I have the following code to cycle through the numeric dirs inside /proc and get the names of the folders by going further into the dir of the given PID:

/proc/PID/cmdline

This is the C code:

  char* getNameByPID(const char* cmdline_CmdLinePath, const int PID){
      char* chrptr_NameOfProcess;
      FILE* fd_CmdLineFile = fopen (cmdline_CmdLinePath, "rt") ;  // open the file for reading text if (fd_CmdLineFile) {
      if (fd_CmdLineFile) {
          chrptr_NameOfProcess = malloc(200);
          if (fscanf(fd_CmdLineFile, "%s", chrptr_NameOfProcess) != 1) {
              free(chrptr_NameOfProcess);
              chrptr_NameOfProcess = NULL;
          }
          fclose(fd_CmdLineFile);
      }   
      return chrptr_NameOfProcess;
  }       
          
  void printInfo(int intHasArgs) {
      DIR* dir_proc = NULL;
      dir_proc = opendir(PROC_DIRECTORY);
          
      if (dir_proc == NULL) {
          perror("Couldn't open the " PROC_DIRECTORY " directory");
      }   
          
      struct dirent* de_DirEntity = NULL;                                                                                                                                                     
      char smaps_CmdLinePath[100];
      char cmdline_CmdLinePath[100];
          
      while ( (de_DirEntity = readdir(dir_proc)) ) {
          if ( de_DirEntity->d_type == DT_DIR ) {
              if ( isNumeric(de_DirEntity->d_name) ) {
                  strcpy(smaps_CmdLinePath, PROC_DIRECTORY);
                  strcpy(cmdline_CmdLinePath, PROC_DIRECTORY);
                  strcat(smaps_CmdLinePath, de_DirEntity->d_name);
                  strcat(cmdline_CmdLinePath, de_DirEntity->d_name);
                  strcat(smaps_CmdLinePath, "/smaps");
                  strcat(cmdline_CmdLinePath, "/cmdline");
                  char* procName = getNameByPID(cmdline_CmdLinePath, atoi(de_DirEntity->d_name));
                  if (procName != NULL && procName[0] != '') {
                      printf("%sn", procName);
                  }
              }
          }
      }   
      closedir(dir_proc) ;
  }

It works as expected (printing the names of all the numeric dirs found), but at the end it prints:

free(): invalid size
Aborted (core dumped)

which tells me there’s some memory leakage, but I did add a check and free memory if the initial malloc was unsuccessful:

if (fscanf(fd_CmdLineFile, "%s", chrptr_NameOfProcess) != 1) {
                  free(chrptr_NameOfProcess);
                  chrptr_NameOfProcess = NULL;
}

I tried also adding the following:

if (procName != NULL && procName[0] != '') {
    printf("%sn", procName);
    free(procName);
}

but this didn’t help the issue either.