1  /* FILE * interface to a struct __printf_buffer.  Multibyte version.
       2     Copyright (C) 2022-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <printf_buffer_as_file.h>
      20  
      21  #include <assert.h>
      22  #include <printf_buffer.h>
      23  
      24  /* Commit the data directly written through the stdio stream.  */
      25  static void
      26  __printf_buffer_as_file_commit (struct __printf_buffer_as_file *file)
      27  {
      28    /* Check that the write pointers in the file stream are consistent
      29       with the next buffer.  */
      30    assert (file->stream._IO_write_ptr >= file->next->write_ptr);
      31    assert (file->stream._IO_write_ptr <= file->next->write_end);
      32    assert (file->stream._IO_write_base == file->next->write_base);
      33    assert (file->stream._IO_write_end == file->next->write_end);
      34  
      35    file->next->write_ptr = file->stream._IO_write_ptr;
      36  }
      37  
      38  /* Pointer the FILE * write buffer into the active printf_buffer
      39     area.  */
      40  static void
      41  __printf_buffer_as_file_switch_to_buffer (struct __printf_buffer_as_file *file)
      42  {
      43    file->stream._IO_write_base = file->next->write_base;
      44    file->stream._IO_write_ptr = file->next->write_ptr;
      45    file->stream._IO_write_end = file->next->write_end;
      46  }
      47  
      48  /* Only a small subset of the vtable functions is implemented here,
      49     following _IO_obstack_jumps.  */
      50  
      51  int
      52  __printf_buffer_as_file_overflow (FILE *fp, int ch)
      53  {
      54    struct __printf_buffer_as_file *file = (struct __printf_buffer_as_file *) fp;
      55  
      56    __printf_buffer_as_file_commit (file);
      57  
      58    /* EOF means only a flush is requested.   */
      59    if (ch != EOF)
      60      __printf_buffer_putc (file->next, ch);
      61  
      62    /* Ensure that flushing actually produces room.  */
      63    if (!__printf_buffer_has_failed (file->next)
      64        && file->next->write_ptr == file->next->write_end)
      65      __printf_buffer_flush (file->next);
      66  
      67    __printf_buffer_as_file_switch_to_buffer (file);
      68  
      69    if (!__printf_buffer_has_failed (file->next))
      70      return (unsigned char) ch;
      71    else
      72      return EOF;
      73  }
      74  
      75  size_t
      76  __printf_buffer_as_file_xsputn (FILE *fp, const void *buf, size_t len)
      77  {
      78    struct __printf_buffer_as_file *file = (struct __printf_buffer_as_file *) fp;
      79  
      80    __printf_buffer_as_file_commit (file);
      81  
      82    /* Copy the data.  */
      83    __printf_buffer_write (file->next, buf, len);
      84  
      85    __printf_buffer_as_file_switch_to_buffer (file);
      86  
      87    if (!__printf_buffer_has_failed (file->next))
      88      return len;
      89    else
      90      /* We may actually have written something.  But the stream is
      91         corrupted in this case anyway, so try not to divine the write
      92         count here.  */
      93      return 0;
      94  }
      95  
      96  void
      97  __printf_buffer_as_file_init (struct __printf_buffer_as_file *file,
      98                                struct __printf_buffer *next)
      99  {
     100    file->stream._lock = NULL;
     101    _IO_no_init (&file->stream, _IO_USER_LOCK, -1, NULL, NULL);
     102    file->vtable = &_IO_printf_buffer_as_file_jumps;
     103  
     104    /* Set up the write buffer from the next buffer.  */
     105    file->next = next;
     106    __printf_buffer_as_file_switch_to_buffer (file);
     107  
     108    /* Mark the read area as inactive, by making all pointers equal.  */
     109    file->stream._IO_read_base = file->stream._IO_write_base;
     110    file->stream._IO_read_ptr = file->stream._IO_write_base;
     111    file->stream._IO_read_end = file->stream._IO_write_base;
     112  }
     113  
     114  bool
     115  __printf_buffer_as_file_terminate (struct __printf_buffer_as_file *file)
     116  {
     117    if (file->stream._flags & _IO_ERR_SEEN)
     118      return false;
     119    else
     120      {
     121        __printf_buffer_as_file_commit (file);
     122        return true;
     123      }
     124  }