Re: [B.A.T.M.A.N.] [PATCHv3] batctl: add sys framework for VLAN support

Antonio Quartulli
2013-09-02T07:03:17Z

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On Thu, Aug 29, 2013 at 08:43:34PM +0200, Marco Dalla Torre wrote:
>
> *sorry for messing up format in previous message, re-sending*

This message should not be here, otherwise it will get included in the commit
messages. Any out of band message should go immediately after the ---.

>
> Allow the batctl tool to take advantage of changes from commit
> e4ff5c153dab054a6cd1c4132f87bc5e77127456 ("add sys framework for VLAN")
> recently added to batman-adv, so that users can execute commands in
> a per VLAN fashion.
>
> If no directory entry corresponding to the user-selected device is found
> at the standard location for non VLAN interfaces
> (/sys/class/net/${base_device}), 'batctl' now looks into directory:
> /sys/devices/virtual/net/${base_device}/mesh/vlan${vid}
> Where:
> -${base_device}: the batman device on top of which the VLAN is sitting
> -${device}: the device interface for the VLAN,

${device} ? I don't see it in the text.

> -${vid}: the identifier assigned to the VLAN.
>
> Information on VLAN devices (base device, vid) necessary to construct the
> directory path is acquired by parsing /proc/net/vlan/${device}.

Ah it is here..what about moving the description below?

>
> If the user-selected command is not supported by the VLAN, an appropriate
> error is shown.
>
> Signed-off-by: Marco Dalla Torre <marco.dallato@gmail.com>
> ---
> functions.c | 3 +++
> main.c | 2 +-
> man/batctl.8 | 2 +-
> sys.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 56 insertions(+), 2 deletions(-)
>
> diff --git a/sys.c b/sys.c
> index b1d7ea8..00d2ed1 100644
> --- a/sys.c
> +++ b/sys.c
> @@ -371,6 +371,37 @@ static void settings_usage(int setting)
> fprintf(stderr, " \t -h print this help\n");
> }
>
> +int get_basedev_vid(char *mesh_iface, char **base_dev, unsigned short *vid)
> +{
> + char *vdev;
> + char line[100];
> + const char path[] = "/proc/net/vlan/";
> + int size = sizeof(path) + sizeof(mesh_iface);
> + FILE *fp = NULL;
> +
> + char *fpath = malloc(size);
> + strcpy(fpath, path);
> + /* prepare path file path: /proc/net/vlan/$mesh_iface*/
> + strcat(fpath, mesh_iface);

I think I asked you before: why don't you use a unique (and more clear) snprintf
here rather than one strcpy and one strcat ?

> +
> + fp = fopen(fpath, "r");
> + if (fp == NULL)
> + return 1;
> +
> + if (fscanf(fp, "%ms %*s %hu %*s %*d %*s %*d", &vdev, vid) == 0)
> + return 0;
> +
> + while (fgets(line, sizeof(line), fp) != NULL) {
> + if (sscanf(line, "Device: %ms", base_dev) == 1)
> + break;
> + }
> + /* handle base device not found case */
> + if (*base_dev == NULL)
> + return 0;
> +
> + return 1;
> +}

The return value of this function is not clear: you return 1 both on error (if
fp == NULL) and on success (at the end). I'd suggest you fix this and to rather
use -1 for error and 0 on success (like standard unix processes/c functions).

Please, provide a comment on top of this function describing what it does, what
do its parameters mean and what it returns. For example of the style to use you
can have a look at most of the functions in the batman-adv kernel module (this
is the so called kernel-doc). It makes much easier to understand functions.

> +
> int handle_sys_setting(char *mesh_iface, int setting, int argc, char **argv)
> {
> int optchar, res = EXIT_FAILURE;
> @@ -392,6 +423,26 @@ int handle_sys_setting(char *mesh_iface, int setting, int argc, char **argv)
> snprintf(path_buff, PATH_BUFF_LEN, SYS_BATIF_PATH_FMT, mesh_iface);
> path_buff[PATH_BUFF_LEN - 1] = '\0';
>
> + if (access(path_buff, F_OK) != 0) {
> + if (errno == ENOENT) {
> + /* path does not exist, no lan interface: check vlan */
> + unsigned short vid = 0;
> + char *base_dev = NULL;
> + if (get_basedev_vid(mesh_iface, &base_dev, &vid) == 1) {
> + free(path_buff);
> + char sys_vlan_path[] =
> + "/sys/devices/virtual/net/%s/mesh/vlan%d/";
> + int size = sizeof(sys_vlan_path) + sizeof(base_dev);
> + path_buff = malloc(size);
> + sprintf(path_buff, sys_vlan_path, base_dev, vid);
> + }
> + } else if (errno == ENOTDIR) {
> + /* not a directory, something wrong here */
> + fprintf(stderr, "Error - expected directory at '%s'\n",
> + path_buff);

I'd rather change this message to something different: ENOTDIR tells you that
something inside the pathname is not a dire while it was supposed to be such.
E.g. /a/b/c/d -> ENOTDIR is set if one of a, b or c is NOT a directory. d is the
file you want to access so that is not checked. This is what "man access" says.

Thanks!

--
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

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