On 14/01/2020 10:15, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2020-01-14 10:09:15)
On 10/01/2020 11:53, Chris Wilson wrote:
-uint64_t i915_type_id(void)
+static char *bus_address(int i915, char *path, int pathlen)
+{
+ struct stat st;
+ int len = -1;
+ int dir;
+ char *s;
+
+ if (fstat(i915, &st) || !S_ISCHR(st.st_mode))
+ return NULL;
+
+ snprintf(path, pathlen, "/sys/dev/char/%d:%d",
+ major(st.st_rdev), minor(st.st_rdev));
+
+ dir = open(path, O_RDONLY);
+ if (dir != -1) {
+ len = readlinkat(dir, "device", path, pathlen - 1);
+ close(dir);
+ }
+ if (len < 0)
+ return NULL;
+
+ path[len] = '\0';
In the realm of hypothetical but an assert that no truncation occurred
would be good.
if (len == pathlen - 1)
return NULL;
?
Although it is not clear to me from man readlinkat how do we distinguish
between truncation and exact fit.
Or you were counting on failure at a later step if truncation occurred?
I did not expect a partial match to ever succeed. We at least know for
the moment the names are fixed.
Maybe try stat(2) in this wrapper to be sure function returns a valid path?
That would have the same danger of a partial match.
True, it would need more string validation - that the returned string
matches the PCI bus address format of xxxx:yy:zz. Failure at a later
step works for now I guess.
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
I think the foolproof solution here is having pmu_name in
/sys/class/drm/cardN/pmu_name. (Or rather
/sys/dev/char/%d:%d/device/pnu_name. :)
True.
Regards,
Tvrtko
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