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

   1 // Wrapper of C-language FILE struct -*- C++ -*-
   2
   3 // Copyright (C) 2000-2019 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/basic_file.h>
  30 #include <fcntl.h>
  31 #include <errno.h>
  32
  33 #ifdef _GLIBCXX_HAVE_POLL
  34 #include <poll.h>
  35 #endif
  36
  37 // Pick up ioctl on Solaris 2.8
  38 #ifdef _GLIBCXX_HAVE_UNISTD_H
  39 #include <unistd.h>
  40 #endif
  41
  42 // Pick up FIONREAD on Solaris 2
  43 #ifdef _GLIBCXX_HAVE_SYS_IOCTL_H
  44 #define BSD_COMP
  45 #include <sys/ioctl.h>
  46 #endif
  47
  48 // Pick up FIONREAD on Solaris 2.5.
  49 #ifdef _GLIBCXX_HAVE_SYS_FILIO_H
  50 #include <sys/filio.h>
  51 #endif
  52
  53 #ifdef _GLIBCXX_HAVE_SYS_UIO_H
  54 #include <sys/uio.h>
  55 #endif
  56
  57 #if defined(_GLIBCXX_HAVE_S_ISREG) || defined(_GLIBCXX_HAVE_S_IFREG)
  58 # include <sys/stat.h>
  59 # ifdef _GLIBCXX_HAVE_S_ISREG
  60 #  define _GLIBCXX_ISREG(x) S_ISREG(x)
  61 # else
  62 #  define _GLIBCXX_ISREG(x) (((x) & S_IFMT) == S_IFREG)
  63 # endif
  64 #endif
  65
  66 #include <limits> // For <off_t>::max() and min() and <streamsize>::max()
  67
  68 namespace
  69 {
  70   // Map ios_base::openmode flags to a string for use in fopen().
  71   // Table of valid combinations as given in [lib.filebuf.members]/2.
  72   static const char*
  73   fopen_mode(std::ios_base::openmode mode)
  74   {
  75     enum
  76       {
  77         in     = std::ios_base::in,
  78         out    = std::ios_base::out,
  79         trunc  = std::ios_base::trunc,
  80         app    = std::ios_base::app,
  81         binary = std::ios_base::binary
  82       };
  83
  84     // _GLIBCXX_RESOLVE_LIB_DEFECTS
  85     // 596. 27.8.1.3 Table 112 omits "a+" and "a+b" modes.
  86     switch (mode & (in|out|trunc|app|binary))
  87       {
  88       case (   out                 ): return "w";
  89       case (   out      |app       ): return "a";
  90       case (             app       ): return "a";
  91       case (   out|trunc           ): return "w";
  92       case (in                     ): return "r";
  93       case (in|out                 ): return "r+";
  94       case (in|out|trunc           ): return "w+";
  95       case (in|out      |app       ): return "a+";
  96       case (in          |app       ): return "a+";
  97
  98       case (   out          |binary): return "wb";
  99       case (   out      |app|binary): return "ab";
 100       case (             app|binary): return "ab";
 101       case (   out|trunc    |binary): return "wb";
 102       case (in              |binary): return "rb";
 103       case (in|out          |binary): return "r+b";
 104       case (in|out|trunc    |binary): return "w+b";
 105       case (in|out      |app|binary): return "a+b";
 106       case (in          |app|binary): return "a+b";
 107
 108       default: return 0; // invalid
 109       }
 110   }
 111
 112   // Wrapper handling partial write.
 113   static std::streamsize
 114   xwrite(int __fd, const char* __s, std::streamsize __n)
 115   {
 116     std::streamsize __nleft = __n;
 117
 118     for (;;)
 119       {
 120         const std::streamsize __ret = write(__fd, __s, __nleft);
 121         if (__ret == -1L && errno == EINTR)
 122           continue;
 123         if (__ret == -1L)
 124           break;
 125
 126         __nleft -= __ret;
 127         if (__nleft == 0)
 128           break;
 129
 130         __s += __ret;
 131       }
 132
 133     return __n - __nleft;
 134   }
 135
 136 #ifdef _GLIBCXX_HAVE_WRITEV
 137   // Wrapper handling partial writev.
