On Thu, Feb 24, 2011 at 02:06:44AM +0000, Kostas Georgiou wrote: > > In any case the slurpfile resizable buffer doesn't really work :(
obviously there is a misunderstanding about what this code does, and it is not "resizable buffer", but avoiding buffer overflows when passed more data than it can handle (which before resulted in buffer overflows and crashes)) > slurpfile only resizes a buffer if it's NULL but this is the case > only at the first call for a metric. and is only used this way when processing /proc/stat where we only really cared about the first line of that file, most of the time. this means that you only care on allocating a buffer that is big enough for the first time the file is read, and considering that it is allocated in page multiples of 4K each it is likely to be fine even if the file grows slightly the next time. > char *bp=NULL; > slurpfile(file, &bp, 32); > ...next polling interval... > /* the buffer isn't resibale any more since it isn't NULL */ > slurpfile(file, &bp, 32); slurpfile wasn't designed to be used this way, specially considering that it will waste more bytes just creating a pointer if you really only wanted to have 32 bytes to begin with. but if you really want to push the code to work in this scenario, no one is preventing you to clean the buffer before calling slurpfile : free(bp); bp = NULL; don't forget though that my objective here was to change the code to avoid the posibility of buffer overflows (which is why the message says that) and the message is there to clarify why something was truncated (while before it would just instead corrupt itself and crash). in summary, slurpfile is a hack, and should be avoided if possible, but was kept in its most benign form until its users can be implemented in a better way. Carlo ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Ganglia-developers mailing list Ganglia-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ganglia-developers
