Question

我是使用rpcgen编程的新手。我创建了一个简单的rpc程序，它在Ubuntu 14.04中提供远程目录列表服务。它使用rpcgen不仅可以生成存根例程，还可以生成XDR例程。

首先是协议文件

const MAXNAMELEM = 255;
typedef string nametype<MAXNAMELEM>;    /*a directory entry*/
typedef struct namenode *namelist;      /*a link in the listing*/

/*a node in the directory listing*/
struct namenode {
    nametype name;  /*name of directory entry*/
    namelist next;  /*next entry*/
};

/*the result of READDIR operation*/
union readdir_res switch (int errornumber) {
    case 0:
        namelist list;  /*no error: return directory listing*/
    default:
        void;           /*error occurred: nothing else to return*/
};

/*the directory program definition*/
program DIRPROG {
    version DIRVERS {
        readdir_res READDIR(nametype) = 1;
    } = 1;
} = 76;

服务器：

#include <rpc/rpc.h>
#include <sys/dir.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>

#include "rdir.h"


readdir_res *readdir_1_svc(nametype *dirname, struct svc_req *req)
{
    DIR *dirp = NULL;
    struct direct *d = NULL;
    namelist nl;
    namelist *nlp = NULL;
    static readdir_res res;     /*must be static*/

    /*open directory*/
    dirp = opendir(*dirname);
    if (dirp == NULL)
    {
        res.errornumber = errno;
        return (&res);
    }

    /*Free previous result*/
    xdr_free(xdr_readdir_res, &res);

    nlp = &res.readdir_res_u.list;
    while (d = readdir(dirp))
    {
        nl = *nlp = (namenode*)malloc(sizeof(namenode));
        nl->name = strdup(d->d_name);
        nlp = &nl->next;
    }
    *nlp = NULL;

    res.errornumber = 0;
    closedir(dirp);
    return (&res);
}

客户：

#include <stdio.h>
#include <rpc/rpc.h>
#include "rdir.h"

int main(int argc, char *argv[])
{
    CLIENT *cl;
    char *server = NULL;
    char *dir = NULL;
    readdir_res *result = NULL;
    namelist nl;

    if (argc != 3)
    {
        fprintf(stderr, "usage: %s host directory\n", argv[0]);
        exit(1);
    }

    /*remember what our command line arguments refer to*/
    server = argv[1];
    dir = argv[2];

    cl = clnt_create(server, DIRPROG, DIRVERS, "tcp");
    if (cl == NULL)
    {
        clnt_pcreateerror(server);
        exit(1);
    }

    result = readdir_1(&dir, cl);
    if (result == NULL)
    {
        clnt_perror(cl, server);
        exit(1);
    }

    if (result->errornumber != 0)
    {
        perror(dir);
        exit(1);
    }

    for (nl = result->readdir_res_u.list; nl!=NULL; nl=nl->next)
    {
        printf("%s\n", nl->name);
    }

    return 0;
}

然后我编译它们：

 rpcgen rdir.x
 gcc rls.c rdir_clnt.c rdir_xdr.c -o rls
 gcc rdir_svc.c dir_proc.c rdir_xdr.c -o dir_svc

当我用指令编译时：

 gcc rdir_svc.c dir_proc.c rdir_xdr.c -o dir_svc

我收到了以下警告：

 esta@esta-U48L:~/Learning/rpcgen/dir_ls$ gcc rdir_svc.c dir_proc.c rdir_xdr.c -o dir_svc
 dir_proc.c: In function ‘readdir_1_svc’:
 dir_proc.c:27:2: warning: passing argument 1 of ‘xdr_free’ from incompatible pointer type [enabled by default]
  xdr_free(xdr_readdir_res, &res);
  ^
In file included from /usr/include/rpc/rpc.h:42:0,
                 from dir_proc.c:1:
/usr/include/rpc/xdr.h:373:13: note: expected ‘xdrproc_t’ but argument is of type ‘bool_t (*)(struct XDR *, struct readdir_res *)’
 extern void xdr_free (xdrproc_t __proc, char *__objp) __THROW;
             ^
dir_proc.c:27:2: warning: passing argument 2 of ‘xdr_free’ from incompatible pointer type [enabled by default]
  xdr_free(xdr_readdir_res, &res);
  ^
In file included from /usr/include/rpc/rpc.h:42:0,
                 from dir_proc.c:1:
/usr/include/rpc/xdr.h:373:13: note: expected ‘char *’ but argument is of type ‘struct readdir_res *’
 extern void xdr_free (xdrproc_t __proc, char *__objp) __THROW;
             ^

有人可以帮我解决警告吗？附：即使有这些警告，程序运行也很好。

Answer 1

您可以安全地将传递的参数转换为xdr_free：

xdr_free((xdrproc_t)xdr_readdir_res, (char *)&res);

ubuntu中rpcgen程序的编译器警告

1 个答案: