Re: [PATCH 1/6] mkfs: Save raw user input field to the opts struct

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Fri, Aug 11, 2017 at 02:30:32PM +0200, Jan Tulak wrote:
> Save exactly what the user gave us for every option.  This way, we will
> never lose the information if we need it to print back an issue.
> (Just add the infrastructure now, used in the next patches.)
> 
> Signed-off-by: Jan Tulak <jtulak@redhat.com>
> 
> ---
> CHANGE:
> * added strdup
> * added boundary checks to set/get functions
> ---
>  mkfs/xfs_mkfs.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 7bb6408f..fa0b475c 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -107,6 +107,11 @@ unsigned int		sectorsize;
>   *     sets what is used with simple specifying the subopt (-d file).
>   *     A special SUBOPT_NEEDS_VAL can be used to require a user-given
>   *     value in any case.
> + *
> + *   raw_input INTERNAL
> + *     Filled raw string from the user, so we never lose that information e.g.
> + *     to print it back in case of an issue.
> + *
>   */
>  struct opt_params {
>  	const char	name;
> @@ -122,6 +127,7 @@ struct opt_params {
>  		long long	minval;
>  		long long	maxval;
>  		long long	defaultval;
> +		char		*raw_input;
>  	}		subopt_params[MAX_SUBOPTS];
>  };
>  
> @@ -730,6 +736,69 @@ struct opt_params mopts = {
>  #define WHACK_SIZE (128 * 1024)
>  
>  /*
> + * Return 0 on success, -ENOMEM if it could not allocate enough memory for
> + * the string to be saved.
> + */
> +static int
> +set_conf_raw(struct opt_params *opt, const int subopt, const char *value)
> +{
> +	if (subopt < 0 || subopt >= MAX_SUBOPTS) {
> +		fprintf(stderr,
> +		"This is a bug: set_conf_raw called with invalid opt/subopt: %c/%d\n",
> +		opt->name, subopt);

ASSERT?  Or, if I'm just foolishly restarting an old bikeshed and the
fprintf/-EINVAL should stay, then the indentation of the arguments needs
fixing.

> +		return -EINVAL;
> +	}
> +	if (value == NULL) {
> +		if (opt->subopt_params[subopt].raw_input != NULL)
> +			free(opt->subopt_params[subopt].raw_input);
> +		opt->subopt_params[subopt].raw_input = NULL;
> +	} else {
> +		opt->subopt_params[subopt].raw_input = strdup(value);
> +		if (opt->subopt_params[subopt].raw_input == NULL)
> +			return -ENOMEM;
> +	}
> +	return 0;
> +}
> +
> +/*
> + * Return 0 on success, -ENOMEM if it could not allocate enough memory for
> + * the string to be saved into the out pointer.
> + */
> +static int
> +get_conf_raw(const struct opt_params *opt, const int subopt, char **out)
> +{
> +	if (subopt < 0 || subopt >= MAX_SUBOPTS) {
> +		fprintf(stderr,
> +		"This is a bug: get_conf_raw called with invalid opt/subopt: %c/%d\n",
> +		opt->name, subopt);
> +		return -EINVAL;

(Same here)

> +	}
> +	*out = strdup(opt->subopt_params[subopt].raw_input);

Given that raw_input can be set to NULL and strdup(NULL) segfaults on
glibc 2.23, do we need a null check of raw_input here?  Is it the case
that get_conf_raw is only called if we (somehow) know that there's a
value to get later?

--D

> +	if (*out == NULL)
> +		return -ENOMEM;
> +	return 0;
> +
> +}
> +
> +/*
> + * Same as get_conf_raw(), except it returns the string through return.
> + * If any error occurs, return NULL.
> + */
> +static char *
> +get_conf_raw_safe(const struct opt_params *opt, const int subopt)
> +{
> +	char *str;
> +
> +	str = NULL;
> +
> +	if (get_conf_raw(opt, subopt, &str) == -ENOMEM) {
> +		fprintf(stderr, "Out of memory!");
> +		return NULL;
> +	}
> +	return str;
> +}
> +
> +/*
>   * Convert lsu to lsunit for 512 bytes blocks and check validity of the values.
>   */
>  static void
> -- 
> 2.13.3
> 
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