libio/strops.c

   1 /* Copyright (C) 1993-2018 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.
  17
  18    As a special exception, if you link the code in this file with
  19    files compiled with a GNU compiler to produce an executable,
  20    that does not cause the resulting executable to be covered by
  21    the GNU Lesser General Public License.  This exception does not
  22    however invalidate any other reasons why the executable file
  23    might be covered by the GNU Lesser General Public License.
  24    This exception applies to code released by its copyright holders
  25    in files containing the exception.  */
  26
  27 #include <assert.h>
  28 #include "strfile.h"
  29 #include "libioP.h"
  30 #include <string.h>
  31 #include <stdio_ext.h>
  32
  33 void
  34 _IO_str_init_static_internal (_IO_strfile *sf, char *ptr, size_t size,
  35                               char *pstart)
  36 {
  37   FILE *fp = &sf->_sbf._f;
  38   char *end;
  39
  40   if (size == 0)
  41     end = __rawmemchr (ptr, '\0');
  42   else if ((size_t) ptr + size > (size_t) ptr)
  43     end = ptr + size;
  44   else
  45     end = (char *) -1;
  46   _IO_setb (fp, ptr, end, 0);
  47
  48   fp->_IO_write_base = ptr;
  49   fp->_IO_read_base = ptr;
  50   fp->_IO_read_ptr = ptr;
  51   if (pstart)
  52     {
  53       fp->_IO_write_ptr = pstart;
  54       fp->_IO_write_end = end;
  55       fp->_IO_read_end = pstart;
  56     }
  57   else
  58     {
  59       fp->_IO_write_ptr = ptr;
  60       fp->_IO_write_end = ptr;
  61       fp->_IO_read_end = end;
  62     }
  63   /* A null _allocate_buffer function flags the strfile as being static. */
  64   sf->_s._allocate_buffer = (_IO_alloc_type) 0;
  65 }
  66
  67 void
  68 _IO_str_init_static (_IO_strfile *sf, char *ptr, int size, char *pstart)
  69 {
  70   return _IO_str_init_static_internal (sf, ptr, size < 0 ? -1 : size, pstart);
  71 }
  72
  73 void
  74 _IO_str_init_readonly (_IO_strfile *sf, const char *ptr, int size)
  75 {
  76   _IO_str_init_static_internal (sf, (char *) ptr, size < 0 ? -1 : size, NULL);
  77   sf->_sbf._f._flags |= _IO_NO_WRITES;
  78 }
  79
  80 int
  81 _IO_str_overflow (FILE *fp, int c)
  82 {
  83   int flush_only = c == EOF;
  84   size_t pos;
  85   if (fp->_flags & _IO_NO_WRITES)
  86       return flush_only ? 0 : EOF;
  87   if ((fp->_flags & _IO_TIED_PUT_GET) && !(fp->_flags & _IO_CURRENTLY_PUTTING))
  88     {
  89       fp->_flags |= _IO_CURRENTLY_PUTTING;
  90       fp->_IO_write_ptr = fp->_IO_read_ptr;
  91       fp->_IO_read_ptr = fp->_IO_read_end;
  92     }
  93   pos = fp->_IO_write_ptr - fp->_IO_write_base;
  94   if (pos >= (size_t) (_IO_blen (fp) + flush_only))
  95     {
  96       if (fp->_flags & _IO_USER_BUF) /* not allowed to enlarge */
  97         return EOF;
  98       else
  99         {
 100           char *new_buf;
 101           char *old_buf = fp->_IO_buf_base;
 102           size_t old_blen = _IO_blen (fp);
 103           size_t new_size = 2 * old_blen + 100;
 104           if (new_size < old_blen)
 105             return EOF;
 106           new_buf
 107             = (char *) (*((_IO_strfile *) fp)->_s._allocate_buffer) (new_size);
 108           if (new_buf == NULL)
 109             {
 110               /*          __ferror(fp) = 1; */
 111               return EOF;
 112             }
 113           if (old_buf)
 114             {
 115               memcpy (new_buf, old_buf, old_blen);
 116               (*((_IO_strfile *) fp)->_s._free_buffer) (old_buf);
 117               /* Make sure _IO_setb won't try to delete _IO_buf_base. */
 118               fp->_IO_buf_base = NULL;
 119             }
 120           memset (new_buf + old_blen, '\0', new_size - old_blen);
 121
 122           _IO_setb (fp, new_buf, new_buf + new_size, 1);
 123           fp->_IO_read_base = new_buf + (fp->_IO_read_base - old_buf);
 124           fp->_IO_read_ptr = new_buf + (fp->_IO_read_ptr - old_buf);
 125           fp->_IO_read_end = new_buf + (fp->_IO_read_end - old_buf);
