libstdc++-v3/config/io/basic_file_stdio.cc

   1 // Wrapper of C-language FILE struct -*- C++ -*-
   2
   3 // Copyright (C) 2000-2024 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 //
  26 // ISO C++ 14882: 27.8  File-based streams
  27 //
  28
  29 #include <bits/largefile-config.h>
  30 #include <bits/basic_file.h>
  31 #include <fcntl.h>
  32 #include <errno.h>
  33
  34 #ifdef _GLIBCXX_HAVE_POLL
  35 #include <poll.h>
  36 #endif
  37
  38 // Pick up ioctl on Solaris 2.8
  39 #ifdef _GLIBCXX_HAVE_UNISTD_H
  40 #include <unistd.h>
  41 #endif
  42
  43 // Pick up FIONREAD on Solaris 2
  44 #ifdef _GLIBCXX_HAVE_SYS_IOCTL_H
  45 #define BSD_COMP
  46 #include <sys/ioctl.h>
  47 #endif
  48
  49 // Pick up FIONREAD on Solaris 2.5.
  50 #ifdef _GLIBCXX_HAVE_SYS_FILIO_H
  51 #include <sys/filio.h>
  52 #endif
  53
  54 #ifdef _GLIBCXX_HAVE_SYS_UIO_H
  55 #include <sys/uio.h>
  56 #endif
  57
  58 #if defined(_GLIBCXX_HAVE_S_ISREG) || defined(_GLIBCXX_HAVE_S_IFREG)
  59 # include <sys/stat.h>
  60 # ifdef _GLIBCXX_HAVE_S_ISREG
  61 #  define _GLIBCXX_ISREG(x) S_ISREG(x)
  62 # else
  63 #  define _GLIBCXX_ISREG(x) (((x) & S_IFMT) == S_IFREG)
  64 # endif
  65 #endif
  66
  67 #include <limits> // For <off_t>::max() and min() and <streamsize>::max()
  68
  69 #if _GLIBCXX_USE__GET_OSFHANDLE
  70 # include <stdint.h> // For intptr_t
  71 # include <io.h>     // For _get_osfhandle
  72 #endif
  73
  74 namespace
  75 {
  76   // Map ios_base::openmode flags to a string for use in fopen().
  77   // Table of valid combinations as given in [lib.filebuf.members]/2.
  78   static const char*
  79   fopen_mode(std::ios_base::openmode mode)
  80   {
  81     enum
  82       {
  83         in     = std::ios_base::in,
  84         out    = std::ios_base::out,
  85         trunc  = std::ios_base::trunc,
  86         app    = std::ios_base::app,
  87         binary = std::ios_base::binary,
  88         noreplace = std::_S_noreplace
  89       };
  90
  91     // _GLIBCXX_RESOLVE_LIB_DEFECTS
  92     // 596. 27.8.1.3 Table 112 omits "a+" and "a+b" modes.
  93     switch (mode & (in|out|trunc|app|binary|noreplace))
  94       {
  95       case (   out                           ): return "w";
  96       case (   out                 |noreplace): return "wx";
  97       case (   out|trunc                     ): return "w";
  98       case (   out|trunc           |noreplace): return "wx";
  99       case (   out      |app                 ): return "a";
 100       case (             app                 ): return "a";
 101       case (in                               ): return "r";
 102       case (in|out                           ): return "r+";
 103       case (in|out|trunc                     ): return "w+";
 104       case (in|out|trunc           |noreplace): return "w+x";
 105       case (in|out      |app                 ): return "a+";
 106       case (in          |app                 ): return "a+";
 107
 108       case (   out          |binary          ): return "wb";
 109       case (   out          |binary|noreplace): return "wbx";
 110       case (   out      |app|binary          ): return "ab";
 111       case (             app|binary          ): return "ab";
 112       case (   out|trunc    |binary          ): return "wb";
 113       case (in              |binary          ): return "rb";
 114       case (in|out          |binary          ): return "r+b";
 115       case (in|out|trunc    |binary          ): return "w+b";
 116       case (in|out|trunc    |binary|noreplace): return "w+bx";
 117       case (in|out      |app|binary          ): return "a+b";
 118       case (in          |app|binary          ): return "a+b";
 119
 120       default: return 0; // invalid
 121       }
 122   }
 123
 124   // Wrapper handling partial write.
