向pthread傳遞以另一個函式指標作為引數的函式指標時出現段錯誤

我正在使用沼澤標準 x86-64 Ubuntu gcc，顯然沒有編譯問題，因為我可以得到一個段錯誤。

我正在嘗試創建一個 pthread 來呼叫一個函式，該函式根據一些先前確定的條件采用另一個函式。也就是說，我試圖通過部分應用其輸入函式來修改執行緒中呼叫的函式。

代碼

#include <stdio.h>
#include <pthread.h>
#include <time.h>
#include <stdlib.h>
#include <stdint.h>

void * (*foo)(void*);
void * (*bar(void (*outputFun)(uint8_t a, short unsigned int b)))(void *);

void baz(u_int8_t a, short unsigned int b) {
    printf("a - b is %d - %d\n", a, b);
}

void bay(u_int8_t a, short unsigned int b) {
    printf("b - a is %d - %d\n", b, a);
}

int main() {
    srand(time(NULL));
    unsigned int random = 1   rand() % 2;
    printf("Our random number is: %d\n", random);

    foo = bar(random > 1 ? *baz : *bay);

    pthread_t thread;
    pthread_create(&thread, NULL,  foo  , NULL);
    // DO SOME STUFF
    pthread_join(thread, NULL);
}

void * (*bar(void (*outputFun)(uint8_t a, short unsigned int b)))(void *) {
    // DO OTHER STUFF
    outputFun(1, 2);
    return NULL;
}

valgrind 錯誤輸出

Our random number is: 2
a - b is 1 - 2
--15699-- REDIR: 0x4914b10 (libc.so.6:calloc) redirected to 0x483dce0 (calloc)
==15699== Thread 2:
==15699== Jump to the invalid address stated on the next line
==15699==    at 0x0: ???
==15699==    by 0x485E608: start_thread (pthread_create.c:477)
==15699==    by 0x4998132: clone (clone.S:95)
==15699==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==15699==
==15699==
==15699== Process terminating with default action of signal 11 (SIGSEGV)
==15699==  Bad permissions for mapped region at address 0x0
==15699==    at 0x0: ???
==15699==    by 0x485E608: start_thread (pthread_create.c:477)
==15699==    by 0x4998132: clone (clone.S:95)
--15699-- REDIR: 0x49136d0 (libc.so.6:free) redirected to 0x483c9d0 (free)
==15699==
==15699== HEAP SUMMARY:
==15699==     in use at exit: 272 bytes in 1 blocks
==15699==   total heap usage: 2 allocs, 1 frees, 1,296 bytes allocated
==15699==
==15699== Searching for pointers to 1 not-freed blocks
==15699== Checked 8,476,712 bytes
==15699==
==15699== LEAK SUMMARY:
==15699==    definitely lost: 0 bytes in 0 blocks
==15699==    indirectly lost: 0 bytes in 0 blocks
==15699==      possibly lost: 272 bytes in 1 blocks
==15699==    still reachable: 0 bytes in 0 blocks
==15699==         suppressed: 0 bytes in 0 blocks
==15699== Rerun with --leak-check=full to see details of leaked memory
==15699==
==15699== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
==15699==
==15699== 1 errors in context 1 of 1:
==15699== Jump to the invalid address stated on the next line
==15699==    at 0x0: ???
==15699==    by 0x485E608: start_thread (pthread_create.c:477)
==15699==    by 0x4998132: clone (clone.S:95)
==15699==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==15699==
==15699== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)

Fwiw，我是一名 Java 開發人員。所以，我需要我能得到的所有幫助，我們將不勝感激。謝謝。

編輯 顯然，我不能讓 C 屈服于我的意愿。

uj5u.com熱心網友回復：

你可以做你想做的，只是不完全是你想要的。

一些問題：

1. 隨著foo = bar(random > 1 ? *baz : *bay);你試圖創建一個 C 沒有的“閉包”
2. 您不能使用（例如*baz）呼叫函式。你需要baz()
3. 但是，我認為你只想要函式的地址（例如）baz

對于執行緒，最后一個引數pthread_create是傳遞給執行緒函式的指標。您可以創建一個struct包含您需要的所有資訊/引數的檔案。您傳遞該結構的地址，執行緒函式可以訪問它。

這是一個以更標準的方式進行等效的重構：

#include <stdio.h>
#include <pthread.h>
#include <time.h>
#include <stdlib.h>
#include <stdint.h>

typedef void (*outputFun) (uint8_t a, short unsigned int b);

typedef struct {
    u_int8_t a;
    unsigned int b;
    outputFun foo;
} args_t;

void
baz(u_int8_t a, short unsigned int b)
{
    printf("a - b is %d - %d\n", a, b);
}

void
bay(u_int8_t a, short unsigned int b)
{
    printf("b - a is %d - %d\n", b, a);
}

void *
bar(void *vp)
{
    args_t *arg = vp;

    // DO OTHER STUFF

    arg->foo(arg->a,arg->b);

    return NULL;
}

int
main(void)
{
    srand(time(NULL));
    unsigned int random = 1   rand() % 2;

    printf("Our random number is: %d\n", random);

    args_t arg;
    arg.foo = (random > 1) ? baz : bay;
    arg.a = 23;
    arg.b = 37;

    pthread_t thread;

    pthread_create(&thread, NULL, bar, &arg);

    // DO SOME STUFF

    pthread_join(thread, NULL);

    return 0;
}

標籤：C 线程 函数指针 pthread 连接

上一篇：如何在不使用指標的情況下在C中無轉換地轉換物件？

下一篇：禁止未使用的靜態函式的錯誤訊息？