[PATCH] more Libsysfs updates

On Thu, Mar 11, 2004 at 02:36:23PM +0100, Kay Sievers wrote:
> On Thu, 2004-03-11 at 15:02, Ananth N Mavinakayanahalli wrote:
> > On Thu, Mar 11, 2004 at 02:04:36PM +0100, Kay Sievers wrote:
> > > On Thu, Mar 11, 2004 at 11:53:50AM +0500, Ananth N Mavinakayanahalli wrote:
> > >
> > > > +#define safestrcpy(to, from)	strncpy(to, from, sizeof(to)-1)
> > > > +#define safestrcat(to, from)	strncat(to, from, sizeof(to) - strlen(to)-1)
> > >
> > > These strings are not terminated with '\0' if from is longer than
> > > the sizeof to.
> >
> > Did not do it on purpose as the "to" elements are either calloc'd or memset to
> > '0' explicitly in the library. Thats the reason I mentioned "scaled down" :)
>
> Ahh, sounds good.
>
> > > > +#define safestrncpy(to, from, maxsize) \
> > > > +do { \
> > > > +	to[maxsize-1] = '\0'; \
> > > > +	strncpy(to, from, maxsize-1); \
> > > > +} while (0)
> > > > +
> > > > +#define safestrncat(to, from, maxsize) \
> > > > +do { \
> > > > +	to[maxsize-1] = '\0'; \
> > > > +	strncat(to, from, maxsize - strlen(to)-1); \
> > > > +} while (0)
> > >
> > > We all expect a similar behavior like strncat/strncpy according to the
> > > names, but these macros are limiting by the target size and do not limit
> > > the count of chars copied.
> > > This is confusing I think and suggest using a different name like
> > > 'safestrcopymax()' or something.
> >
> > Good point.. will make the change
>
> Nice. I've had these *n* names too and I forgot about the logic and only
> 10 days later I introduced a ugly bug cause I can't limit the count of
> copied chars :)

Inlined is the patch for this... applies on the earlier _BIG_ patch.

1 files changed, 8 insertions, 8 deletions

diff --git a/libsysfs/sysfs_class.c b/libsysfs/sysfs_class.c
index 7a696355ca..59ef0be48e 100644
--- a/libsysfs/sysfs_class.c
+++ b/libsysfs/sysfs_class.c
@@ -509,16 +509,16 @@ static int get_classdev_path(const char *classname, const char *clsdev,
 	}
 	if (strncmp(classname, SYSFS_BLOCK_NAME,
 				sizeof(SYSFS_BLOCK_NAME)) == 0) {
-		safestrncat(path, "/", len);
-		safestrncat(path, SYSFS_BLOCK_NAME, len);
+		safestrcatmax(path, "/", len);
+		safestrcatmax(path, SYSFS_BLOCK_NAME, len);
 	} else {
-		safestrncat(path, "/", len);
-		safestrncat(path, SYSFS_CLASS_NAME, len);
-		safestrncat(path, "/", len);
-		safestrncat(path, classname, len);
+		safestrcatmax(path, "/", len);
+		safestrcatmax(path, SYSFS_CLASS_NAME, len);
+		safestrcatmax(path, "/", len);
+		safestrcatmax(path, classname, len);
 	}
-	safestrncat(path, "/", len);
-	safestrncat(path, clsdev, len);
+	safestrcatmax(path, "/", len);
+	safestrcatmax(path, clsdev, len);
 	return 0;
 }