[Pkg-shadow-devel] Bug#1032393: Bug#1032393: [PATCH v2 2/2] debian/control: Add libbsd-dev and pkg-config

[Alejandro Colomar]

Hi Paul,

On 3/12/23 02:44, Paul Eggert wrote:
> From 54fac7560f87a134c4d3045ce7048f4819c4e492 Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert at cs.ucla.edu>
> Date: Sat, 11 Mar 2023 00:38:24 -0800
> Subject: [PATCH 5/8] Avoid silent truncation of console file data
> 
> * libmisc/console.c (is_listed): Rework so that there is no
> fixed-size buffer, and no need to use fgets or strlcpy or strtok.
> Instead, the code works with arbitrary-sized input,
> without silently truncating data or mishandling NUL
> bytes in the console file.
> 
> Signed-off-by: Paul Eggert <eggert at cs.ucla.edu>
> ---
>  libmisc/console.c | 41 ++++++++++++++++++++---------------------
>  1 file changed, 20 insertions(+), 21 deletions(-)
> 
> diff --git a/libmisc/console.c b/libmisc/console.c
> index 7e2132dd..8264e1a3 100644
> --- a/libmisc/console.c
> +++ b/libmisc/console.c
> @@ -24,7 +24,6 @@
>  static bool is_listed (const char *cfgin, const char *tty, bool def)
>  {
>  	FILE *fp;
> -	char buf[1024], *s;
>  	const char *cons;
>  
>  	/*
> @@ -43,17 +42,17 @@ static bool is_listed (const char *cfgin, const char *tty, bool def)
>  	 */
>  
>  	if (*cons != '/') {
> -		char *pbuf;
> -		strlcpy (buf, cons, sizeof (buf));
> -		pbuf = &buf[0];
> -		while ((s = strtok (pbuf, ":")) != NULL) {
> -			if (strcmp (s, tty) == 0) {
> +		size_t ttylen = strlen (tty);

Please separate the initialization from the declaration, and
leave a blank line in between.

> +		for (;;) {
> +			if (strncmp (cons, tty, ttylen) == 0
> +			    && (cons[ttylen] == ':' || !cons[ttylen])) {
>  				return true;
>  			}
> -
> -			pbuf = NULL;
> +			cons = strchr (cons, ':');
> +			if (!cons)
> +				return false;
> +			cons++;
>  		}
> -		return false;
>  	}
>  
>  	/*
> @@ -70,21 +69,22 @@ static bool is_listed (const char *cfgin, const char *tty, bool def)
>  	 * See if this tty is listed in the console file.
>  	 */
>  
> -	while (fgets (buf, sizeof (buf), fp) != NULL) {
> -		/* Remove optional trailing '\n'. */
> -		buf[strcspn (buf, "\n")] = '\0';
> -		if (strcmp (buf, tty) == 0) {
> -			(void) fclose (fp);
> -			return true;
> +	const char *tp = tty;
> +	bool listed = false;

Please -Wdeclaration-after-statement.  If the declaration is
so far that it helps mix declarations with code, it may be the
time to split something into a helper function...

Cheers,

Alex

> +	for (int c; 0 <= (c = getc (fp)); ) {
> +		if (c == '\n') {
> +			if (tp && !*tp) {
> +				listed = true;
> +				break;
> +			}
> +			tp = tty;
> +		} else if (tp) {
> +			tp = *tp == c && c ? tp + 1 : NULL;
>  		}
>  	}
>  
> -	/*
> -	 * This tty isn't a console.
> -	 */
> -
>  	(void) fclose (fp);
> -	return false;
> +	return listed;
>  }
>  
>  /*
> @@ -105,4 +105,3 @@ bool console (const char *tty)
>  
>  	return is_listed ("CONSOLE", tty, true);
>  }
> -
> -- 
> 2.37.2
> 


-- 
<http://www.alejandro-colomar.es/>
GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
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