From 918fb606174dcf42553be65e3d2306996c52488f Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Tue, 21 Apr 2020 00:13:51 +0200
Subject: Implement recursive configuration file parsing (Fixes #59)

---
 README.md     |  4 ++++
 config.c      | 25 +++++++++++++++++++++++--
 midimonster.c |  2 +-
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 12d87eb..a7ca212 100644
--- a/README.md
+++ b/README.md
@@ -76,6 +76,10 @@ lines of the form `option = value`.
 Lines starting with a semicolon are treated as comments and ignored. Inline comments
 are not currently supported.
 
+Configuration files may be included recursively in other configuration files using
+the syntax `[include <file>]`. This will read the referenced configuration file as
+if it were inserted at that point.
+
 Example configuration files may be found in [configs/](configs/).
 
 ### Backend and instance configuration
diff --git a/config.c b/config.c
index aef4f87..b5e0747 100644
--- a/config.c
+++ b/config.c
@@ -2,6 +2,11 @@
 #include <ctype.h>
 #include <unistd.h>
 #include <errno.h>
+#ifndef _WIN32
+#include <linux/limits.h>
+#endif
+
+#define BACKEND_NAME "core/cfg"
 #include "midimonster.h"
 #include "config.h"
 #include "backend.h"
@@ -349,6 +354,10 @@ static int config_line(char* line){
 				}
 			}
 		}
+		else if(!strncmp(line, "[include ", 9)){
+			line[strlen(line) - 1] = 0;
+			return config_read(line + 9);
+		}
 		else if(!strcmp(line, "[map]")){
 			//mapping configuration
 			parser_state = map;
@@ -493,7 +502,7 @@ int config_read(char* cfg_filepath){
 	char* line_raw = NULL;
 
 	//create heap copy of file name because original might be in readonly memory
-	char* source_dir = strdup(cfg_filepath), *source_file = NULL;
+	char* source_dir = strdup(cfg_filepath), *source_file = NULL, original_dir[PATH_MAX * 2] = "";
 	#ifdef _WIN32
 	char path_separator = '\\';
 	#else
@@ -510,6 +519,12 @@ int config_read(char* cfg_filepath){
 	if(source_file){
 		*source_file = 0;
 		source_file++;
+
+		if(!getcwd(original_dir, sizeof(original_dir))){
+			fprintf(stderr, "Failed to read current working directory: %s\n", strerror(errno));
+			goto bail;
+		}
+
 		if(chdir(source_dir)){
 			fprintf(stderr, "Failed to change to configuration file directory %s: %s\n", source_dir, strerror(errno));
 			goto bail;
@@ -519,10 +534,11 @@ int config_read(char* cfg_filepath){
 		source_file = source_dir;
 	}
 
+	fprintf(stderr, "Reading configuration file %s\n", cfg_filepath);
 	source = fopen(source_file, "r");
 
 	if(!source){
-		fprintf(stderr, "Failed to open configuration file for reading\n");
+		fprintf(stderr, "Failed to open %s for reading\n", cfg_filepath);
 		goto bail;
 	}
 
@@ -536,6 +552,11 @@ int config_read(char* cfg_filepath){
 
 	rv = 0;
 bail:
+	//change back to previous directory to allow recursive configuration file parsing
+	if(source_file && source_dir != source_file){
+		chdir(original_dir);
+	}
+
 	free(source_dir);
 	if(source){
 		fclose(source);
diff --git a/midimonster.c b/midimonster.c
index 8100607..1065e5c 100644
--- a/midimonster.c
+++ b/midimonster.c
@@ -482,7 +482,7 @@ int main(int argc, char** argv){
 
 	//read config
 	if(config_read(cfg_file)){
-		fprintf(stderr, "Failed to read configuration file %s\n", cfg_file);
+		fprintf(stderr, "Failed to parse master configuration file %s\n", cfg_file);
 		backends_stop();
 		routing_cleanup();
 		fds_free();
-- 
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