Re: [PATCH v2] Add SVR4 psABI specific parser for AUXV entries

[Simon Marchi <simark@simark.ca>]

> diff --git a/gdb/auxv.c b/gdb/auxv.c
> index c13d7a22eb9..28e8d2f704d 100644
> --- a/gdb/auxv.c
> +++ b/gdb/auxv.c
> @@ -248,34 +248,65 @@ memory_xfer_auxv (struct target_ops *ops,
>    return procfs_xfer_auxv (readbuf, writebuf, offset, len, xfered_len);
>  }
> 
> -/* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
> -   Return 0 if *READPTR is already at the end of the buffer.
> -   Return -1 if there is insufficient buffer for a whole entry.
> -   Return 1 if an entry was read into *TYPEP and *VALP.  */
> -int
> -default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
> -		   gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
> +/* This function compared to other auxv_parse functions: it takes the size of
> +   the auxv type field as a parameter.  */
> +
> +static int
> +generic_auxv_parse (struct gdbarch *gdbarch, gdb_byte **readptr,
> +		    gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp,
> +		    int sizeof_auxv_type)
>  {
> -  const int sizeof_auxv_field = gdbarch_ptr_bit (target_gdbarch ())
> -				/ TARGET_CHAR_BIT;
> -  const enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
> +  struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
> +  const int sizeof_auxv_val = TYPE_LENGTH (ptr_type);
> +  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
>    gdb_byte *ptr = *readptr;
> 
>    if (endptr == ptr)
>      return 0;
> 
> -  if (endptr - ptr < sizeof_auxv_field * 2)
> +  if (endptr - ptr < 2 * sizeof_auxv_val)
>      return -1;
> 
> -  *typep = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
> -  ptr += sizeof_auxv_field;
> -  *valp = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
> -  ptr += sizeof_auxv_field;
> +  *typep = extract_unsigned_integer (ptr, sizeof_auxv_type, byte_order);
> +  /* Even if the auxv type takes less space than an auxv value, there is
> +     padding after the type such that the value is aligned on a multiple of
> +     its size (and this is why we advance by `sizeof_auxv_val` and not
> +     `sizeof_auxv_type`.  */

The parenthesis in the comment is not closed.

> diff --git a/gdb/auxv.h b/gdb/auxv.h
> index a5a932ec80e..c1d11ea2c7b 100644
> --- a/gdb/auxv.h
> +++ b/gdb/auxv.h
> @@ -25,12 +25,27 @@
>  /* See "include/elf/common.h" for the definition of valid AT_* values.  */
> 
>  /* The default implementation of to_auxv_parse, used by the target
> -   stack.  */
> +   stack.
> 
> +   Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
> +   Return 0 if *READPTR is already at the end of the buffer.
> +   Return -1 if there is insufficient buffer for a whole entry.
> +   Return 1 if an entry was read into *TYPEP and *VALP.  */
>  extern int default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
>  			       gdb_byte *endptr, CORE_ADDR *typep,
>  			       CORE_ADDR *valp);
> 
> +/* The SVR4 psABI implementation of to_auxv_parse, that uses an int to
> +   store the type rather than long as assumed by the default parser.
> +
> +   Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
> +   Return 0 if *READPTR is already at the end of the buffer.
> +   Return -1 if there is insufficient buffer for a whole entry.
> +   Return 1 if an entry was read into *TYPEP and *VALP.  */
> +extern int svr4_auxv_parse (struct gdbarch *gdbarch, gdb_byte **readptr,
> +			       gdb_byte *endptr, CORE_ADDR *typep,
> +			       CORE_ADDR *valp);

The last two lines are not properly aligned on the parenthesis.

Simon