores->key + 2;
-		context[strlen(context) - strlen(GIT_IGNORE_FILE)] = '\0';
-	}
 
 	scan = buffer;
 
@@ -64,9 +63,6 @@ static int parse_ignore_file(
 	}
 
 	git__free(match);
-	/* restore file path used for context */
-	if (context)
-		context[strlen(context)] = '.'; /* first char of GIT_IGNORE_FILE */
 
 	return error;
 }

tests/attr/ignore.c

@@ -130,22 +130,18 @@ void test_attr_ignore__skip_gitignore_directory(void)
 
 void test_attr_ignore__expand_tilde_to_homedir(void)
 {
-	git_buf path = GIT_BUF_INIT;
+	git_buf cleanup = GIT_BUF_INIT;
 	git_config *cfg;
 
 	assert_is_ignored(false, "example.global_with_tilde");
 
-	/* construct fake home with fake global excludes */
-
-	cl_must_pass(p_mkdir("home", 0777));
-	cl_git_pass(git_path_prettify(&path, "home", NULL));
-	cl_git_pass(git_libgit2_opts(
-		GIT_OPT_SET_SEARCH_PATH, GIT_CONFIG_LEVEL_GLOBAL, path.ptr));
+	cl_fake_home(&cleanup);
 
-	cl_git_mkfile("home/globalexcludes", "# found me\n*.global_with_tilde\n");
+	/* construct fake home with fake global excludes */
+	cl_git_mkfile("home/globalexclude", "# found me\n*.global_with_tilde\n");
 
 	cl_git_pass(git_repository_config(&cfg, g_repo));
-	cl_git_pass(git_config_set_string(cfg, "core.excludesfile", "~/globalexcludes"));
+	cl_git_pass(git_config_set_string(cfg, "core.excludesfile", "~/globalexclude"));
 	git_config_free(cfg);
 
 	git_attr_cache_flush(g_repo); /* must reset to pick up change */
@@ -154,8 +150,9 @@ void test_attr_ignore__expand_tilde_to_homedir(void)
 
 	cl_git_pass(git_futils_rmdir_r("home", NULL, GIT_RMDIR_REMOVE_FILES));
 
-	cl_git_pass(git_libgit2_opts(
-		GIT_OPT_SET_SEARCH_PATH, GIT_CONFIG_LEVEL_GLOBAL, NULL));
+	cl_fake_home_cleanup(&cleanup);
 
-	git_buf_free(&path);
+	git_attr_cache_flush(g_repo); /* must reset to pick up change */
+
+	assert_is_ignored(false, "example.global_with_tilde");
 }

tests/clar_libgit2.c

@@ -490,3 +490,24 @@ void clar__assert_equal_file(
 	clar__assert_equal(file, line, "mismatched file length", 1, "%"PRIuZ,
 		(size_t)expected_bytes, (size_t)total_bytes);
 }
+
+void cl_fake_home(git_buf *restore)
+{
+	git_buf path = GIT_BUF_INIT;
+
+	cl_git_pass(git_libgit2_opts(
+		GIT_OPT_GET_SEARCH_PATH, GIT_CONFIG_LEVEL_GLOBAL, restore));
+
+	cl_must_pass(p_mkdir("home", 0777));
+	cl_git_pass(git_path_prettify(&path, "home", NULL));
+	cl_git_pass(git_libgit2_opts(
+		GIT_OPT_SET_SEARCH_PATH, GIT_CONFIG_LEVEL_GLOBAL, path.ptr));
+	git_buf_free(&path);
+}
+
+void cl_fake_home_cleanup(git_buf *restore)
+{
+	cl_git_pass(git_libgit2_opts(
+		GIT_OPT_SET_SEARCH_PATH, GIT_CONFIG_LEVEL_GLOBAL, restore->ptr));
+	git_buf_free(restore);
+}

tests/clar_libgit2.h

@@ -120,4 +120,7 @@ int cl_repo_get_bool(git_repository *repo, const char *cfg);
 
 void cl_repo_set_string(git_repository *repo, const char *cfg, const char *value);
 
+void cl_fake_home(git_buf *restore);
+void cl_fake_home_cleanup(git_buf *restore);
+
 #endif

tests/status/ignore.c

@@ -364,6 +364,62 @@ void test_status_ignore__subdirectories_not_at_root(void)
 	cl_assert_equal_i(0, counts.wrong_sorted_path);
 }
 
+void test_status_ignore__leading_slash_ignores(void)
+{
+	git_status_options opts = GIT_STATUS_OPTIONS_INIT;
+	status_entry_counts counts;
+	git_buf home = GIT_BUF_INIT;
+	static const char *paths_2[] = {
+		"dir/.gitignore",
+		"dir/a/ignore_me",
+		"dir/b/ignore_me",
+		"dir/ignore_me",
+		"ignore_also/file",
+		"ignore_me",
+		"test/.gitignore",
+		"test/ignore_me/and_me/file",
+		"test/ignore_me/file",
+		"test/ignore_me/file2",
+	};
+	static const unsigned int statuses_2[] = {
+		GIT_STATUS_WT_NEW,  GIT_STATUS_WT_NEW,  GIT_STATUS_WT_NEW,
+		GIT_STATUS_IGNORED, GIT_STATUS_IGNORED, GIT_STATUS_IGNORED,
+		GIT_STATUS_WT_NEW, GIT_STATUS_WT_NEW, GIT_STATUS_WT_NEW, GIT_STATUS_WT_NEW,
+	};
+
+	make_test_data();
+
+	cl_fake_home(&home);
+	cl_git_mkfile("home/.gitignore", "/ignore_me\n");
+	{
+		git_config *cfg;
+		cl_git_pass(git_repository_config(&cfg, g_repo));
+		cl_git_pass(git_config_set_string(
+			cfg, "core.excludesfile", "~/.gitignore"));
+		git_config_free(cfg);
+	}
+
+	cl_git_rewritefile("empty_standard_repo/.git/info/exclude", "/ignore_also\n");
+	cl_git_rewritefile("empty_standard_repo/dir/.gitignore", "/ignore_me\n");
+	cl_git_rewritefile("empty_standard_repo/test/.gitignore", "/and_me\n");
+
+	memset(&counts, 0x0, sizeof(status_entry_counts));
+	counts.expected_entry_count = 10;
+	counts.expected_paths = paths_2;
+	counts.expected_statuses = statuses_2;
+
+	opts.flags = GIT_STATUS_OPT_DEFAULTS | GIT_STATUS_OPT_RECURSE_IGNORED_DIRS;
+
+	cl_git_pass(git_status_foreach_ext(
+		g_repo, &opts, cb_status__normal, &counts));
+
+	cl_assert_equal_i(counts.expected_entry_count, counts.entry_count);
+	cl_assert_equal_i(0, counts.wrong_status_flags_count);
+	cl_assert_equal_i(0, counts.wrong_sorted_path);
+
+	cl_fake_home_cleanup(&home);
+}
+
 void test_status_ignore__adding_internal_ignores(void)
 {
 	int ignored;