On Fri, May 22, 2009 at 12:04:24PM +0530, Bharata B Rao wrote:
> On Mon, May 18, 2009 at 02:17:46PM +0530, Dhaval Giani wrote:
> > This set of APIs will allow the caller to query the mount table
> > and find out what controller is mounted at what path.
> >
> > Test program has been included in the patch. Running the test program
> > results in
> >
> > [dha...@gondor tests]$ ../libtool --mode=execute ./get_controller
> > Controller cpu is mounted at /cgroup
> > Controller cpuacct is mounted at /cgroup
> > Controller memory is mounted at /cgroup1
> > [dha...@gondor tests]$
> >
> > Which is the setup on this system.
> >
> > Signed-off-by: Dhaval Giani <[email protected]>
> > Cc: Jan Safranek <[email protected]>
> >
> > ---
> > include/libcgroup.h | 12 ++++++
> > src/api.c | 85
> > +++++++++++++++++++++++++++++++++++++++++++++++++
> > src/libcgroup.map | 3 +
> > tests/Makefile.am | 3 +
> > tests/get_controller.c | 35 ++++++++++++++++++++
> > 5 files changed, 137 insertions(+), 1 deletion(-)
> >
> > Index: libcg/src/api.c
> > ===================================================================
> > --- libcg.orig/src/api.c
> > +++ libcg/src/api.c
> > @@ -2525,3 +2525,88 @@ int cgroup_get_task_begin(char *cgroup,
> >
> > return ret;
> > }
> > +
> > +
> > +int cgroup_get_controller_end(void **handle)
> > +{
> > + int *key = (int *) *handle;
>
> You call it key here and at other places you call it pos. Want to be
> consistent ?
>
Sure, will make the change.
> > +
> > + if (!cgroup_initialized)
> > + return ECGROUPNOTINITIALIZED;
> > +
> > + if (!key)
> > + return ECGINVAL;
> > +
> > + free(key);
> > + *handle = NULL;
> > +
> > + return 0;
> > +}
> > +/*
> > + * name and path will be allocated by the API. The caller *must* free
> > + * name and path before calling into the API again else there will be
> > + * leaks.
>
> Hmm do you think we are better off taking allocated pointers (of size
> FILENAME_MAX) instead of this semantics where user provides pointers, library
> allocates them, but user frees them.
>
I'm not sure. Buffer overflows? I've seen both types of
uses so I am not i any camp.
> > + */
> > +int cgroup_get_controller_next(void **handle, char **name, char **path)
> > +{
> > + int error = 0;
> > + int *pos = (int *) *handle;
> > + int ret = 0;
> > +
> > + if (!cgroup_initialized)
> > + return ECGROUPNOTINITIALIZED;
> > +
> > + if (!pos)
> > + return ECGINVAL;
> > +
> > + pthread_rwlock_rdlock(&cg_mount_table_lock);
> > +
> > + if (cg_mount_table[*pos].name[0] == '\0') {
> > + ret = ECGEOF;
> > + goto out_unlock;
> > + }
> > +
> > + *name = strdup(cg_mount_table[*pos].name);
> > +
> > + if (!*name) {
> > + last_errno = errno;
> > + ret = ECGOTHER;
> > + goto out_unlock;
> > + }
> > +
> > + *path = strdup(cg_mount_table[*pos].path);
> > +
> > + if (!*path) {
> > + last_errno = errno;
> > + ret = ECGOTHER;
> > + goto out_unlock;
> > + }
> > +
> > + (*pos)++;
> > + *handle = pos;
> > +
> > +out_unlock:
> > + pthread_rwlock_unlock(&cg_mount_table_lock);
> > + return ret;
> > +}
> > +
> > +int cgroup_get_controller_begin(void **handle, char **name, char **path)
> > +{
> > + int *pos;
> > +
> > + if (!cgroup_initialized)
> > + return ECGROUPNOTINITIALIZED;
> > +
> > + pos = malloc(sizeof(int));
> > +
> > + if (!pos) {
> > + last_errno = errno;
> > + return ECGOTHER;
> > + }
>
> Do you want to validate name and path pointers with a !NULL check here and
> elsewhere ?
>
No. Since we are going to allocate them.
--
regards,
Dhaval
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