improves error output in routine xfopen

src/core/xstdio.c

@@ -51,8 +51,15 @@ SymPrefix(xfopen)(const char *path, const char *mode,
                   const char *source, int line)
 {
   FILE *fp;
-  if ((fp = fopen(path, mode)) == NULL)
-    SymPrefix(abort)(SymPrefix(default_comm), strerror(errno), source, line);
+  if ((fp = fopen(path, mode)) == NULL) {
+    char const format_string[] = "%s (path: \"%s\")";
+    char const * err_string = strerror(errno);
+    char * error_buffer =
+      xmalloc(strlen(format_string) + strlen(err_string) + strlen(path));
+    sprintf(error_buffer, "xfopen: %s (path: \"%s\")", err_string, path);
+    SymPrefix(abort)(SymPrefix(default_comm), error_buffer, source, line);
+    free(error_buffer);
+  }
   return fp;
 }