stdio-common/printf_buffer_as_file.c

   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 }