 125   static std::streamsize
 126 #ifdef _GLIBCXX_USE_STDIO_PURE
 127   xwrite(FILE *__file, const char* __s, std::streamsize __n)
 128 #else
 129   xwrite(int __fd, const char* __s, std::streamsize __n)
 130 #endif
 131   {
 132     std::streamsize __nleft = __n;
 133
 134     for (;;)
 135       {
 136 #ifdef _GLIBCXX_USE_STDIO_PURE
 137         const std::streamsize __ret = fwrite(__s, 1, __nleft, __file);
 138         if (__ret == 0 && ferror(__file))
 139           break;
 140 #else
 141         const std::streamsize __ret = write(__fd, __s, __nleft);
 142         if (__ret == -1L && errno == EINTR)
 143           continue;
 144         if (__ret == -1L)
 145           break;
 146 #endif
 147         __nleft -= __ret;
 148         if (__nleft == 0)
 149           break;
 150
 151         __s += __ret;
 152       }
 153
 154     return __n - __nleft;
 155   }
 156
 157 #if defined(_GLIBCXX_HAVE_WRITEV) && !defined(_GLIBCXX_USE_STDIO_PURE)
 158   // Wrapper handling partial writev.
 159   static std::streamsize
 160   xwritev(int __fd, const char* __s1, std::streamsize __n1,
 161           const char* __s2, std::streamsize __n2)
 162   {
 163     std::streamsize __nleft = __n1 + __n2;
 164     std::streamsize __n1_left = __n1;
 165
 166     struct iovec __iov[2];
 167     __iov[1].iov_base = const_cast<char*>(__s2);
 168     __iov[1].iov_len = __n2;
 169
 170     for (;;)
 171       {
 172         __iov[0].iov_base = const_cast<char*>(__s1);
 173         __iov[0].iov_len = __n1_left;
 174
 175         const std::streamsize __ret = writev(__fd, __iov, 2);
 176         if (__ret == -1L && errno == EINTR)
 177           continue;
 178         if (__ret == -1L)
 179           break;
 180
 181         __nleft -= __ret;
 182         if (__nleft == 0)
 183           break;
 184
 185         const std::streamsize __off = __ret - __n1_left;
 186         if (__off >= 0)
 187           {
 188             __nleft -= xwrite(__fd, __s2 + __off, __n2 - __off);
 189             break;
 190           }
 191
 192         __s1 += __ret;
 193         __n1_left -= __ret;
 194       }
 195
 196     return __n1 + __n2 - __nleft;
 197   }
 198 #endif
 199 } // anonymous namespace
 200
 201
 202 namespace std _GLIBCXX_VISIBILITY(default)
 203 {
 204 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 205
 206   // Definitions for __basic_file<char>.
 207   __basic_file<char>::__basic_file(__c_lock* /*__lock*/) throw()
 208   : _M_cfile(NULL), _M_cfile_created(false) { }
 209
 210   __basic_file<char>::~__basic_file()
 211   { this->close(); }
 212
 213   __basic_file<char>*
 214   __basic_file<char>::sys_open(__c_file* __file, ios_base::openmode)
 215   {
 216     __basic_file* __ret = NULL;
 217     if (!this->is_open() && __file)
 218       {
 219         int __err, __save_errno = errno;
 220         // POSIX guarantees that fflush sets errno on error, but C doesn't.
