liblzma: Use symbol versioning.

Symbol versioning is enabled by default on GNU/Linux,
other GNU-based systems, and FreeBSD.

I'm not sure how stable this is, so it may need
backward-incompatible changes before the next release.

The idea is that alpha and beta symbols are considered
unstable and require recompiling the applications that
use those symbols. Once a symbol is stable, it may get
extended with new features in ways that don't break
compatibility with older ABI & API.

The mydist target runs validate_map.sh which should
catch some probable problems in liblzma.map. Otherwise
I would forget to update the map file for new releases.

1 files changed, 68 insertions, 0 deletions

diff --git a/src/liblzma/validate_map.sh b/src/liblzma/validate_map.sh
new file mode 100644
index 00000000..3aee4668
--- /dev/null
+++ b/src/liblzma/validate_map.sh
@@ -0,0 +1,68 @@
+#!/bin/sh
+
+###############################################################################
+#
+# Check liblzma.map for certain types of errors
+#
+# Author: Lasse Collin
+#
+# This file has been put into the public domain.
+# You can do whatever you want with this file.
+#
+###############################################################################
+
+LC_ALL=C
+export LC_ALL
+
+STATUS=0
+
+cd "$(dirname "$0")"
+
+# Get the list of symbols that aren't defined in liblzma.map.
+SYMS=$(sed -n 's/^extern LZMA_API([^)]*) \([a-z0-9_]*\)(.*$/\1;/p' \
+		api/lzma/*.h \
+	| sort \
+	| grep -Fve "$(sed '/[{}:*]/d;/^$/d;s/^	//' liblzma.map)")
+
+# Check that there are no old alpha or beta versions listed.
+VER=$(cd ../.. && sh build-aux/version.sh)
+NAMES=
+case $VER in
+	*alpha | *beta)
+		NAMES=$(sed -n 's/^.*XZ_\([^ ]*\)\(alpha\|beta\) .*$/\1\2/p' \
+			liblzma.map | grep -Fv "$VER")
+		;;
+esac
+
+# Check for duplicate lines. It can catch missing dependencies.
+DUPS=$(sort liblzma.map | sed '/^$/d;/^global:$/d' | uniq -d)
+
+# Print error messages if needed.
+if test -n "$SYMS$NAMES$DUPS"; then
+	echo
+	echo 'validate_map.sh found problems from liblzma.map:'
+	echo
+
+	if test -n "$SYMS"; then
+		echo 'liblzma.map lacks the following symbols:'
+		echo "$SYMS"
+		echo
+	fi
+
+	if test -n "$NAMES"; then
+		echo 'Obsolete alpha or beta version names:'
+		echo "$NAMES"
+		echo
+	fi
+
+	if test -n "$DUPS"; then
+		echo 'Duplicate lines:'
+		echo "$DUPS"
+		echo
+	fi
+
+	STATUS=1
+fi
+
+# Exit status is 1 if problems were found, 0 otherwise.
+exit "$STATUS"