ACK: [PATCH 3/5] lib: fwts_alloc: avoid using void * pointer arithmetic

[Alex Hung]

On 14-09-11 10:05 PM, Colin King wrote:
> From: Colin Ian King <colin.king at canonical.com>
>
> cppcheck reports:
>    When using void pointers in calculations, the behaviour is undefined
>
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
>   src/lib/src/fwts_alloc.c | 11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/src/lib/src/fwts_alloc.c b/src/lib/src/fwts_alloc.c
> index 9610159..2a8fcd9 100644
> --- a/src/lib/src/fwts_alloc.c
> +++ b/src/lib/src/fwts_alloc.c
> @@ -19,6 +19,7 @@
>   #include <sys/mman.h>
>   #include <string.h>
>   #include <stdio.h>
> +#include <stdint.h>
>   #include <unistd.h>
>   #include <stddef.h>
>   
> @@ -83,7 +84,7 @@ static void *fwts_low_mmap(const size_t requested_size)
>   		if ((first_addr_start == NULL) &&
>   		    (addr_start > (void*)LIMIT_START)) {
>   			size_t sz = (requested_size + CHUNK_SIZE) & ~(CHUNK_SIZE - 1);
> -			void *addr = addr_start - sz;
> +			void *addr = (uint8_t*)addr_start - sz;
>   
>   			/*
>   			 * If addr is over the 2GB limit and we know
> @@ -108,7 +109,7 @@ static void *fwts_low_mmap(const size_t requested_size)
>   		 */
>   		if ((last_addr_end != NULL) &&
>   		    (last_addr_end < (void*)LIMIT_2GB)) {
> -			if ((addr_start - last_addr_end) > (ptrdiff_t)requested_size) {
> +			if (((uint8_t *)addr_start - (uint8_t *)last_addr_end) > (ptrdiff_t)requested_size) {
>   				void *addr = last_addr_end;
>   				ret = mmap(addr, requested_size, PROT_READ | PROT_WRITE,
>   					MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1, 0);
> @@ -176,7 +177,7 @@ void *fwts_low_calloc(const size_t nmemb, const size_t size)
>   	hdr->size = n;
>   	hdr->magic = FWTS_ALLOC_MAGIC;
>   
> -	return (ret + sizeof(fwts_mmap_header));
> +	return (void *)((uint8_t *)ret + sizeof(fwts_mmap_header));
>   }
>   
>   /*
> @@ -201,7 +202,7 @@ void *fwts_low_realloc(const void *ptr, const size_t size)
>   		return fwts_low_malloc(size);
>   
>   	hdr = (fwts_mmap_header *)
> -		(ptr - sizeof(fwts_mmap_header));
> +		((uint8_t *)ptr - sizeof(fwts_mmap_header));
>   
>   	/* sanity check */
>   	if (hdr->magic != FWTS_ALLOC_MAGIC)
> @@ -224,7 +225,7 @@ void fwts_low_free(const void *ptr)
>   {
>   	if (ptr) {
>   		fwts_mmap_header *hdr = (fwts_mmap_header *)
> -			(ptr - sizeof(fwts_mmap_header));
> +			((uint8_t *)ptr - sizeof(fwts_mmap_header));
>   		if (hdr->magic == FWTS_ALLOC_MAGIC)
>   			munmap(hdr, hdr->size);
>   	}

Acked-by: Alex Hung <alex.hung at canonical.com>