libio/obprintf.c

   1 /* Print output of stream to given obstack.
   2    Copyright (C) 1996-2024 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 <assert.h>
  20 #include <math_ldbl_opt.h>
  21 #include <obstack.h>
  22 #include <printf.h>
  23 #include <stdarg.h>
  24 #include <printf_buffer.h>
  25
  26 struct __printf_buffer_obstack
  27 {
  28   struct __printf_buffer base;
  29   struct obstack *obstack;
  30
  31   /* obstack_1grow is called for compatibility reasons.  This needs
  32      one extra character, and this is the backing store for it.  */
  33   char ch;
  34 };
  35
  36 void
  37 __printf_buffer_flush_obstack (struct __printf_buffer_obstack *buf)
  38 {
  39   /* About to switch buffers, so record the bytes written so far.  */
  40   buf->base.written += buf->base.write_ptr - buf->base.write_base;
  41
  42   if (buf->base.write_ptr == &buf->ch + 1)
  43     {
  44       /* Errors are reported via a callback mechanism (presumably for
  45          process termination).  */
  46       obstack_1grow (buf->obstack, buf->ch);
  47       buf->base.write_base = obstack_next_free (buf->obstack);
  48       buf->base.write_ptr = buf->base.write_base;
  49       size_t size = obstack_room (buf->obstack);
  50       buf->base.write_end = buf->base.write_ptr + size;
  51       /* Reserve the space on the obstack size.  */
  52       obstack_blank_fast (buf->obstack, size);
  53     }
  54   else
  55     {
  56       /* Obtain the extra character.  */
  57       buf->base.write_base = &buf->ch;
  58       buf->base.write_ptr = &buf->ch;
  59       buf->base.write_end = &buf->ch + 1;
  60     }
  61 }
  62
  63 int
  64 __obstack_vprintf_internal (struct obstack *obstack, const char *format,
  65                             va_list args, unsigned int mode_flags)
  66 {
  67   /* Legacy setup code for compatibility.  */
  68   size_t room = obstack_room (obstack);
  69   size_t size = obstack_object_size (obstack) + room;
  70   if (size == 0)
  71     {
  72       /* Get more memory.  */
  73       obstack_make_room (obstack, 64);
  74
  75       /* Recompute how much room we have.  */
  76       room = obstack_room (obstack);
  77       size = room;
  78
  79       assert (size != 0);
  80     }
  81
  82   struct __printf_buffer_obstack buf;
  83   {
  84     /* The obstack write location might be in the middle of an object.  */
  85     char *ptr = obstack_next_free (obstack);
  86     char *end = obstack_base (obstack) + size;
  87     __printf_buffer_init (&buf.base, ptr, end - ptr,
  88                           __printf_buffer_mode_obstack);
  89   }
  90   buf.obstack = obstack;
  91
  92   /* Now allocate the rest of the current chunk.  */
  93   obstack_blank_fast (obstack, room);
  94
  95   __printf_buffer (&buf.base, format, args, mode_flags);
  96
  97   if (buf.base.write_ptr == &buf.ch + 1)
  98     /* buf.ch is in use.  Put it into the obstack.  */
  99     obstack_1grow (buf.obstack, buf.ch);
 100   else if (buf.base.write_ptr != &buf.ch)
 101     /* Shrink the buffer to the space we really currently need.  */
 102     obstack_blank_fast (buf.obstack, buf.base.write_ptr - buf.base.write_end);
 103
 104   return __printf_buffer_done (&buf.base);
 105 }
 106
 107 int
 108 __obstack_vprintf (struct obstack *obstack, const char *format, va_list ap)
 109 {
 110   return __obstack_vprintf_internal (obstack, format, ap, 0);
 111 }
 112 ldbl_weak_alias (__obstack_vprintf, obstack_vprintf)
 113
 114 int
 115 __obstack_printf (struct obstack *obstack, const char *format, ...)
 116 {
 117   int result;
 118   va_list ap;
 119   va_start (ap, format);
 120   result = __obstack_vprintf_internal (obstack, format, ap, 0);
 121   va_end (ap);
 122   return result;
 123 }
 124 ldbl_weak_alias (__obstack_printf, obstack_printf)