Re: [PATCH V2] Support 'b' format for printing raw bytes with fdtget

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

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On Wed, Dec 08, 2021 at 06:00:55PM +0100, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal-g1n6cQUeyibVItvQsEIGlw@public.gmane.org>
> 
> FT is sometimes used for storing raw data. That is quite common for
> U-Boot FIT images.
> 
> Extracting such data is not trivial currently. Using type 's' (string)
> will replace every 0x00 (NUL) with 0x20 (space). Using type 'x' will
> print bytes but in xxd incompatible format.
> 
> This commit adds support for 'b' (binary) format. Example usage:
> fdtget -t b firmware.itb /images/foo data > image.raw
> 
> Support for encoding isn't added as there isn't any clean way of passing
> binary data as command line argument.
> 
> Signed-off-by: Rafał Miłecki <rafal-g1n6cQUeyibVItvQsEIGlw@public.gmane.org>
> ---
> V2: Update usage info & add tests
> 
> Alternatively I could use e.g. "r" (raw) instead of "b" (binary) if you
> find it more accurate. Please let me know.
> ---
>  Documentation/manual.txt |  2 +-
>  fdtget.c                 |  5 +++++
>  fdtput.c                 |  2 ++
>  tests/run_tests.sh       |  2 ++
>  tests/utilfdt_test.c     |  5 ++++-
>  util.c                   | 21 +++++++++++----------
>  util.h                   |  3 ++-
>  7 files changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/Documentation/manual.txt b/Documentation/manual.txt
> index 97e53b9..73e0593 100644
> --- a/Documentation/manual.txt
> +++ b/Documentation/manual.txt
> @@ -712,7 +712,7 @@ The syntax of the fdtget command is:
>  
>  where options are:
>  
> -    <type>    s=string, i=int, u=unsigned, x=hex
> +    <type>    s=string, i=int, u=unsigned, x=hex, b=binary
>          Optional modifier prefix:
>              hh or b=byte, h=2 byte, l=4 byte (default)

I don't think using "b" as both a type specifier, and a length
modifier is a good idea.  You can probably disambiguate them in
parsing, but it's still likely to cause confusion.

How about "r" for "raw"?

>  
> diff --git a/fdtget.c b/fdtget.c
> index 54fc6a0..6e4abf1 100644
> --- a/fdtget.c
> +++ b/fdtget.c
> @@ -97,6 +97,11 @@ static int show_data(struct display_info *disp, const char *data, int len)
>  	if (len == 0)
>  		return 0;
>  
> +	if (disp->type == 'b') {
> +		fwrite(data, 1, len, stdout);
> +		return 0;
> +	}
> +
>  	is_string = (disp->type) == 's' ||
>  		(!disp->type && util_is_printable_string(data, len));
>  	if (is_string) {
> diff --git a/fdtput.c b/fdtput.c
> index 428745a..99b0bf9 100644
> --- a/fdtput.c
> +++ b/fdtput.c
> @@ -433,6 +433,8 @@ int main(int argc, char *argv[])
>  			if (utilfdt_decode_type(optarg, &disp.type,
>  					&disp.size))
>  				usage("Invalid type string");
> +			if (disp.type == 'b')
> +				usage("Unsupported binary data type");
>  			break;
>  
>  		case 'v':
> diff --git a/tests/run_tests.sh b/tests/run_tests.sh
> index d100d5a..484be18 100755
> --- a/tests/run_tests.sh
> +++ b/tests/run_tests.sh
> @@ -855,6 +855,8 @@ fdtget_tests () {
>      run_fdtget_test 8000 -tx $dtb /cpus/PowerPC,970@1 d-cache-size
>      run_fdtget_test "61 62 63 0" -tbx $dtb /randomnode tricky1
>      run_fdtget_test "a b c d de ea ad be ef" -tbx $dtb /randomnode blob
> +    run_fdtget_test "MyBoardName\0MyBoardFamilyName\0" -tb $dtb / compatible
> +    run_fdtget_test "\x0a\x0b\x0c\x0d\xde\xea\xad\xbe\xef" -tb $dtb /randomnode blob
>  
>      # Here the property size is not a multiple of 4 bytes, so it should fail
>      run_wrap_error_test $DTGET -tlx $dtb /randomnode mixed
> diff --git a/tests/utilfdt_test.c b/tests/utilfdt_test.c
> index c621759..906f250 100644
> --- a/tests/utilfdt_test.c
> +++ b/tests/utilfdt_test.c
> @@ -73,6 +73,9 @@ static void check_sizes(char *modifier, int expected_size)
>  
>  	*ptr = 's';
>  	check(fmt, 's', -1);
> +
> +	*ptr = 'b';
> +	check(fmt, 'b', -1);
>  }
>  
>  static void test_utilfdt_decode_type(void)
> @@ -90,7 +93,7 @@ static void test_utilfdt_decode_type(void)
>  	/* try every other character */
>  	checkfail("");
>  	for (ch = ' '; ch < 127; ch++) {
> -		if (!strchr("iuxs", ch)) {
> +		if (!strchr("iuxsb", ch)) {
>  			*fmt = ch;
>  			fmt[1] = '\0';
>  			checkfail(fmt);
> diff --git a/util.c b/util.c
> index 40274fb..b9e88f1 100644
> --- a/util.c
> +++ b/util.c
> @@ -340,24 +340,25 @@ int utilfdt_decode_type(const char *fmt, int *type, int *size)
>  
>  	/* get the conversion qualifier */
>  	*size = -1;
> -	if (strchr("hlLb", *fmt)) {
> -		qualifier = *fmt++;
> -		if (qualifier == *fmt) {
> -			switch (*fmt++) {
> -/* TODO:		case 'l': qualifier = 'L'; break;*/
> -			case 'h':
> +	for (; *(fmt + 1); fmt++) {
> +		if (!strchr("hlLb", *fmt))
> +			return -1;
> +		if (qualifier) {
> +			if (*fmt == 'h' && qualifier == 'h')
>  				qualifier = 'b';
> -				break;
> -			}
> +			else
> +				return -1;
> +		} else {
> +			qualifier = *fmt;
>  		}
>  	}
>  
>  	/* we should now have a type */
> -	if ((*fmt == '\0') || !strchr("iuxs", *fmt))
> +	if (!strchr("iuxsb", *fmt))
>  		return -1;
>  
>  	/* convert qualifier (bhL) to byte size */
> -	if (*fmt != 's')
> +	if (*fmt != 's' && *fmt != 'b')
>  		*size = qualifier == 'b' ? 1 :
>  				qualifier == 'h' ? 2 :
>  				qualifier == 'l' ? 4 : -1;
> diff --git a/util.h b/util.h
> index c45b2c2..fa381fc 100644
> --- a/util.h
> +++ b/util.h
> @@ -143,6 +143,7 @@ int utilfdt_write_err(const char *filename, const void *blob);
>   *		i	signed integer
>   *		u	unsigned integer
>   *		x	hex
> + *		b	binary
>   *
>   * TODO: Implement ll modifier (8 bytes)
>   * TODO: Implement o type (octal)
> @@ -160,7 +161,7 @@ int utilfdt_decode_type(const char *fmt, int *type, int *size);
>   */
>  
>  #define USAGE_TYPE_MSG \
> -	"<type>\ts=string, i=int, u=unsigned, x=hex\n" \
> +	"<type>\ts=string, i=int, u=unsigned, x=hex, b=binary\n" \
>  	"\tOptional modifier prefix:\n" \
>  	"\t\thh or b=byte, h=2 byte, l=4 byte (default)";
>  

-- 
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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