ubuntu下rpcgen程序的編譯警告

Question

我是用rpcgen編程的新手。我創建了一個簡單的rpc程序，它在Ubuntu 14.04中提供了遠程目錄列表服務。它使用rpcgen不僅生成存根例程，而且還生成XDR例程。

首先，協議文件

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; 

服務器：

#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); 
} 

客戶端：

#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; 
} 

然後我把它們編譯：

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 

當我編譯指令：

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

我得到了以下警告：

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; 
      ^

任何人可以幫助我的警告？ P.S.即使有這些警告，程序也可以正常運行。

Answer 1

您可以放心地投你傳遞參數給xdr_free：

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