Re: [PATCH v3 5/8] gzip: move input buffer handling into gunzip state

[Jan Beulich <jbeulich@xxxxxxxx>]

On 24.04.2024 18:34, Daniel P. Smith wrote:
> --- a/xen/common/gzip/gunzip.c
> +++ b/xen/common/gzip/gunzip.c
> @@ -10,13 +10,12 @@ struct gunzip_state {
>      unsigned char *window;
>      /* window pointer: */
>      unsigned int wp;
> -};
> -
> -static unsigned char *__initdata inbuf;
> -static unsigned int __initdata insize;
>  
> -/* Index of next byte to be processed in inbuf: */
> -static unsigned int __initdata inptr;
> +    unsigned char *inbuf;
> +    size_t insize;
> +    /* Index of next byte to be processed in inbuf: */
> +    unsigned int inptr;

I'm puzzled by the (suddenly) different types, seeing that ...

> +};
>  
>  #define malloc(a)       xmalloc_bytes(a)
>  #define free(a)         xfree(a)
> @@ -51,14 +50,14 @@ static __init void error(const char *x)
>      panic("%s\n", x);
>  }
>  
> -static __init uch get_byte(void) {
> -    if ( inptr >= insize )
> +static __init uch get_byte(struct gunzip_state *s) {
> +    if ( s->inptr >= s->insize )

... both are compared with one another.

> @@ -1129,29 +1129,29 @@ static int __init gunzip(struct gunzip_state *s)
>          error("Input has invalid flags");
>          return -1;
>      }
> -    NEXTBYTE(); /* Get timestamp */
> -    NEXTBYTE();
> -    NEXTBYTE();
> -    NEXTBYTE();
> +    NEXTBYTE(s); /* Get timestamp */
> +    NEXTBYTE(s);
> +    NEXTBYTE(s);
> +    NEXTBYTE(s);
>  
> -    NEXTBYTE();  /* Ignore extra flags for the moment */
> -    NEXTBYTE();  /* Ignore OS type for the moment */
> +    NEXTBYTE(s);  /* Ignore extra flags for the moment */
> +    NEXTBYTE(s);  /* Ignore OS type for the moment */
>  
>      if ((flags & EXTRA_FIELD) != 0) {
> -        unsigned len = (unsigned)NEXTBYTE();
> -        len |= ((unsigned)NEXTBYTE())<<8;
> -        while (len--) (void)NEXTBYTE();
> +        unsigned len = (unsigned)NEXTBYTE(s);
> +        len |= ((unsigned)NEXTBYTE(s))<<8;
> +        while (len--) (void)NEXTBYTE(s);

Would you mind moving the body of this while() to its own line, as you
touch this anyway?

>      }
>  
>      /* Get original file name if it was truncated */
>      if ((flags & ORIG_NAME) != 0) {
>          /* Discard the old name */
> -        while (NEXTBYTE() != 0) /* null */ ;
> +        while (NEXTBYTE(s) != 0) /* null */ ;
>      }
>  
>      /* Discard file comment if any */
>      if ((flags & COMMENT) != 0) {
> -        while (NEXTBYTE() != 0) /* null */ ;
> +        while (NEXTBYTE(s) != 0) /* null */ ;
>      }

For these two doing the same may help, too.

Jan