[pacman-dev] [PATCH] makepkg: tell the compiler to record debugging info for debug packages

[Eli Schwartz]

In commit 8b0d59b83a60eb504567590346119fe4cd891cad support was added for
storing the source files of binaries in debug packages. This made use of
the debugedit program which is part of the RPM package manager, which is
not very standalone.

The same effect can be achieved using -fdebug-prefix-map, an option
accepted by both the gcc and clang compilers which modifies how the
compiler itself stores the references to the source files rather than
requiring us to later edit the produced binaries. This also removes the
dependency on external programs like debugedit.

As a result of this change, source files will only be effectively added
for programs which actually use the exported CFLAGS. This is a reasonable
tradeoff as we expect our CFLAGS to be used rather than ignored. Upstream
software which do not produce useful debug packages are expected to fix
their build systems to respect the environment CFLAGS.

Signed-off-by: Eli Schwartz <eschwartz at archlinux.org>
---
 doc/makepkg.conf.5.txt              |  6 ++++++
 etc/makepkg.conf.in                 |  2 ++
 scripts/libmakepkg/tidy/strip.sh.in | 11 ++++-------
 scripts/makepkg.sh.in               |  4 ++++
 4 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/doc/makepkg.conf.5.txt b/doc/makepkg.conf.5.txt
index d61858ca..ca74c2dd 100644
--- a/doc/makepkg.conf.5.txt
+++ b/doc/makepkg.conf.5.txt
@@ -215,6 +215,12 @@ Options
 	instruct makepkg which files to remove from the package. This is
 	useful for index files that are added by multiple packages.
 
+**DBGSRCDIR=**"/usr/src/debug"::
+	If `strip` and `debug` are specified in the `OPTIONS` array, this variable
+	will instruct makepkg where to place source files for installed binaries.
+	The compiler will be instructed to link this directory for the debugger
+	search path.
+
 **PKGDEST=**"/path/to/directory"::
 	If this value is not set, packages will, by default, be placed in the
 	current directory (location of the linkman:PKGBUILD[5]). Many people
diff --git a/etc/makepkg.conf.in b/etc/makepkg.conf.in
index d2beef50..33c4e92d 100644
--- a/etc/makepkg.conf.in
+++ b/etc/makepkg.conf.in
@@ -99,6 +99,8 @@ MAN_DIRS=({usr{,/local}{,/share},opt/*}/{man,info})
 DOC_DIRS=(usr/{,local/}{,share/}{doc,gtk-doc} opt/*/{doc,gtk-doc})
 #-- Files to be removed from all packages (if purge is specified)
 PURGE_TARGETS=(usr/{,share}/info/dir .packlist *.pod)
+#-- Directory, if any, to store source code in for debug packages
+DBGSRCDIR="/usr/src/debug"
 
 #########################################################################
 # PACKAGE OUTPUT
diff --git a/scripts/libmakepkg/tidy/strip.sh.in b/scripts/libmakepkg/tidy/strip.sh.in
index 76562808..49e8aacd 100644
--- a/scripts/libmakepkg/tidy/strip.sh.in
+++ b/scripts/libmakepkg/tidy/strip.sh.in
@@ -58,14 +58,11 @@ strip_file() {
 		# copy source files to debug directory
 		local f t
 		while read -r f; do
-			t=${f/"$srcdir"/$dbgsrc}
-			mkdir -p "${t%/*}"
-			cp -- "$f" "$t"
+			t=${f/$dbgsrc/"$srcdir"}
+			mkdir -p "${f%/*}"
+			cp -- "$t" "$f"
 		done < <(source_files "$binary")
 
-		# adjust debug symbols to point at sources
-		debugedit -b "${srcdir}" -d /usr/src/debug/ -i "$binary" &> /dev/null
-
 		# copy debug symbols to debug directory
 		mkdir -p "$dbgdir/${binary%/*}"
 		objcopy --only-keep-debug "$binary" "$dbgdir/$binary.debug"
@@ -107,7 +104,7 @@ tidy_strip() {
 		if check_option "debug" "y"; then
 
 			dbgdir="$pkgdirbase/$pkgbase- at DEBUGSUFFIX@/usr/lib/debug"
-			dbgsrc="$pkgdirbase/$pkgbase- at DEBUGSUFFIX@/usr/src/debug"
+			dbgsrc="$pkgdirbase/$pkgbase- at DEBUGSUFFIX@$DBGSRCDIR"
 			mkdir -p "$dbgdir" "$dbgsrc"
 		fi
 
diff --git a/scripts/makepkg.sh.in b/scripts/makepkg.sh.in
index b25e4106..b74da0a5 100644
--- a/scripts/makepkg.sh.in
+++ b/scripts/makepkg.sh.in
@@ -379,6 +379,10 @@ prepare_buildenv() {
 	fi
 
 	if check_option "debug" "y"; then
+		if [[ -v DBGSRCDIR ]]; then
+			DEBUG_CFLAGS+=" -fdebug-prefix-map=$srcdir=$DBGSRCDIR"
+			DEBUG_CXXFLAGS+=" -fdebug-prefix-map=$srcdir=$DBGSRCDIR"
+		fi
 		CFLAGS+=" $DEBUG_CFLAGS"
 		CXXFLAGS+=" $DEBUG_CXXFLAGS"
 	fi
-- 
2.14.2