4 files changed, 69 insertions, 7 deletions

diff --git a/src/config_file.c b/src/config_file.c
index 87a430759..5e862d487 100644
--- a/src/config_file.c
+++ b/src/config_file.c
@@ -256,7 +256,11 @@ static int config_open(git_config_file *cfg)
 	diskfile_backend *b = (diskfile_backend *)cfg;
 
 	error = git_futils_readbuffer(&b->reader.buffer, b->file_path);
-	if(error < GIT_SUCCESS)
+	/* It's fine if the file doesn't exist */
+	if (error == GIT_ENOTFOUND)
+		return GIT_SUCCESS;
+
+	if (error < GIT_SUCCESS)
 		goto cleanup;
 
 	error = config_parse(b);
@@ -714,6 +718,9 @@ static int skip_bom(diskfile_backend *cfg)
 {
 	static const char *utf8_bom = "\xef\xbb\xbf";
 
+	if (cfg->reader.buffer.len < sizeof(utf8_bom))
+		return GIT_SUCCESS;
+
 	if (memcmp(cfg->reader.read_ptr, utf8_bom, sizeof(utf8_bom)) == 0)
 		cfg->reader.read_ptr += sizeof(utf8_bom);
 
@@ -882,14 +889,23 @@ static int config_write(diskfile_backend *cfg, cvar_t *var)
 
 	/* We need to read in our own config file */
 	error = git_futils_readbuffer(&cfg->reader.buffer, cfg->file_path);
-	if (error < GIT_SUCCESS) {
+	if (error < GIT_SUCCESS && error != GIT_ENOTFOUND) {
 		return git__rethrow(error, "Failed to read existing config file %s", cfg->file_path);
 	}
 
 	/* Initialise the reading position */
-	cfg->reader.read_ptr = cfg->reader.buffer.data;
-	cfg->reader.eof = 0;
-	data_start = cfg->reader.read_ptr;
+	if (error == GIT_ENOTFOUND) {
+		error = GIT_SUCCESS;
+		cfg->reader.read_ptr = NULL;
+		cfg->reader.eof = 1;
+		data_start = NULL;
+		cfg->reader.buffer.len = 0;
+		cfg->reader.buffer.data = NULL;
+	} else {
+		cfg->reader.read_ptr = cfg->reader.buffer.data;
+		cfg->reader.eof = 0;
+		data_start = cfg->reader.read_ptr;
+	}
 
 	/* Lock the file */
 	error = git_filebuf_open(&file, cfg->file_path, 0);
diff --git a/tests-clay/clay.h b/tests-clay/clay.h
index 812209be1..3db9600b3 100644
--- a/tests-clay/clay.h
+++ b/tests-clay/clay.h
@@ -59,6 +59,7 @@ void cl_fixture_cleanup(const char *fixture_name);
  */
 extern void test_buf_basic__printf(void);
 extern void test_buf_basic__resize(void);
+extern void test_config_new__write_new_config(void);
 extern void test_config_stress__cleanup(void);
 extern void test_config_stress__dont_break_on_invalid_input(void);
 extern void test_config_stress__initialize(void);
diff --git a/tests-clay/clay_main.c b/tests-clay/clay_main.c
index 6d964b1ba..2f9a49d36 100644
--- a/tests-clay/clay_main.c
+++ b/tests-clay/clay_main.c
@@ -108,6 +108,9 @@ static const struct clay_func _clay_cb_buf_basic[] = {
     {"printf", &test_buf_basic__printf},
 	{"resize", &test_buf_basic__resize}
 };
+static const struct clay_func _clay_cb_config_new[] = {
+    {"write_new_config", &test_config_new__write_new_config}
+};
 static const struct clay_func _clay_cb_config_stress[] = {
     {"dont_break_on_invalid_input", &test_config_stress__dont_break_on_invalid_input}
 };
@@ -229,6 +232,12 @@ static const struct clay_suite _clay_suites[] = {
         _clay_cb_buf_basic, 2
     },
 	{
+        "config::new",
+        {NULL, NULL},
+        {NULL, NULL},
+        _clay_cb_config_new, 1
+    },
+	{
         "config::stress",
         {"initialize", &test_config_stress__initialize},
         {"cleanup", &test_config_stress__cleanup},
@@ -362,8 +371,8 @@ static const struct clay_suite _clay_suites[] = {
     }
 };
 
-static size_t _clay_suite_count = 23;
-static size_t _clay_callback_count = 70;
+static size_t _clay_suite_count = 24;
+static size_t _clay_callback_count = 71;
 
 /* Core test functions */
 static void
diff --git a/tests-clay/config/new.c b/tests-clay/config/new.c
new file mode 100644
index 000000000..285cc4af8
--- /dev/null
+++ b/tests-clay/config/new.c
@@ -0,0 +1,36 @@
+#include "clay_libgit2.h"
+
+#include "filebuf.h"
+#include "fileops.h"
+#include "posix.h"
+
+#define TEST_CONFIG "git-new-config"
+
+void test_config_new__write_new_config(void)
+{
+	const char *out;
+	struct git_config_file *file;
+	git_config *config;
+
+	cl_git_pass(git_config_file__ondisk(&file, TEST_CONFIG));
+	cl_git_pass(git_config_new(&config));
+	cl_git_pass(git_config_add_file(config, file, 0));
+
+	cl_git_pass(git_config_set_string(config, "color.ui", "auto"));
+	cl_git_pass(git_config_set_string(config, "core.editor", "ed"));
+
+	git_config_free(config);
+
+	cl_git_pass(git_config_file__ondisk(&file, TEST_CONFIG));
+	cl_git_pass(git_config_new(&config));
+	cl_git_pass(git_config_add_file(config, file, 0));
+
+	cl_git_pass(git_config_get_string(config, "color.ui", &out));
+	cl_assert(strcmp(out, "auto") == 0);
+	cl_git_pass(git_config_get_string(config, "core.editor", &out));
+	cl_assert(strcmp(out, "ed") == 0);
+
+	git_config_free(config);
+
+	p_unlink(TEST_CONFIG);
+}