unifdef: use memcpy instead of strncpy

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@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[dongkyun.s: cherry-pick stable linux-4.9.y commit 37370fadd2da for gcc 9 build]

Change-Id: I2f005aa7c6642d76d818f1fda7722f345095b8a9

diff --git a/scripts/unifdef.c b/scripts/unifdef.c
index 7493c0e..db00e3e 100644 (file)
--- 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();  ignoreon(); }
 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); }