[lxc-devel] [PATCH] lxc-ls: check for ENOMEM and tweaking
Serge Hallyn
serge.hallyn at ubuntu.com
Fri Jan 15 21:10:51 UTC 2016
Quoting Christian Brauner (christian.brauner at mailbox.org):
> On Fri, Jan 15, 2016 at 08:40:19PM +0000, Serge Hallyn wrote:
> > Quoting Christian Brauner (christian.brauner at mailbox.org):
> > > If lxc_container_new() fails we check for ENOMEN and goto out if ENOMEM is not
> > > set we will simply continue. The same goes for the call to regcomp() but
> > > instead of checking for ENOMEM we need to check for REG_ESPACE.
> > >
> > > Tweaking: Since lxc-ls might have to gather a lot of containers and I don't
> > > know if compilers will always optimize this let's move all variable
> > > declarations outside of the loop. They should still be fairly self explanatory.
> >
> > It's just a stack pointer move so it's not really needed, so I think
> > readability should win out.
> >
> > Now the biggest penalty to this would be the lock_path[MAXPATHLEN],
> > but that is *always* already declared before the recursive ls_get
> > anyway, so we always take the hit.
> alloca()?
Only if you do it inside the conditional so that it gets
freed when it leaves scope. Because otherwise you still have
to guess at a size (or go through all lxc_names in advance to
find the max size).
alloca in the local scope would be fine, so would just doing malloc and
realloc and freeing at exit.
> >
> > > Signed-off-by: Christian Brauner <christian.brauner at mailbox.org>
> > > ---
> > > src/lxc/lxc_ls.c | 57 ++++++++++++++++++++++++++++++++------------------------
> > > 1 file changed, 33 insertions(+), 24 deletions(-)
> > >
> > > diff --git a/src/lxc/lxc_ls.c b/src/lxc/lxc_ls.c
> > > index a4ab9b6..7d46426 100644
> > > --- a/src/lxc/lxc_ls.c
> > > +++ b/src/lxc/lxc_ls.c
> > > @@ -341,25 +341,37 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > goto out;
> > > }
> > >
> > > + char lock_path[MAXPATHLEN];
> > > + char *curr_path, *name, *newpath, *tmp;
> > > + const char *state_tmp;
> > > + int check = 0;
> > > + size_t i;
> > > + bool running;
> > > struct ls *l = NULL;
> > > struct lxc_container *c = NULL;
> > > - size_t i;
> > > + struct wrapargs wargs = (struct wrapargs){.args = NULL};
> > > for (i = 0; i < (size_t)num; i++) {
> > > - char *name = containers[i];
> > > + name = containers[i];
> > >
> > > /* Filter container names by regex the user gave us. */
> > > if (args->ls_regex) {
> > > regex_t preg;
> > > - if (regcomp(&preg, args->ls_regex, REG_NOSUB | REG_EXTENDED) != 0)
> > > + check = regcomp(&preg, args->ls_regex, REG_NOSUB | REG_EXTENDED);
> > > + if (check == REG_ESPACE) /* we're out of memory */
> > > + goto out;
> > > + else if (check != 0)
> > > continue;
> > > - int rc = regexec(&preg, name, 0, NULL, 0);
> > > + check = regexec(&preg, name, 0, NULL, 0);
> > > regfree(&preg);
> > > - if (rc != 0)
> > > + if (check != 0)
> > > continue;
> > > }
> > >
> > > + errno = 0;
> > > c = lxc_container_new(name, path);
> > > - if (!c)
> > > + if ((errno == ENOMEM) && !c)
> > > + goto out;
> > > + else if (!c)
> > > continue;
> > >
> > > if (!c->is_defined(c))
> > > @@ -367,7 +379,7 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > >
> > > /* This does not allocate memory so no worries about freeing it
> > > * when we goto next or out. */
> > > - const char *state_tmp = c->state(c);
> > > + state_tmp = c->state(c);
> > > if (!state_tmp)
> > > state_tmp = "UNKNOWN";
> > >
> > > @@ -380,11 +392,11 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > if (args->ls_stopped && strcmp(state_tmp, "STOPPED"))
> > > goto put_and_next;
> > >
> > > - bool running = c->is_running(c);
> > > + running = c->is_running(c);
> > >
> > > - char *grp_tmp = ls_get_groups(c, running);
> > > - if (!ls_has_all_grps(grp_tmp, args->groups)) {
> > > - free(grp_tmp);
> > > + tmp = ls_get_groups(c, running);
> > > + if (!ls_has_all_grps(tmp, args->groups)) {
> > > + free(tmp);
> > > goto put_and_next;
> > > }
> >
> > Unrelated to this patch, but I just noticed that if ls_new() fails you'll leak
> > the 'tmp'.
