debuginfod: Support queries for ELF/DWARF sections

Add new function debuginfod_find_section which queries debuginfod
servers for the raw binary contents of the specified ELF/DWARF section
in a file matching the given build-id.

Extend the server webapi to support section queries. Section query
URLS have the following format: /buildid/BUILDID/section/SECTION

The server will attempt to extract the section from a debuginfo file
matching the given build-id.  If the debuginfo file cannot be found
or the section has type SHT_NOBITS, the server will attempt to extract
the section from the executable file matching the build-id.

If the server is built without section query support, the client will
attempt to download the debuginfo matching the build-id and extract the
section.  If the debuginfo file cannot be found or the section has type
SHT_NOBITS, the server will attempt to download the executable file
matching the build-id and extract the section.

Signed-off-by: Aaron Merey <amerey@redhat.com>

3 files changed, 143 insertions, 1 deletions

diff --git a/tests/ChangeLog b/tests/ChangeLog
index a240a705..fb0dce82 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,8 @@
+2022-10-31  Aaron Merey  <amerey@redhat.com>
+
+	* Makefile.am (TESTS): Add run-debuginfod-section.sh.
+	* run-debuginfod-section.sh: New test.
+
 2022-09-20  Yonggang Luo  <luoyonggang@gmail.com>
 