 221         errno = 0;
 222         do
 223           __err = fflush(__file);
 224         while (__err && errno == EINTR);
 225         errno = __save_errno;
 226         if (!__err)
 227           {
 228             _M_cfile = __file;
 229             _M_cfile_created = false;
 230             __ret = this;
 231           }
 232       }
 233     return __ret;
 234   }
 235
 236   __basic_file<char>*
 237   __basic_file<char>::sys_open(int __fd, ios_base::openmode __mode) throw ()
 238   {
 239     __basic_file* __ret = NULL;
 240     const char* __c_mode = fopen_mode(__mode);
 241     if (__c_mode && !this->is_open() && (_M_cfile = fdopen(__fd, __c_mode)))
 242       {
 243         char* __buf = NULL;
 244         _M_cfile_created = true;
 245         if (__fd == 0)
 246           setvbuf(_M_cfile, __buf, _IONBF, 0);
 247         __ret = this;
 248       }
 249     return __ret;
 250   }
 251
 252   __basic_file<char>*
 253   __basic_file<char>::open(const char* __name, ios_base::openmode __mode,
 254                            int /*__prot*/)
 255   {
 256     __basic_file* __ret = NULL;
 257     const char* __c_mode = fopen_mode(__mode);
 258     if (__c_mode && !this->is_open())
 259       {
 260         if ((_M_cfile = fopen(__name, __c_mode)))
 261           {
 262             _M_cfile_created = true;
 263             __ret = this;
 264           }
 265       }
 266     return __ret;
 267   }
 268
 269 #if _GLIBCXX_HAVE__WFOPEN && _GLIBCXX_USE_WCHAR_T
 270   __basic_file<char>*
 271   __basic_file<char>::open(const wchar_t* __name, ios_base::openmode __mode)
 272   {
 273     __basic_file* __ret = NULL;
 274     const char* __c_mode = fopen_mode(__mode);
 275     if (__c_mode && !this->is_open())
 276       {
 277         wchar_t __wc_mode[4] = { };
 278         int __i = 0;
 279         do
 280           {
 281             switch(__c_mode[__i]) {
 282             case 'a': __wc_mode[__i] = L'a'; break;
 283             case 'b': __wc_mode[__i] = L'b'; break;
 284             case 'r': __wc_mode[__i] = L'r'; break;
 285             case 'w': __wc_mode[__i] = L'w'; break;
 286             case '+': __wc_mode[__i] = L'+'; break;
 287             default: return __ret;
 288             }
 289           }
 290         while (__c_mode[++__i]);
 291
 292         if ((_M_cfile = _wfopen(__name, __wc_mode)))
 293           {
 294             _M_cfile_created = true;
 295             __ret = this;
 296           }
 297       }
 298     return __ret;
 299   }
 300 #endif
 301
 302   bool
 303   __basic_file<char>::is_open() const throw ()
 304   { return _M_cfile != 0; }
 305
 306 #ifndef _GLIBCCXX_USE_STDIO_PURE
 307   int
 308   __basic_file<char>::fd() throw ()
 309   { return fileno(_M_cfile); }
 310 #endif
 311
 312   __c_file*
 313   __basic_file<char>::file() throw ()
 314   { return _M_cfile; }
 315
 316   __basic_file<char>*
 317   __basic_file<char>::close()
 318   {
 319     __basic_file* __ret = static_cast<__basic_file*>(NULL);
 320     if (this->is_open())
 321       {
 322         int __err = 0;
 323         if (_M_cfile_created)
 324           __err = fclose(_M_cfile);
 325         _M_cfile = 0;
 326         if (!__err)
 327           __ret = this;
 328       }
 329     return __ret;
 330   }
 331
 332   streamsize
 333   __basic_file<char>::xsgetn(char* __s, streamsize __n)
 334   {
 335     streamsize __ret;
 336 #ifdef _GLIBCXX_USE_STDIO_PURE
 337     __ret = fread(__s, 1, __n, this->file());
 338     if (__ret == 0 && ferror(this->file()))
 339       __ret = -1;
 340 #else
 341     do
 342       __ret = read(this->fd(), __s, __n);
 343     while (__ret == -1L && errno == EINTR);
 344 #endif
 345     return __ret;
 346   }
 347
 348   streamsize
 349   __basic_file<char>::xsputn(const char* __s, streamsize __n)
 350   {
 351 #ifdef _GLIBCXX_USE_STDIO_PURE
 352     return xwrite(this->file(), __s, __n);
 353 #else
