allow for making a shared library (Ref: #137) (#152)

README.md

@@ -71,6 +71,13 @@ If you want to turn on optimizations, do
 cmake -DCMAKE_BUILD_TYPE=Release . && make
 ```
 
+If you want to build as a library, (necessary to build lsquic itself
+as as shared library) do:
+
+```
+cmake -DBUILD_SHARED_LIBS=1 . && make
+```
+
 Building LSQUIC Library
 -----------------------
 
@@ -89,13 +96,23 @@ git submodule update
 
 2. Compile the library
 
+Statically:
+
 
 ```
 # $BORINGSSL is the top-level BoringSSL directory from the previous step
 cmake -DBORINGSSL_DIR=$BORINGSSL .
 make
 ```
 
+As a dynamic library:
+
+```
+cmake -DAS_SHARED_LIB=true .
+make
+```
+
+
 3. Run tests
 
 ```

src/liblsquic/CMakeLists.txt

@@ -109,5 +109,9 @@ SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DXXH_HEADER_NAME=\\\"lsquic_xxhash.h\\\"")
 SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DLSQPACK_ENC_LOGGER_HEADER=\\\"lsquic_qpack_enc_logger.h\\\"")
 SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DLSQPACK_DEC_LOGGER_HEADER=\\\"lsquic_qpack_dec_logger.h\\\"")
 
-add_library(lsquic STATIC ${lsquic_STAT_SRCS} )
-
+IF(DEFINED AS_SHARED_LIB)
+  add_library(lsquic SHARED ${lsquic_STAT_SRCS} )
+  TARGET_LINK_LIBRARIES(lsquic PRIVATE ${BORINGSSL_LIB_ssl} ${BORINGSSL_LIB_crypto} /usr/lib/libz.so)
+ELSE()
+  add_library(lsquic STATIC ${lsquic_STAT_SRCS})
+ENDIF()