Question

I have encountered a strange issue while listing files in a subtree which are only directories or regular files. The files are listed but the size of the files after the following program traverses them becomes zero. How do I prevent that? Is it because of the stat()?

struct list_rec{
    int seqno;
    int path_length;
    char *file_path;
};
FILE *listoffiles;
int no_of_files;/*couter to keep track of files visited*/
static int list_the_files(const char *fpath,const struct stat *sb, int tflag, struct FTW *ftwbuf)
{
  int fd;
  struct list_rec t;
  struct stat buff;

  if(stat(fpath,&buff) == -1)
 printf("Error reading inode");

  /*the file will be listed if it is directory or if it is a regular file and can be   opened for writing*/
  if(S_ISDIR(buff.st_mode)==0)
  {
 //printf("\nIT IS NOT A DIRECTORY %s",fpath);
if(S_ISREG(buff.st_mode)!=0)
{
    //printf("IT IS A REGULAR FILE %s",fpath);
    fd = open  (fpath,O_WRONLY|O_CREAT|O_TRUNC,S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
    if(fd != -1)
    {
        close(fd);
        no_of_files = no_of_files+1;
        t.seqno = no_of_files;
        t.path_length = strlen(fpath)+1;
        t.file_path = malloc(sizeof(char)*t.path_length);
        strcpy(t.file_path,fpath);

        fwrite(&t.seqno,sizeof(int),1,listoffiles);
        fwrite(&t.path_length,sizeof(int),1,listoffiles);
        fwrite(t.file_path,sizeof(char)*t.path_length,1,listoffiles);

        free(t.file_path);
    }
    else
        printf("\n is regular but could not open %s",fpath);
}
else
    printf("\nNot a regular file %s",fpath);    
 }
 else
 {
    no_of_files = no_of_files+1;
t.seqno = no_of_files;
t.path_length = strlen(fpath)+1;
t.file_path = malloc(sizeof(char)*t.path_length);
strcpy(t.file_path,fpath);

fwrite(&t.seqno,sizeof(int),1,listoffiles);
fwrite(&t.path_length,sizeof(int),1,listoffiles);
fwrite(t.file_path,sizeof(char)*t.path_length,1,listoffiles);

free(t.file_path);
  }
 return 0;
 }

 int main(int argc, char *argv[])
 {
   listoffiles = fopen("/home/juggler/files.txt","w+b");
   no_of_files = 0;
   ftw(argv[1],list_the_files,20);
   fwrite(&no_of_files,sizeof(int),1,listoffiles);//Writing the total number of    records at the end of the file
  }

Thanks. Help will be much appreciated

Answer 1

You’re opening files with O_WRONLY and O_TRUNC, which will truncate the file to 0 length. You probably just want O_RDONLY.