 354     return xwrite(this->fd(), __s, __n);
 355 #endif
 356   }
 357
 358   streamsize
 359   __basic_file<char>::xsputn_2(const char* __s1, streamsize __n1,
 360                                const char* __s2, streamsize __n2)
 361   {
 362     streamsize __ret = 0;
 363 #if defined(_GLIBCXX_HAVE_WRITEV) && !defined(_GLIBCXX_USE_STDIO_PURE)
 364     __ret = xwritev(this->fd(), __s1, __n1, __s2, __n2);
 365 #else
 366     if (__n1)
 367 #ifdef _GLIBCXX_USE_STDIO_PURE
 368       __ret = xwrite(this->file(), __s1, __n1);
 369 #else
 370       __ret = xwrite(this->fd(), __s1, __n1);
 371 #endif
 372
 373     if (__ret == __n1)
 374 #ifdef _GLIBCXX_USE_STDIO_PURE
 375       __ret += xwrite(this->file(), __s2, __n2);
 376 #else
 377       __ret += xwrite(this->fd(), __s2, __n2);
 378 #endif
 379 #endif
 380     return __ret;
 381   }
 382
 383   namespace
 384   {
 385     inline streamoff
 386     get_file_offset(__basic_file<char>* __f)
 387     {
 388 #ifdef _GLIBCXX_USE_STDIO_PURE
 389 # ifdef _GLIBCXX_USE_FSEEKO_FTELLO
 390       return ftello(__f->file());
 391 # else
 392       return ftell(__f->file());
 393 # endif
 394 #else
 395       return lseek(__f->fd(), 0, (int)ios_base::cur);
 396 #endif
 397     }
 398   }
 399
 400   streamoff
 401   __basic_file<char>::seekoff(streamoff __off, ios_base::seekdir __way) throw ()
 402   {
 403 #ifdef _GLIBCXX_USE_STDIO_PURE
 404 #ifdef _GLIBCXX_USE_FSEEKO_FTELLO
 405     if _GLIBCXX17_CONSTEXPR (sizeof(off_t) > sizeof(long))
 406       {
 407         if (fseeko(this->file(), __off, __way))
 408           return -1;
 409       }
 410     else
 411 #endif
 412       {
 413         if (__off > numeric_limits<long>::max()
 414               || __off < numeric_limits<long>::min())
 415           return -1;
 416         if (fseek(this->file(), __off, __way))
 417           return -1;
 418       }
 419     return __way == ios_base::beg ? __off : std::get_file_offset(this);
 420 #else
 421     if _GLIBCXX17_CONSTEXPR (sizeof(streamoff) > sizeof(off_t))
 422       if (__off > numeric_limits<off_t>::max()
 423             || __off < numeric_limits<off_t>::min())
 424       return -1L;
 425     return lseek(this->fd(), __off, __way);
 426 #endif
 427   }
 428
 429   int
 430   __basic_file<char>::sync()
 431   { return fflush(_M_cfile); }
 432
 433   streamsize
 434   __basic_file<char>::showmanyc()
 435   {
 436 #if !defined(_GLIBCXX_NO_IOCTL) && !defined(_GLIBCXX_USE_STDIO_PURE)
 437 #ifdef FIONREAD
 438     // Pipes and sockets.
 439     int __num = 0;
 440     int __r = ioctl(this->fd(), FIONREAD, &__num);
 441     if (!__r && __num >= 0)
 442       return __num;
 443 #endif
 444 #endif
 445
 446 #if defined(_GLIBCXX_HAVE_POLL) && !defined(_GLIBCXX_USE_STDIO_PURE)
 447     // Cheap test.
 448     struct pollfd __pfd[1];
 449     __pfd[0].fd = this->fd();
 450     __pfd[0].events = POLLIN;
 451     if (poll(__pfd, 1, 0) <= 0)
 452       return 0;
 453 #endif
 454
 455 #if defined(_GLIBCXX_HAVE_S_ISREG) || defined(_GLIBCXX_HAVE_S_IFREG)
 456     // Regular files.
 457     struct stat __buffer;
 458     const int __err = fstat(this->fd(), &__buffer);
 459     if (!__err && _GLIBCXX_ISREG(__buffer.st_mode))
 460       {
 461         const streamoff __off = __buffer.st_size - std::get_file_offset(this);
 462         return std::min(__off, streamoff(numeric_limits<streamsize>::max()));
 463       }
 464 #endif
 465     return 0;
 466   }
 467
 468   __basic_file<char>::native_handle_type
 469   __basic_file<char>::native_handle() const noexcept
 470   {
 471 #ifdef _GLIBCXX_USE_STDIO_PURE
 472     return _M_cfile;
 473 #elif _GLIBCXX_USE__GET_OSFHANDLE
 474     const intptr_t handle = _M_cfile ? _get_osfhandle(fileno(_M_cfile)) : -1;
 475     return reinterpret_cast<native_handle_type>(handle);
 476 #else
 477     return fileno(_M_cfile);
 478 #endif
 479   }
 480
 481 _GLIBCXX_END_NAMESPACE_VERSION
 482 } // namespace
 483