From 656703759d7d3eac6e8c86f1121cde7dfd6d8cbd Mon Sep 17 00:00:00 2001 From: "ananth@in.ibm.com" Date: Fri, 12 Mar 2004 00:57:36 -0800 Subject: [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. --- libsysfs/sysfs_dir.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'libsysfs/sysfs_dir.c') 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; -- cgit v1.2.3-54-g00ecf