From 5d4cf4d445b2829deac9c755f65c98151eabc157 Mon Sep 17 00:00:00 2001
From: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Date: Wed, 1 Jun 2022 14:11:27 +0200
Subject: gprs: ipc_gprs_define_pdp_context_setup: fix truncated string

Without that fix, when compiling libsamsung-ipc with
--enable-strict-cflags, we have the following error:

    gprs.c: In function 'ipc_gprs_define_pdp_context_setup':
    gprs.c:38:9: error:
    'strncpy' specified bound 124 equals destination size
    [-Werror=stringop-truncation]
       38 |         strncpy((char *) data->apn, apn, sizeof(data->apn));
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It comes from the fact that the size of data->apn is fixed (to 124) in
include/gprs.h:
    struct ipc_gprs_define_pdp_context_data {
            unsigned char enable;
            unsigned char cid;
            unsigned char magic;
            unsigned char apn[124];
    } __attribute__((__packed__));

The issue is that in ipc_gprs_define_pdp_context_setup we had the
following code:
    int ipc_gprs_define_pdp_context_setup(
    	struct ipc_gprs_define_pdp_context_data *data,
	unsigned char enable,
    	unsigned char cid,
	const char *apn)
    {
        [...]
        strncpy((char *) data->apn, apn, sizeof(data->apn));
        [...]
	return 0;
    }

And in the strcpy(3) manual we have:
    The strncpy() function is similar, except that at most n bytes of
    src are copied.  Warning: If there is no null byte among the first
    n bytes of src, the string placed in dest will not be
    null-terminated.

So if we have an apn of 124 or more characters, the copied data will
not be null terminated hence the warning.

Since apn is a character array and not a string, and that the field is
padded with zeros anyway we can use memcpy instead.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
---
 samsung-ipc/gprs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/samsung-ipc/gprs.c b/samsung-ipc/gprs.c
index 89f06e7..64d94f9 100644
--- a/samsung-ipc/gprs.c
+++ b/samsung-ipc/gprs.c
@@ -35,7 +35,7 @@ int ipc_gprs_define_pdp_context_setup(
 	data->cid = cid;
 	data->magic = 0x02;
 
-	strncpy((char *) data->apn, apn, sizeof(data->apn));
+	memcpy(data->apn, apn, sizeof(data->apn));
 
 	return 0;
 }
-- 
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