How to compile COBOL program into shared library

最新推荐文章于 2023-04-01 22:05:00 发布

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本文介绍如何将COBOL和C语言程序混合编译为单一共享库，并通过C程序调用。示例包括使用COBOL-IT编译器创建共享库libmylib.so的过程，以及主要执行文件mypgm如何加载并调用共享库中的函数。

This sample describe how compile mixed COBOL and C program into a single shared library, and used by C program.

1. HELLOCBL.cbl: provide a COBOL function

2. HELLOCPP.c : provide a C function

3. mypgm.cc: the major executable file

1 and 2 is compiled into a shared library libmylib.so

COBOL-IT compiler is used.

HELLOCBL.cbl

       IDENTIFICATION   DIVISION.
       PROGRAM-ID.      HELLOCBL.
       ENVIRONMENT      DIVISION.
       INPUT-OUTPUT     SECTION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
         01  ARG        PIC X(50) VALUE SPACES.
       LINKAGE SECTION.
         01  PARM-SIZE  PIC S9(8) COMP-5.
         01  PARM-DATA  PIC X(256).
       PROCEDURE DIVISION USING PARM-SIZE PARM-DATA.
           DISPLAY "HELLOCBL PARM-SIZE=[" PARM-SIZE "]".
           DISPLAY "HELLOCBL PARM-DATA=[" PARM-DATA(1:PARM-SIZE) "]".
           MOVE 2 TO RETURN-CODE.
           GOBACK.
      *    STOP RUN.

HELLOCPP.c

//extern "C"
int HELLOCPP(int i, char * buffer) {
    printf("HELLOCPP PARM-SIZE=[%d]\n", i);
    printf("HELLOCPP PARM-DATA=[%s]\n", buffer);
    return 1;
}

mypgm.cpp

#include <string.h>
#include <dlfcn.h>

#include <libcob.h>

typedef int (* func_t)(int, char *);

void * loadHandle(const char * library) {
    void * handle = dlopen(library, RTLD_LAZY | RTLD_GLOBAL);
    char * errmsg = dlerror();
    if (errmsg != NULL) {
        printf("Cannot load shared library: [%s]: [%s]", library, errmsg);
        return NULL;
    }
    if (handle == NULL) {
        printf("Cannot load shared library: [%s]", library);
        return NULL;
    }
    return handle;
}

func_t loadFunction(void * handle, const char * name) {
    func_t func = (func_t) dlsym(handle, name);
    if (func == 0) {
        printf("Cannot get dlsym: [%s]", name);
        return NULL;
    }
    return func;
}

void callcppfunc(void * handle) {
    func_t funcpp = loadFunction(handle, "HELLOCPP");
    if (funcpp != NULL) {
        int ret = funcpp(5, "1234567890");
        printf("HELLOCPP return %d\n", ret);
    }
}

void callcblfunc(int argc, char * argv[]) {
    cit_runtime_t * rtd = cob_get_rtd();
    cob_init(rtd, argc, argv);

    int size = 5;
    char buffer[] = { "1234567890" };
    void *  cobargv[3];
    cobargv[0] = (void *)&size;
    cobargv[1] = (void *)buffer;
    cobargv[2] = NULL;

    int ret = cobcall("HELLOCBL", 2, cobargv);
    printf("HELLOCBL return %d\n", ret);
    cob_rtd_tidy(rtd);
}

int main(int argc, char *argv[])
{
    const char * library = "libmylib.so";
    void * handle = loadHandle(library);
    if (handle != NULL) {
        callcppfunc(handle);
        callcblfunc(argc, argv);
    }
    return 0;
}

makefile

PROGRAM=mypgm
LIBRARY=libmylib.so

all: $(PROGRAM) $(LIBRARY)

mypgm: mypgm.cpp
        g++ $< -g -o $@ -I$(COBDIR)/include -L$(COBDIR)/lib -lcobit -ldl

$(LIBRARY): HELLOCBL.cbl HELLOCPP.c
        cobc -fno-C-cmd-line -Wlinkage -b -g -v -fixed $^ -o $(@F) -std=mf -fmf-gnt -constant "UPPER-CALL=1"

clean:
        -rm -rf c *.lst *.lis *.int *.idy $(LIBRARY) $(PROGRAM)

Execution

$ make
$ ./mypgm 
HELLOCPP PARM-SIZE=[5]
HELLOCPP PARM-DATA=[1234567890]
HELLOCPP return 1
HELLOCBL PARM-SIZE=[+0000000005]
HELLOCBL PARM-DATA=[12345]
HELLOCBL return 2

the end