如何使用 mingw32 在 cygwin 下构建和测试 libffi？

Question

检查（最新）标签 v3.2.1 后：

% sh autogen.sh
% ./configure CC=i686-pc-mingw32-gcc
% make check

所有测试似乎都失败了。

使用 CC=gcc，测试似乎可以正常工作。不幸的是，我需要生成的构建没有 cygwin 依赖项，因为我正在构建一个 JNI DLL。

Answer 1

我尝试使用 MSYS2 环境和 mingw-w64 构建 libffi，但遇到了同样的问题：

a)当我运行make check时，所有测试似乎都失败了@

b) 当我尝试使用 -lffi 编译 libffi Hello World 示例时， 链接器抱怨对所有 ffi 相关符号的未解析引用（这些符号确实包含在 libffi.a 中，但可能由于循环依赖和目标文件的顺序，链接器无法收集所有符号）

幸运的是，如果我删除 -lffi 并包含所有由 libffi make 操作创建的目标文件 (*.o)，则创建的可执行文件运行良好。

这是我使用的 libffi Hello World 示例的链接： http://www.chiark.greenend.org.uk/doc/libffi-dev/html/Closure-Example.html

[编辑]

经过一些额外的实验，我设法通过将-lffi 替换为-Wl,--whole-archive,-lffi,--no-whole-archive 来编译程序。这样，链接器将包含来自libffi.a 的所有目标文件，并且一切正常。

这是 Hello World 示例 (hello.c)，其中包含我使用的详细步骤，以防有人发现此信息有用：

/*
 * Steps for building libffi on Windows and running this Hello World example:
 *
 * 1. Download and install the latest version of MSYS2
 *    a) download the latest (64-bit or 32-bit) installer from http://msys2.github.io
 *    b) run the installer accepting default settings
 *    c) execute the following commands to update the system core
 *        pacman -Sy pacman
 *        pacman -Syu
 *        pacman -Su
 *    d) restart MSYS2, if requested to do so
 *    e) execute the following command to install development tools
 *       for 64-bit gcc:
 *        pacman --needed -S base-devel dejagnu mingw-w64-x86_64-gcc
 *       for 32-bit gcc:
 *        pacman --needed -S base-devel dejagnu mingw-w64-i686-gcc
 *    f) restart MSYS2
 * 2. Download and compile the latest version of libffi
 *    a) download the latest source code bundle from https://github.com/libffi/libffi/releases
 *    b) unpack the source code bundle in MSYS2 tmp directory (e.g. C:\msys64\tmp)
 *    c) execute the following MSYS2 commands to compile libffi (adapt the version number):
 *        cd /tmp/libffi-3.2.1
 *        ./autogen.sh
 *        ./configure --prefix=/tmp/out --enable-static --disable-shared
 *        make
 *    d) optionally, execute the following command to run the tests:
 *        make check
 *    e) copy the distributable files to the configured /tmp/out directory
 *        make install
 *       the following files are needed for the next step:
 *        /tmp/out/lib/libffi.a
 *        /tmp/out/lib/libffi-3.2.1/include/ffi.h
 *        /tmp/out/lib/libffi-3.2.1/include/ffitarget.h
 * 3. Compile this example
 *    a) copy this file to MSYS2 tmp directory (e.g. C:\msys64\tmp\hello.c)
 *    b) execute the following MSYS2 command to compile the example:
 *        gcc -I /tmp/out/lib/libffi-3.2.1/include -L /tmp/out/lib -lffi -o /tmp/hello /tmp/hello.c
 *    c) run the example (/tmp/hello.exe), the output should be:
 *        Hello World!
 *
 * Troubleshooting
 *
 * If the tests seem to fail and the compilation in step 3b) above reports undefined references to 'ffi_*' symbols,
 * try compiling using the following command instead:
 *        gcc -I /tmp/out/lib/libffi-3.2.1/include -L /tmp/out/lib -Wl,--whole-archive,-lffi,--no-whole-archive -o /tmp/hello /tmp/hello.c
 * Another alternative is to try linking the original libffi object files (*.o) and drop -lffi as follows:
 * For 64-bit version:
 *        export SRC=/tmp/libffi-3.2.1/x86_64-w64-mingw32/src
 *        gcc -I /tmp/out/lib/libffi-3.2.1/include -o /tmp/hello /tmp/hello.c $SRC/prep_cif.o $SRC/types.o $SRC/raw_api.o $SRC/java_raw_api.o $SRC/closures.o $SRC/x86/ffi.o $SRC/x86/win64.o
 * For 32-bit version:
 *        export SRC=/tmp/libffi-3.2.1/i686-w64-mingw32/src
 *        gcc -I /tmp/out/lib/libffi-3.2.1/include -o /tmp/hello /tmp/hello.c $SRC/prep_cif.o $SRC/types.o $SRC/raw_api.o $SRC/java_raw_api.o $SRC/closures.o $SRC/x86/ffi.o $SRC/x86/win32.o
 */

#include <stdio.h>
#include <ffi.h>

/* Acts like puts with the file given at time of enclosure */
void puts_binding(ffi_cif* cif, void* ret, void* args[], void* stream) {
  *(ffi_arg*) ret = fputs(*(char**) args[0], (FILE*) stream);
}

typedef int (*puts_t)(char*);

int main() {
  ffi_cif cif; /* The call interface */
  ffi_type* args[1]; /* The array of pointers to function argument types */
  ffi_closure* closure; /* The allocated closure writable address */
  void* bound_puts; /* The allocated closure executable address */
  int rc; /* The function invocation return code */

  /* Allocate closure (writable address) and bound_puts (executable address) */
  closure = ffi_closure_alloc(sizeof(ffi_closure), &bound_puts);

  if (closure) {
    /* Initialize the array of pointers to function argument types */
    args[0] = &ffi_type_pointer;

    /* Initialize the call interface describing the function prototype */
    if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1, &ffi_type_sint, args) == FFI_OK) {
      /* Initialize the closure, setting stream to stdout */
      if (ffi_prep_closure_loc(closure, &cif, puts_binding, stdout, bound_puts) == FFI_OK) {
        rc = ((puts_t) bound_puts)("Hello World!");
        /* rc now holds the result of the call to fputs */
      }
    }
  }

  /* Deallocate both closure, and bound_puts */
  ffi_closure_free(closure);

  return 0;
}