是否可以重複導致編譯錯誤的C源代碼？

按照另一個question I had asked earlier我想我可能已經找到了我的問題，但我需要專家的眼球。是否可以重複導致編譯錯誤的C源代碼？

我發現文件/net/ipv4/tcp_zero_copy.c這導致了我的內核編譯失敗。

當我在C/C++編輯器中查看文件時，我對C或C++沒有多少了解，它看起來像相同的代碼重複了一遍（我認爲是4次）。

我的問題很簡單;

這足以導致編譯器出現問題嗎？如果相同的代碼在同一個文件中反覆出現？

這是該文件的源代碼（總共148行，從頭到尾）;

/* 
* Support routines for TCP zero copy transmit 
* 
* Created by Vladislav Bolkhovitin 
* 
* This program is free software; you can redistribute it and/or 
*  modify it under the terms of the GNU General Public License 
*  version 2 as published by the Free Software Foundation. 
*/ 

#include <linux/skbuff.h> 

net_get_page_callback_t net_get_page_callback __read_mostly; 
EXPORT_SYMBOL(net_get_page_callback); 

net_put_page_callback_t net_put_page_callback __read_mostly; 
EXPORT_SYMBOL(net_put_page_callback); 

/* 
* Caller of this function must ensure that at the moment when it's called 
* there are no pages in the system with net_priv field set to non-zero 
* value. Hence, this function, as well as net_get_page() and net_put_page(), 
* don't need any protection. 
*/ 
int net_set_get_put_page_callbacks(
    net_get_page_callback_t get_callback, 
    net_put_page_callback_t put_callback) 
{ 
    int res = 0; 

    if ((net_get_page_callback != NULL) && (get_callback != NULL) && 
     (net_get_page_callback != get_callback)) { 
     res = -EBUSY; 
     goto out; 
    } 

    if ((net_put_page_callback != NULL) && (put_callback != NULL) && 
     (net_put_page_callback != put_callback)) { 
     res = -EBUSY; 
     goto out; 
    } 

    net_get_page_callback = get_callback; 
    net_put_page_callback = put_callback; 

out: 
    return res; 
} 
EXPORT_SYMBOL(net_set_get_put_page_callbacks); 
/* 
* Support routines for TCP zero copy transmit 
* 
* Created by Vladislav Bolkhovitin 
* 
* This program is free software; you can redistribute it and/or 
*  modify it under the terms of the GNU General Public License 
*  version 2 as published by the Free Software Foundation. 
*/ 

#include <linux/skbuff.h> 

net_get_page_callback_t net_get_page_callback __read_mostly; 
EXPORT_SYMBOL(net_get_page_callback); 

net_put_page_callback_t net_put_page_callback __read_mostly; 
EXPORT_SYMBOL(net_put_page_callback); 

/* 
* Caller of this function must ensure that at the moment when it's called 
* there are no pages in the system with net_priv field set to non-zero 
* value. Hence, this function, as well as net_get_page() and net_put_page(), 
* don't need any protection. 
*/ 
int net_set_get_put_page_callbacks(
    net_get_page_callback_t get_callback, 
    net_put_page_callback_t put_callback) 
{ 
    int res = 0; 

    if ((net_get_page_callback != NULL) && (get_callback != NULL) && 
     (net_get_page_callback != get_callback)) { 
     res = -EBUSY; 
     goto out; 
    } 

    if ((net_put_page_callback != NULL) && (put_callback != NULL) && 
     (net_put_page_callback != put_callback)) { 
     res = -EBUSY; 
     goto out; 
    } 

    net_get_page_callback = get_callback; 
    net_put_page_callback = put_callback; 

out: 
    return res; 
} 
EXPORT_SYMBOL(net_set_get_put_page_callbacks); 
/* 
* Support routines for TCP zero copy transmit 
* 
* Created by Vladislav Bolkhovitin 
* 
* This program is free software; you can redistribute it and/or 
*  modify it under the terms of the GNU General Public License 
*  version 2 as published by the Free Software Foundation. 
*/ 

#include <linux/skbuff.h> 

net_get_page_callback_t net_get_page_callback __read_mostly; 
EXPORT_SYMBOL(net_get_page_callback); 

net_put_page_callback_t net_put_page_callback __read_mostly; 
EXPORT_SYMBOL(net_put_page_callback); 

/* 
* Caller of this function must ensure that at the moment when it's called 
* there are no pages in the system with net_priv field set to non-zero 
* value. Hence, this function, as well as net_get_page() and net_put_page(), 
* don't need any protection. 
*/ 
int net_set_get_put_page_callbacks(
    net_get_page_callback_t get_callback, 
    net_put_page_callback_t put_callback) 
{ 
    int res = 0; 

    if ((net_get_page_callback != NULL) && (get_callback != NULL) && 
     (net_get_page_callback != get_callback)) { 
     res = -EBUSY; 
     goto out; 
    } 

    if ((net_put_page_callback != NULL) && (put_callback != NULL) && 
     (net_put_page_callback != put_callback)) { 
     res = -EBUSY; 
     goto out; 
    } 

    net_get_page_callback = get_callback; 
    net_put_page_callback = put_callback; 

out: 
    return res; 
} 
EXPORT_SYMBOL(net_set_get_put_page_callbacks);

