newlib/libc/stdio/fread.c

   1 /*
   2  * Copyright (c) 1990, 2007 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * and/or other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 /*
  19 FUNCTION
  20 <<fread>>, <<fread_unlocked>>---read array elements from a file
  21
  22 INDEX
  23         fread
  24 INDEX
  25         fread_unlocked
  26 INDEX
  27         _fread_r
  28 INDEX
  29         _fread_unlocked_r
  30
  31 SYNOPSIS
  32         #include <stdio.h>
  33         size_t fread(void *restrict <[buf]>, size_t <[size]>, size_t <[count]>,
  34                      FILE *restrict <[fp]>);
  35
  36         #define _BSD_SOURCE
  37         #include <stdio.h>
  38         size_t fread_unlocked(void *restrict <[buf]>, size_t <[size]>, size_t <[count]>,
  39                      FILE *restrict <[fp]>);
  40
  41         #include <stdio.h>
  42         size_t _fread_r(struct _reent *<[ptr]>, void *restrict <[buf]>,
  43                         size_t <[size]>, size_t <[count]>, FILE *restrict <[fp]>);
  44
  45         #include <stdio.h>
  46         size_t _fread_unlocked_r(struct _reent *<[ptr]>, void *restrict <[buf]>,
  47                         size_t <[size]>, size_t <[count]>, FILE *restrict <[fp]>);
  48
  49 DESCRIPTION
  50 <<fread>> attempts to copy, from the file or stream identified by
  51 <[fp]>, <[count]> elements (each of size <[size]>) into memory,
  52 starting at <[buf]>.   <<fread>> may copy fewer elements than
  53 <[count]> if an error, or end of file, intervenes.
  54
  55 <<fread>> also advances the file position indicator (if any) for
  56 <[fp]> by the number of @emph{characters} actually read.
  57
  58 <<fread_unlocked>> is a non-thread-safe version of <<fread>>.
  59 <<fread_unlocked>> may only safely be used within a scope
  60 protected by flockfile() (or ftrylockfile()) and funlockfile().  This
  61 function may safely be used in a multi-threaded program if and only
  62 if they are called while the invoking thread owns the (FILE *)
  63 object, as is the case after a successful call to the flockfile() or
  64 ftrylockfile() functions.  If threads are disabled, then
  65 <<fread_unlocked>> is equivalent to <<fread>>.
  66
  67 <<_fread_r>> and <<_fread_unlocked_r>> are simply reentrant versions of the
  68 above that take an additional reentrant structure pointer argument: <[ptr]>.
  69
  70 RETURNS
  71 The result of <<fread>> is the number of elements it succeeded in
  72 reading.
  73
  74 PORTABILITY
  75 ANSI C requires <<fread>>.
  76
  77 <<fread_unlocked>> is a BSD extension also provided by GNU libc.
  78
  79 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  80 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  81 */
  82
  83 #include <_ansi.h>
  84 #include <stdio.h>
  85 #include <string.h>
  86 #include <malloc.h>
  87 #include "local.h"
  88
  89 #ifdef __IMPL_UNLOCKED__
  90 #define _fread_r _fread_unlocked_r
  91 #define fread fread_unlocked
  92 #endif
  93
  94 #ifdef __SCLE
  95 static size_t
  96 crlf_r (struct _reent * ptr,
  97        FILE * fp,
  98        char * buf,
  99        size_t count,
 100        int eof)
 101 {
 102   int r;
 103   char *s, *d, *e;
 104
 105   if (count == 0)
 106     return 0;
 107
 108   e = buf + count;
 109   for (s=d=buf; s<e-1; s++)
 110     {
 111       if (*s == '\r' && s[1] == '\n')
 112         s++;
 113       *d++ = *s;
 114     }
 115   if (s < e)
 116     {
 117       if (*s == '\r')
 118         {
 119           int c = __sgetc_raw_r (ptr, fp);
 120           if (c == '\n')
 121             *s = '\n';
 122           else
 123             ungetc (c, fp);
 124         }
 125       *d++ = *s++;
 126     }
 127
 128
 129   while (d < e)
 130     {
 131       r = _getc_r (ptr, fp);
 132       if (r == EOF)
 133         return count - (e-d);
 134       *d++ = r;
 135     }
 136
 137   return count;
 138
 139 }
 140
 141 #endif
 142
 143 size_t
 144 _fread_r (struct _reent * ptr,
