尝试在 C 中重新制作 linux 查找命令

Question

我的任务是重新制作 find 命令的部分功能。我尝试做的第一部分只是正常的“查找”，它列出了该目录中的所有文件和子目录。我正在使用实际的查找命令来测试我的结果。

是否有明显遗漏的内容导致我打印不正确的文件路径？

图片顺序：

C代码
预期输出
实际输出

我用来测试的目录树

void readSub (char* subDir)
{
 DIR *sub_dp = opendir(subDir); //Opens directory stream

 struct dirent *subDirp; //define sub directory pointer
 struct stat buf; //define file status struct

 char t1[] = ".";
 char t2[] = "..";
 char t3[] = "/";

 if(sub_dp != NULL) // Was directory successfully opened
 {
         //read each entry one time only
         while((subDirp = readdir(sub_dp)) != NULL)
         {
                 char *temp = subDirp -> d_name; //check if first entry was a sub directory

                 //avoid searching for . and ..
                 if(strcmp(temp, t1) != 0 && strcmp(temp, t2) != 0)
                 {
                         char *tempSub = t3;
                         tempSub = strcat(tempSub, temp); //add / to entry name
                         char *temp_full_path = malloc(sizeof(char) * 2000);
                         temp_full_path = strcpy(temp_full_path, subDir);
                         strcat(temp_full_path, tempSub); //gives full path

                         printf("%s\n", temp_full_path);
                         DIR *subsubDP = opendir(temp_full_path); //try to open

                         if(subsubDP != NULL) //if not NULL then subsubDP is sub directory
                         {
                                 closedir(subsubDP); //will get opened in recursive call
                                 readSub(temp_full_path); //recursive call
                         }
                 }
         } //end of while loop
         closedir(sub_dp); //close directory stream
 }

 else
 {
         printf("Can't open directory\n");
         exit(2);
 }
}

int main(int argc, char **argv)
{
        char *dir;

 if(argc < 2)
 {
         dir = ".";
 }

 else
 {
         dir = argv[1];
 }

 readSub(dir);

 exit(0);
}

Answer 1

问题是

tempSub = strcat(tempSub, temp); //add / to entry name

tempSub指向t3数组，只有2个字节。将 temp 连接到它会写入数组边界之外，这会导致未定义的行为。

您应该通过将 subDir、t3、temp 的长度加上空终止符的 1 来计算 temp_full_path 的总长度，并分配它.由于您只在当前循环迭代中需要它，因此您可以使用 variable-length 数组而不是 malloc()（您的代码永远不会调用 free(temp_full_path)）。

替换

 char *tempSub = t3;
 tempSub = strcat(tempSub, temp); //add / to entry name
 char *temp_full_path = malloc(sizeof(char) * 2000);
 temp_full_path = strcpy(temp_full_path, subDir);
 strcat(temp_full_path, tempSub); //gives full path

和

char temp_full_path[strlen(subDir) + strlen(t3) + strlen(temp) + 1];
sprintf(temp_full_path, "%s%s%s", subDir, t3, temp);

尝试在 C 中重新制作 linux 查找命令

Trying to remake linux find command in C

c

linux

filesystems

find