[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 <sean...@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