On 05/07/2011 01:53 AM, Francois-Xavier Bourlet wrote:
ok thanks for all the information and example.
I believe that rather than trying to iterate over every containers
running or not and trying to merge the result we could simply iterate
only on running container, or only stopped container (I simplify). So
lxc_for_each could simply take a state in parameter, in case we are
looking for running containers we only have to look in /proc/net/unix
else browsing LXCPATH.
But then what about state like booting/stopping etc? Is
booting/stopping are "running" in some way? Maybe rather than passing
a state to lxc_for_each we can imagine a boolean parameter with the
notion of *active* *inactive*, or something with a better name to
introduce the fact we are looking for "running" container or simply
registered ones?
I have to run really ofter lxc_for_each, and adding complexity (and so
slowing down the function) is a big concern for me. I dont need a full
list of every containers in every state, but only whats is actually
present in the cgroup filesystem and what is registered. I would
prefer to let the user (the developer using lxc_for_each) decide and
implement itself the appropriate complexity.
Ok, as the name of 'volatile' container is already presented in the man
page, we can add this boolean to lxc_for_each and let the caller of this
function to handle the duplicate names.
In attachment the routine to look for containers in /proc/net/unix and
not in LXCPATH/<name>.
So when 'volatile' is set, this routine should be called otherwise the
other one I sent in a previous email.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#define LXCPATH "/var/lib/lxc"
static int is_volatile(const char *name)
{
char *path;
int ret;
if (asprintf(&path, LXCPATH "/%s", name) < 0)
return -1;
ret = access(path, F_OK);
free(path);
return !!ret;
}
int main(int argc, char *argv[])
{
const char *file = "/proc/net/unix";
const char *format = "%*lx: %*x %*x %*d %*d %*d %*d @" LXCPATH "/%s";
char buffer[MAXPATHLEN];
FILE *f;
int ret;
f = fopen(file, "r");
if (!f) {
perror("fopen '%s' failed");
return -1;
}
for (ret = fscanf(f, "%*[^\n]"); ret != EOF; ret = fscanf(f, format, buffer)) {
char *aux;
if (!ret) {
ret = fscanf(f, "%*[^\n]");
continue;
}
aux = strchr(buffer, '/');
*aux = '\0';
printf("%s : [%sregistered]\n", buffer, is_volatile(buffer) ?
"not " : "");
}
fclose(f);
return 0;
}
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