cmake_modules/FindZLIB.cmake

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# ZLIB_HOME environmental variable is used to check for ZLIB headers and static library

# ZLIB_INCLUDE_DIR: directory containing headers
# ZLIB_LIBS: directory containing ZLIB libraries
# ZLIB_STATIC_LIB: path to zlib.a
# ZLIB_FOUND: whether ZLIB has been found

if( NOT "${ZLIB_HOME}" STREQUAL "")
    file (TO_CMAKE_PATH "${ZLIB_HOME}" _zlib_path)
endif()

message (STATUS "ZLIB_HOME: ${ZLIB_HOME}")

find_path (ZLIB_INCLUDE_DIR zlib.h HINTS
  ${_zlib_path}
  NO_DEFAULT_PATH
  PATH_SUFFIXES "include")

if (NOT ZLIB_STATIC_LIB_NAME)
  set (ZLIB_STATIC_LIB_NAME z)
endif()

find_library (ZLIB_LIBRARIES NAMES ${ZLIB_STATIC_LIB_NAME} HINTS
  ${_zlib_path}
  PATH_SUFFIXES "lib")

if (ZLIB_INCLUDE_DIR AND ZLIB_LIBRARIES)
  set (ZLIB_FOUND TRUE)
  get_filename_component (ZLIB_LIBS ${ZLIB_LIBRARIES} PATH )
  set (ZLIB_HEADER_NAME zlib.h)
  set (ZLIB_HEADER ${ZLIB_INCLUDE_DIR}/${ZLIB_HEADER_NAME})
  set (ZLIB_STATIC_LIB ${ZLIB_LIBS}/${CMAKE_STATIC_LIBRARY_PREFIX}${ZLIB_STATIC_LIB_NAME}${CMAKE_STATIC_LIBRARY_SUFFIX})
else ()
  set (ZLIB_FOUND FALSE)
endif ()

if (ZLIB_FOUND)
  message (STATUS "Found the ZLIB header: ${ZLIB_HEADER}")
  message (STATUS "Found the ZLIB library: ${ZLIB_STATIC_LIB}")
else()
  if (_zlib_path)
    set (ZLIB_ERR_MSG "Could not find ZLIB. Looked in ${_zlib_path}.")
  else ()
    set (ZLIB_ERR_MSG "Could not find ZLIB in system search paths.")
  endif()

  if (ZLIB_FIND_REQUIRED)
    message (FATAL_ERROR "${ZLIB_ERR_MSG}")
  else ()
    message (STATUS "${ZLIB_ERR_MSG}")
  endif ()
endif()

mark_as_advanced (
  ZLIB_INCLUDE_DIR
  ZLIB_STATIC_LIB
  ZLIB_LIBS
  ZLIB_LIBRARIES
)