Re: patch 1/2 debuginfod client

[Mark Wielaard <mark@klomp.org>]

Hi,

On Mon, 2019-10-28 at 15:06 -0400, Frank Ch. Eigler wrote:
> From 3e1f8d93569004d06902459d84baceb636e139d5 Mon Sep 17 00:00:00 2001
> From: Aaron Merey <amerey@redhat.com>
> Date: Mon, 28 Oct 2019 13:29:26 -0400
> Subject: [PATCH 1/2] debuginfod 1/2: client side
> 
> Introduce the debuginfod/ subdirectory, containing the client for a
> new debuginfo-over-http service, in shared-library and command-line
> forms.  Two functions in libdwfl make calls into the client library to
> fetch elf/dwarf files by buildid, as a fallback.  Instead of normal
> dynamic linking (thus pulling in a variety of curl dependencies),
> the libdwfl hooks use dlopen/dlsym.  Server & tests coming in patch 2.
> 
> Signed-off-by: Aaron Merey <amerey@redhat.com>
> Signed-off-by: Frank Ch. Eigler <fche@redhat.com>

A few comments on the first (top-level) part, just to make progress.

> diff --git a/ChangeLog b/ChangeLog
> index 911cf35432c9..4f33657df976 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,9 @@
> +2019-10-28  Aaron Merey  <amerey@redhat.com>
> +
> +	* debuginfod/: New directory for debuginfod code.
> +	* Makefile.am (SUBDIRS): Recurse there.
> +	* configure.ac (--enable-debuginfod): New flag & checks.
> +
>  2019-07-05  Omar Sandoval  <osandov@fb.com>
>  
>  	* configure.ac: Get rid of --enable-libebl-subdir.
> diff --git a/Makefile.am b/Makefile.am
> index 52f64fc904f4..bd8926b52344 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -29,6 +29,10 @@ pkginclude_HEADERS = version.h
>  SUBDIRS = config m4 lib libelf libcpu backends libebl libdwelf libdwfl libdw \
>  	  libasm src po doc tests
>  
> +if DEBUGINFOD
> +SUBDIRS += debuginfod
> +endif
> +
>  EXTRA_DIST = elfutils.spec GPG-KEY NOTES CONTRIBUTING \
>  	     COPYING COPYING-GPLV2 COPYING-LGPLV3

I was afraid this wouldn't play nice with make dist, but ...

"If SUBDIRS is defined conditionally using Automake
conditionals, Automake will define DIST_SUBDIRS automatically
from the possible values of SUBDIRS in all conditions."
https://www.gnu.org/software/automake/manual/html_node/SUBDIRS-vs-DIST_005fSUBDIRS.html

So this is fine.

> diff --git a/config/Makefile.am b/config/Makefile.am
> index 9d292cee66c8..6425718efc54 100644
> --- a/config/Makefile.am
> +++ b/config/Makefile.am
> @@ -32,7 +32,7 @@ EXTRA_DIST = elfutils.spec.in known-dwarf.awk 10-default-yama-scope.conf
>  	     libelf.pc.in libdw.pc.in
>  
>  pkgconfigdir = $(libdir)/pkgconfig
> -pkgconfig_DATA = libelf.pc libdw.pc
> +pkgconfig_DATA = libelf.pc libdw.pc libdebuginfod.pc
>  
>  if MAINTAINER_MODE
>  $(srcdir)/elfutils.spec.in: $(top_srcdir)/NEWS

Nice to have a separate libdebuginfod.pc

> diff --git a/config/libdebuginfod.pc.in b/config/libdebuginfod.pc.in
> new file mode 100644
> index 000000000000..46722a76b593
> --- /dev/null
> +++ b/config/libdebuginfod.pc.in
> @@ -0,0 +1,12 @@
> +prefix=@prefix@
> +exec_prefix=@exec_prefix@
> +libdir=@libdir@
> +includedir=@includedir@
> +
> +Name: debuginfod
> +Description: elfutils library to query debuginfo files from debuginfod servers
> +Version: @VERSION@
> +URL: http://elfutils.org/
> +
> +Libs: -L${libdir} -ldebuginfod
> +Cflags: -I${includedir}

No Requires on libelf or libdw?

