Question

我正在尝试创建一个复制程序，它接受源和目标目录并将目录从源复制到目标。两个目录名都是文件路径的情况，它的工作原理。对于source是文件而目标是目录的情况，它可以工作。但是，对于源和目录都是目录的情况，它不能正常工作，甚至不是非多级别目录的简单情况。。请建议版本。

#include<stdio.h>
#include<string.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<dirent.h>
#include<stdlib.h>
#include<unistd.h>

void copyfile(char source[],char destination[]);
void traverse(char source[],char destination[]);
int isdir(char path[]);

int main(int argc,char *argv[])
{
    if(argc<3)
    {
        printf("ERROR: Improper syntax\n");
        printf("\t./copy [source path] [destination path]\n");
        exit(0);
    }

    char *source=(char *)malloc(sizeof(char)*strlen(argv[1])+1);
    char *destination=(char *)malloc(sizeof(char)*strlen(argv[2])+1);

    strcpy(source,argv[1]);
    strcpy(destination,argv[2]);

    if(isdir(source)&&!isdir(destination))
    {
        printf("Destination cannot be a file\n");
        exit(0);
    }   
    if(isdir(source)&&isdir(destination))
        traverse(source,destination);
    else copyfile(source,destination);

    return 0;
}

void copyfile(char source[],char destination[])
{
    int c;

    if(!isdir(source)&&isdir(destination))
    {
        char *fname=strrchr(source,'/');
        if(realloc(destination,strlen(destination)+strlen(source)+2)==NULL)
        {
            printf("Memory reallocation error\n");
            exit(0);
        }
        strcat(destination,fname);  
    }

    FILE *f1,*f2;
    f1=fopen(source,"r");
    f2=fopen(destination,"w");

    if(f1==NULL)
    {
        printf("File does not exists");
        return;
    }

    if(f2==NULL)
    {
        printf("File copying error: Directory may or may not exist\n");
        return;
    }

    while((c=fgetc(f1))!=EOF)
        fputc(c,f2);

    fclose(f1);
    fclose(f2);
    return;
}

int isdir(char path[])
{
    struct stat dir;
    stat(path,&dir);
    if(S_ISREG(dir.st_mode))
        return 0;
    if(S_ISDIR(dir.st_mode))
        return 1;
    printf("The source is not a file, neither a dir\n");
    exit(0);
}

void traverse(char source[],char destination[])
{   
    char *fname=strrchr(source,'/');

    char *tdest=(char *)malloc(strlen(destination)+strlen(fname)+1+6);

    strcpy(tdest,"mkdir ");
    strcat(tdest,destination);
    strcat(tdest,fname);
    system(tdest);
    if(realloc(destination,(strlen(destination)+strlen(fname))*sizeof(char)+1)==NULL)
    {
        printf("Destination rellocaion pointer inturrupted\n");
        exit(0);
    }
    strcat(destination,fname);  

    DIR *d1;
    if((d1=opendir(source))==NULL)
    {
        printf("Source access inturrupted\n");
        exit(0);
    }

    struct dirent *cwd;

    struct stat dir;
    while((cwd=readdir(d1))!=NULL)
    {   
        char *tsource=(char *)malloc((strlen(source)+strlen(cwd->d_name))*sizeof(char)+2);
        stat(cwd->d_name,&dir);
        if(S_ISDIR(dir.st_mode))
        {
            if(strcmp(cwd->d_name,".")==0||strcmp(cwd->d_name,"..")==0)continue;        

            traverse(source,destination);
        }

        strcpy(tsource,source);
        strcat(tsource,"/");
        strcat(tsource,cwd->d_name);
        copyfile(tsource,destination);
    }

    closedir(d1);       
    return;
}

Answer 1

您使用realloc失败：必须将其返回值分配（通常是重新分配）给指针。

npm install node-gyp rebuild

请注意，对malloc的所有调用都应该避免转换返回值，并且所有返回的值都必须为NULL检查。

正如@Quentin正确评论的那样，请注意，如果destination = realloc(destination, (strlen(destination)+strlen(fname))*sizeof(char)+1); if (destination == NULL) { printf("Destination rellocaion pointer inturrupted\n"); exit(0); }失败，目标指向的内存将被泄露：该内存的地址将丢失。所以要非常安全地做到这一点，你可以使用临时变量：

realloc

还要注意，必须释放所有char *temp = realloc(destination, (strlen(destination)+strlen(fname))*sizeof(char)+1); if (temp == NULL) { printf("Destination rellocaion pointer inturrupted\n"); exit(0); } destination = temp;个块，即使程序终止时OS会为您释放它。这是编码和避免未来内存泄漏问题的最佳方法：malloc内存，直到特定内存不再使用。

为什么在这个复制目录的程序代码中出现逻辑错误？

1 个答案: