使用emscripten生成wasm文件

Question

我想用emscripten编译SealPIR库来生成一个wasm文件。使用此命令时：emcmake cmake .

我得到了这个错误：

CMake Error at CMakeLists.txt:19 (find_package):
  By not providing "FindSEAL.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "SEAL", but
  CMake did not find one.

  Could not find a package configuration file provided by "SEAL" (requested
  version 3.2.0) with any of the following names:

    SEALConfig.cmake
    seal-config.cmake

  Add the installation prefix of "SEAL" to CMAKE_PREFIX_PATH or set
  "SEAL_DIR" to a directory containing one of the above files.  If "SEAL"
  provides a separate development package or SDK, be sure it has been
  installed.


-- Configuring incomplete, errors occurred!
See also "/home/Zied/webassembly/SealPIR/CMakeFiles/CMakeOutput.log".
emcmake: error: 'cmake . -DCMAKE_TOOLCHAIN_FILE=/home/Zied/webassembly/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -DCMAKE_CROSSCOMPILING_EMULATOR="/home/Zied/webassembly/emsdk/node/14.15.5_64bit/bin/node"' failed (1)  

密封件安装正确。当我在不使用emcmake的情况下运行相同的命令时，它工作得很好。这是我的CMakeList

cmake_minimum_required(VERSION 3.10)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

project(SealPIR VERSION 2.1 LANGUAGES CXX)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)

add_executable(main 
    main.cpp
)

add_library(sealpir STATIC
  pir.cpp
  pir_client.cpp
  pir_server.cpp
)

find_package(SEAL 3.2.0 EXACT REQUIRED)

target_link_libraries(main sealpir SEAL::seal)

Answer 1

当使用工具链文件进行交叉编译时，CMake将默认禁用系统库。它不会搜索任何目录，以避免查找与目标系统不兼容的文件。

你认为你没有使用工具链文件？再想一想！emcmake对你隐瞒了这一点。仔细查看错误输出。

在这里，您编译了SEAL库，但将其安装在默认路径中，即/usr/local。

我们可以告诉CMake在那里显式搜索，但我不建议，但如果有效，您可以尝试：

emcmake cmake . -CMAKE_PREFIX_PATH=/usr/local

正确的解决方案是创建一个包含所有emscripten库的目录：

# In the SEAL build directory
emcmake cmake .. -DCMAKE_INSTALL_PREFIX=/home/anblic/webassembly/install

然后，在该目录中安装库后，可以在与安装路径相同的目录中设置前缀路径：

# Assuming you're in a build/ subdirectory
emcmake cmake .. -DCMAKE_PREFIX_PATH=/home/anblic/webassembly/install