[PATCH] mtd: sm_ftl: Replace deprecated strncpy with sysfs_emit in sm_attr_show

[PATCH] mtd: sm_ftl: Replace deprecated strncpy with sysfs_emit in sm_attr_show

[Thorsten Blum]

strncpy() is deprecated [1] for NUL-terminated destination buffers
because it does not guarantee NUL termination. It also unnecessarily
NUL-pads the destination buffer if the source is shorter. Replace it
with sysfs_emit() using the "%.*s" format specifier and supply the
length 'sm_attr->len' to improve sm_attr_show().

Return the number of characters actually written to 'buf' instead of
'sm_attr->len'.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 drivers/mtd/sm_ftl.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mtd/sm_ftl.c b/drivers/mtd/sm_ftl.c
index abc7b186353f..987d481bf265 100644
--- a/drivers/mtd/sm_ftl.c
+++ b/drivers/mtd/sm_ftl.c
@@ -44,8 +44,7 @@ static ssize_t sm_attr_show(struct device *dev, struct device_attribute *attr,
 	struct sm_sysfs_attribute *sm_attr =
 		container_of(attr, struct sm_sysfs_attribute, dev_attr);
 
-	strncpy(buf, sm_attr->data, sm_attr->len);
-	return sm_attr->len;
+	return sysfs_emit(buf, "%.*s", sm_attr->len, sm_attr->data);
 }
 
 
-- 
2.51.1


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Re: [PATCH] mtd: sm_ftl: Replace deprecated strncpy with sysfs_emit in sm_attr_show

[Miquel Raynal]

On Sun, 23 Nov 2025 19:21:02 +0100, Thorsten Blum wrote:
> strncpy() is deprecated [1] for NUL-terminated destination buffers
> because it does not guarantee NUL termination. It also unnecessarily
> NUL-pads the destination buffer if the source is shorter. Replace it
> with sysfs_emit() using the "%.*s" format specifier and supply the
> length 'sm_attr->len' to improve sm_attr_show().
> 
> Return the number of characters actually written to 'buf' instead of
> 'sm_attr->len'.
> 
> [...]

Applied to mtd/next, thanks!

[1/1] mtd: sm_ftl: Replace deprecated strncpy with sysfs_emit in sm_attr_show
      commit: f3dc4d9898bc98e3cf569f038d90a5fec7bfc44a

Patche(s) should be available on mtd/linux.git and will be
part of the next PR (provided that no robot complains by then).

Kind regards,
Miquèl


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