 126           fp->_IO_write_ptr = new_buf + (fp->_IO_write_ptr - old_buf);
 127
 128           fp->_IO_write_base = new_buf;
 129           fp->_IO_write_end = fp->_IO_buf_end;
 130         }
 131     }
 132
 133   if (!flush_only)
 134     *fp->_IO_write_ptr++ = (unsigned char) c;
 135   if (fp->_IO_write_ptr > fp->_IO_read_end)
 136     fp->_IO_read_end = fp->_IO_write_ptr;
 137   return c;
 138 }
 139 libc_hidden_def (_IO_str_overflow)
 140
 141 int
 142 _IO_str_underflow (FILE *fp)
 143 {
 144   if (fp->_IO_write_ptr > fp->_IO_read_end)
 145     fp->_IO_read_end = fp->_IO_write_ptr;
 146   if ((fp->_flags & _IO_TIED_PUT_GET) && (fp->_flags & _IO_CURRENTLY_PUTTING))
 147     {
 148       fp->_flags &= ~_IO_CURRENTLY_PUTTING;
 149       fp->_IO_read_ptr = fp->_IO_write_ptr;
 150       fp->_IO_write_ptr = fp->_IO_write_end;
 151     }
 152   if (fp->_IO_read_ptr < fp->_IO_read_end)
 153     return *((unsigned char *) fp->_IO_read_ptr);
 154   else
 155     return EOF;
 156 }
 157 libc_hidden_def (_IO_str_underflow)
 158
 159 /* The size of the valid part of the buffer.  */
 160
 161 ssize_t
 162 _IO_str_count (FILE *fp)
 163 {
 164   return ((fp->_IO_write_ptr > fp->_IO_read_end
 165            ? fp->_IO_write_ptr : fp->_IO_read_end)
 166           - fp->_IO_read_base);
 167 }
 168
 169
 170 static int
 171 enlarge_userbuf (FILE *fp, off64_t offset, int reading)
 172 {
 173   if ((ssize_t) offset <= _IO_blen (fp))
 174     return 0;
 175
 176   ssize_t oldend = fp->_IO_write_end - fp->_IO_write_base;
 177
 178   /* Try to enlarge the buffer.  */
 179   if (fp->_flags & _IO_USER_BUF)
 180     /* User-provided buffer.  */
 181     return 1;
 182
 183   size_t newsize = offset + 100;
 184   char *oldbuf = fp->_IO_buf_base;
 185   char *newbuf
 186     = (char *) (*((_IO_strfile *) fp)->_s._allocate_buffer) (newsize);
 187   if (newbuf == NULL)
 188     return 1;
 189
 190   if (oldbuf != NULL)
 191     {
 192       memcpy (newbuf, oldbuf, _IO_blen (fp));
 193       (*((_IO_strfile *) fp)->_s._free_buffer) (oldbuf);
 194       /* Make sure _IO_setb won't try to delete
 195          _IO_buf_base. */
 196       fp->_IO_buf_base = NULL;
 197     }
 198
 199   _IO_setb (fp, newbuf, newbuf + newsize, 1);
 200
 201   if (reading)
 202     {
 203       fp->_IO_write_base = newbuf + (fp->_IO_write_base - oldbuf);
 204       fp->_IO_write_ptr = newbuf + (fp->_IO_write_ptr - oldbuf);
 205       fp->_IO_write_end = newbuf + (fp->_IO_write_end - oldbuf);
 206       fp->_IO_read_ptr = newbuf + (fp->_IO_read_ptr - oldbuf);
 207
 208       fp->_IO_read_base = newbuf;
 209       fp->_IO_read_end = fp->_IO_buf_end;
 210     }
 211   else
 212     {
 213       fp->_IO_read_base = newbuf + (fp->_IO_read_base - oldbuf);
 214       fp->_IO_read_ptr = newbuf + (fp->_IO_read_ptr - oldbuf);
 215       fp->_IO_read_end = newbuf + (fp->_IO_read_end - oldbuf);
 216       fp->_IO_write_ptr = newbuf + (fp->_IO_write_ptr - oldbuf);
 217
 218       fp->_IO_write_base = newbuf;
 219       fp->_IO_write_end = fp->_IO_buf_end;
 220     }
 221
 222   /* Clear the area between the last write position and th
 223      new position.  */
 224   assert (offset >= oldend);
 225   if (reading)
 226     memset (fp->_IO_read_base + oldend, '\0', offset - oldend);
 227   else
 228     memset (fp->_IO_write_base + oldend, '\0', offset - oldend);
 229
 230   return 0;
 231 }
 232
 233 static void
 234 _IO_str_switch_to_get_mode (FILE *fp)
 235 {
 236   if (_IO_in_backup (fp))
 237     fp->_IO_read_base = fp->_IO_backup_base;
 238   else
 239     {
 240       fp->_IO_read_base = fp->_IO_buf_base;
 241       if (fp->_IO_write_ptr > fp->_IO_read_end)
 242         fp->_IO_read_end = fp->_IO_write_ptr;
 243     }
 244   fp->_IO_read_ptr = fp->_IO_read_end = fp->_IO_write_ptr;
 245
 246   fp->_flags &= ~_IO_CURRENTLY_PUTTING;
 247 }
 248
 249 off64_t
 250 _IO_str_seekoff (FILE *fp, off64_t offset, int dir, int mode)
 251 {
 252   off64_t new_pos;
 253
 254   if (mode == 0 && (fp->_flags & _IO_TIED_PUT_GET))
 255     mode = (fp->_flags & _IO_CURRENTLY_PUTTING ? _IOS_OUTPUT : _IOS_INPUT);
