+static void open_file_on_demand(const char *file, FILE **fp_inout,
+ const char *what)
+{
+ FILE *fp;
+
+ if (!*fp_inout) {
+ fp = fopen(file, "w");
+ if (!fp)
+ bail_syserr(errno, "failed to open %s file `%s'", what, file);
+ fprintf(fp, "## %s\n\n", what);
+ *fp_inout = fp;
+ }
+}
+
+static void check_write(FILE *fp, const char *what)
+{
+ fflush(fp);
+ if (ferror(fp)) bail_syserr(errno, "error writing %s file", what);
+}
+
+static void carefully_fclose(FILE *fp, const char *what)
+{
+ if (fp && (ferror(fp) || fclose(fp)))
+ bail_syserr(errno, "error writing %s file", what);
+}
+