c - 在 C 中调试递归线程调用

Question

最近一天半，只要有空闲时间，我就一直在调试我的代码，但我不知道我的代码有什么问题。当我将 close() 函数添加到递归调用时，程序为我提供了一个无效指针。但是，当我删除 close() 函数调用时，程序运行正常，只是它没有执行它应该执行的操作，即:

• 将一个用户的所有文件大小相加输入目录
• 打开子目录，如果有的话，添加up里面的所有文件子目录

相反，它将输入目录中的所有文件大小相加，并且能够打开最后一个子目录并将该目录中的文件添加到总文件大小计数中。

我正在尝试用线程来做到这一点。 main() 函数从用户输入目录创建一个主线程并立即运行 opendirectory()。

/*
 * Iterates through given directory
 */
void *opendirectory(void *t)
{
 pthread_mutex_lock(&dirlock);
 DIR *dpntr;
 struct dirent *dentry;
 char new_directory[512], dir = t;

 printf("OPENING DIRECTORY ... %s\n", t);

 /* Checks if given directory can be opened */
 if((dpntr = opendir(t)) == NULL) {
  printf("DIRECTORY FAILED ...%s\n",t);
  perror("ERROR -- COULD NOT OPEN DIR");
  pthread_exit(NULL);
 }

 printf("DIRECTORY OPENED: %s\n", t);

 /* Read each file in current directory */
 while ((dentry = readdir(dpntr)) != NULL ) {
  /* Ignore special directories */
  if(strcmp(dentry -> d_name, ".") == 0 || strcmp(dentry -> d_name, "..") == 0) {
   continue;
  } else {
   compilelist( t, dentry->d_name );
  }
 }

 pthread_mutex_unlock(&dirlock);
 /* Checks if directory can be closed */
 if(closedir(dpntr) < 0)
  printf("ERROR CLOSING %s.\n", t);

}

此函数将确定是否应创建新线程并应递归运行。

/*
 * Determines if current file is a directory
 * Creates a new thread if true
 */
void compilelist (const char* dirname, const char *filename)
{
    pthread_mutex_lock(&filelock);
    struct stat statdata;
    char *filepathname, *dpntr;

    /* Allocate memory for filepathname */
    if((filepathname = (char *) malloc(sizeof(char) * strlen(dirname))) == NULL)
    {
        printf("CANNOT ALLOCATE MEMORY FOR FILE PATH NAME.");
        pthread_exit(NULL);
    }

    /* Concats directory name with file name */
    if(dirname[strlen(dirname) -1] == '/')
    {
        pthread_mutex_lock(&pathlock);
        sprintf(filepathname, "%s%s", dirname, filename);
        pthread_mutex_unlock(&pathlock);
    }else
    {
        pthread_mutex_lock(&pathlock);
        sprintf(filepathname, "%s/%s", dirname, filename);
        pthread_mutex_unlock(&pathlock);
    }

    lstat(filepathname, &statdata);

    /* Calls print_statdata() if current item is a file */
    if(!(S_ISDIR(statdata.st_mode)))
    {
        printf("FILE: %s\n", filepathname);
        if(!stat( filepathname, &statdata))
        {
            print_statdata( filename, &statdata );
        }
        else {
            fprintf (stderr, "GETTING STAT FOR %s", filepathname);
            perror( "ERROR IN STATDATA WHILE GETTING STAT");
        }
    }
    /* Recursive call to opendirectory() */
    else {
        pthread_mutex_lock(&dircountlock);
        dirCount++;
        pthread_mutex_unlock(&dircountlock);
        dpntr = filepathname;
        free(filepathname);
        printf("SUB-DIRECTORY THREAD: %s\nTHREAD ID NUMBER: %d\n", dpntr, dirCount);
        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
        pthread_create(&threads[dirCount-1], &attr, opendirectory, (void *)dpntr);
    }

    pthread_mutex_unlock(&filelock);

}

这是main()

/*
 * Main function prompts user for a directory
 */
int main(int argc, char *argv[])
{
    int i;
    char *dPtr;
    // pthread_attr_t attr;

    printf("ENTER A DIRECTORY:\n\t");
    scanf("%s", directory);
    dPtr = directory;

    /* Initialize mutex and condition variable objects */
    pthread_mutex_init(&mutex, NULL);
    pthread_mutex_init(&filelock, NULL);
    pthread_mutex_init(&dirlock, NULL);
    pthread_mutex_init(&dircountlock, NULL);
    pthread_cond_init (&count_threshold_cv, NULL);

    /* For portability, explicitly create threads in a joinable state */
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    pthread_create(&threads[0], &attr, opendirectory, (void *)dPtr);

    /* Wait for all threads to complete */
    for (i = 0; i < dirCount; i++) {
        pthread_join(threads[i], NULL);
    }

    printf("TOTAL DIRECTORY SIZE: %d\n", dirSize);

    /* Clean up and exit */
    pthread_attr_destroy(&attr);
    pthread_mutex_destroy(&mutex);
    pthread_mutex_destroy(&filelock);
    pthread_mutex_destroy(&dirlock);
    pthread_mutex_destroy(&dircountlock);
    pthread_cond_destroy(&count_threshold_cv);
    pthread_exit (NULL);

}

还有全局变量...

pthread_mutex_t mutex;
pthread_mutex_t dirlock;
pthread_mutex_t filelock;
pthread_mutex_t dircountlock;
pthread_mutex_t threadlock;
pthread_cond_t count_threshold_cv;
pthread_attr_t attr;
pthread_t threads[128]; // handles up to 128 threads (i.e. 128 directories, change accordingly)
char directory[512];
int dirSize = 0;
int dirCount = 1; // user's input directory

感觉compilelist()函数底层调用的pthread_create()没有正常工作。 threads[] 指的是默认大小为 20 的全局线程数组，假设目录总数不超过 20 个。由于用户的输入目录，dirCount 从 1 开始，并随着遇到新目录而增加。

Answer 1

您的代码:

dpntr = opendir(t)

...

if(closedir(t) < 0)

应该是:

if(closedir(dpntr) < 0)