[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, 3 insertions, 3 deletions

diff --git a/libsysfs/sysfs_dir.c b/libsysfs/sysfs_dir.c
index be54a1cf86..8ce8522200 100644
--- a/libsysfs/sysfs_dir.c
+++ b/libsysfs/sysfs_dir.c
@@ -239,10 +239,10 @@ int sysfs_write_attribute(struct sysfs_attribute *sysattr,
 			sysattr->value = (char *)realloc
 				(sysattr->value, length);
 			sysattr->len = length;
-			safestrncpy(sysattr->value, new_value, length);
+			safestrcpymax(sysattr->value, new_value, length);
 		} else {
 			/*"length" of the new value is same as old one */ 
-			safestrncpy(sysattr->value, new_value, length);
+			safestrcpymax(sysattr->value, new_value, length);
 		}
 	}
 			
@@ -348,7 +348,7 @@ int sysfs_read_attribute_value(const char *attrpath,
 	if (length > vsize) 
 		dprintf("Value length %d is larger than supplied buffer %d\n",
 			length, vsize);
-	safestrncpy(value, attr->value, vsize);
+	safestrcpymax(value, attr->value, vsize);
 	sysfs_close_attribute(attr);
 
 	return 0;