> diff --git a/configure.ac b/configure.ac
> index 9be34d124387..738a96f18bf5 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -60,6 +60,8 @@ AC_CONFIG_FILES([m4/Makefile])
>  dnl The RPM spec file.  We substitute a few values in the file.
>  AC_CONFIG_FILES([elfutils.spec:config/elfutils.spec.in])
>  
> +dnl debuginfo-server client & server parts.
> +AC_CONFIG_FILES([debuginfod/Makefile])
>  
>  AC_CANONICAL_HOST
>  
> @@ -86,6 +88,8 @@ AS_IF([test "$use_locks" = yes],
>  AH_TEMPLATE([USE_LOCKS], [Defined if libraries should be thread-safe.])
>  
>  AC_PROG_CC
> +AC_PROG_CXX
> +AX_CXX_COMPILE_STDCXX(11, noext, optional)
>  AC_PROG_RANLIB
>  AC_PROG_YACC
>  AM_PROG_LEX
> @@ -538,7 +542,7 @@ AM_CONDITIONAL(STANDALONE, false)dnl Used in tests/Makefile.am, which see.
>  AC_CONFIG_FILES([tests/Makefile])
>  
>  dnl pkgconfig files
> -AC_CONFIG_FILES([config/libelf.pc config/libdw.pc])
> +AC_CONFIG_FILES([config/libelf.pc config/libdw.pc config/libdebuginfod.pc])

My only concern is that these might slow down configure when debuginfod
isn't enabled? Can/Should they be moved later after the enable test?

>  # Get the definitions necessary to create the Makefiles in the po
>  # subdirectories.  This is a small subset of the gettext rules.
> @@ -641,6 +645,22 @@ if test "$HAVE_BUNZIP2" = "no"; then
>    AC_MSG_WARN([No bunzip2, needed to run make check])
>  fi
>  
> +# Look for libmicrohttpd, libcurl, libarchive, sqlite for debuginfo server
> +# minimum versions as per rhel7.  Single --enable-* option arranges to build
> +# both client libs and server process.
> +
> +PKG_PROG_PKG_CONFIG
> +AC_ARG_ENABLE([debuginfod], AC_HELP_STRING([--enable-debuginfod], [Build debuginfo server and client solib]))
> +AS_IF([test "x$enable_debuginfod" = "xyes"], [
> +    AC_DEFINE([ENABLE_DEBUGINFOD],[1],[Build debuginfo-server])
> +    PKG_CHECK_MODULES([libmicrohttpd],[libmicrohttpd >= 0.9.33])
> +    PKG_CHECK_MODULES([libcurl],[libcurl >= 7.29.0])
> +    PKG_CHECK_MODULES([sqlite3],[sqlite3 >= 3.7.17])
> +    PKG_CHECK_MODULES([libarchive],[libarchive >= 3.1.2])
> +], [enable_debuginfod="no"])
> +AM_CONDITIONAL([DEBUGINFOD],[test "x$enable_debuginfod" = "xyes"])

Would it be better to enable by default with an error to disable if any
dependencies (and CXX compiler?) aren't found?

If not, then I think you should add it explicitly to the
AM_DISTCHECK_CONFIGURE_FLAGS in Makefile.am.

>  AC_OUTPUT
>  
>  AC_MSG_NOTICE([
> @@ -669,6 +689,7 @@ AC_MSG_NOTICE([
>    OTHER FEATURES
>      Deterministic archives by default  : ${default_ar_deterministic}
>      Native language support            : ${USE_NLS}
> +    Debuginfo server support           : ${enable_debuginfod}

client and server support?

Cheers,

Mark