Re: [Qemu-trivial] [PATCH for 2.10 26/35] linux-user: use is_error() to avoid warnings and make the code clearer

[Laurent Vivier <laurent@vivier.eu>]

Le 24/07/2017 à 20:27, Philippe Mathieu-Daudé a écrit :
> linux-user/flatload.c:740:9: warning: Loss of sign in implicit conversion
>     if (res > (unsigned long)-4096)
>         ^~~
> 
> Reported-by: Clang Static Analyzer
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

> ---
>  linux-user/flatload.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/linux-user/flatload.c b/linux-user/flatload.c
> index a35a560904..10c529910f 100644
> --- a/linux-user/flatload.c
> +++ b/linux-user/flatload.c
> @@ -224,8 +224,9 @@ static int decompress_exec(
>  		ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);
>  		if (ret <= 0)
>  			break;
> -		if (ret >= (unsigned long) -4096)
> +                if (is_error(ret)) {
>  			break;
> +                }
>  		len -= ret;
>  
>  		strm.next_in = buf;
> @@ -283,8 +284,7 @@ calc_reloc(abi_ulong r, struct lib_info *p, int curid, int internalp)
>                      "in same module (%d != %d)\n",
>                      (unsigned) r, curid, id);
>              goto failed;
> -        } else if ( ! p[id].loaded &&
> -                    load_flat_shared_library(id, p) > (unsigned long) -4096) {
> +        } else if (!p[id].loaded && is_error(load_flat_shared_library(id, p))) {
>              fprintf(stderr, "BINFMT_FLAT: failed to load library %d\n", id);
>              goto failed;
>          }
> @@ -523,9 +523,10 @@ static int load_flat_file(struct linux_binprm * bprm,
>                  fpos = 0;
>                  result = bprm->file->f_op->read(bprm->file,
>                                  (char *) textpos, text_len, &fpos);
> -                if (result < (unsigned long) -4096)
> +                if (!is_error(result)) {
>                          result = decompress_exec(bprm, text_len, (char *) datapos,
>                                           data_len + (relocs * sizeof(unsigned long)), 0);
> +                }
>          }
>          else
>  #endif
> @@ -693,8 +694,9 @@ static int load_flat_shared_library(int id, struct lib_info *libs)
>  
>  	res = prepare_binprm(&bprm);
>  
> -	if (res <= (unsigned long)-4096)
> +        if (!is_error(res)) {
>  		res = load_flat_file(&bprm, libs, id, NULL);
> +        }
>  	if (bprm.file) {
>  		allow_write_access(bprm.file);
>  		fput(bprm.file);
> @@ -737,8 +739,9 @@ int load_flt_binary(struct linux_binprm *bprm, struct image_info *info)
>  
>  
>      res = load_flat_file(bprm, libinfo, 0, &stack_len);
> -    if (res > (unsigned long)-4096)
> +    if (is_error(res)) {
>              return res;
> +    }
>  
>      /* Update data segment pointers for all libraries */
>      for (i=0; i<MAX_SHARED_LIBS; i++) {
>