tools/configurator: support --var-file for outputting VAR=VAL format.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tools/configurator/configurator.c

@@ -684,13 +684,14 @@ int main(int argc, const char *argv[])
 	const char *outflag = DEFAULT_OUTPUT_EXE_FLAG;
 	const char *configurator_cc = NULL;
 	const char *orig_cc;
+	const char *varfile = NULL;
 
 	if (argc > 0)
 		progname = argv[0];
 
 	while (argc > 1) {
 		if (strcmp(argv[1], "--help") == 0) {
-			printf("Usage: configurator [-v] [-O<outflag>] [--configurator-cc=<compiler-for-tests>] [<compiler> <flags>...]\n"
+			printf("Usage: configurator [-v] [--var-file=<filename>] [-O<outflag>] [--configurator-cc=<compiler-for-tests>] [<compiler> <flags>...]\n"
 			       "  <compiler> <flags> will have \"<outflag> <outfile> <infile.c>\" appended\n"
 			       "Default: %s %s %s\n",
 			       DEFAULT_COMPILER, DEFAULT_FLAGS,
@@ -719,6 +720,10 @@ int main(int argc, const char *argv[])
 			configurator_cc = argv[1] + 18;
 			argc--;
 			argv++;
+		} else if (strncmp(argv[1], "--var-file=", 11) == 0) {
+			varfile = argv[1] + 11;
+			argc--;
+			argv++;
 		} else {
 			break;
 		}
@@ -739,6 +744,24 @@ int main(int argc, const char *argv[])
 	remove(OUTPUT_FILE);
 	remove(INPUT_FILE);
 
+	if (varfile) {
+		FILE *vars;
+
+		if (strcmp(varfile, "-") == 0)
+			vars = stdout;
+		else {
+			vars = fopen(varfile, "a");
+			if (!vars)
+				c12r_err(2, "Could not open %s", varfile);
+		}
+		for (i = 0; i < sizeof(tests)/sizeof(tests[0]); i++)
+			fprintf(vars, "%s=%u\n", tests[i].name, tests[i].answer);
+		if (vars != stdout) {
+			if (fclose(vars) != 0)
+				c12r_err(2, "Closing %s", varfile);
+		}
+	}
+
 	printf("/* Generated by CCAN configurator */\n"
 	       "#ifndef CCAN_CONFIG_H\n"
 	       "#define CCAN_CONFIG_H\n");