Re: [Qemu-devel] [PATCH] A hexdump function that also displays UTF-8 strings contained in the dumped buffer.

[Anthony Liguori]

On Mon, Nov 11, 2013 at 10:29 AM, Mike Day <address@hidden> wrote:
> This function is used by a forthcomingQemu monitor command that dumps
> contents of OpenFirmware Device Trees. It dumps contents of a buffer
> as hex in the same format as the existing function but also also
> appends any UTF-8 strings in human-readable format.
>
> Like the existing hexdump function, this function may be used
> elsewhere in Qemu, and it shares the same prototype as the existing
> function.
>
> In both functions, check for a NULL prefix parameter and omit printing
> the prefix if it is null.
>
> Here is a sample of the output of both functions with no prefix string:
>
> 0000:  61 62 33 64  62 65 65 66  65 62 34 64  66 62 65 03
> 0010:  67 62 35 64  68 01 05 03  69 62 36 64  6a 01 06 03
> 0020:  6b 62 37 64  6c 01 07 03  6d 62 38 64  6e 01 08 03
> 0030:  6f 62 39 64  70 01 09 03  71 62 78 64
>
> 0000:  61 62 33 64  62 65 65 66  65 62 34 64  66 62 65 03   ab3dbeefeb4dfbe.
> 0010:  67 62 35 64  68 01 05 03  69 62 36 64  6a 01 06 03   gb5dh...ib6dj...
> 0020:  6b 62 37 64  6c 01 07 03  6d 62 38 64  6e 01 08 03   kb7dl...mb8dn...
> 0030:  6f 62 39 64  70 01 09 03  71 62 78 64                ob9dp...qbxd
>
> Signed-off-by: Mike Day <address@hidden>
> ---
>  include/qemu-common.h |  2 ++
>  util/hexdump.c        | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/include/qemu-common.h b/include/qemu-common.h
> index 5054836..7b8e2b9 100644
> --- a/include/qemu-common.h
> +++ b/include/qemu-common.h
> @@ -435,6 +435,8 @@ int mod_utf8_codepoint(const char *s, size_t n, char 
> **end);
>   */
>
>  void qemu_hexdump(const char *buf, FILE *fp, const char *prefix, size_t 
> size);
> +/* include any strings alongside the hex output */
> +void qemu_hexdump_str(gchar *buf, FILE *fp, const gchar *prefix, size_t len);
>
>  /* vector definitions */
>  #ifdef __ALTIVEC__
> diff --git a/util/hexdump.c b/util/hexdump.c
> index 969b340..a920c81 100644
> --- a/util/hexdump.c
> +++ b/util/hexdump.c
> @@ -21,7 +21,11 @@ void qemu_hexdump(const char *buf, FILE *fp, const char 
> *prefix, size_t size)
>
>      for (b = 0; b < size; b++) {
>          if ((b % 16) == 0) {
> -            fprintf(fp, "%s: %04x:", prefix, b);
> +            if (prefix) {
> +                fprintf(fp, "%s: %04x:", prefix, b);
> +            } else {
> +                fprintf(fp, "%04x:", b);
> +            }
>          }
>          if ((b % 4) == 0) {
>              fprintf(fp, " ");
> @@ -35,3 +39,45 @@ void qemu_hexdump(const char *buf, FILE *fp, const char 
> *prefix, size_t size)
>          fprintf(fp, "\n");
>      }
>  }
> +
> +/* print any strings along side the hex dump */
> +void qemu_hexdump_str(gchar *buf, FILE *fp, const gchar *prefix, size_t len)
> +{
> +
> +    gchar *inp, *linep;
> +    int i, offset = 0;
> +    inp = linep = buf;
> +
> +    do {
> +        if (prefix) {
> +            fprintf(fp, "%s: %04x:  ", prefix, offset);
> +        } else {
> +            fprintf(fp, "%04x:  ", offset);
> +        }
> +        for (i = 0; i < 16 && len > 0; i++, len--, offset++, inp++) {
> +            if (i && !(i % 4)) {
> +                fprintf(fp, " ");
> +            }
> +            fprintf(fp, "%02hx ", *inp);
> +        }
> +        int j;
> +        if (i < 16) {
> +            for (j = 16 - i; j; --j) {
> +                fprintf(fp, "   ");
> +                if (j && (!(j % 4))) {
> +                    fprintf(fp, " ");
> +                }
> +            }
> +        }
> +        fprintf(fp, "  ");
> +        for (j = 0; j < i; j++) {
> +            if (*(linep + j) < 0x20 || *(linep + j) > 0x7e) {

You can use qemu_isprint() for this.

> +                fprintf(fp, "%c", '.');
> +            } else {
> +                fprintf(fp, "%c", *(linep + j));

Even though the comment says "UTF-8", this isn't actually handling
UTF-8. Just ascii.

You should fold this into whatever forthcoming patch you are submitting.

Regards,

Anthony Liguori

> +            }
> +        }
> +        fprintf(fp, "\n");
> +        linep = inp;
> +    } while (len);
> +}
>