[CRIU] [PATCH] Fix RPC configuration file handling

Andrei Vagin avagin at gmail.com
Fri Dec 14 20:39:19 MSK 2018


On Thu, Dec 13, 2018 at 10:46:33AM +0000, Adrian Reber wrote:
> From: Adrian Reber <areber at redhat.com>
> 
> While writing runc test cases to verify that runc correctly uses RPC
> configuration files it became clear that some things were not working as
> they are supposed to. Looking closer at the code to set log files
> via RPC configuration files I discovered that the code seems wrong (at
> least I did not understand it any more (or the intentions behind it)).
> 
> This code tries to simplify that logic a bit and add more comments to
> make clear what the intentions of the RPC configuration file code is.
> 
> Signed-off-by: Adrian Reber <areber at redhat.com>
> ---
>  criu/cr-service.c | 37 +++++++++++++++++++++++++++++++------
>  1 file changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/criu/cr-service.c b/criu/cr-service.c
> index 4a9983a..61139d4 100644
> --- a/criu/cr-service.c
> +++ b/criu/cr-service.c
> @@ -292,23 +292,38 @@ static int setup_opts_from_req(int sk, CriuOpts *req)
>  			xfree(tmp_imgs);
>  			goto err;
>  		}
> -		if (tmp_output && opts.output && !strncmp(tmp_output, opts.output, PATH_MAX))
> +		/* If this is non-NULL, the RPC configuration file had a value, use it.*/
> +		if (opts.output)
>  			output_changed_by_rpc_conf = true;
> -		if (tmp_work && opts.work_dir && !strncmp(tmp_work, opts.work_dir, PATH_MAX))
> +		/* If this is NULL, use the old value if it was set. */
> +		if (!opts.output && tmp_output)
> +			opts.output = xstrdup(tmp_output);



tmp_output is a copy of opts.output:
tmp_output = xstrdup(opts.output);

Why do we need xstrdup() here? Maybe something like this:

opts.output = tmp_output;
tmp_output = NULL;


BTW: xstrdup can fail, so we have to check its return value.


> +
> +		if (opts.work_dir)
>  			work_changed_by_rpc_conf = true;
> -		if (tmp_imgs && opts.imgs_dir && !strncmp(tmp_imgs, opts.imgs_dir, PATH_MAX))
> +		if (!opts.work_dir && tmp_work)
> +			opts.work_dir = xstrdup(tmp_work);
> +
> +		if (opts.imgs_dir)
>  			imgs_changed_by_rpc_conf = true;
> +		/*
> +		 * As the images directory is a required RPC setting, it is not
> +		 * necessary to use the value from other configuration files.
> +		 * Either it is set in the RPC configuration file or it is set
> +		 * via RPC.
> +		 */
>  		xfree(tmp_output);
>  		xfree(tmp_work);
>  		xfree(tmp_imgs);
>  	}
>  
>  	/*
> -	 * open images_dir
> +	 * open images_dir - images_dir_fd is a required RPC parameter
> +	 *
>  	 * This assumes that if opts.imgs_dir is set we have a value
>  	 * from the configuration file parser. The test to see that
>  	 * imgs_changed_by_rpc_conf is true is used to make sure the value
> -	 * is not the same as from one of the other configuration files.
> +	 * is from the RPC configuration file.
>  	 * The idea is that only the RPC configuration file is able to
>  	 * overwrite RPC settings:
>  	 *  * apply_config(global_conf)
> @@ -338,10 +353,16 @@ static int setup_opts_from_req(int sk, CriuOpts *req)
>  
>  	/* chdir to work dir */
>  	if (opts.work_dir && work_changed_by_rpc_conf)
> +		/* Use the value from the RPC configuration file first. */
>  		strncpy(work_dir_path, opts.work_dir, PATH_MAX - 1);
>  	else if (req->has_work_dir_fd)
> +		/* Use the value set via RPC. */
>  		sprintf(work_dir_path, "/proc/%d/fd/%d", ids.pid, req->work_dir_fd);
> +	else if (opts.work_dir)
> +		/* Use the value from one of the other configuration files. */
> +		strncpy(work_dir_path, opts.work_dir, PATH_MAX - 1);
>  	else
> +		/* Use the images directory a work directory. */
>  		strcpy(work_dir_path, images_dir_path);
>  
>  	if (chdir(work_dir_path)) {
> @@ -350,7 +371,11 @@ static int setup_opts_from_req(int sk, CriuOpts *req)
>  	}
>  
>  	/* initiate log file in work dir */
> -	if (req->log_file && !(opts.output  && output_changed_by_rpc_conf)) {
> +	if (req->log_file && !(opts.output && output_changed_by_rpc_conf)) {

output_changed_by_rpc_conf is true only if opts.output isn't NULL

> +		/*
> +		 * If RPC sets a log file and if there nothing from the
> +		 * RPC configuration file, use the RPC value.
> +		 */
>  		if (strchr(req->log_file, '/')) {
>  			pr_perror("No subdirs are allowed in log_file name");
>  			goto err;
> -- 
> 1.8.3.1
> 


More information about the CRIU mailing list