Re: [Qemu-devel] [PATCH v6 04/11] dump: Add API to write elf notes to buffer

[Laszlo Ersek <lersek@redhat.com>]

some tangential comments:

On 01/05/14 08:27, Qiao Nuohan wrote:
> the function can be used by write_elf32_notes/write_elf64_notes to write notes
> to a buffer. If fd_write_vmcore is used, write_elf32_notes/write_elf64_notes
> will write elf notes to vmcore directly. Instead, if buf_write_note is used,
> elf notes will be written to opaque->note_buf at first.
> 
> Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
> ---
>  dump.c |   19 +++++++++++++++++++
>  1 files changed, 19 insertions(+), 0 deletions(-)
> 
> diff --git a/dump.c b/dump.c
> index 764db39..3b9cf00 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -76,6 +76,9 @@ typedef struct DumpState {
>      int64_t begin;
>      int64_t length;
>      Error **errp;
> +
> +    void *note_buf;
> +    size_t note_buf_offset;
>  } DumpState;
>  
>  static int dump_cleanup(DumpState *s)
> @@ -754,6 +757,22 @@ static int write_buffer(int fd, bool flag_flatten, off_t offset, void *buf,
>      return 0;
>  }
>  
> +static int buf_write_note(void *buf, size_t size, void *opaque)
> +{

"const void *buf" would have been more "elegant".

> +    DumpState *s = opaque;
> +
> +    /* note_buf is not enough */
> +    if (s->note_buf_offset + size > s->note_size) {
> +        return -1;
> +    }
> +
> +    memcpy(s->note_buf + s->note_buf_offset, buf, size);

Giving type "uint8_t" to "*note_buf" would have been preferable.
Addition to a pointer-to-void is a constraint violation in standard C
("... operand shall be a pointer to an object type ..."), ie. it's a gcc
extension here, but I guess we can live with it.

Using s->note_size as limit seems correct.

> +
> +    s->note_buf_offset += size;
> +
> +    return 0;
> +}
> +
>  static ram_addr_t get_start_block(DumpState *s)
>  {
>      GuestPhysBlock *block;
> 

Reviewed-by: Laszlo Ersek <lersek@redhat.com>