Thread: Problem redirecting multiple pipes with multiple children

Hi there, I've been working on a function that works like a pipeline of a shell but receives a directory, go over it an search for every file to send it to a filter, something like this in bash "cat dir/* | cmd_1 | cmd_2 | ... | cmd_N", The only problem i have with the code is the redirection of the pipe descriptors.

Code:

  int main(int argc, char* argv[]){ 

       char** cmd;
       int Number_cmd;
        
       cmd = &(argv[2]); /*list of cmds*/
       Number_cmd = argc-2;       /*number of cmds*/

       filter();
       directory(argv[1]);      
       return 0;
      }    

    void filter(void){

        if(Number_cmd != 0){
         
          int p,i;
          int fd[2];

          for(i=0;i<Number_cmd;i++)
              pipe(fd);

          for(p=(Number_cmd-1); p>=0; p--){
            switch(fork()){
                   case -1:
      
                      perror("fork");
                      exit(1);

                    case  0:       /* Child */
                       close(fd[1]);
                       close(0);
                       dup(fd[0]);
                       close(fd[0]); 
    
                      execlp(filter[p], filter[p], NULL);
                      perror("exec");
                      exit(1);

                    default:             /* Father */
                       close(fd[0]);          
                       close(1);
                       dup(fd[1]);                
                       close(fd[1]);
                       break;
                    }
                  }
                } 
              }

       void directory(char* directory_name){
                DIR* dir = NULL;
                struct dirent* ent;
                char fich[1024];
                char buff[4096];
                int fd, reading;
                struct stat sdata;
               
                dir = opendir(directory_name);
                      while((ent=readdir(dir))!=NULL){
                      
                       if(ent->d_name[0]=='.')
                            continue;
                    
                    fich[0]='\0'; 
                    strcat(fich, directory_name); 
                    strcat(fich, "/");          
                     strcat(fich, ent->d_name); 
                    stat(fich,&sdata)
    
                    if(S_ISDIR(sdata.st_mode))
                             continue;

                    fd = open(fich, O_RDONLY)
                     while((reading= read(fd, buff, 4096)) > 0){
                       (write(1, buff, reading) < reading);
                          continue;
                           }
           
                      close(fd);  
                      }
                   closedir(dir);
                   }

The code is seems to work fine except when i run it with more than one command in example ("./filter DIR wc rev") in this case it returns

wc: standard input: Bad file descriptor
wc: -: Bad file descriptor
0 0 0

Thank everyone in advance (sorry for my english i am not a native english speaker)

That code would not even compile, let alone link and run, or produce bad output. main() calls a non-existent function named filter(), and the function preparar_filtros() which does the forking is never called.

Try providing a small sample of actual code that actually exhibits your problem.

No amount of challenges with english justify not providing representative code.