Re: [Ganglia-developers] Dynamically resizable buffer for slurpfile()

[Kostas G. <k.g...@at...>]

On Wed, Feb 23, 2011 at 05:12:03PM -0800, Bernard Li wrote:

> Hi Carlo:
> 
> On Wed, Feb 23, 2011 at 9:42 AM, Bernard Li <be...@va...> wrote:
> 
> > I tested under EL5 and EL6 and it was't able to get past the initial
> > buffer size.  I believe what I did was:
> 
> Correction.  It works on EL6, but not on EL5:
> 
> [CentOS 5.5 x86_64 with kernel 2.6.18-194.32.1.el5]
> 
> read(3, "2.6.18-194.32.1.", 16)         = 16
> read(3, "", 16)                         = 0
> 
> [RHEL6b2 x86_64 with kernel 2.6.32-37.el6.x86_64]
> 
> read(3, "2.6.32-37.el6.x8", 16)         = 16
> read(3, "6_64\n", 16)                   = 5
> 
> The issue may be specific to files in /proc/sys, because I tried
> reading /proc/stat on CentOS 5.5 and it worked fine.

In any case the slurpfile resizable buffer doesn't really work :(
slurpfile only resizes a buffer if it's NULL but this is the case
only at the first call for a metric.

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);  

Kostas