On Tue, Oct 27, 2026 at 06:01:17AM -0600, Simon Glass wrote:
> When the node being written to does not exist, fdtput just prints
> FDT_ERR_NOTFOUND - nothing points to -p, which creates missing nodes, so
> it is easy to conclude that fdtput cannot add nodes at all.
> 
> When creating a node with -c, the error also names the full path, even
> though it is the parent which is missing.
> 
> Add a hint to use -p when a node is missing, both when writing a
> property and when creating a node. Report the parent path when it is
> the parent which is missing.
> 
> Add tests that writing a property or creating a node fails when a parent
> node is missing and -p is not given.
> 
> Assisted-by: Claude:claude-opus-5-5
> Signed-off-by: Simon Glass <sjg@chromium.org>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
> 
>  fdtput.c           | 20 ++++++++++++++++++--
>  tests/run_tests.sh |  4 ++++
>  2 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/fdtput.c b/fdtput.c
> index 4094015..c9973d5 100644
> --- a/fdtput.c
> +++ b/fdtput.c
> @@ -47,6 +47,22 @@ static void report_error(const char *name, int namelen, int err)
>  		fdt_strerror(err));
>  }
>  
> +/**
> + * Report an error looking up a node which must exist before writing to it.
> + *
> + * If the node is missing, suggest -p, since it creates missing nodes.
> + *
> + * @param name		Node name to report error on
> + * @param namelen	Length of node name, or -1 to use entire string
> + * @param err		Error number to report (-FDT_ERR_...)
> + */
> +static void report_node_error(const char *name, int namelen, int err)
> +{
> +	report_error(name, namelen, err);
> +	if (err == -FDT_ERR_NOTFOUND)
> +		fprintf(stderr, "Use -p to create missing nodes\n");
> +}
> +
>  /**
>   * Encode a series of arguments in a property value.
>   *
> @@ -182,7 +198,7 @@ static int store_key_value(char **blob, const char *node_name,
>  
>  	node = fdt_path_offset(*blob, node_name);
>  	if (node < 0) {
> -		report_error(node_name, -1, node);
> +		report_node_error(node_name, -1, node);
>  		return -1;
>  	}
>  
> @@ -284,7 +300,7 @@ static int create_node(char **blob, const char *node_name)
>  		node = fdt_path_offset(*blob, path);
>  		free(path);
>  		if (node < 0) {
> -			report_error(node_name, -1, node);
> +			report_node_error(node_name, p - node_name, node);
>  			return -1;
>  		}
>  	}
> diff --git a/tests/run_tests.sh b/tests/run_tests.sh
> index 77f0a81..7254e53 100755
> --- a/tests/run_tests.sh
> +++ b/tests/run_tests.sh
> @@ -962,6 +962,10 @@ fdtput_tests () {
>      run_wrap_error_test $DTPUT $dtb -c /chosen
>      run_wrap_error_test $DTPUT $dtb -c /chosen/son
>  
> +    # Missing nodes are not created without -p
> +    run_wrap_error_test $DTPUT $dtb -c /blackadder/the-second
> +    run_wrap_error_test $DTPUT $dtb /blackadder/the-second cost -ts high
> +
>      # Automatic node creation
>      run_wrap_test $DTPUT $dtb -cp /blackadder/the-second/turnip \
>  	/blackadder/the-second/potato
> -- 
> 2.43.0
> 
> 

-- 
David Gibson (he or they)	| 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