[U-Boot] [PATCH] fix: tools: kwbimage.c: Initialize headersz to suppress warning

[Thomas Petazzoni]

Dear Lukasz Majewski,

Thanks for your patch.

On Fri, 21 Nov 2014 09:22:43 +0100, Lukasz Majewski wrote:
> When building with my toolchain (4.8.2):
> CROSS_COMPILE=/home/lukma/work/ptxdist/toolchains/arm/OSELAS.Toolchain-2013.12.0/arm-v7a-linux-gnueabi/gcc-4.8.2-glibc-2.18-binutils-2.24-kernel-3.12-sanitized/bin/arm-v7a-linux-gnueabi-

Well, your target toolchain doesn't have much to do about the issue.
tools/kwbimage.c is built for the host.

> I see following WARNING:
> tools/kwbimage.c: In function "kwbimage_set_header":
> tools/kwbimage.c:803:8: warning: "headersz" may be used uninitialized in this function [-Wmaybe-uninitialized]
>   memcpy(ptr, image, headersz);
>         ^
> This fix aims to suppress it.
> 
> Signed-off-by: Lukasz Majewski <l.majewski at samsung.com>
> ---
>  tools/kwbimage.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/kwbimage.c b/tools/kwbimage.c
> index c50f2e2..2c302e5 100644
> --- a/tools/kwbimage.c
> +++ b/tools/kwbimage.c
> @@ -728,7 +728,7 @@ static void kwbimage_set_header(void *ptr, struct stat *sbuf, int ifd,
>  	FILE *fcfg;
>  	void *image = NULL;
>  	int version;
> -	size_t headersz;
> +	size_t headersz = 0;
>  	uint32_t checksum;
>  	int ret;
>  	int size;

Looking briefly again at the code, I believe the warning from gcc is
probably bogus. Here is the code:

        size_t headersz;
	[...]
        version = image_get_version();
        switch (version) {
                /*
                 * Fallback to version 0 if no version is provided in the
                 * cfg file
                 */
        case -1:
        case 0:
                image = image_create_v0(&headersz, params, sbuf->st_size);
                break;

        case 1:
                image = image_create_v1(&headersz, params, sbuf->st_size);
                break;

        default:
                fprintf(stderr, "Unsupported version %d\n", version);
                free(image_cfg);
                exit(EXIT_FAILURE);
        }
	[...]
        /* Finally copy the header into the image area */
        memcpy(ptr, image, headersz);

So the usage of 'headersz' is only done if we have gone through either
the -1/0/1 cases. In the 'default' case, we exit the tool, so the
memcpy() is never reached. Maybe gcc doesn't realize we're getting out
of the function in the default case.

But oh well, if it fixes a warning :-)

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com