From: "Jonathan Armani" <jonathan@armani.tech>
Subject: Re: libsndio: simplify cookie handling
To: "Alexandre Ratchov" <alex@caoua.org>, tech@openbsd.org
Date: Sat, 14 Mar 2026 15:27:57 +0100


ok

On Fri, Mar 13, 2026, at 12:08, Alexandre Ratchov wrote:
> Simple asnprintf(3) calls can replace the "clever" malloc(3) and
> memcpy(3) calls that are much harder to review imo.
>
> OK?
>
> Index: aucat.c
> ===================================================================
> RCS file: /cvs/src/lib/libsndio/aucat.c,v
> diff -u -p -r1.81 aucat.c
> --- aucat.c	12 Mar 2026 15:35:24 -0000	1.81
> +++ aucat.c	13 Mar 2026 11:03:35 -0000
> @@ -204,30 +204,20 @@ _aucat_wdata(struct aucat *hdl, const vo
>  static int
>  aucat_mkcookie(unsigned char *cookie)
>  {
> -#define COOKIE_DIR	"/.sndio"
> -#define COOKIE_SUFFIX	"/.sndio/cookie"
> -#define TEMPL_SUFFIX	".XXXXXXXX"
>  	struct stat sb;
> -	char *home, *path = NULL, *tmp = NULL;
> -	size_t home_len, path_len;
> +	char *home, *dir = NULL, *path = NULL, *tmp = NULL;
>  	int fd, len;
> 
> -	/* please gcc */
> -	path_len = 0xdeadbeef;
> -
>  	/*
>  	 * try to load the cookie
>  	 */
>  	home = issetugid() ? NULL : getenv("HOME");
>  	if (home == NULL)
>  		goto bad_gen;
> -	home_len = strlen(home);
> -	path = malloc(home_len + sizeof(COOKIE_SUFFIX));
> -	if (path == NULL)
> +	if (asprintf(&dir, "%s/.sndio", home) == -1)
> +		goto bad_gen;
> +	if (asprintf(&path, "%s/cookie", dir) == -1)
>  		goto bad_gen;
> -	memcpy(path, home, home_len);
> -	memcpy(path + home_len, COOKIE_SUFFIX, sizeof(COOKIE_SUFFIX));
> -	path_len = home_len + sizeof(COOKIE_SUFFIX) - 1;
>  	fd = open(path, O_RDONLY|O_CLOEXEC);
>  	if (fd == -1) {
>  		if (errno != ENOENT)
> @@ -265,21 +255,12 @@ bad_gen:
>  	 * try to save the cookie
>  	 */
> 
> -	if (home == NULL)
> +	if (path == NULL)
>  		goto done;
> -	tmp = malloc(path_len + sizeof(TEMPL_SUFFIX));
> -	if (tmp == NULL)
> +	if (mkdir(dir, 0755) == -1 && errno != EEXIST)
>  		goto done;
> -
> -	/* create ~/.sndio directory */
> -	memcpy(tmp, home, home_len);
> -	memcpy(tmp + home_len, COOKIE_DIR, sizeof(COOKIE_DIR));
> -	if (mkdir(tmp, 0755) == -1 && errno != EEXIST)
> +	if (asprintf(&tmp, "%s.XXXXXXXX", path) == -1)
>  		goto done;
> -
> -	/* create cookie file in it */
> -	memcpy(tmp, path, path_len);
> -	memcpy(tmp + path_len, TEMPL_SUFFIX, sizeof(TEMPL_SUFFIX));
>  	fd = mkstemp(tmp);
>  	if (fd == -1) {
>  		DPERROR(tmp);
> @@ -299,6 +280,7 @@ bad_gen:
>  done:
>  	free(tmp);
>  	free(path);
> +	free(dir);
>  	return 1;
>  }