C: 结构 X 没有名为 Y 的成员

Question

我正在使用 XINU 操作系统开发一个项目，在向系统添加管道时，在尝试向我之前创建的结构中添加和使用新成员时，出现编译器错误。老实说，我看不出我的代码有什么问题，特别是当我将它与因变量名称而异的工作片段进行比较时。

“/pipcreate.c:21:错误:'struct Pipent'没有名为'owner'的成员”

至于注释掉的两行(reader = PR_CURR，writer = PR_CURR)，如果我取消注释它们，并注释掉“owner”行，它确实可以正常编译。

是否有什么问题是显而易见的，而我却完全忽略了它？

管道.h

/*typedef int32 pipid32 inside of kernel.h*/

/* Max number of pipes in the system */
#ifndef NPIP
#define NPIP    10
#endif

/* Pipe state constants */

#define PIPE_FREE   0   /* pipe table entry is unused   */
#define PIPE_USED   1   /* pipe is currently used   */
#define PIPE_CONNECTED  2   /* pipe is currently connected  */

/* Misc pipe definitions */

#define isbadpipid(x)   ( ((pid32)(x) < 0) || \
          ((pid32)(x) >= NPIP) || \
          (piptab[(x)].pipstate == PIPE_FREE))

/* Definition of pipe table */

struct pipent {         /* entry in the pipe table  */
uint32 pipstate;    /* pipe state: PIP_FREE, ect.   */
uint32 pipid;       /* pipe ID in table         */
char buffer[256];   /* buffer to write to       */
pid32 writer;       /* pid for writer       */
pid32 reader;       /* pid for reader       */
pid32 owner;        /* CURR_PID upon pipe being created */
};

extern struct pipent piptab[];
extern int32 pipcount;

pipcreate.c

#include <xinu.h>
#include <string.h>

static pipid32 newpipid(void);
/*------------------------------------------------------------------------
 *  pipcreate - 
 *------------------------------------------------------------------------
 */
syscall pipcreate(void){
    intmask mask;     /* saved interrupt mask   */

//struct pipent piptab[];
struct pipent *piptr;       /* ptr to pipe's table entry */
pipid32 pipid;              /* ID of newly created pipe */

mask = disable();

pipid = newpipid();         /* pipid to return */
piptr->pipstate = PIPE_USED;
piptr->owner = PR_CURR;
    //piptr->writer = PR_CURR;
    //piptr->reader = PR_CURR;

pipcount++;                 /* increment number of pipes */
piptr = &piptab[pipid];

restore(mask);
return pipid;
}

//newpipid - obtain a new (free) pipe ID
local pipid32 newpipid(void)
{
uint32 i;   
static pipid32 nextpipid = 1;
/* Check all NPIP slots */
for(i = 0; i < NPIP; i++){
    nextpipid %= NPIP;  /* wrap around to beginning */
    if(piptab[nextpipid].pipstate == PIPE_FREE){
        return nextpipid++;
    } else {
        nextpipid++;
    }
}
return (pid32) SYSERR;
}

Answer 1

一种可能性是源文件pipcreat.c实际上并不包含pipe.h(从显示的#include列表来看，似乎没有)。对此的一个简单检查是向 pipeline.h 添加一个明显的语法错误，并查看编译器是否提示它。