 	* Makefile.am (EXTRA_DIST): Remove debuginfod-rpms/hello2.spec.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index ced4a826..356b3fbf 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -247,7 +247,8 @@ TESTS += run-debuginfod-dlopen.sh \
          run-debuginfod-x-forwarded-for.sh \
          run-debuginfod-response-headers.sh \
          run-debuginfod-extraction-passive.sh \
-	 run-debuginfod-webapi-concurrency.sh
+	 run-debuginfod-webapi-concurrency.sh \
+	 run-debuginfod-section.sh
 endif
 if !OLD_LIBMICROHTTPD
 # Will crash on too old libmicrohttpd
@@ -554,6 +555,7 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
 	     run-debuginfod-response-headers.sh \
              run-debuginfod-extraction-passive.sh \
              run-debuginfod-webapi-concurrency.sh \
+	     run-debuginfod-section.sh \
 	     debuginfod-rpms/fedora30/hello2-1.0-2.src.rpm \
 	     debuginfod-rpms/fedora30/hello2-1.0-2.x86_64.rpm \
 	     debuginfod-rpms/fedora30/hello2-debuginfo-1.0-2.x86_64.rpm \
diff --git a/tests/run-debuginfod-section.sh b/tests/run-debuginfod-section.sh
new file mode 100755
index 00000000..a3cae349
--- /dev/null
+++ b/tests/run-debuginfod-section.sh
@@ -0,0 +1,135 @@
+#!/usr/bin/env bash
+#
+# Copyright (C) 2019-2021 Red Hat, Inc.
+# This file is part of elfutils.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/debuginfod-subr.sh
+
+# for test case debugging, uncomment:
+set -x
+unset VALGRIND_CMD
+
+DB=${PWD}/.debuginfod_tmp.sqlite
+tempfiles $DB
+export DEBUGINFOD_CACHE_PATH=${PWD}/.client_cache
+
+# Set up directories for scanning
+mkdir F
+mkdir R
+cp -rvp ${abs_srcdir}/debuginfod-rpms R
+
+# This variable is essential and ensures no time-race for claiming ports occurs
+# set base to a unique multiple of 100 not used in any other 'run-debuginfod-*' test
+base=13000
+get_ports
+
+# We use -t0 and -g0 here to turn off time-based scanning & grooming.
+# For testing purposes, we just sic SIGUSR1 at the process.
+
+env LD_LIBRARY_PATH=$ldpath DEBUGINFOD_URLS= ${abs_builddir}/../debuginfod/debuginfod $VERBOSE \
+    -R R -F F -p $PORT1 -d $DB -t0 -g0 -v F > vlog$PORT1 2>&1 &
+PID1=$!
+tempfiles vlog$PORT1
+errfiles vlog$PORT1
+# Server must become ready
+wait_ready $PORT1 'ready' 1
+# And initial scan should be done
+wait_ready $PORT1 'thread_work_total{role="traverse"}' 1
+
+export DEBUGINFOD_URLS=http://127.0.0.1:$PORT1
+
+# Check thread comm names
+ps -q $PID1 -e -L -o '%p %c %a' | grep groom
+ps -q $PID1 -e -L -o '%p %c %a' | grep scan
+ps -q $PID1 -e -L -o '%p %c %a' | grep traverse
+
+########################################################################
+
+# Compile a simple program, strip its debuginfo and save the build-id.
+# Also move the debuginfo into another directory so that elfutils
+# cannot find it without debuginfod.
+tempfiles prog.c
+echo "int main() { return 0; }" > ${PWD}/prog.c
+
+gcc -Wl,--build-id -g -o F/prog ${PWD}/prog.c
+
+testrun ${abs_top_builddir}/src/strip -g -f F/prog.debug ${PWD}/F/prog
+BUILDID=`env LD_LIBRARY_PATH=$ldpath ${abs_builddir}/../src/readelf \
+          -a F/prog | grep 'Build ID' | cut -d ' ' -f 7`
+
+kill -USR1 $PID1
+# Wait till both files are in the index.
+wait_ready $PORT1 'thread_work_total{role="traverse"}' 2
+wait_ready $PORT1 'thread_work_pending{role="scan"}' 0
+wait_ready $PORT1 'thread_busy{role="scan"}' 0
+
+########################################################################
+
+# Build-id for a file in the one of the testsuite's F31 rpms
+RPM_BUILDID=420e9e3308971f4b817cc5bf83928b41a6909d88
+
+# Download sections from files indexed with -F
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $BUILDID .debug_info
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $BUILDID .text
+
+# Download sections from files indexed with -R
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $RPM_BUILDID .debug_info
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $RPM_BUILDID .text
+
+# Verify that the downloaded files match the contents of the original sections
+tempfiles ${BUILDID}.debug_info
+objcopy F/prog.debug -O binary --only-section=.debug_info --set-section-flags .debug_info=alloc $BUILDID.debug_info
+cmp ${BUILDID}.debug_info ${DEBUGINFOD_CACHE_PATH}/${BUILDID}/section-.debug_info
+
+tempfiles ${BUILDID}.text
+objcopy F/prog -O binary --only-section=.text ${BUILDID}.text
+cmp ${BUILDID}.text ${DEBUGINFOD_CACHE_PATH}/${BUILDID}/section-.text
+
+# Download the original debuginfo/executable files.
+DEBUGFILE=`env LD_LIBRARY_PATH=$ldpath ${abs_top_builddir}/debuginfod/debuginfod-find debuginfo $RPM_BUILDID`
+EXECFILE=`env LD_LIBRARY_PATH=$ldpath ${abs_top_builddir}/debuginfod/debuginfod-find executable $RPM_BUILDID`
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv debuginfo $BUILDID
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv executable $BUILDID
+
+if test "$(arch)" == "x86_64"; then
+  tempfiles DEBUGFILE.debug_info
+  objcopy $DEBUGFILE -O binary --only-section=.debug_info --set-section-flags .debug_info=alloc DEBUGFILE.debug_info
+  testrun diff -u DEBUGFILE.debug_info ${DEBUGINFOD_CACHE_PATH}/${RPM_BUILDID}/section-.debug_info
+
+  tempfiles EXECFILE.text
+  objcopy $EXECFILE -O binary --only-section=.text EXECFILE.text
+  testrun diff -u EXECFILE.text ${DEBUGINFOD_CACHE_PATH}/${RPM_BUILDID}/section-.text
+fi
+
+# Kill the server.
+kill $PID1
+wait $PID1
+PID1=0
+
+# Delete the section files from the cache.
+rm -f ${DEBUGINFOD_CACHE_PATH}/${RPM_BUILDID}/section-.text
+rm -f ${DEBUGINFOD_CACHE_PATH}/${RPM_BUILDID}/section-.debug_info
+rm -f ${DEBUGINFOD_CACHE_PATH}/${BUILDID}/section-.text
+rm -f ${DEBUGINFOD_CACHE_PATH}/${BUILDID}/section-.debug_info
+
+# Verify that the client can extract sections from the debuginfo or executable
+# if they're already in the cache.
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $BUILDID .debug_info
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $BUILDID .text
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $RPM_BUILDID .debug_info
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find -vvv section $RPM_BUILDID .text
+
+exit 0