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Re: [PATCH 5/6] Add a new gdbarch method to print a single AUXV entry.
- From: Pedro Alves <palves at redhat dot com>
- To: John Baldwin <jhb at FreeBSD dot org>, gdb-patches at sourceware dot org, binutils at sourceware dot org
- Date: Tue, 21 Jun 2016 00:40:16 +0100
- Subject: Re: [PATCH 5/6] Add a new gdbarch method to print a single AUXV entry.
- Authentication-results: sourceware.org; auth=none
- References: <20160616060202 dot 63470-1-jhb at FreeBSD dot org> <20160616060202 dot 63470-6-jhb at FreeBSD dot org>
On 06/16/2016 07:02 AM, John Baldwin wrote:
> Different platforms have different meanings for auxiliary vector
> entries. The 'print_auxv' gdbarch method allows an architecture
> to output a suitable description for platform-specific entries.
>
> A fprint_single_auxv function is split out of fprint_target_auxv.
> This function outputs the description of a single auxiliary vector
> entry to the specified file using caller-supplied formatting and
> strings to describe the vector type.
>
> The existing switch on auxiliary vector types is moved out of
> fprint_target_auxv into a new default_print_auxv function.
> default_print_auxv chooses an appropriate format and description
> and calls fprint_single_auxv to describe a single vector entry.
>
> fprint_target_auxv now invokes the gdbarch 'print_auxv' function
> on each vector entry. If the function is not present or returns
> zero, default_printf_auxv is called to output a description for
> the vector.
I like the idea. Though, I think we can simplify this. How about:
- make default_print_auxv be the default gdbarch_print_auxv
implementation, in gdbarch.sh.
- make fprint_target_auxv calls gdbarch_print_auxv unconditionally.
- remove the support for gdbarch_print_auxv returning 0. Instead,
implementations that want to defer to default_print_auxv simply
call it directly.
Also, I think it'd be a bit less confusing to rename things like this:
gdbarch_print_auxv -> gdbarch_print_auxv_entry
default_print_auxv -> default_print_auxv_entry
fprint_single_auxv -> fprint_auxv_entry
This way methods that print a single entry are consistently named,
and not so easily confused with methods that print the whole table,
like fprint_target_auxv.
>
>
> +/* Print a description of a single AUXV entry on the specified file. */
> +void
Empty line between comment and function.
> +fprint_single_auxv (struct ui_file *file, const char *name,
> + const char *description, enum auxv_format flavor,
> + CORE_ADDR type, CORE_ADDR val)
> +{
> + fprintf_filtered (file, "%-4s %-20s %-30s ",
> + plongest (type), name, description);
If not translatable, wrap string in () [not _()], in order to
avoid ARI complaints.
> + switch (flavor)
> + {
> + case dec:
> + fprintf_filtered (file, "%s\n", plongest (val));
> + break;
> + case hex:
> + fprintf_filtered (file, "%s\n", paddress (target_gdbarch (), val));
> + break;
> + case str:
> + {
> + struct value_print_options opts;
> +
> + get_user_print_options (&opts);
> + if (opts.addressprint)
> + fprintf_filtered (file, "%s ", paddress (target_gdbarch (), val));
> + val_print_string (builtin_type (target_gdbarch ())->builtin_char,
> + NULL, val, -1, file, &opts);
> + fprintf_filtered (file, "\n");
> + }
Likewise the other format strings.
> +
> +static void
> +default_print_auxv (struct ui_file *file, CORE_ADDR type, CORE_ADDR val)
> +{
Intro comment. Something like "default implementation of ...".
> +
> /* Print the contents of the target's AUXV on the specified file. */
> int
> fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
> {
> + struct gdbarch *gdbarch = target_gdbarch();
Space before open parenthesis.
> diff --git a/gdb/auxv.h b/gdb/auxv.h
> index 9efe604..91d94f9 100644
> --- a/gdb/auxv.h
> +++ b/gdb/auxv.h
> @@ -46,6 +46,14 @@ extern int target_auxv_parse (struct target_ops *ops,
> extern int target_auxv_search (struct target_ops *ops,
> CORE_ADDR match, CORE_ADDR *valp);
>
> +/* Print a description of a single AUXV entry on the specified file. */
> +enum auxv_format { dec, hex, str };
These very generic names used to be OK, because they were
defined inside the function. But now that this is in a header,
the potential for conflict is much higher. hex could conflict
with std::hex, for instance. Please rename the values to
for example: AUXV_FORMAT_DEC / AUXV_FORMAT_HEX / AUXV_FORMAT_STR.
We should add a comment for what each value means, too, since
we lost the pass of obvious-because-of-locality.
> +
> +extern void fprint_single_auxv (struct ui_file *file, const char *name,
> + const char *description,
> + enum auxv_format flavor, CORE_ADDR type,
I'd find it more consistent to call parameter "format" instead of "flavor",
which then avoids people looking for enum auxv_flavor.
> +# Print the description of a single auxv entry described by TYPE and VAL
> +# to FILE. Return 0 and output no description if the TYPE is unknown.
> +# Return 0 if the TYPE of the auxv entry is unknown.
> +# Return 1 if a description was output.
> +M:int:print_auxv:struct ui_file *file, CORE_ADDR type, CORE_ADDR val:file, type, val
Thanks,
Pedro Alves