From 06cdb3f75e27aae06c16b10e936ddd908ea4e5c5 Mon Sep 17 00:00:00 2001
From: Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
Date: Mon, 4 Jul 2016 22:38:04 +0100
Subject: [PATCH] Specify the soname in the library and its name

This provides users of this library the guarantee that the ABI will
stay stable when MAJOR will reach 1, and will stay backwards compatible
for the entire duration of the 1.x.y branch.

It does require the maintainers to always update the version in the
Makefile at every ABI change.
---
 Makefile | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 0d5ddd6..accc760 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,9 @@
 #!/usr/bin/make -f
 
+MAJOR := 0
+MINOR := 1
+PATCH := 0
+VERSION := $(MAJOR).$(MINOR).$(PATCH)
 BUILD_DIR := build
 RELEASE_OPTIMIZE_FLAGS ?= -g -O3
 DEBUG_OPTIMIZE_FLAGS ?= -g -O0
@@ -9,8 +13,10 @@ CC = gcc
 EMCC = emcc
 AFL_CC = afl-gcc
 AFL_CXX = afl-g++
-RELEASE_TARGET := $(BUILD_DIR)/libolm.so
-DEBUG_TARGET := $(BUILD_DIR)/libolm_debug.so
+RELEASE_TARGET := $(BUILD_DIR)/libolm.so.$(VERSION)
+RELEASE_SYMLINKS := $(BUILD_DIR)/libolm.so.$(MAJOR) $(BUILD_DIR)/libolm.so
+DEBUG_TARGET := $(BUILD_DIR)/libolm_debug.so.$(VERSION)
+DEBUG_SYMLINKS := $(BUILD_DIR)/libolm_debug.so.$(MAJOR) $(BUILD_DIR)/libolm_debug.so
 JS_TARGET := javascript/olm.js
 
 JS_EXPORTED_FUNCTIONS := javascript/exported_functions.json
@@ -87,22 +93,30 @@ $(JS_TARGET): LDFLAGS += $(JS_OPTIMIZE_FLAGS)
 
 ### top-level targets
 
-lib: $(RELEASE_TARGET)
+lib: $(RELEASE_TARGET) $(RELEASE_SYMLINKS)
 .PHONY: lib
 
 $(RELEASE_TARGET): $(RELEASE_OBJECTS)
 	$(CXX) $(LDFLAGS) --shared -fPIC \
+            -Wl,-soname,libolm.so.$(MAJOR) \
             -Wl,--version-script,version_script.ver \
             $(OUTPUT_OPTION) $(RELEASE_OBJECTS)
 
-debug: $(DEBUG_TARGET)
+$(RELEASE_SYMLINKS):
+	ln -s libolm.so.$(VERSION) $@
+
+debug: $(DEBUG_TARGET) $(DEBUG_SYMLINKS)
 .PHONY: debug
 
 $(DEBUG_TARGET): $(DEBUG_OBJECTS)
 	$(CXX) $(LDFLAGS) --shared -fPIC \
+            -Wl,-soname,libolm_debug.so.$(MAJOR) \
             -Wl,--version-script,version_script.ver \
             $(OUTPUT_OPTION) $(DEBUG_OBJECTS)
 
+$(DEBUG_SYMLINKS):
+	ln -s libolm_debug.so.$(VERSION) $@
+
 js: $(JS_TARGET)
 .PHONY: js