prepstrip: extract buildid with readelf to avoid debugedit when possible

The readelf utility is much more common than debugedit.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/bin/ebuild-helpers/prepstrip b/bin/ebuild-helpers/prepstrip
index 67ceeadb0425d55bd29c62f7b93097c1c209718b..7a08ababb95624163849ad28c606bc2175ace0e2 100755 (executable)
--- a/bin/ebuild-helpers/prepstrip
+++ b/bin/ebuild-helpers/prepstrip
@@ -26,10 +26,13 @@ if ${RESTRICT_strip} || ${FEATURES_nostrip} ; then
        ${FEATURES_installsources} || exit 0
 fi
 
-STRIP=${STRIP:-${CHOST}-strip}
-type -P -- ${STRIP} > /dev/null || STRIP=strip
-OBJCOPY=${OBJCOPY:-${CHOST}-objcopy}
-type -P -- ${OBJCOPY} > /dev/null || OBJCOPY=objcopy
+# look up the tools we might be using
+for t in STRIP:strip OBJCOPY:objcopy READELF:readelf ; do
+       v=${t%:*} # STRIP
+       t=${t#*:} # strip
+       eval ${v}=\"${!v:-${CHOST}-${t}}\"
+       type -P -- ${!v} >/dev/null || eval ${v}=${t}
+done
 
 # We'll leave out -R .note for now until we can check out the relevance
 # of the section when it has the ALLOC flag set on it ...
@@ -65,8 +68,15 @@ save_elf_sources() {
        local x=$1
        local inode=$(inode_var_name "$x")
        [[ -n ${!inode} ]] && return 0
-       debugedit -b "${WORKDIR}" -d "${prepstrip_sources_dir}" \
-               -l "${T}"/debug.sources "${x}"
+
+       # since we're editing the ELF here, we should recompute the build-id
+       # (the -i flag below).  save that output so we don't need to recompute
+       # it later on in the save_elf_debug step.
+       buildid=$(debugedit -i \
+               -b "${WORKDIR}" \
+               -d "${prepstrip_sources_dir}" \
+               -l "${T}"/debug.sources \
+               "${x}")
 }
 
 save_elf_debug() {
@@ -78,9 +88,6 @@ save_elf_debug() {
        # dont save debug info twice
        [[ ${x} == *".debug" ]] && return 0
 
-       # this will recompute the build-id, but for now that's ok
-       local buildid="$( ${debugedit_found} && debugedit -i "${x}" )"
-
        mkdir -p "${y%/*}"
 
        local inode=$(inode_var_name "$x")
@@ -95,6 +102,12 @@ save_elf_debug() {
                chmod ${args} "${y}"
        fi
 
+       # if we don't already have build-id from debugedit, look it up
+       if [[ -z ${buildid} ]] ; then
+               # convert the readelf output to something useful
+               buildid=$(${READELF} -x .note.gnu.build-id "${x}" 2>/dev/null \
+                       | awk '$NF ~ /GNU/ { getline; printf $2$3$4$5; getline; print $2 }')
+       fi
        if [[ -n ${buildid} ]] ; then
                local buildid_dir="${D}usr/lib/debug/.build-id/${buildid:0:2}"
                local buildid_file="${buildid_dir}/${buildid:2}"
@@ -165,6 +178,7 @@ do
        # actually causes problems.  install sources for all
        # elf types though cause that stuff is good.
 
+       buildid=
        if [[ ${f} == *"current ar archive"* ]] ; then
                vecho "   ${x:${#D}}"
                if ${strip_this} ; then