 256
 257   bool was_writing = (fp->_IO_write_ptr > fp->_IO_write_base
 258                      || _IO_in_put_mode (fp));
 259   if (was_writing)
 260     _IO_str_switch_to_get_mode (fp);
 261
 262   if (mode == 0)
 263     {
 264       new_pos = fp->_IO_read_ptr - fp->_IO_read_base;
 265     }
 266   else
 267     {
 268       ssize_t cur_size = _IO_str_count(fp);
 269       new_pos = EOF;
 270
 271       /* Move the get pointer, if requested. */
 272       if (mode & _IOS_INPUT)
 273         {
 274           ssize_t base;
 275           switch (dir)
 276             {
 277             case _IO_seek_set:
 278               base = 0;
 279               break;
 280             case _IO_seek_cur:
 281               base = fp->_IO_read_ptr - fp->_IO_read_base;
 282               break;
 283             default: /* case _IO_seek_end: */
 284               base = cur_size;
 285               break;
 286             }
 287           ssize_t maxval = SSIZE_MAX - base;
 288           if (offset < -base || offset > maxval)
 289             {
 290               __set_errno (EINVAL);
 291               return EOF;
 292             }
 293           base += offset;
 294           if (base > cur_size
 295               && enlarge_userbuf (fp, base, 1) != 0)
 296             return EOF;
 297           fp->_IO_read_ptr = fp->_IO_read_base + base;
 298           fp->_IO_read_end = fp->_IO_read_base + cur_size;
 299           new_pos = base;
 300         }
 301
 302       /* Move the put pointer, if requested. */
 303       if (mode & _IOS_OUTPUT)
 304         {
 305           ssize_t base;
 306           switch (dir)
 307             {
 308             case _IO_seek_set:
 309               base = 0;
 310               break;
 311             case _IO_seek_cur:
 312               base = fp->_IO_write_ptr - fp->_IO_write_base;
 313               break;
 314             default: /* case _IO_seek_end: */
 315               base = cur_size;
 316               break;
 317             }
 318           ssize_t maxval = SSIZE_MAX - base;
 319           if (offset < -base || offset > maxval)
 320             {
 321               __set_errno (EINVAL);
 322               return EOF;
 323             }
 324           base += offset;
 325           if (base > cur_size
 326               && enlarge_userbuf (fp, base, 0) != 0)
 327             return EOF;
 328           fp->_IO_write_ptr = fp->_IO_write_base + base;
 329           new_pos = base;
 330         }
 331     }
 332   return new_pos;
 333 }
 334 libc_hidden_def (_IO_str_seekoff)
 335
 336 int
 337 _IO_str_pbackfail (FILE *fp, int c)
 338 {
 339   if ((fp->_flags & _IO_NO_WRITES) && c != EOF)
 340     return EOF;
 341   return _IO_default_pbackfail (fp, c);
 342 }
 343 libc_hidden_def (_IO_str_pbackfail)
 344
 345 void
 346 _IO_str_finish (FILE *fp, int dummy)
 347 {
 348   if (fp->_IO_buf_base && !(fp->_flags & _IO_USER_BUF))
 349     (((_IO_strfile *) fp)->_s._free_buffer) (fp->_IO_buf_base);
 350   fp->_IO_buf_base = NULL;
 351
 352   _IO_default_finish (fp, 0);
 353 }
 354
 355 const struct _IO_jump_t _IO_str_jumps libio_vtable =
 356 {
 357   JUMP_INIT_DUMMY,
 358   JUMP_INIT(finish, _IO_str_finish),
 359   JUMP_INIT(overflow, _IO_str_overflow),
 360   JUMP_INIT(underflow, _IO_str_underflow),
 361   JUMP_INIT(uflow, _IO_default_uflow),
 362   JUMP_INIT(pbackfail, _IO_str_pbackfail),
 363   JUMP_INIT(xsputn, _IO_default_xsputn),
 364   JUMP_INIT(xsgetn, _IO_default_xsgetn),
 365   JUMP_INIT(seekoff, _IO_str_seekoff),
 366   JUMP_INIT(seekpos, _IO_default_seekpos),
 367   JUMP_INIT(setbuf, _IO_default_setbuf),
 368   JUMP_INIT(sync, _IO_default_sync),
 369   JUMP_INIT(doallocate, _IO_default_doallocate),
 370   JUMP_INIT(read, _IO_default_read),
 371   JUMP_INIT(write, _IO_default_write),
 372   JUMP_INIT(seek, _IO_default_seek),
 373   JUMP_INIT(close, _IO_default_close),
 374   JUMP_INIT(stat, _IO_default_stat),
 375   JUMP_INIT(showmanyc, _IO_default_showmanyc),
 376   JUMP_INIT(imbue, _IO_default_imbue)
 377 };