config: turn die_on_error into caller-facing enum

The config code has a die_on_error flag, which lets us emit
an error() instead of dying when we see a bogus config file.
But there's no way for a caller of the config code to set
this: it's auto-set based on whether we're reading a file or
a blob.

Instead, let's add it to the config_options struct. When
it's not set (or we have no options) we'll continue to fall
back to the existing file/blob behavior.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -31,7 +31,7 @@ struct config_source {
 	enum config_origin_type origin_type;
 	const char *name;
 	const char *path;
-	int die_on_error;
+	enum config_error_action default_error_action;
 	int linenr;
 	int eof;
 	struct strbuf value;
@@ -809,10 +809,18 @@ static int git_parse_source(config_fn_t fn, void *data,
 				      cf->linenr, cf->name);
 	}
 
-	if (cf->die_on_error)
+	switch (opts && opts->error_action ?
+		opts->error_action :
+		cf->default_error_action) {
+	case CONFIG_ERROR_DIE:
 		die("%s", error_msg);
-	else
+		break;
+	case CONFIG_ERROR_ERROR:
 		error_return = error("%s", error_msg);
+		break;
+	case CONFIG_ERROR_UNSET:
+		BUG("config error action unset");
+	}
 
 	free(error_msg);
 	return error_return;
@@ -1520,7 +1528,7 @@ static int do_config_from_file(config_fn_t fn,
 	top.origin_type = origin_type;
 	top.name = name;
 	top.path = path;
-	top.die_on_error = 1;
+	top.default_error_action = CONFIG_ERROR_DIE;
 	top.do_fgetc = config_file_fgetc;
 	top.do_ungetc = config_file_ungetc;
 	top.do_ftell = config_file_ftell;
@@ -1569,7 +1577,7 @@ int git_config_from_mem(config_fn_t fn, const enum config_origin_type origin_typ
 	top.origin_type = origin_type;
 	top.name = name;
 	top.path = NULL;
-	top.die_on_error = 0;
+	top.default_error_action = CONFIG_ERROR_ERROR;
 	top.do_fgetc = config_buf_fgetc;
 	top.do_ungetc = config_buf_ungetc;
 	top.do_ftell = config_buf_ftell;

config.h

@@ -54,6 +54,11 @@ struct config_options {
 	const char *git_dir;
 	config_parser_event_fn_t event_fn;
 	void *event_fn_data;
+	enum config_error_action {
+		CONFIG_ERROR_UNSET = 0, /* use source-specific default */
+		CONFIG_ERROR_DIE, /* die() on error */
+		CONFIG_ERROR_ERROR, /* error() on error, return -1 */
+	} error_action;
 };
 
 typedef int (*config_fn_t)(const char *, const char *, void *);