[PATCH 4/4] bareboximd: make the '-c' option work again

[Ahmad Fatoum]

Hello Antony,

On 28.10.21 03:28, Antony Pavlov wrote:
> bareboximd with the '-c' option craches while
> trying to alter an image file, e.g.:
> 
>     barebox$ git describe
>     v2021.10.0-125-gd136ec5ac6
>     barebox$ make ARCH=arm CROSS_COMPILE=aarch64-linux-gnu- imx_v8_defconfig
>     ...
>     barebox$ make ARCH=arm CROSS_COMPILE=aarch64-linux-gnu-
>     ...
>     images built:
>     barebox-nxp-imx8mm-evk.img
>     barebox-prt-prt8mm.img
>     barebox-nxp-imx8mn-evk.img
>     barebox-nxp-imx8mp-evk.img
>     barebox-nxp-imx8mq-evk.img
>     barebox-zii-imx8mq-dev.img
>     barebox-phytec-phycore-imx8mq.img
>     barebox$ ./scripts/bareboximd images/barebox-phytec-phycore-imx8mq.img
>     build: #1 Thu Oct 28 01:11:07 UTC 2021
>     buildsystem version:
>     crc32: 0x00000000
>     release: 2021.10.0-00125-gd136ec5ac6
>     barebox$ ./scripts/bareboximd -c images/barebox-phytec-phycore-imx8mq.img
>     Segmentation fault (core dumped)
> 
> The problem is that the bareboximd uses mmap() on an image file
> in read-only mode.
> 
> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
> ---
>  scripts/bareboximd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/bareboximd.c b/scripts/bareboximd.c
> index c3dcb4dcf0..fe0d274380 100644
> --- a/scripts/bareboximd.c
> +++ b/scripts/bareboximd.c
> @@ -97,7 +97,7 @@ static int read_file_2(const char *filename, size_t *size, void **outbuf, size_t
>  		goto close;
>  	}
>  
> -	buf = mmap(NULL, max_size, PROT_READ, MAP_SHARED, fd, 0);
> +	buf = mmap(NULL, max_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

I think this here only works incidentally, by failing and then doing a malloc. See mmap(2):

Errors: EACCES    MAP_SHARED was requested and PROT_WRITE is set, but fd is  not  open 
                  in  read/write  (O_RDWR)  mode.

Correct would be MAP_PRIVATE. I sent a patch to that effect yesterday:
https://lore.barebox.org/barebox/20211027060150.28184-1-a.fatoum@pengutronix.de/T/#u

>  	if (buf == MAP_FAILED ) {
>  		buf = malloc(max_size);
>  		if (!buf) {
> 


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