tools/configurator: support --header-file if we don't want to write to stdout.

Works well with --autotools-style.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tools/configurator/configurator.c

@@ -703,6 +703,8 @@ int main(int argc, const char *argv[])
 	const char *configurator_cc = NULL;
 	const char *orig_cc;
 	const char *varfile = NULL;
+	const char *headerfile = NULL;
+	FILE *outf;
 
 	if (argc > 0)
 		progname = argv[0];
@@ -746,6 +748,10 @@ int main(int argc, const char *argv[])
 			like_a_libtool = true;
 			argc--;
 			argv++;
+		} else if (strncmp(argv[1], "--header-file=", 14) == 0) {
+			headerfile = argv[1] + 14;
+			argc--;
+			argv++;
 		} else {
 			break;
 		}
@@ -791,21 +797,36 @@ int main(int argc, const char *argv[])
 		}
 	}
 
-	printf("/* Generated by CCAN configurator */\n"
+	if (headerfile) {
+		start_test("Writing header to ", headerfile);
+		outf = fopen(headerfile, "w");
+		if (!outf)
+			c12r_err(2, "Could not open %s", headerfile);
+	} else
+		outf = stdout;
+
+	fprintf(outf, "/* Generated by CCAN configurator */\n"
 	       "#ifndef CCAN_CONFIG_H\n"
 	       "#define CCAN_CONFIG_H\n");
-	printf("#ifndef _GNU_SOURCE\n");
-	printf("#define _GNU_SOURCE /* Always use GNU extensions. */\n");
-	printf("#endif\n");
-	printf("#define CCAN_COMPILER \"%s\"\n", orig_cc);
+	fprintf(outf, "#ifndef _GNU_SOURCE\n");
+	fprintf(outf, "#define _GNU_SOURCE /* Always use GNU extensions. */\n");
+	fprintf(outf, "#endif\n");
+	fprintf(outf, "#define CCAN_COMPILER \"%s\"\n", orig_cc);
 	cmd = connect_args(argv + 1, "", "");
-	printf("#define CCAN_CFLAGS \"%s\"\n", cmd);
+	fprintf(outf, "#define CCAN_CFLAGS \"%s\"\n", cmd);
 	free(cmd);
-	printf("#define CCAN_OUTPUT_EXE_CFLAG \"%s\"\n\n", outflag);
+	fprintf(outf, "#define CCAN_OUTPUT_EXE_CFLAG \"%s\"\n\n", outflag);
 	/* This one implies "#include <ccan/..." works, eg. for tdb2.h */
-	printf("#define HAVE_CCAN 1\n");
+	fprintf(outf, "#define HAVE_CCAN 1\n");
 	for (i = 0; i < sizeof(tests)/sizeof(tests[0]); i++)
-		printf("#define %s %u\n", tests[i].name, tests[i].answer);
-	printf("#endif /* CCAN_CONFIG_H */\n");
+		fprintf(outf, "#define %s %u\n", tests[i].name, tests[i].answer);
+	fprintf(outf, "#endif /* CCAN_CONFIG_H */\n");
+
+	if (headerfile) {
+		if (fclose(outf) != 0)
+			c12r_err(2, "Closing %s", headerfile);
+		end_test(1);
+	}
+
 	return 0;
 }