[RFC PATCH 10/28] cli: lil: Add printf-style format helper for errors

[Sean Anderson]

This adds a helper for dynamically-created error messages.

Signed-off-by: Sean Anderson <seanga2 at gmail.com>
---

 common/cli_lil.c | 43 ++++++++++++++++++++++++++++++++-----------
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/common/cli_lil.c b/common/cli_lil.c
index 1bdf0e5265..f29c8065d8 100644
--- a/common/cli_lil.c
+++ b/common/cli_lil.c
@@ -113,6 +113,9 @@ struct expreval {
 static struct lil_value *next_word(struct lil *lil);
 static void register_stdcmds(struct lil *lil);
 static void lil_set_error(struct lil *lil, enum lil_error err, const char *msg);
+static void lil_set_errorf(struct lil *lil, enum lil_error err,
+			   const char *fmt, ...)
+	__attribute((format(__printf__, 3, 4)));
 
 #ifdef LIL_ENABLE_POOLS
 static struct lil_value **pool;
@@ -1121,12 +1124,9 @@ struct lil_value *lil_parse(struct lil *lil, const char *code, size_t codelen,
 
 			if (!cmd) {
 				if (words->v[0]->l) {
-					char msg[64];
-
-					snprintf(msg, sizeof(msg),
-						 "unknown function %s",
-						 words->v[0]->d);
-					lil_set_error(lil, LIL_ERR_NOCMD, msg);
+					lil_set_errorf(lil, LIL_ERR_NOCMD,
+						       "unknown function %s",
+						       words->v[0]->d);
 					goto cleanup;
 				}
 			} else {
@@ -1180,6 +1180,30 @@ static void lil_set_error(struct lil *lil, enum lil_error err, const char *msg)
 	lil->err_msg = strdup(msg);
 }
 
+static void lil_set_errorf(struct lil *lil, enum lil_error err,
+			   const char *fmt, ...)
+{
+	va_list args, saveargs;
+	size_t n;
+
+	assert(!lil->err);
+	free(lil->err_msg);
+	lil->err = err;
+
+	va_start(args, fmt);
+	va_copy(saveargs, args);
+	n = vsnprintf(NULL, 0, fmt, args) + 1;
+	va_end(args);
+
+	lil->err_msg = calloc(1, n);
+	if (!lil->err_msg) {
+		lil->err = LIL_ERR_OOM;
+		return;
+	}
+	vsnprintf(lil->err_msg, n, fmt, saveargs);
+	va_end(saveargs);
+}
+
 enum lil_error lil_error(struct lil *lil, const char **msg)
 {
 	enum lil_error err = lil->err;
@@ -1968,11 +1992,8 @@ static struct lil_value *fnc_rename(struct lil *lil, size_t argc,
 	newname = lil_to_string(argv[1]);
 	func = lil_find_cmd(lil, oldname);
 	if (!func) {
-		char *msg = malloc(24 + strlen(oldname));
-
-		sprintf(msg, "unknown function '%s'", oldname);
-		lil_set_error(lil, LIL_ERR_NOCMD, msg);
-		free(msg);
+		lil_set_errorf(lil, LIL_ERR_NOCMD, "unknown function %s",
+			       oldname);
 		return NULL;
 	}
 
-- 
2.32.0