使用CMake的External Project安装libcurl4-openssl-dev

Question

目前在我的一个项目中，我有这段代码：

find_package(CURL REQUIRED)
if(${CURL_FOUND})
else(${CURL_FOUND})
    message(STATUS "Could not find libcURL.  This dependency will be downloaded.")
    ExternalProject_Add(
        libcurl
        GIT_REPOSITORY "git://github.com/bagder/curl.git"
        GIT_TAG "1b6bc02fb926403f04061721f9159e9887202a96"
        SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/lib/curl
        PATCH_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/lib/cURL/buildconf
        CONFIGURE_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/lib/cURL/configure --prefix=<INSTALL_DIR>
        BUILD_COMMAND ${MAKE}
        UPDATE_COMMAND ""
        INSTALL_COMMAND ""
        LOG_DOWNLOAD ON
        LOG_UPDATE ON
        LOG_CONFIGURE ON
        LOG_BUILD ON
        LOG_TEST ON
        LOG_INSTALL ON
    )
    ExternalProject_Get_Property(libcurl source_dir)
    ExternalProject_Get_Property(libcurl binary_dir)
    set(CURL_SOURCE_DIR ${source_dir})
    set(CURL_BINARY_DIR ${binary_dir})
    set(CURL_LIBRARIES ${CURL_BINARY_DIR}/lib/.libs/libcurl.dylib)
    include_directories(${CURL_SOURCE_DIR})
    set(DEPENDENCIES ${DEPENDENCIES} libcurl)
endif(${CURL_FOUND})

该项目的主要优先事项之一是尽可能方便最终用户安装，同时仍然从头开始编译。但在运行CMake时，我遇到了一些代码错误，出现了以下错误：

CMake Error at /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:97 (MESSAGE):
  Could NOT find CURL (missing: CURL_LIBRARY CURL_INCLUDE_DIR)
Call Stack (most recent call first):
  /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:288 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake-2.8/Modules/FindCURL.cmake:52 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  CMakeLists.txt:29 (find_package)

这个错误是因为在运行CMake的系统上没有安装libcurl4-openssl-dev。我想知道如何使用CMake安装这个依赖项。有什么建议吗？

- syb0rg

Answer 1

find_package中的REQUIRED参数意味着如果找不到该软件包，CMake将报告错误并停止。看起来您希望在运行find_package时允许curl软件包不存在，但如果需要，可以下载它。

您可能需要使用以下内容：

find_package(CURL)

if(NOT ${CURL_FOUND})
    message(WARNING "Could not find libcURL.  This dependency will be downloaded. To avoid this you can install curl yourself using the standard methods for your platform.")

    ...

endif()

- bames53