Hi Stéphane,
On Tue, Nov 12, 2013 at 10:51 PM, Stéphane Graber <stgra...@ubuntu.com> wrote:
> On Tue, Nov 12, 2013 at 10:47:06PM -0500, S.Çağlar Onur wrote:
>> Adding block/char devices to running container is a common operation so
>> provide a common implementation for users to consume.
>>
>> changes since v2;
>> * removed duplicated code
>>
>
> lxc-device which currently implements something like that as a tool in
> python also lets the user set an alternate path inside the container.
> Can we have the C API offer the same feature so I can use the new API
> instead of keeping my own implementation?
Sure thing, in fact lxc-device is the reason why I come up with this
patch. I wanted to provide the same functionality to Go users and
implemented it in Go first but then I thought we can have this in the
C API and all bindings (and users) can use it. I'll try to add
alternate path to it and will re-send, assuming having this in the API
is acceptable.
>> Signed-off-by: S.Çağlar Onur <cag...@10ur.org>
>> ---
>> src/lxc/lxccontainer.c | 84
>> ++++++++++++++++++++++++++++++++++++++++++++++++++
>> src/lxc/lxccontainer.h | 9 ++++++
>> 2 files changed, 93 insertions(+)
>>
>> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
>> index 05ca643..c21bc96 100644
>> --- a/src/lxc/lxccontainer.c
>> +++ b/src/lxc/lxccontainer.c
>> @@ -62,6 +62,8 @@
>> #endif
>> #endif
>>
>> +#define MAX_BUFFER 4096
>> +
>> lxc_log_define(lxc_container, lxc);
>>
>> static bool file_exists(char *f)
>> @@ -2920,6 +2922,86 @@ static bool lxcapi_may_control(struct lxc_container
>> *c)
>> return lxc_try_cmd(c->name, c->config_path) == 0;
>> }
>>
>> +static bool add_remove_device_node(struct lxc_container *c, char *src_path,
>> bool add)
>> +{
>> + int ret;
>> + struct stat st;
>> + char value[MAX_BUFFER];
>> + char dest_path[MAXPATHLEN];
>> +
>> + /* make sure container is running */
>> + if (!c->is_running(c)) {
>> + ERROR("container is not running");
>> + return false;
>> + }
>> +
>> + /* prepare dest_path */
>> + ret = snprintf(dest_path, MAXPATHLEN, "/proc/%d/root%s",
>> c->init_pid(c), src_path);
>> + if (ret < 0 || ret >= MAXPATHLEN)
>> + return false;
>> +
>> + if (add) {
>> + /* make sure that we can access src_path */
>> + if(access(src_path, F_OK) < 0 || stat(src_path, &st) < 0)
>> + return false;
>> + } else {
>> + /* make sure that we can access dest_path */
>> + if(access(dest_path, F_OK) < 0 || stat(dest_path, &st) < 0)
>> + return false;
>> + }
>> +
>> + /* continue if path is character device or block device */
>> + if S_ISCHR(st.st_mode)
>> + ret = snprintf(value, MAX_BUFFER, "c %d:%d rwm",
>> major(st.st_rdev), minor(st.st_rdev));
>> + else if S_ISBLK(st.st_mode)
>> + ret = snprintf(value, MAX_BUFFER, "b %d:%d rwm",
>> major(st.st_rdev), minor(st.st_rdev));
>> + else
>> + return false;
>> +
>> + /* check snprintf return code */
>> + if (ret < 0 || ret >= MAX_BUFFER)
>> + return false;
>> +
>> + /* remove dest_path if it exists */
>> + if(access(dest_path, F_OK) == 0) {
>> + if (unlink(dest_path) < 0) {
>> + ERROR("unlink failed");
>> + return false;
>> + }
>> + }
>> +
>> + if (add) {
>> + /* create the device node */
>> + if (mknod(dest_path, st.st_mode, st.st_rdev) < 0) {
>> + ERROR("mknod failed");
>> + return false;
>> + }
>> +
>> + /* add to device list */
>> + if (!c->set_cgroup_item(c, "devices.allow", value)) {
>> + ERROR("set_cgroup_item failed while adding the device
>> node");
>> + return false;
>> + }
>> + } else {
>> + /* remove from device list */
>> + if (!c->set_cgroup_item(c, "devices.deny", value)) {
>> + ERROR("set_cgroup_item failed while removing the
>> device node");
>> + return false;
>> + }
>> + }
>> + return true;
>> +}
>> +
>> +static bool lxcapi_add_device_node(struct lxc_container *c, char *path)
>> +{
>> + return add_remove_device_node(c, path, true);
>> +}
>> +
>> +static bool lxcapi_remove_device_node(struct lxc_container *c, char *path)
>> +{
>> + return add_remove_device_node(c, path, false);
>> +}
>> +
>> static int lxcapi_attach_run_waitl(struct lxc_container *c,
>> lxc_attach_options_t *options, const char *program, const char *arg, ...)
>> {
>> va_list ap;
>> @@ -3041,6 +3123,8 @@ struct lxc_container *lxc_container_new(const char
>> *name, const char *configpath
>> c->snapshot_restore = lxcapi_snapshot_restore;
>> c->snapshot_destroy = lxcapi_snapshot_destroy;
>> c->may_control = lxcapi_may_control;
>> + c->add_device_node = lxcapi_add_device_node;
>> + c->remove_device_node = lxcapi_remove_device_node;
>>
>> /* we'll allow the caller to update these later */
>> if (lxc_log_init(NULL, "none", NULL, "lxc_container", 0,
>> c->config_path)) {
>> diff --git a/src/lxc/lxccontainer.h b/src/lxc/lxccontainer.h
>> index 486035a..a94de9a 100644
>> --- a/src/lxc/lxccontainer.h
>> +++ b/src/lxc/lxccontainer.h
>> @@ -236,6 +236,15 @@ struct lxc_container {
>> * and the caller may not access it. Return true otherwise.
>> */
>> bool (*may_control)(struct lxc_container *c);
>> +
>> + /*
>> + * Returns true if given device succesfully added to container
>> + */
>> + bool (*add_device_node)(struct lxc_container *c, char *path);
>> + /*
>> + * Returns true if given device succesfully removed from container
>> + */
>> + bool (*remove_device_node)(struct lxc_container *c, char *path);
>> };
>>
>> struct lxc_snapshot {
>> --
>> 1.8.3.2
>>
>>
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>
> --
> Stéphane Graber
> Ubuntu developer
> http://www.ubuntu.com
--
S.Çağlar Onur <cag...@10ur.org>
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