From 2cd73a33c26ea6510a2f50359b1c550cd9b4fead Mon Sep 17 00:00:00 2001 From: Sergei Trofimovich Date: Tue, 28 Nov 2023 22:17:21 +0000 Subject: [PATCH] sway/config.c: use `memcpy()` for known buffer size `gcc-14` added a new warning around dangerous use of `strncpy()` withi known overflow: ../sway/config.c: In function 'do_var_replacement': ../sway/config.c:983:33: error: '__builtin___strncpy_chk' specified bound depends on the length of the source argument [-Werror=stringop-truncation] 983 | strncpy(newptr, var->value, vvlen); | ^ ../sway/config.c:971:45: note: length computed here 971 | int vvlen = strlen(var->value); | ^~~~~~~~~~~~~~~~~~ It's a bit fishy to rely on truncating behaviour of `strncpy()`. The change uses `memcpy()` as more explicit way to express copy of `vvlen` bytes. --- sway/config.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sway/config.c b/sway/config.c index 8c8c148d..4b51dc73 100644 --- a/sway/config.c +++ b/sway/config.c @@ -975,7 +975,7 @@ char *do_var_replacement(char *str) { int offset = find - str; strncpy(newptr, str, offset); newptr += offset; - strncpy(newptr, var->value, vvlen); + memcpy(newptr, var->value, vvlen); newptr += vvlen; strcpy(newptr, find + vnlen); free(str);