stdio-common/wprintf_buffer_as_file.c

   1 /* FILE * interface to a struct __wprintf_buffer.  Wide version.
   2    Copyright (C) 2022-2024 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 __wprintf_buffer_as_file_commit (struct __wprintf_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->wide_stream._IO_write_ptr >= file->next->write_ptr);
  31   assert (file->wide_stream._IO_write_ptr <= file->next->write_end);
  32   assert (file->wide_stream._IO_write_base == file->next->write_base);
  33   assert (file->wide_stream._IO_write_end == file->next->write_end);
  34
  35   file->next->write_ptr = file->wide_stream._IO_write_ptr;
  36 }
  37
  38 /* Pointer the FILE * write buffer into the active struct __wprintf_buffer
  39    area.  */
  40 static void
  41 __wprintf_buffer_as_file_switch_to_buffer (struct __wprintf_buffer_as_file *file)
  42 {
  43   file->wide_stream._IO_write_base = file->next->write_base;
  44   file->wide_stream._IO_write_ptr = file->next->write_ptr;
  45   file->wide_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 wint_t
  52 __wprintf_buffer_as_file_overflow (FILE *fp, int ch)
  53 {
  54   struct __wprintf_buffer_as_file *file
  55     = (struct __wprintf_buffer_as_file *) fp;
  56
  57   __wprintf_buffer_as_file_commit (file);
  58
  59   /* EOF means only a flush is requested.   */
  60   if (ch != WEOF)
  61     __wprintf_buffer_putc (file->next, ch);
  62   else
  63     ch = 0;
  64
  65   /* Ensure that flushing actually produces room.  */
  66   if (!__wprintf_buffer_has_failed (file->next)
  67       && file->next->write_ptr == file->next->write_end)
  68     __wprintf_buffer_flush (file->next);
  69
  70   __wprintf_buffer_as_file_switch_to_buffer (file);
  71
  72   if (!__wprintf_buffer_has_failed (file->next))
  73     return (unsigned char) ch;
  74   else
  75     return WEOF;
  76 }
  77
  78 size_t
  79 __wprintf_buffer_as_file_xsputn (FILE *fp, const void *buf, size_t len)
  80 {
  81   struct __wprintf_buffer_as_file *file
  82     = (struct __wprintf_buffer_as_file *) fp;
  83
  84   __wprintf_buffer_as_file_commit (file);
  85
  86   /* Copy the data.  */
  87   __wprintf_buffer_write (file->next, buf, len);
  88
  89   __wprintf_buffer_as_file_switch_to_buffer (file);
  90
  91   if (!__wprintf_buffer_has_failed (file->next))
  92     return len;
  93   else
  94     /* We may actually have written something.  But the stream is
  95        corrupted in this case anyway, so try not to divine the write
  96        count here.  */
  97     return 0;
  98 }
  99
 100 void
 101 __wprintf_buffer_as_file_init (struct __wprintf_buffer_as_file *file,
 102                                struct __wprintf_buffer *next)
 103 {
 104   file->stream._lock = NULL;
 105   _IO_no_init (&file->stream, _IO_USER_LOCK, 0, &file->wide_stream,
 106                &_IO_wprintf_buffer_as_file_jumps);
 107   _IO_fwide (&file->stream, 1);
 108
 109   /* Set up the write buffer from the next buffer.  */
 110   file->next = next;
 111   __wprintf_buffer_as_file_switch_to_buffer (file);
 112
 113   /* Mark the read area as inactive, by making all pointers equal.  */
 114   file->stream._IO_read_base = file->stream._IO_write_base;
 115   file->stream._IO_read_ptr = file->stream._IO_write_base;
 116   file->stream._IO_read_end = file->stream._IO_write_base;
 117 }
 118
 119 bool
 120 __wprintf_buffer_as_file_terminate (struct __wprintf_buffer_as_file *file)
 121 {
 122   if (file->stream._flags & _IO_ERR_SEEN)
 123     return false;
 124   else
 125     {
 126       __wprintf_buffer_as_file_commit (file);
 127       return true;
 128     }
 129 }