How to use GCC to build DLL by DEF file in MinGW?_gcc 使用 def文件-优快云博客

本文链接：https://blog.youkuaiyun.com/hello_wyq/article/details/4063356

本文介绍了如何使用GCC和DEF文件在MinGW环境中构建DLL。通过DEF文件，可以更灵活地导出匿名函数，并设置调用约定(__stdcall, __cdecl, __pascal)，而无需在头文件中添加__declspec dllexport或dllimport前缀。方法包括编辑DEF文件、源代码，然后使用dllwrap.exe生成DLL，并进行测试。" 45843283,1398710,使用cytoscape.js和Flask展示neo4j关系图,"['前端开发', '后端开发', '数据库', '可视化']

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How to use GCC to build DLL by DEF file in MinGW?

The “How to generate DLL files by GCC in the MinGW” has described how to generate DLL file by the declaring prefix(__declspec( dllexport ) or __declspec( dllimport )) of functions + GCC tools(GCC, pexports). In normal case, it is enough to cater for the user requirements, but if users want to add anonymous functions or change the calling conventions(__stdcall, __cdecl, __pascal), how to do?

DEF file can play a role of these requirements. Firstly, let’s understand the format of DEF.

LIBRARY DllName.dll

EXPORTS

[__stdcall/__cdecl/__pascal]DllFunction[@BytesOfParamList] @SlotNumber

…

IMPORTS

OtherDllName.OtherDllFunction

…

--- LIBRARY section indicates the name of DLL.

--- EXPORTS section lists the functions of interface in the DLL.

--- IMPORTS section describes the dependence of this DLL, such as these functions of other DLL.

--- [Options] they are optional, and can be ignored.

--- SlotNumber is a number of slot, and increase from 1 to the number of your functions

Ok, let’s show an example to make it clear.

1. Edit hello.def

1 LIBRARY hello.dll

2 EXPORTS

3 MyDllSay @1

4 hello = MyDllSay @2

Herein, hello is an anonymous function of MyDllSay, and can be invoked by other program.

2. Edit hello.c

1 #include <stdio.h>

3 void MyDllSay( void )

4 {

5 printf( "I am a DLL function generated by GCC in the MinGW environment./n" );

6 }

3. Build DLL

$ gcc -c -O3 hello.c

$ dllwrap.exe --def hello.def -o hello.dll hello.o --output-lib libhello.a

$ lib.exe /machine:i386 /def:hello.def /out:hello.lib

dllwrap.exe produces a DLL by a DEF file. Readers input “dllwrap.exe --help” to acquire its usage. In fact, it depends gcc, ld and dlltool to fulfill its tasks.

4. Test DLL

a) Edit test.c

1 #include <stdio.h>

3 extern void hello( void );

5 int main( void )

6 {

7 hello();

9 return 0;

10 }

b) Compile and Execute it

1) Use GCC

$ gcc -o test test.c -L./ -lhello

$ ./test.exe

I am a DLL function generated by GCC in the MinGW environment.

2) Use VC

$ cl test.c -link hello.lib

$ ./test.exe

I am a DLL function generated by GCC in the MinGW environment.

[Summarization]

1. It is a complementary method for “How to generate DLL files by GCC in the MinGW”. To some extents, it looks more flexible, and programmers needn’t add prefix(__declspec( dllexport ) or __declspec( dllimport )) in the header file. Each function is easy to be exported or hidden in the rule of DEF file.

2. Anonymous function can be used. Users can follow their naming rules when calling these functions.

3. __stdcall, __cdecl and __pascal calling convention are available. It is agile for programmer to cross the different programming language with the help of prefix. I prefer __stdcall when DLL is generated^_^.