 145        void *__restrict buf,
 146        size_t size,
 147        size_t count,
 148        FILE * __restrict fp)
 149 {
 150   register size_t resid;
 151   register char *p;
 152   register int r;
 153   size_t total;
 154
 155   if ((resid = count * size) == 0)
 156     return 0;
 157
 158   CHECK_INIT(ptr, fp);
 159
 160   _newlib_flockfile_start (fp);
 161   if (ORIENT (fp, -1) != -1)
 162     {
 163       count = 0;
 164       goto ret;
 165     }
 166   if (fp->_r < 0)
 167     fp->_r = 0;
 168   total = resid;
 169   p = buf;
 170
 171 #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
 172
 173   /* Optimize unbuffered I/O.  */
 174   if (fp->_flags & __SNBF)
 175     {
 176       /* First copy any available characters from ungetc buffer.  */
 177       int copy_size = resid > fp->_r ? fp->_r : resid;
 178       (void) memcpy ((void *) p, (void *) fp->_p, (size_t) copy_size);
 179       fp->_p += copy_size;
 180       fp->_r -= copy_size;
 181       p += copy_size;
 182       resid -= copy_size;
 183
 184       /* If still more data needed, free any allocated ungetc buffer.  */
 185       if (HASUB (fp) && resid > 0)
 186         FREEUB (ptr, fp);
 187
 188       /* Finally read directly into user's buffer if needed.  */
 189       while (resid > 0)
 190         {
 191           int rc = 0;
 192           /* save fp buffering state */
 193           void *old_base = fp->_bf._base;
 194           void * old_p = fp->_p;
 195           int old_size = fp->_bf._size;
 196           /* allow __refill to use user's buffer */
 197           fp->_bf._base = (unsigned char *) p;
 198           fp->_bf._size = resid;
 199           fp->_p = (unsigned char *) p;
 200           rc = __srefill_r (ptr, fp);
 201           /* restore fp buffering back to original state */
 202           fp->_bf._base = old_base;
 203           fp->_bf._size = old_size;
 204           fp->_p = old_p;
 205           resid -= fp->_r;
 206           p += fp->_r;
 207           fp->_r = 0;
 208           if (rc)
 209             {
 210 #ifdef __SCLE
 211               if (fp->_flags & __SCLE)
 212                 {
 213                   _newlib_flockfile_exit (fp);
 214                   return crlf_r (ptr, fp, buf, total-resid, 1) / size;
 215                 }
 216 #endif
 217               _newlib_flockfile_exit (fp);
 218               return (total - resid) / size;
 219             }
 220         }
 221     }
 222   else
 223 #endif /* !PREFER_SIZE_OVER_SPEED && !__OPTIMIZE_SIZE__ */
 224     {
 225       while (resid > (r = fp->_r))
 226         {
 227           (void) memcpy ((void *) p, (void *) fp->_p, (size_t) r);
 228           fp->_p += r;
 229           /* fp->_r = 0 ... done in __srefill */
 230           p += r;
 231           resid -= r;
 232           if (__srefill_r (ptr, fp))
 233             {
 234               /* no more input: return partial result */
 235 #ifdef __SCLE
 236               if (fp->_flags & __SCLE)
 237                 {
 238                   _newlib_flockfile_exit (fp);
 239                   return crlf_r (ptr, fp, buf, total-resid, 1) / size;
 240                 }
 241 #endif
 242               _newlib_flockfile_exit (fp);
 243               return (total - resid) / size;
 244             }
 245         }
 246       (void) memcpy ((void *) p, (void *) fp->_p, resid);
 247       fp->_r -= resid;
 248       fp->_p += resid;
 249     }
 250
 251   /* Perform any CR/LF clean-up if necessary.  */
 252 #ifdef __SCLE
 253   if (fp->_flags & __SCLE)
 254     {
 255       _newlib_flockfile_exit (fp);
 256       return crlf_r(ptr, fp, buf, total, 0) / size;
 257     }
 258 #endif
 259 ret:
 260   _newlib_flockfile_end (fp);
 261   return count;
 262 }
 263
 264 #ifndef _REENT_ONLY
 265 size_t
 266 fread (void *__restrict  buf,
 267        size_t size,
 268        size_t count,
 269        FILE *__restrict fp)
 270 {
 271    return _fread_r (_REENT, buf, size, count, fp);
 272 }
 273 #endif