lib/stdio-read.c

   1 /* POSIX compatible FILE stream read function.
   2    Copyright (C) 2008-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2011.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file 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 Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser 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 /* Don't assume that UNICODE is not defined.  */
  47 #  undef GetNamedPipeHandleState
  48 #  define GetNamedPipeHandleState GetNamedPipeHandleStateA
  49
  50 #  define CALL_WITH_ERRNO_FIX(RETTYPE, EXPRESSION, FAILED) \
  51   if (ferror (stream))                                                        \
  52     return (EXPRESSION);                                                      \
  53   else                                                                        \
  54     {                                                                         \
  55       RETTYPE ret;                                                            \
  56       SetLastError (0);                                                       \
  57       ret = (EXPRESSION);                                                     \
  58       if (FAILED)                                                             \
  59         {                                                                     \
  60           if (GetLastError () == ERROR_NO_DATA && ferror (stream))            \
  61             {                                                                 \
  62               int fd = fileno (stream);                                       \
  63               if (fd >= 0)                                                    \
  64                 {                                                             \
  65                   HANDLE h = (HANDLE) _get_osfhandle (fd);                    \
  66                   if (GetFileType (h) == FILE_TYPE_PIPE)                      \
  67                     {                                                         \
  68                       /* h is a pipe or socket.  */                           \
  69                       DWORD state;                                            \
  70                       if (GetNamedPipeHandleState (h, &state, NULL, NULL,     \
  71                                                    NULL, NULL, 0)             \
  72                           && (state & PIPE_NOWAIT) != 0)                      \
  73                         /* h is a pipe in non-blocking mode.                  \
  74                            Change errno from EINVAL to EAGAIN.  */            \
  75                         errno = EAGAIN;                                       \
  76                     }                                                         \
  77                 }                                                             \
  78             }                                                                 \
  79         }                                                                     \
  80       return ret;                                                             \
  81     }
  82
  83 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
  84    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
  85 #  if GNULIB_SCANF
  86 int
  87 scanf (const char *format, ...)
  88 {
  89   int retval;
  90   va_list args;
  91
  92   va_start (args, format);
  93   retval = vfscanf (stdin, format, args);
  94   va_end (args);
  95
  96   return retval;
  97 }
  98 #  endif
  99
 100 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
 101    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
 102 #  if GNULIB_FSCANF
 103 int
 104 fscanf (FILE *stream, const char *format, ...)
 105 {
 106   int retval;
 107   va_list args;
 108
 109   va_start (args, format);
 110   retval = vfscanf (stream, format, args);
 111   va_end (args);
 112
 113   return retval;
 114 }
 115 #  endif
 116
 117 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
 118    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
 119 #  if GNULIB_VSCANF
 120 int
 121 vscanf (const char *format, va_list args)
 122 {
 123   return vfscanf (stdin, format, args);
 124 }
 125 #  endif
 126
 127 /* Enable this function definition only if gnulib's <stdio.h> has prepared it.
 128    Otherwise we get a function definition conflict with mingw64's <stdio.h>.  */
 129 #  if GNULIB_VFSCANF
 130 int
 131 vfscanf (FILE *stream, const char *format, va_list args)
 132 #undef vfscanf
 133 {
 134   CALL_WITH_ERRNO_FIX (int, vfscanf (stream, format, args), ret == EOF)
 135 }
 136 #  endif
 137
 138 int
 139 getchar (void)
 140 {
 141   return fgetc (stdin);
 142 }
 143
 144 int
 145 fgetc (FILE *stream)
 146 #undef fgetc
 147 {
 148   CALL_WITH_ERRNO_FIX (int, fgetc (stream), ret == EOF)
 149 }
 150
 151 char *
 152 fgets (char *s, int n, FILE *stream)
 153 #undef fgets
 154 {
 155   CALL_WITH_ERRNO_FIX (char *, fgets (s, n, stream), ret == NULL)
 156 }
 157
 158 /* We intentionally don't bother to fix gets.  */
 159
 160 size_t
 161 fread (void *ptr, size_t s, size_t n, FILE *stream)
 162 #undef fread
 163 {
 164   CALL_WITH_ERRNO_FIX (size_t, fread (ptr, s, n, stream), ret < n)
 165 }
 166
 167 # endif
 168 #endif