我正在关注here的内核教程
我在编译文件时遇到问题.
尝试编译时出现以下错误：
main.c:8: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:8: error: conflicting types for ‘memcpy’
./include/system.h:5: note: previous declaration of ‘memcpy’ was here
main.c: In function ‘memcpy’:
main.c:12: error: ‘count’ undeclared (first use in this function)
main.c:12: error: (Each undeclared identifier is reported only once
main.c:12: error: for each function it appears in.)
main.c: At top level:
main.c:16: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:16: error: conflicting types for ‘memset’
./include/system.h:6: note: previous declaration of ‘memset’ was here
main.c: In function ‘memset’:
main.c:19: error: ‘count’ undeclared (first use in this function)
main.c: At top level:
main.c:23: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:23: error: conflicting types for ‘memsetw’
./include/system.h:7: note: previous declaration of ‘memsetw’ was here
main.c: In function ‘memsetw’:
main.c:26: error: ‘count’ undeclared (first use in this function)
main.c: At top level:
main.c:30: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘strlen’
main.c:49: warning: return type of ‘main’ is not ‘int’
main.c: In function ‘main’:
main.c:64: warning: pointer targets in passing argument 1 of ‘puts’ differ in signedness
./include/system.h:13: note: expected ‘unsigned char *’ but argument is of type ‘char *’
main.c:51: warning: unused variable ‘i’
scrn.c: In function ‘scroll’:
scrn.c:24: warning: passing argument 1 of ‘memcpy’ from incompatible pointer type
./include/system.h:5: note: expected ‘unsigned char *’ but argument is of type ‘short unsigned int *’
scrn.c:24: warning: passing argument 2 of ‘memcpy’ from incompatible pointer type
./include/system.h:5: note: expected ‘const unsigned char *’ but argument is of type ‘short unsigned int *’
scrn.c: In function ‘puts’:
scrn.c:139: warning: pointer targets in passing argument 1 of ‘strlen’ differ in signedness
./include/system.h:8: note: expected ‘const char *’ but argument is of type ‘unsigned char *’
我的文件是教程中文件的精确副本.
我可以看到在main.c中,函数的定义如下
void * memcpy(void * dest,const void * src,size_t count)
但在我的system.h文件中,它们的定义如下
extern unsigned char * memcpy(unsigned char * dest,const unsigned char * src,int count)
C不是我的主要语言,但我正在学习它,因此,如果我的问题很简单,我会道歉,但我认为这些定义应该相同吗？
解决方法:
可能是您的问题是size_t与平台上的int不同,或者根本没有正确指定size_t.指针类型应该确定(从技术上讲,它们也应该匹配,但是在大多数系统上,sizeof(char *)== sizeof(void *)).
如果您正在开发自己的内核,则需要编写自己的system.h.如果您同时编写system.h和main.c,则可以根据需要使它们匹配.如果看一下this page of the tutorial,您会看到标头和C源代码都将memcpy声明为：
unsigned char *memcpy(unsigned char *dest, const unsigned char *src, int count);
但是,如果您在教程末尾下载示例源文件,则会发现它是：
void *memcpy(void *dest, const void *src, size_t count);
查看该文件的顶部,您会发现以下注释：
/* bkerndev - Bran's Kernel Development Tutorial
* By: Brandon F. (friesenb@gmail.com)
* Desc: Main.c: C code entry.
*
* Notes: No warranty expressed or implied. Use at own risk. */
看起来您似乎不想按照本教程进行操作,而是要像从教程中剪切并粘贴代码一样.就像试图通过跟随一本书来学习进行脑外科手术一样.您可能会使其正常工作,但是如果您真的不了解自己在做什么……好吧,请帮个忙,不要将其用于任何重要的事情.
标签：kernel,c-3,linux 来源： https://codeday.me/bug/20191107/2002445.html
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