lib/stdio-read.c

   1 /* POSIX compatible FILE stream read function.
   2    Copyright (C) 2008-2018 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2011.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <stdio.h>
  22
  23 /* Replace these functions only if module 'nonblocking' is requested.  */
  24 #if GNULIB_NONBLOCKING
  25
  26 /* On native Windows platforms, when read() is called on a non-blocking pipe
  27    with an empty buffer, ReadFile() fails with error GetLastError() =
  28    ERROR_NO_DATA, and read() in consequence fails with error EINVAL.  This
  29    read() function is at the basis of the function which fills the buffer of
  30    a FILE stream.  */
  31
  32 # if defined _WIN32 && ! defined __CYGWIN__
  33
  34 #  include <errno.h>
  35 #  include <io.h>
  36
  37 #  define WIN32_LEAN_AND_MEAN  /* avoid including junk */
  38 #  include <windows.h>
  39
  40 #  if GNULIB_MSVC_NOTHROW
  41 #   include "msvc-nothrow.h"
  42 #  else
  43 #   include <io.h>
  44 #  endif
  45
  46 #  define CALL_WITH_ERRNO_FIX(RETTYPE, EXPRESSION, FAILED) \
  47   if (ferror (stream))                                                        \
  48     return (EXPRESSION);                                                      \
  49   else                                                                        \
  50     {                                                                         \
  51       RETTYPE ret;                                                            \
  52       SetLastError (0);                                                       \
  53       ret = (EXPRESSION);                                                     \
  54       if (FAILED)                                                             \
  55         {                                                                     \
  56           if (GetLastError () == ERROR_NO_DATA && ferror (stream))            \
  57             {                                                                 \
  58               int fd = fileno (stream);                                       \
  59               if (fd >= 0)                                                    \
  60                 {                                                             \
  61                   HANDLE h = (HANDLE) _get_osfhandle (fd);                    \
  62                   if (GetFileType (h) == FILE_TYPE_PIPE)                      \
  63                     {                                                         \
  64                       /* h is a pipe or socket.  */                           \
  65                       DWORD state;                                            \
  66                       if (GetNamedPipeHandleState (h, &state, NULL, NULL,     \
  67                                                    NULL, NULL, 0)             \
  68                           && (state & PIPE_NOWAIT) != 0)                      \
  69                         /* h is a pipe in non-blocking mode.                  \
  70                            Change errno from EINVAL to EAGAIN.  */            \
  71                         errno = EAGAIN;                                       \
  72                     }                                                         \
  73                 }                                                             \
  74             }                                                                 \
  75         }                                                                     \
  76       return ret;                                                             \
  77     }
  78
  79 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
  80    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
  81 #  if GNULIB_SCANF
  82 int
  83 scanf (const char *format, ...)
  84 {
  85   int retval;
  86   va_list args;
  87
  88   va_start (args, format);
  89   retval = vfscanf (stdin, format, args);
  90   va_end (args);
  91
  92   return retval;
  93 }
  94 #  endif
  95
  96 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
  97    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
  98 #  if GNULIB_FSCANF
  99 int
 100 fscanf (FILE *stream, const char *format, ...)
 101 {
 102   int retval;
 103   va_list args;
 104
 105   va_start (args, format);
 106   retval = vfscanf (stream, format, args);
 107   va_end (args);
 108
 109   return retval;
 110 }
 111 #  endif
 112
 113 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
 114    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
 115 #  if GNULIB_VSCANF
 116 int
 117 vscanf (const char *format, va_list args)
 118 {
 119   return vfscanf (stdin, format, args);
 120 }
 121 #  endif
 122
 123 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
 124    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
 125 #  if GNULIB_VFSCANF
 126 int
 127 vfscanf (FILE *stream, const char *format, va_list args)
 128 #undef vfscanf
 129 {
 130   CALL_WITH_ERRNO_FIX (int, vfscanf (stream, format, args), ret == EOF)
 131 }
 132 #  endif
 133
 134 int
 135 getchar (void)
 136 {
 137   return fgetc (stdin);
 138 }
 139
 140 int
 141 fgetc (FILE *stream)
 142 #undef fgetc
 143 {
 144   CALL_WITH_ERRNO_FIX (int, fgetc (stream), ret == EOF)
 145 }
 146
 147 char *
 148 fgets (char *s, int n, FILE *stream)
 149 #undef fgets
 150 {
 151   CALL_WITH_ERRNO_FIX (char *, fgets (s, n, stream), ret == NULL)
 152 }
 153
 154 /* We intentionally don't bother to fix gets.  */
 155
 156 size_t
 157 fread (void *ptr, size_t s, size_t n, FILE *stream)
 158 #undef fread
 159 {
 160   CALL_WITH_ERRNO_FIX (size_t, fread (ptr, s, n, stream), ret < n)
 161 }
 162
 163 # endif
 164 #endif