Re: [PATCH 2/6 v2] gdb: Add command 'maint set/show debuginfod download-sections'

[Andrew Burgess <aburgess@redhat.com>]

Aaron Merey <amerey@redhat.com> writes:

> v1: https://sourceware.org/pipermail/gdb-patches/2023-February/197461.html
>
> v2 removes 'set debuginfod enabled lazy' and replaces it with
> 'maint set debuginfod download-sections'.
>
> Commit message:
>
> This setting controls whether GDB may attempt to download ELF/DWARF
> sections from debuginfod servers.
>
> This setting is enabled by default if gdb is built with debuginfod
> section download support (requires libdebuginfod 0.188).
>
> Also update debuginfod command help text and gdb.texinfo with
> information on section downloading and the new command.
> ---
>  gdb/debuginfod-support.c | 66 ++++++++++++++++++++++++++++++++++++++--
>  gdb/doc/gdb.texinfo      | 16 ++++++++--
>  2 files changed, 77 insertions(+), 5 deletions(-)
>
> diff --git a/gdb/debuginfod-support.c b/gdb/debuginfod-support.c
> index 8be43a91dcc..6d0521b64e2 100644
> --- a/gdb/debuginfod-support.c
> +++ b/gdb/debuginfod-support.c
> @@ -31,6 +31,10 @@
>  static cmd_list_element *set_debuginfod_prefix_list;
>  static cmd_list_element *show_debuginfod_prefix_list;
>  
> +/* maint set/show debuginfod commands.  */
> +static cmd_list_element *maint_set_debuginfod_cmdlist;
> +static cmd_list_element *maint_show_debuginfod_cmdlist;
> +
>  static const char debuginfod_on[] = "on";
>  static const char debuginfod_off[] = "off";
>  static const char debuginfod_ask[] = "ask";
> @@ -50,6 +54,13 @@ static const char *debuginfod_enabled =
>    debuginfod_off;
>  #endif
>  
> +static bool debuginfod_download_sections =
> +#if defined(HAVE_LIBDEBUGINFOD_FIND_SECTION)
> +  true;
> +#else
> +  false;
> +#endif
> +
>  static unsigned int debuginfod_verbose = 1;
>  
>  #ifndef HAVE_LIBDEBUGINFOD
> @@ -424,7 +435,7 @@ debuginfod_section_query (const unsigned char *build_id,
>    return scoped_fd (-ENOSYS);
>  #else
>  
> - if (!debuginfod_is_enabled ())
> + if (!debuginfod_download_sections || !debuginfod_is_enabled ())
>      return scoped_fd (-ENOSYS);
>  
>    debuginfod_client *c = get_debuginfod_client ();
> @@ -550,6 +561,31 @@ show_debuginfod_verbose_command (ui_file *file, int from_tty,
>  	      value);
>  }
>  
> +/* Set callback for "maint set debuginfod download-sections".  */
> +
> +static void
> +maint_set_debuginfod_download_sections (bool value)
> +{
> +#if !defined(HAVE_LIBDEBUGINFOD_FIND_SECTION)
> +  if (value)
> +    {
> +      error (_("Support for section downloading is not compiled into GDB. " \
> +"Defaulting to \"off\"."));
> +      return;
> +    }
> +#endif
> +
> +  debuginfod_download_sections = value;
> +}
> +
> +/* Get callback for "maint set debuginfod download-sections".  */
> +
> +static bool
> +maint_get_debuginfod_download_sections ()
> +{
> +  return debuginfod_download_sections;
> +}
> +
>  /* Register debuginfod commands.  */
>  
>  void _initialize_debuginfod ();
> @@ -568,8 +604,11 @@ _initialize_debuginfod ()
>  			_("Set whether to use debuginfod."),
>  			_("Show whether to use debuginfod."),
>  			_("\
> -When on, enable the use of debuginfod to download missing debug info and\n\
> -source files."),
> +When set to \"on\", enable the use of debuginfod to download missing\n\
> +debug info and source files. GDB may also download components of debug\n\
> +info instead of entire files. \"off\" disables the use of debuginfod.\n\
> +When set to \"ask\", a prompt may ask whether to enable or disable\n\
> +debuginfod." ),
>  			set_debuginfod_enabled,
>  			get_debuginfod_enabled,
>  			show_debuginfod_enabled,
> @@ -600,4 +639,25 @@ query.\nTo disable, set to zero.  Verbose output is displayed by default."),
>  			     show_debuginfod_verbose_command,
>  			     &set_debuginfod_prefix_list,
>  			     &show_debuginfod_prefix_list);
> +
> +  /* maint set/show debuginfod */
> +  add_setshow_prefix_cmd ("debuginfod", class_maintenance,
> +			  _("Set debuginfod specific variables."),
> +			  _("Show debuginfod specific variables."),
> +			  &maint_set_debuginfod_cmdlist,
> +			  &maint_show_debuginfod_cmdlist,
> +			  &maintenance_set_cmdlist, &maintenance_show_cmdlist);
> +
> +  /* maint set/show debuginfod download-sections */
> +  add_setshow_boolean_cmd ("download-sections", class_maintenance, _("\
> +Set whether debuginfod may download individual ELF/DWARF sections."), _("\
> +Show whether debuginfod may download individual ELF/DWARF sections."), _("\
> +When enabled, debuginfod may attempt to download individual ELF/DWARF \
> +sections from debug info files.\nIf disabled, only whole debug info files \
> +may be downloaded."),
> +			  maint_set_debuginfod_download_sections,
> +			  maint_get_debuginfod_download_sections,
> +			  nullptr,
> +			  &maint_set_debuginfod_cmdlist,
> +			  &maint_show_debuginfod_cmdlist);
>  }
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index fc55c4e7b43..91da9777fd6 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -40872,6 +40872,16 @@ Create a core file? (y or n) @kbd{n}
>  (@value{GDBP})
>  @end smallexample
>  
> +@kindex maint set debuginfod
> +@kindex maint show debuginfod

We should probably add something like:

 @cindex debuginfod, maintenance commands

to help folk find this.

Thanks,
Andrew

> +@item maint set debuginfod download-sections
> +@itemx maint set debuginfod download-sections @r{[}on|off@r{]}
> +@itemx maint show debuginfod download-sections
> +Controls whether @value{GDBN} will attempt to download individual
> +ELF/DWARF sections from @code{debuginfod}.  If disabled, only
> +whole debug info files will be downloaded.  This could result
> +in @value{GDBN} downloading larger amounts of data.
> +
>  @cindex @value{GDBN} internal error
>  @cindex internal errors, control of @value{GDBN} behavior
>  @cindex demangler crashes
> @@ -49382,8 +49392,10 @@ regarding @code{debuginfod}.
>  @item set debuginfod enabled
>  @itemx set debuginfod enabled on
>  @cindex enable debuginfod
> -@value{GDBN} will attempt to query @code{debuginfod} servers when missing debug
> -info or source files.
> +@value{GDBN} will attempt to query @code{debuginfod} servers for missing debug
> +info or source files.  @value{GDBN} may attempt to download individual ELF/DWARF
> +sections such as @code{.gdb_index} to help reduce the total amount of data
> +downloaded from debuginfod servers.
>  
>  @item set debuginfod enabled off
>  @value{GDBN} will not attempt to query @code{debuginfod} servers when missing
> -- 
> 2.40.1