Re: [PATCH v2 5/6] libfdt: Add fdt_setprop_inplace_namelen_partial

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Mon, Jul 11, 2016 at 09:56:22PM +0200, Maxime Ripard wrote:
> Add a function to modify inplace only a portion of a property..
> 
> This is especially useful when the property is an array of values, and you
> want to update one of them without changing the DT size.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> Acked-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>

Reviewed-by: David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>

Now it just needs some testcases..

> ---
>  libfdt/fdt_wip.c | 29 +++++++++++++++++++++++++----
>  libfdt/libfdt.h  | 21 +++++++++++++++++++++
>  2 files changed, 46 insertions(+), 4 deletions(-)
> 
> diff --git a/libfdt/fdt_wip.c b/libfdt/fdt_wip.c
> index c5bbb68d3273..fd53e0b67416 100644
> --- a/libfdt/fdt_wip.c
> +++ b/libfdt/fdt_wip.c
> @@ -55,21 +55,42 @@
>  
>  #include "libfdt_internal.h"
>  
> +int fdt_setprop_inplace_namelen_partial(void *fdt, int nodeoffset,
> +					const char *name, int namelen,
> +					uint32_t index, const void *val,
> +					int len)
> +{
> +	void *propval;
> +	int proplen;
> +
> +	propval = fdt_getprop_namelen_w(fdt, nodeoffset, name, namelen,
> +					&proplen);
> +	if (!propval)
> +		return proplen;
> +
> +	if (proplen < (len + index))
> +		return -FDT_ERR_NOSPACE;
> +
> +	memcpy((unsigned char *)propval + index, val, len);
> +	return 0;
> +}
> +
>  int fdt_setprop_inplace(void *fdt, int nodeoffset, const char *name,
>  			const void *val, int len)
>  {
> -	void *propval;
> +	const void *propval;
>  	int proplen;
>  
> -	propval = fdt_getprop_w(fdt, nodeoffset, name, &proplen);
> +	propval = fdt_getprop(fdt, nodeoffset, name, &proplen);
>  	if (! propval)
>  		return proplen;
>  
>  	if (proplen != len)
>  		return -FDT_ERR_NOSPACE;
>  
> -	memcpy(propval, val, len);
> -	return 0;
> +	return fdt_setprop_inplace_namelen_partial(fdt, nodeoffset, name,
> +						   strlen(name), 0,
> +						   val, len);
>  }
>  
>  static void _fdt_nop_region(void *start, int len)
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index 1da2c540b607..a22a16b6878a 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -1072,6 +1072,27 @@ int fdt_size_cells(const void *fdt, int nodeoffset);
>  /* Write-in-place functions                                           */
>  /**********************************************************************/
>  
> +/**
> + * fdt_setprop_inplace_namelen_partial - change a property's value,
> + *                                       but not its size
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node whose property to change
> + * @name: name of the property to change
> + * @namelen: number of characters of name to consider
> + * @index: index of the property to change in the array
> + * @val: pointer to data to replace the property value with
> + * @len: length of the property value
> + *
> + * Identical to fdt_setprop_inplace(), but modifies the given property
> + * starting from the given index, and using only the first characters
> + * of the name. It is useful when you want to manipulate only one value of
> + * an array and you have a string that doesn't end with \0.
> + */
> +int fdt_setprop_inplace_namelen_partial(void *fdt, int nodeoffset,
> +					const char *name, int namelen,
> +					uint32_t index, const void *val,
> +					int len);
> +
>  /**
>   * fdt_setprop_inplace - change a property's value, but not its size
>   * @fdt: pointer to the device tree blob

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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