[PATCH 4.4 25/91] unifdef: use memcpy instead of strncpy

From: Greg Kroah-Hartman
Date: Tue Dec 11 2018 - 11:19:50 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

commit 38c7b224ce22c25fed04007839edf974bd13439d upstream.

New versions of gcc reasonably warn about the odd pattern of

strncpy(p, q, strlen(q));

which really doesn't make sense: the strncpy() ends up being just a slow
and odd way to write memcpy() in this case.

There was a comment about _why_ the code used strncpy - to avoid the
terminating NUL byte, but memcpy does the same and avoids the warning.

Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

scripts/unifdef.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/scripts/unifdef.c
+++ b/scripts/unifdef.c
@@ -395,7 +395,7 @@ usage(void)
* When we have processed a group that starts off with a known-false
* #if/#elif sequence (which has therefore been deleted) followed by a
* #elif that we don't understand and therefore must keep, we edit the
- * latter into a #if to keep the nesting correct. We use strncpy() to
+ * latter into a #if to keep the nesting correct. We use memcpy() to
* overwrite the 4 byte token "elif" with "if " without a '\0' byte.
* When we find a true #elif in a group, the following block will
@@ -450,7 +450,7 @@ static void Idrop (void) { Fdrop(); ign
static void Itrue (void) { Ftrue(); ignoreon(); }
static void Ifalse(void) { Ffalse(); ignoreon(); }
/* modify this line */
-static void Mpass (void) { strncpy(keyword, "if ", 4); Pelif(); }
+static void Mpass (void) { memcpy(keyword, "if ", 4); Pelif(); }
static void Mtrue (void) { keywordedit("else"); state(IS_TRUE_MIDDLE); }
static void Melif (void) { keywordedit("endif"); state(IS_FALSE_TRAILER); }
static void Melse (void) { keywordedit("endif"); state(IS_FALSE_ELSE); }