Exception strings include msg from type and custom msg

src/exception_t.c

@@ -1,4 +1,7 @@
 #include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
 
 #include "exception_t.h"
 
@@ -6,12 +9,13 @@ exception_t*
 exception_init() {
   exception_t *e = (exception_t*) malloc(sizeof(exception_t));
   e->type = NO_ERROR;
-  e->msg = NULL;
+  e->msg = malloc(CHAR_MAX);
   return e;
 }
 
 void
 exception_free(exception_t *e) {
+  free(e->msg);
   free(e);
 }
 
@@ -19,3 +23,22 @@ int
 exception_null(const exception_t *e) {
   return e->type == NO_ERROR;
 }
+
+char*
+exception_prestr(const exception_t *e) {
+  switch(e->type) {
+  case NO_ERROR: return "No error\n";
+  case NO_FILE: return "No file found";
+  case XML_FILE_MISSING: return "XML file missing";
+  case XML_READ_FILE_FAIL: return "XML file reading failed";
+  case MD5SUM_GEN_FAIL: return "MD5sum generation failed";
+  case MD5SUM_VERIFY_FAIL: return "MD5sum verification failed";
+  }
+}
+
+char*
+exception_str(const exception_t *e, char* msg) {
+  if (e->type != NO_ERROR) sprintf(msg, "%s: %s\n", exception_prestr(e), e->msg);
+  else sprintf(msg, "%s\n", exception_prestr(e));
+  return msg;
+}

src/exception_t.h

@@ -25,6 +25,6 @@ int
 exception_null(const exception_t *e);
 
 char*
-exception_str(exception_t *e);
+exception_str(const exception_t *e, char* msg);
 
 #endif