Re: [Powertop] Device list sort function bug

Sometimes PowerTOP dies with a Segmentation Fault while generating the report. Little investigation shown that it dies while sorting the device list. The problem is that comparison function devlist_sort is incorrect. The function should return true if first argument "preceeds" second. But when strcmp() is used, it can return -1, 0 and 1. So both -1 and 1 values are silently converted to true, which is wrong. It confuses the sort() function and it crosses boundary of array. Here is the patch: --8<--Cut-here---------------------------------------------------------------- diff -purN powertop-il/src/devlist.cpp powertop-il-fix/src/devlist.cpp --- powertop-il/src/devlist.cpp 2012-07-03 17:00:50.000000000 +0400 +++ powertop-il-fix/src/devlist.cpp 2012-07-03 20:01:05.896232845 +0400 @@ -273,7 +273,7 @@ static bool devlist_sort(struct devuser if (i->pid != j->pid) return i->pid< j->pid; - return strcmp(i->device, j->device); + return (strcmp(i->device, j->device)< 0); } static const char *dev_class(int line) --8<--------------------------------------------------------------------------