> Thanks!
>
> >
> > >
> > > @@ -396,7 +408,7 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > /* How deeply nested are we? */
> > > l->nestlvl = lvl;
> > >
> > > - l->groups = grp_tmp;
> > > + l->groups = tmp;
> > >
> > > l->running = running;
> > >
> > > @@ -422,7 +434,7 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > if (!l->state)
> > > goto put_and_next;
> > >
> > > - char *tmp = ls_get_config_item(c, "lxc.start.auto", running);
> > > + tmp = ls_get_config_item(c, "lxc.start.auto", running);
> > > if (tmp)
> > > l->autostart = atoi(tmp);
> > > free(tmp);
> > > @@ -450,12 +462,10 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > /* Get nested containers: Only do this after we have gathered
> > > * all other information we need. */
> > > if (args->ls_nesting && running) {
> > > - struct wrapargs wargs = (struct wrapargs){.args = NULL};
> > > -
> > > /* Open a socket so that the child can communicate with
> > > * us. */
> > > - int ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, wargs.pipefd);
> > > - if (ret == -1)
> > > + check = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, wargs.pipefd);
> > > + if (check == -1)
> > > goto put_and_next;
> > >
> > > /* Set the next nesting level. */
> > > @@ -472,12 +482,12 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > >
> > > /* fork(): Attach to the namespace of the child and run
> > > * ls_get() in it which is called in ls_get_wrapper(). */
> > > - int status = c->attach(c, ls_get_wrapper, &wargs, &aopt, &out);
> > > + check = c->attach(c, ls_get_wrapper, &wargs, &aopt, &out);
> > > /* close the socket */
> > > close(wargs.pipefd[1]);
> > >
> > > /* Retrieve all information we want from the child. */
> > > - if (status == 0)
> > > + if (check == 0)
> > > if (ls_deserialize(wargs.pipefd[0], m, size) == -1)
> > > goto put_and_next;
> > >
> > > @@ -495,7 +505,7 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > * need a path-extractor function. We face the same
> > > * problem with the ovl_mkdir() function in
> > > * lxcoverlay.{c,h}. */
> > > - char *curr_path = ls_get_config_item(c, "lxc.rootfs", running);
> > > + curr_path = ls_get_config_item(c, "lxc.rootfs", running);
> > > if (!curr_path)
> > > goto put_and_next;
> > >
> > > @@ -504,7 +514,7 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > * nested containers. What we do is simply create a
> > > * growing path which will lead us into the rootfs of
> > > * the next container where it stores its containers. */
> > > - char *newpath = lxc_append_paths(basepath, curr_path);
> > > + newpath = lxc_append_paths(basepath, curr_path);
> > > free(curr_path);
> > > if (!newpath)
> > > goto put_and_next;
> > > @@ -512,9 +522,8 @@ static int ls_get(struct ls **m, size_t *size, const struct lxc_arguments *args,
> > > /* We want to remove all locks we created under
> > > * /run/lxc/lock so we create a string pointing us to
> > > * the lock path for the current container. */
> > > - char lock_path[MAXPATHLEN];
> > > - int ret = snprintf(lock_path, MAXPATHLEN, "%s/lxc/lock/%s/%s", RUNTIME_PATH, path, name);
> > > - if (ret < 0 || ret >= MAXPATHLEN)
> > > + check = snprintf(lock_path, MAXPATHLEN, "%s/lxc/lock/%s/%s", RUNTIME_PATH, path, name);
> > > + if (check < 0 || ret >= MAXPATHLEN)
> >
> > You need to add a /g at the end of that :%s :) (^ ret)
> Are you mocking my vim skills? :D
Haha, no, we always forget that at times :)
> I'll just group the ls_nesting = 0 patch and this patch together and send again.
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