 138   static std::streamsize
 139   xwritev(int __fd, const char* __s1, std::streamsize __n1,
 140           const char* __s2, std::streamsize __n2)
 141   {
 142     std::streamsize __nleft = __n1 + __n2;
 143     std::streamsize __n1_left = __n1;
 144
 145     struct iovec __iov[2];
 146     __iov[1].iov_base = const_cast<char*>(__s2);
 147     __iov[1].iov_len = __n2;
 148
 149     for (;;)
 150       {
 151         __iov[0].iov_base = const_cast<char*>(__s1);
 152         __iov[0].iov_len = __n1_left;
 153
 154         const std::streamsize __ret = writev(__fd, __iov, 2);
 155         if (__ret == -1L && errno == EINTR)
 156           continue;
 157         if (__ret == -1L)
 158           break;
 159
 160         __nleft -= __ret;
 161         if (__nleft == 0)
 162           break;
 163
 164         const std::streamsize __off = __ret - __n1_left;
 165         if (__off >= 0)
 166           {
 167             __nleft -= xwrite(__fd, __s2 + __off, __n2 - __off);
 168             break;
 169           }
 170
 171         __s1 += __ret;
 172         __n1_left -= __ret;
 173       }
 174
 175     return __n1 + __n2 - __nleft;
 176   }
 177 #endif
 178 } // anonymous namespace
 179
 180
 181 namespace std _GLIBCXX_VISIBILITY(default)
 182 {
 183 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 184
 185   // Definitions for __basic_file<char>.
 186   __basic_file<char>::__basic_file(__c_lock* /*__lock*/) throw()
 187   : _M_cfile(NULL), _M_cfile_created(false) { }
 188
 189   __basic_file<char>::~__basic_file()
 190   { this->close(); }
 191
 192   __basic_file<char>*
 193   __basic_file<char>::sys_open(__c_file* __file, ios_base::openmode)
 194   {
 195     __basic_file* __ret = NULL;
 196     if (!this->is_open() && __file)
 197       {
 198         int __err, __save_errno = errno;
 199         // POSIX guarantees that fflush sets errno on error, but C doesn't.
 200         errno = 0;
 201         do
 202           __err = fflush(__file);
 203         while (__err && errno == EINTR);
 204         errno = __save_errno;
 205         if (!__err)
 206           {
 207             _M_cfile = __file;
 208             _M_cfile_created = false;
 209             __ret = this;
 210           }
 211       }
 212     return __ret;
 213   }
 214
 215   __basic_file<char>*
 216   __basic_file<char>::sys_open(int __fd, ios_base::openmode __mode) throw ()
 217   {
 218     __basic_file* __ret = NULL;
 219     const char* __c_mode = fopen_mode(__mode);
 220     if (__c_mode && !this->is_open() && (_M_cfile = fdopen(__fd, __c_mode)))
 221       {
 222         char* __buf = NULL;
 223         _M_cfile_created = true;
 224         if (__fd == 0)
 225           setvbuf(_M_cfile, __buf, _IONBF, 0);
 226         __ret = this;
 227       }
 228     return __ret;
 229   }
 230
 231   __basic_file<char>*
 232   __basic_file<char>::open(const char* __name, ios_base::openmode __mode,
 233                            int /*__prot*/)
 234   {
 235     __basic_file* __ret = NULL;
 236     const char* __c_mode = fopen_mode(__mode);
 237     if (__c_mode && !this->is_open())
 238       {
 239 #ifdef _GLIBCXX_USE_LFS
 240         if ((_M_cfile = fopen64(__name, __c_mode)))
 241 #else
 242         if ((_M_cfile = fopen(__name, __c_mode)))
 243 #endif
 244           {
 245             _M_cfile_created = true;
 246             __ret = this;
 247           }
 248       }
 249     return __ret;
 250   }
 251
 252 #if _GLIBCXX_HAVE__WFOPEN && _GLIBCXX_USE_WCHAR_T
 253   __basic_file<char>*
 254   __basic_file<char>::open(const wchar_t* __name, ios_base::openmode __mode)
 255   {
 256     __basic_file* __ret = NULL;
 257     const char* __c_mode = fopen_mode(__mode);
 258     if (__c_mode && !this->is_open())
 259       {
 260         wchar_t __wc_mode[4] = { };
 261         int __i = 0;
 262         do
 263           {
 264             switch(__c_mode[__i]) {
 265             case 'a': __wc_mode[__i] = L'a'; break;
 266             case 'b': __wc_mode[__i] = L'b'; break;
