Function tee_files

src/tee.c:230–343

   Return true if successful.  */

static bool
tee_files (int nfiles, char **files, bool pipe_check)
{
  size_t n_outputs = 0;
  int *descriptors;
  bool *out_pollable IF_LINT ( = NULL);
  char buffer[BUFSIZ];
  ssize_t bytes_read = 0;
  int first_out = 0;  /* idx of first non-null output in descriptors */
  bool ok = true;
  int flags = O_WRONLY | O_CREAT | O_BINARY | (append ? O_APPEND : O_TRUNC);

  xset_binary_mode (STDIN_FILENO, O_BINARY);
  xset_binary_mode (STDOUT_FILENO, O_BINARY);
  fadvise (stdin, FADVISE_SEQUENTIAL);

  /* Set up FILES[0 .. NFILES] and DESCRIPTORS[0 .. NFILES].
     In both arrays, entry 0 corresponds to standard output.  */

  descriptors = xnmalloc (nfiles + 1, sizeof *descriptors);
  if (pipe_check)
    out_pollable = xnmalloc (nfiles + 1, sizeof *out_pollable);
  files--;
  descriptors[0] = STDOUT_FILENO;
  if (pipe_check)
    out_pollable[0] = iopoll_output_ok (descriptors[0]);
  files[0] = bad_cast (_("standard output"));
  n_outputs++;

  for (int i = 1; i <= nfiles; i++)
    {
      /* Do not treat "-" specially - as mandated by POSIX.  */
      descriptors[i] = open (files[i], flags, MODE_RW_UGO);
      if (descriptors[i] < 0)
        {
          if (pipe_check)
            out_pollable[i] = false;
          error (output_error == output_error_exit
                 || output_error == output_error_exit_nopipe,
                 errno, "%s", quotef (files[i]));
          ok = false;
        }
      else
        {
          if (pipe_check)
            out_pollable[i] = iopoll_output_ok (descriptors[i]);
          n_outputs++;
        }
    }

  while (n_outputs)
    {
      if (pipe_check && out_pollable[first_out])
        {
          /* Monitor for input, or errors on first valid output.  */
          int err = iopoll (STDIN_FILENO, descriptors[first_out], true);

          /* Close the output if it became a broken pipe.  */