mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Julia Lawall <julia@diku.dk>
To: al@alarsen.net, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org
Subject: [PATCH 4/4] fs/qnx4: decrement sizeof size in strncmp
Date: Thu, 12 Nov 2009 08:49:44 +0100 (CET)	[thread overview]
Message-ID: <Pine.LNX.4.64.0911120849260.16627@ask.diku.dk> (raw)

From: Julia Lawall <julia@diku.dk>

As observed by Joe Perches, sizeof of a constant string includes the
trailing 0.  If what is wanted is to check the initial characters of
another string, this trailing 0 should not be taken into account.  If an
exact match is wanted, strcmp should be used instead.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression foo;
constant char *abc;
@@

strncmp(foo, abc, 
- sizeof(abc)
+ sizeof(abc)-1
 )
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 fs/qnx4/inode.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/qnx4/inode.c b/fs/qnx4/inode.c
index 449f5a6..0614b00 100644
--- a/fs/qnx4/inode.c
+++ b/fs/qnx4/inode.c
@@ -221,7 +221,9 @@ static const char *qnx4_checkroot(struct super_block *sb)
 				rootdir = (struct qnx4_inode_entry *) (bh->b_data + i * QNX4_DIR_ENTRY_SIZE);
 				if (rootdir->di_fname != NULL) {
 					QNX4DEBUG((KERN_INFO "rootdir entry found : [%s]\n", rootdir->di_fname));
-					if (!strncmp(rootdir->di_fname, QNX4_BMNAME, sizeof QNX4_BMNAME)) {
+					if (!strncmp(rootdir->di_fname,
+						     QNX4_BMNAME,
+						     sizeof QNX4_BMNAME - 1)) {
 						found = 1;
 						qnx4_sb(sb)->BitMap = kmalloc( sizeof( struct qnx4_inode_entry ), GFP_KERNEL );
 						if (!qnx4_sb(sb)->BitMap) {

             reply	other threads:[~2009-11-12  7:49 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-12  7:49 Julia Lawall [this message]
2009-11-12  9:25 ` Anders Larsen
2009-11-12 10:05   ` Julia Lawall
2009-11-12 10:14   ` Julia Lawall
2009-11-12 10:22 ` sizeof vs strlen (was Re: [PATCH 4/4] fs/qnx4: decrement sizeof size in strncmp) Bernd Petrovitsch
2009-11-12 10:37   ` Julia Lawall
2009-11-12 15:33   ` Julia Lawall
2009-11-13 16:42     ` Bernd Petrovitsch
2009-11-12 23:49 ` [PATCH 4/4] fs/qnx4: decrement sizeof size in strncmp David Wagner
2009-11-13  0:06   ` Joe Perches
2009-11-12 22:08 Anders Larsen
2009-12-18 14:26 ` Jiri Kosina

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=Pine.LNX.4.64.0911120849260.16627@ask.diku.dk \
    --to=julia@diku.dk \
    --cc=al@alarsen.net \
    --cc=kernel-janitors@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®