**編輯**

而且我只是用記事本++到它看起來像他們結束的代碼的各個塊進行比較。根據比較工具全部3塊互相匹配。

這是從它死亡的地方到它返回給我的命令提示符的編譯器輸出。

CC  net/ipv4/tcp_zero_copy.o 
net/ipv4/tcp_zero_copy.c:63:1: error: redefinition of â__kcrctab_net_get_page_callbackâ 
net/ipv4/tcp_zero_copy.c:14:1: note: previous definition of â__kcrctab_net_get_page_callbackâ was here 
net/ipv4/tcp_zero_copy.c:63:1: error: redefinition of â__kstrtab_net_get_page_callbackâ 
net/ipv4/tcp_zero_copy.c:14:1: note: previous definition of â__kstrtab_net_get_page_callbackâ was here 
net/ipv4/tcp_zero_copy.c:63:1: error: redefinition of â__ksymtab_net_get_page_callbackâ 
net/ipv4/tcp_zero_copy.c:14:1: note: previous definition of â__ksymtab_net_get_page_callbackâ was here 
net/ipv4/tcp_zero_copy.c:66:1: error: redefinition of â__kcrctab_net_put_page_callbackâ 
net/ipv4/tcp_zero_copy.c:17:1: note: previous definition of â__kcrctab_net_put_page_callbackâ was here 
net/ipv4/tcp_zero_copy.c:66:1: error: redefinition of â__kstrtab_net_put_page_callbackâ 
net/ipv4/tcp_zero_copy.c:17:1: note: previous definition of â__kstrtab_net_put_page_callbackâ was here 
net/ipv4/tcp_zero_copy.c:66:1: error: redefinition of â__ksymtab_net_put_page_callbackâ 
net/ipv4/tcp_zero_copy.c:17:1: note: previous definition of â__ksymtab_net_put_page_callbackâ was here 
net/ipv4/tcp_zero_copy.c:74:5: error: redefinition of ânet_set_get_put_page_callbacksâ 
net/ipv4/tcp_zero_copy.c:25:5: note: previous definition of ânet_set_get_put_page_callbacksâ was here 
net/ipv4/tcp_zero_copy.c:98:1: error: redefinition of â__kcrctab_net_set_get_put_page_callbacksâ 
net/ipv4/tcp_zero_copy.c:49:1: note: previous definition of â__kcrctab_net_set_get_put_page_callbacksâ was here 
net/ipv4/tcp_zero_copy.c:98:1: error: redefinition of â__kstrtab_net_set_get_put_page_callbacksâ 
net/ipv4/tcp_zero_copy.c:49:1: note: previous definition of â__kstrtab_net_set_get_put_page_callbacksâ was here 
net/ipv4/tcp_zero_copy.c:98:1: error: redefinition of â__ksymtab_net_set_get_put_page_callbacksâ 
net/ipv4/tcp_zero_copy.c:49:1: note: previous definition of â__ksymtab_net_set_get_put_page_callbacksâ was here 
make[2]: *** [net/ipv4/tcp_zero_copy.o] Error 1 
make[1]: *** [net/ipv4] Error 2 
make: *** [net] Error 2 
[email protected]:/usr/src/linux# ls

來源

2011-08-21 ianc1215

直接的答案是肯定的，這是一個問題。更有趣的答案將是這個問題發生的原因或方式。 –

@Solignis：這是哪個版本的內核？（完整版，包括平臺，操作系統等） –

這取決於被重複什麼，

函數聲明重複不會給任何錯誤。
重複的函數定義會給出錯誤。
正在創建\定義爲相同名稱的變量會給出錯誤。

#2 & #3給出錯誤，因爲他們打破了ODR（一個定義規則）。

void doSomething(); //no error 
void doSomething(); 
void doSomething(); 

void doSomething() 
{ 

} 

int main() 
{ 
    int i; //error 
    int i; 
    doSomething(); 
    return 1; 
}

在此代碼：

net_get_page_callback_t net_get_page_callback __read_mostly;

限定可變的，並且這樣做多次，導致相同的命名變量的多個定義，因而重定義錯誤。

來源

2011-08-21 07:21:11

所以它們是多餘的？所以刪除它們並保持代碼塊＃1？一切都應該好？ – ianc1215

@Solignis：是的，他們是簡化版，也許有人在代碼中不小心複製了粘貼的代碼塊？ –

是啊不知道如何可以通過。無論如何希望它會在這次工作。 – ianc1215

函數在翻譯單元中被多次定義是錯誤的。這是發生在這裏的事情。嘗試發佈編譯中的前幾個錯誤消息。

來源

2011-08-21 07:21:50

我從它死亡的地方添加了輸出。 – ianc1215

是的，錯誤消息證實了這一點。 –

是否可以重複導致編譯錯誤的C源代碼？

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