cmake/FindLibevent.cmake

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# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
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#
#     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.

# - Try to find libevent
#.rst
# FindLibevent
# ------------
#
# Find Libevent include directories and libraries. Invoke as::
#
#   find_package(Libevent
#     [version] [EXACT]   # Minimum or exact version
#     [REQUIRED]          # Fail if Libevent is not found
#     [COMPONENT <C>...]) # Libraries to look for
#
# Valid components are one or more of:: libevent core extra pthreads openssl.
# Note that 'libevent' contains both core and extra. You must specify one of
# them for the other components.
#
# This module will define the following variables::
#
#  LIBEVENT_FOUND        - True if headers and requested libraries were found
#  LIBEVENT_INCLUDE_DIRS - Libevent include directories
#  LIBEVENT_LIBRARIES    - Libevent libraries to be linked
#  LIBEVENT_<C>_FOUND    - Component <C> was found (<C> is uppercase)
#  LIBEVENT_<C>_LIBRARY  - Library to be linked for Libevent component <C>.

find_package(PkgConfig QUIET)
pkg_check_modules(PC_LIBEVENT QUIET libevent)

# Support preference of static libs by adjusting CMAKE_FIND_LIBRARY_SUFFIXES
if( Libevent_USE_STATIC_LIBS )
  set(_libevent_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES    :${CMAKE_FIND_LIBRARY_SUFFIXES})                                                                       
    if(WIN32)
        list(INSERT CMAKE_FIND_LIBRARY_SUFFIXES 0 .lib .a)
    else()
        set(CMAKE_FIND_LIBRARY_SUFFIXES .a)
    endif()
else()
  set(_libevent_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES    :${CMAKE_FIND_LIBRARY_SUFFIXES})
    if(WIN32)
        list(INSERT CMAKE_FIND_LIBRARY_SUFFIXES 0 .dll .so)
    else()
        set(CMAKE_FIND_LIBRARY_SUFFIXES .so)
    endif()
endif()
# Look for the Libevent 2.0 or 1.4 headers
find_path(LIBEVENT_INCLUDE_DIR
  NAMES
    WIN32-Code/event2/event-config.h
    event2/event-config.h
    event-config.h
  PATHS ${CMAKE_SOURCE_DIR}/bin/include C:/libevent/include ${CMAKE_SOURCE_DIR}/win32-deps/include
  HINTS
    ${PC_LIBEVENT_INCLUDE_DIRS}
)

# ------------------------------------------------------------------------
#  Prefix initialization 
# ------------------------------------------------------------------------
set(Libevent_LIB_PREFIX "")
set(LIBEVENT_EVENT_CONFIG_DIR ${LIBEVENT_INCLUDE_DIR})
if(WIN32)
  set(Libevent_LIB_PREFIX "lib")
  set(LIBEVENT_EVENT_CONFIG_DIR "${LIBEVENT_INCLUDE_DIR}/../WIN32-Code/")
endif()

if(LIBEVENT_INCLUDE_DIR)
  set(_version_regex "^#define[ \t]+_EVENT_VERSION[ \t]+\"([^\"]+)\".*")
  if(EXISTS "${LIBEVENT_EVENT_CONFIG_DIR}/event2/event-config.h")
    # Libevent 2.0
    file(STRINGS "${LIBEVENT_EVENT_CONFIG_DIR}/event2/event-config.h"
      LIBEVENT_VERSION REGEX "${_version_regex}")     
  else()
    # Libevent 1.4
    if(EXISTS "${LIBEVENT_EVENT_CONFIG_DIR}/event-config.h")
      file(STRINGS "${LIBEVENT_EVENT_CONFIG_DIR}/event-config.h"
        LIBEVENT_VERSION REGEX "${_version_regex}")
    endif()    
  endif()
  string(REGEX REPLACE "${_version_regex}" "\\1"
    LIBEVENT_VERSION "${LIBEVENT_VERSION}")
  unset(_version_regex)
endif()

set(_LIBEVENT_REQUIRED_VARS)
if(WIN32)
  set(Libevent_FIND_COMPONENTS ${Libevent_LIB_PREFIX}event core extras) 
else()
  set(Libevent_FIND_COMPONENTS ${Libevent_LIB_PREFIX}event core extra pthreads)
endif()  
message(status "** libevent components: ${Libevent_FIND_COMPONENTS}")
foreach(COMPONENT ${Libevent_FIND_COMPONENTS})
  set(_LIBEVENT_LIBNAME "${Libevent_LIB_PREFIX}event")
  # Note: compare two variables to avoid a CMP0054 policy warning
  if(COMPONENT STREQUAL _LIBEVENT_LIBNAME)
    set(_LIBEVENT_LIBNAME "${Libevent_LIB_PREFIX}event")
  else()
    set(_LIBEVENT_LIBNAME "${Libevent_LIB_PREFIX}event_${COMPONENT}")
  endif()
  string(TOUPPER "${COMPONENT}" COMPONENT_UPPER)
  message(status "** ${_LIBEVENT_LIBNAME}")
  find_library(LIBEVENT_${COMPONENT_UPPER}_LIBRARY
    NAMES ${_LIBEVENT_LIBNAME}
    PATHS ${CMAKE_SOURCE_DIR}/bin/lib C:/libevent-2.0.22-stable C:/libevent-2.0.22-stable/lib C:/libevent/lib ${CMAKE_SOURCE_DIR}/win32-deps/lib
    HINTS ${PC_LIBEVENT_LIBRARY_DIRS}
  )
  if(LIBEVENT_${COMPONENT_UPPER}_LIBRARY)
    set(Libevent_${COMPONENT}_FOUND 1)
  endif()
  list(APPEND _LIBEVENT_REQUIRED_VARS LIBEVENT_${COMPONENT_UPPER}_LIBRARY)
endforeach()
unset(_LIBEVENT_LIBNAME)

include(FindPackageHandleStandardArgs)
# handle the QUIETLY and REQUIRED arguments and set LIBEVENT_FOUND to TRUE
# if all listed variables are TRUE and the requested version matches.
find_package_handle_standard_args(Libevent REQUIRED_VARS
                                  ${_LIBEVENT_REQUIRED_VARS}
                                  LIBEVENT_INCLUDE_DIR
                                  VERSION_VAR LIBEVENT_VERSION
                                  HANDLE_COMPONENTS)

if(LIBEVENT_FOUND)
  set(LIBEVENT_INCLUDE_DIRS  ${LIBEVENT_INCLUDE_DIR})
  set(LIBEVENT_LIBRARIES)
  foreach(COMPONENT ${Libevent_FIND_COMPONENTS})
    string(TOUPPER "${COMPONENT}" COMPONENT_UPPER)
    list(APPEND LIBEVENT_LIBRARIES ${LIBEVENT_${COMPONENT_UPPER}_LIBRARY})
    set(LIBEVENT_${COMPONENT_UPPER}_FOUND ${Libevent_${COMPONENT}_FOUND})
  endforeach()
endif()

mark_as_advanced(LIBEVENT_INCLUDE_DIR ${_LIBEVENT_REQUIRED_VARS})

# Restore the original find library ordering
if( Libevent_USE_STATIC_LIBS )    
  set(CMAKE_FIND_LIBRARY_SUFFIXES ${_libevent_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES})                                                                        
endif()
unset(_LIBEVENT_REQUIRED_VARS)