[PATCH] cmd: efidebug: fix a failure of "boot rm" sub-command

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Fri, Feb 28, 2020 at 07:05:39PM +0100, Heinrich Schuchardt wrote:
> On 2/28/20 1:05 AM, AKASHI Takahiro wrote:
> > There is a wrong usage of utf8_utf16_strncpy() in "boot rm" command, and
> > then it will end up with a failure of this command due to a wrong
> > value of an interim variable ("var_name16").
> > 
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > ---
> >   cmd/efidebug.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/cmd/efidebug.c b/cmd/efidebug.c
> > index 576e95b395dc..3a50dafbbca6 100644
> > --- a/cmd/efidebug.c
> > +++ b/cmd/efidebug.c
> > @@ -641,7 +641,7 @@ static int do_efi_boot_rm(cmd_tbl_t *cmdtp, int flag,
> >   	int id, i;
> >   	char *endp;
> >   	char var_name[9];
> > -	u16 var_name16[9];
> > +	u16 var_name16[9], *p;
> >   	efi_status_t ret;
> > 
> >   	if (argc == 1)
> > @@ -654,7 +654,8 @@ static int do_efi_boot_rm(cmd_tbl_t *cmdtp, int flag,
> >   			return CMD_RET_FAILURE;
> > 
> >   		sprintf(var_name, "Boot%04X", id);
> > -		utf8_utf16_strncpy((u16 **)&var_name16, var_name, 9);
> > +		p = var_name16;
> > +		utf8_utf16_strncpy(&p, var_name, 9);
> 
> This is duplicating code in do_efi_boot_add(). Please, consider putting
> the following codeblock into separate function:

No.

> ??????? id = (int)simple_strtoul(argv[1], &endp, 16);
> ????????if (*endp != '\0' || id > 0xffff)
> ????????????????return CMD_RET_USAGE;
> 
> ????????sprintf(var_name, "Boot%04X", id);
> ????????p = var_name16;
> ????????utf8_utf16_strncpy(&p, var_name, 9);

Frankly, I don't like this function's prototype because it is different
from "normal" corresponding C libraries.
Moreover, as far as I notice, there is no use case where the first
parameter which is modified after calling is used in any code.

Thanks,
-Takahiro Akashi

> try_load_entry() has another implementation.
> 
> Best regards
> 
> Heinrich
> 
> > 
> >   		ret = EFI_CALL(RT->set_variable(var_name16, &guid, 0, 0, NULL));
> >   		if (ret) {
> > 
>