 267             case 'r': __wc_mode[__i] = L'r'; break;
 268             case 'w': __wc_mode[__i] = L'w'; break;
 269             case '+': __wc_mode[__i] = L'+'; break;
 270             default: return __ret;
 271             }
 272           }
 273         while (__c_mode[++__i]);
 274
 275         if ((_M_cfile = _wfopen(__name, __wc_mode)))
 276           {
 277             _M_cfile_created = true;
 278             __ret = this;
 279           }
 280       }
 281     return __ret;
 282   }
 283 #endif
 284
 285   bool
 286   __basic_file<char>::is_open() const throw ()
 287   { return _M_cfile != 0; }
 288
 289   int
 290   __basic_file<char>::fd() throw ()
 291   { return fileno(_M_cfile); }
 292
 293   __c_file*
 294   __basic_file<char>::file() throw ()
 295   { return _M_cfile; }
 296
 297   __basic_file<char>*
 298   __basic_file<char>::close()
 299   {
 300     __basic_file* __ret = static_cast<__basic_file*>(NULL);
 301     if (this->is_open())
 302       {
 303         int __err = 0;
 304         if (_M_cfile_created)
 305           __err = fclose(_M_cfile);
 306         _M_cfile = 0;
 307         if (!__err)
 308           __ret = this;
 309       }
 310     return __ret;
 311   }
 312
 313   streamsize
 314   __basic_file<char>::xsgetn(char* __s, streamsize __n)
 315   {
 316     streamsize __ret;
 317     do
 318       __ret = read(this->fd(), __s, __n);
 319     while (__ret == -1L && errno == EINTR);
 320     return __ret;
 321   }
 322
 323   streamsize
 324   __basic_file<char>::xsputn(const char* __s, streamsize __n)
 325   { return xwrite(this->fd(), __s, __n); }
 326
 327   streamsize
 328   __basic_file<char>::xsputn_2(const char* __s1, streamsize __n1,
 329                                const char* __s2, streamsize __n2)
 330   {
 331     streamsize __ret = 0;
 332 #ifdef _GLIBCXX_HAVE_WRITEV
 333     __ret = xwritev(this->fd(), __s1, __n1, __s2, __n2);
 334 #else
 335     if (__n1)
 336       __ret = xwrite(this->fd(), __s1, __n1);
 337
 338     if (__ret == __n1)
 339       __ret += xwrite(this->fd(), __s2, __n2);
 340 #endif
 341     return __ret;
 342   }
 343
 344   streamoff
 345   __basic_file<char>::seekoff(streamoff __off, ios_base::seekdir __way) throw ()
 346   {
 347 #ifdef _GLIBCXX_USE_LFS
 348     return lseek64(this->fd(), __off, __way);
 349 #else
 350     if (__off > numeric_limits<off_t>::max()
 351         || __off < numeric_limits<off_t>::min())
 352       return -1L;
 353     return lseek(this->fd(), __off, __way);
 354 #endif
 355   }
 356
 357   int
 358   __basic_file<char>::sync()
 359   { return fflush(_M_cfile); }
 360
 361   streamsize
 362   __basic_file<char>::showmanyc()
 363   {
 364 #ifndef _GLIBCXX_NO_IOCTL
 365 #ifdef FIONREAD
 366     // Pipes and sockets.
 367     int __num = 0;
 368     int __r = ioctl(this->fd(), FIONREAD, &__num);
 369     if (!__r && __num >= 0)
 370       return __num;
 371 #endif
 372 #endif
 373
 374 #ifdef _GLIBCXX_HAVE_POLL
 375     // Cheap test.
 376     struct pollfd __pfd[1];
 377     __pfd[0].fd = this->fd();
 378     __pfd[0].events = POLLIN;
 379     if (poll(__pfd, 1, 0) <= 0)
 380       return 0;
 381 #endif
 382
 383 #if defined(_GLIBCXX_HAVE_S_ISREG) || defined(_GLIBCXX_HAVE_S_IFREG)
 384     // Regular files.
 385 #ifdef _GLIBCXX_USE_LFS
 386     struct stat64 __buffer;
 387     const int __err = fstat64(this->fd(), &__buffer);
 388     if (!__err && _GLIBCXX_ISREG(__buffer.st_mode))
 389       {
 390         const streamoff __off = __buffer.st_size - lseek64(this->fd(), 0,
 391                                                            ios_base::cur);
 392         return std::min(__off, streamoff(numeric_limits<streamsize>::max()));
 393       }
 394 #else
 395     struct stat __buffer;
 396     const int __err = fstat(this->fd(), &__buffer);
 397     if (!__err && _GLIBCXX_ISREG(__buffer.st_mode))
 398       return __buffer.st_size - lseek(this->fd(), 0, ios_base::cur);
 399 #endif
 400 #endif
 401     return 0;
 402   }
 403
 404 _GLIBCXX_END_NAMESPACE_VERSION
 405 } // namespace
 406