From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kMsRU-0004Wo-Nf for barebox@lists.infradead.org; Mon, 28 Sep 2020 12:39:46 +0000 From: Ahmad Fatoum Date: Mon, 28 Sep 2020 14:39:42 +0200 Message-Id: <20200928123942.26970-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH] readkey: shrink table of known escape sequences in size To: barebox@lists.infradead.org Cc: Ahmad Fatoum Instead of storing pointers to 4-byte strings, we could just store the characters directly in the struct. Can save us up to 18 pointers worth of space. We could save 18 x 1 byte more of static storage by making the strings 3 bytes of length as the nul byte need not be stored explicitly for strings of maximal length. For clarity, this optimization is omitted for now. We still use strncmp, instead of strcmp use runs risk of accidental out of bounds reads when longer escape sequences are added. This can't occur with strncmp. Signed-off-by: Ahmad Fatoum --- v1 -> v2: - Maintain a nul delimiter always at the cost of 18 more bytes (Sascha) --- lib/readkey.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/lib/readkey.c b/lib/readkey.c index c26e9d51aba9..6a4ddf14a99d 100644 --- a/lib/readkey.c +++ b/lib/readkey.c @@ -20,8 +20,10 @@ #include #include +#define MAX_ESC_LEN 4 + struct esc_cmds { - const char *seq; + const char seq[MAX_ESC_LEN]; unsigned char val; }; @@ -49,7 +51,7 @@ static const struct esc_cmds esccmds[] = { int read_key(void) { unsigned char c; - unsigned char esc[5]; + unsigned char esc[MAX_ESC_LEN + 2]; c = getchar(); if (c == 27) { @@ -67,7 +69,7 @@ int read_key(void) } esc[i] = 0; for (i = 0; i < ARRAY_SIZE(esccmds); i++){ - if (!strcmp(esc, esccmds[i].seq)) + if (!strncmp(esc, esccmds[i].seq, MAX_ESC_LEN)) return esccmds[i].val; } return -1; -- 2.28.0 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox