Add -e flag to enforce variables exist

1 files changed, 21 insertions, 3 deletions

diff --git a/tmpl.c b/tmpl.c
index 8e49c10..d12da8a 100644
--- a/tmpl.c
+++ b/tmpl.c
@@ -5,6 +5,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdarg.h>
+#include <stdbool.h>
 #include <stdlib.h>
 
 enum {
@@ -31,6 +32,8 @@ static struct block stack[32] = { 0 };
 static int stack_top = 0;
 static size_t lineno = 0;
 
+static bool fail_missing = false;
+
 static void
 die(const char *fmt, ...)
 {
@@ -53,6 +56,7 @@ die(const char *fmt, ...)
 static const char *
 getvar(const char *name)
 {
+	const char *env;
 	struct var *var;
 
 	for (var = vars; var; var = var->next) {
@@ -60,7 +64,11 @@ getvar(const char *name)
 			return var->value;
 	}
 
-	return getenv(name);
+	env = getenv(name);
+	if (!env && fail_missing)
+		die("not set: '%s'", name);
+
+	return env;
 }
 
 static void
@@ -208,12 +216,22 @@ int
 main(int argc, char **argv)
 {
 	const char *path;
-	char **arg;
+	char **arg, **dst;
 
 	if (!argc) return 1;
+
+	for (dst = arg = argv + 1; *arg; arg++) {
+		if (!strcmp(*arg, "-e")) {
+			fail_missing = true;
+		} else {
+			*dst++ = *arg;
+		}
+	}
+	*dst = NULL;
+
 	for (arg = argv + 1; *arg; arg++) {
 		if (!strcmp(*arg, "-h") || !strcmp(*arg, "--help")) {
-			fprintf(stderr, "Usage: tmpl [-c CONFIG].. "
+			fprintf(stderr, "Usage: tmpl [-e] [-c CONFIG].. "
 				"[-D NAME=VALUE].. FILE..\n");
 			return 1;
 		} else if (!strcmp(*arg, "-D") || !strcmp(*arg, "--define")) {