Emit better errors from config file parser

base.c

@@ -301,7 +301,7 @@ static int base_onexit(parser_section *section)
 	}
 
 	if (err)
-		parser_error(section->context, err);
+		parser_error(section->context, "%s", err);
 
 	if (!err)
 		instance.configured = 1;

log.c

@@ -23,7 +23,7 @@
 #include "utils.h"
 #include "log.h"
 
-static const char *lowmem = "<Can't print error, not enough memory>";
+const char *error_lowmem = "<Can't print error, not enough memory>";
 
 typedef void (*log_func)(const char *file, int line, const char *func, int priority, const char *message, const char *appendix);
 
@@ -159,7 +159,7 @@ void _log_vwrite(const char *file, int line, const char *func, int do_errno, int
 		message = (const char*)EVBUFFER_DATA(buff);
 	}
 	else
-		message = lowmem;
+		message = error_lowmem;
 
 	log_msg(file, line, func, priority, message, do_errno ? strerror(saved_errno) : NULL);
 

log.h

@@ -8,6 +8,8 @@
 #define log_errno(prio, msg...) _log_write(__FILE__, __LINE__, __func__, 1, prio, ## msg)
 #define log_error(prio, msg...) _log_write(__FILE__, __LINE__, __func__, 0, prio, ## msg)
 
+extern const char *error_lowmem;
+
 int log_preopen(const char *dst, bool log_debug, bool log_info);
 void log_open();
 

main.c

@@ -100,7 +100,7 @@ int main(int argc, char **argv)
 		return EXIT_FAILURE;
 	}
 
-	parser_context* parser = parser_start(f, NULL);
+	parser_context* parser = parser_start(f);
 	if (!parser) {
 		perror("Not enough memory for parser");
 		return EXIT_FAILURE;

parser.c

@@ -38,7 +38,6 @@ struct parser_context_t {
 	parser_section *sections;
 	int line;
 	int error;
-	parser_errhandler errhandler;
 	struct {
 		size_t size;
 		size_t filled;
@@ -47,22 +46,33 @@ struct parser_context_t {
 };
 
 
-void parser_error(parser_context *context, const char *msg)
+void parser_error(parser_context *context, const char *fmt, ...)
 {
-	context->error = 1;
-	if (context->errhandler)
-		context->errhandler(msg, context->line);
+	va_list ap;
+	struct evbuffer *buff = evbuffer_new();
+	const char *msg;
+
+	va_start(ap, fmt);
+	if (buff) {
+		evbuffer_add_vprintf(buff, fmt, ap);
+		msg = (const char*)EVBUFFER_DATA(buff);
+	}
 	else
+		msg = error_lowmem;
+	va_end(ap);
+
+	context->error = 1;
 	fprintf(stderr, "file parsing error at line %u: %s\n", context->line, msg);
+	if (buff)
+		evbuffer_free(buff);
 }
 
-parser_context* parser_start(FILE *fd, parser_errhandler errhandler)
+parser_context* parser_start(FILE *fd)
 {
 	parser_context *ret = calloc(1, sizeof(parser_context));
 	if (!ret)
 		return NULL;
 	ret->fd = fd;
-	ret->errhandler = errhandler;
 	ret->buffer.size = 128; // should be big enough to fetch whole ``line``
 	ret->buffer.data = malloc(ret->buffer.size);
 	if (!ret->buffer.data) {
@@ -322,9 +332,9 @@ static int vp_in_addr(parser_context *context, void *addr, const char *token)
 		}
 		else {
 			if (err == EAI_SYSTEM)
-				parser_error(context, strerror(errno));
+				parser_error(context, "unable to resolve %s, error %d (%s)", token, errno, strerror(errno));
 			else
-				parser_error(context, gai_strerror(err));
+				parser_error(context, "unable to resolve %s, getaddrinfo error %d (%s)", token, err, gai_strerror(err));
 			return -1;
 		}
 	}
@@ -533,7 +543,7 @@ int parser_run(parser_context *context)
 							parser_error(context, "value can't be parsed");
 					}
 					else {
-						parser_error(context, "assignment with unknown key");
+						parser_error(context, "assignment with unknown key <%s>", key_token);
 					}
 				}
 				else {

parser.h

@@ -38,12 +38,14 @@ struct parser_section_t {
 
 
 
-typedef void (*parser_errhandler)(const char *errmsg, int line);
-
-parser_context* parser_start(FILE *fd, parser_errhandler errhandler);
+parser_context* parser_start(FILE *fd);
 void parser_add_section(parser_context *context, parser_section *section);
 int parser_run(parser_context *context);
-void parser_error(parser_context *context, const char *msg);
+void parser_error(parser_context *context, const char *fmt, ...)
+#if defined(__GNUC__)
+	__attribute__ (( format (printf, 2, 3) ))
+#endif
+;
 void parser_stop(parser_context *context);
 
 /* vim:set tabstop=4 softtabstop=4 shiftwidth=4: */

redsocks.c

@@ -187,7 +187,7 @@ static int redsocks_onexit(parser_section *section)
 	}
 
 	if (err)
-		parser_error(section->context, err);
+		parser_error(section->context, "%s", err);
 
 	return err ? -1 : 0;
 }