newlib/libc/stdio/fwrite.c

   1 /*
   2  * Copyright (c) 1990 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 <<fwrite>>, <<fwrite_unlocked>>---write array elements
  21
  22 INDEX
  23         fwrite
  24 INDEX
  25         fwrite_unlocked
  26 INDEX
  27         _fwrite_r
  28 INDEX
  29         _fwrite_unlocked_r
  30
  31 SYNOPSIS
  32         #include <stdio.h>
  33         size_t fwrite(const void *restrict <[buf]>, size_t <[size]>,
  34                       size_t <[count]>, FILE *restrict <[fp]>);
  35
  36         #define _BSD_SOURCE
  37         #include <stdio.h>
  38         size_t fwrite_unlocked(const void *restrict <[buf]>, size_t <[size]>,
  39                       size_t <[count]>, FILE *restrict <[fp]>);
  40
  41         #include <stdio.h>
  42         size_t _fwrite_r(struct _reent *<[ptr]>, const void *restrict <[buf]>, size_t <[size]>,
  43                       size_t <[count]>, FILE *restrict <[fp]>);
  44
  45         #include <stdio.h>
  46         size_t _fwrite_unlocked_r(struct _reent *<[ptr]>, const void *restrict <[buf]>, size_t <[size]>,
  47                       size_t <[count]>, FILE *restrict <[fp]>);
  48
  49 DESCRIPTION
  50 <<fwrite>> attempts to copy, starting from the memory location
  51 <[buf]>, <[count]> elements (each of size <[size]>) into the file or
  52 stream identified by <[fp]>.  <<fwrite>> may copy fewer elements than
  53 <[count]> if an error intervenes.
  54
  55 <<fwrite>> also advances the file position indicator (if any) for
  56 <[fp]> by the number of @emph{characters} actually written.
  57
  58 <<fwrite_unlocked>> is a non-thread-safe version of <<fwrite>>.
  59 <<fwrite_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 <<fwrite_unlocked>> is equivalent to <<fwrite>>.
  66
  67 <<_fwrite_r>> and <<_fwrite_unlocked_r>> are simply reentrant versions of the
  68 above that take an additional reentrant structure argument: <[ptr]>.
  69
  70 RETURNS
  71 If <<fwrite>> succeeds in writing all the elements you specify, the
  72 result is the same as the argument <[count]>.  In any event, the
  73 result is the number of complete elements that <<fwrite>> copied to
  74 the file.
  75
  76 PORTABILITY
  77 ANSI C requires <<fwrite>>.
  78
  79 <<fwrite_unlocked>> is a BSD extension also provided by GNU libc.
  80
  81 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  82 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  83 */
  84
  85 #if defined(LIBC_SCCS) && !defined(lint)
  86 static char sccsid[] = "%W% (Berkeley) %G%";
  87 #endif /* LIBC_SCCS and not lint */
  88
  89 #include <_ansi.h>
  90 #include <stdio.h>
  91 #include <string.h>
  92 #if 0
  93 #include <sys/stdc.h>
  94 #endif
  95 #include "local.h"
  96 #if 1
  97 #include "fvwrite.h"
  98 #endif
  99
 100 #ifdef __IMPL_UNLOCKED__
 101 #define _fwrite_r _fwrite_unlocked_r
 102 #define fwrite fwrite_unlocked
 103 #endif
 104
 105 /*
 106  * Write `count' objects (each size `size') from memory to the given file.
 107  * Return the number of whole objects written.
 108  */
 109
 110 size_t
 111 _fwrite_r (struct _reent * ptr,
 112        const void *__restrict buf,
 113        size_t size,
 114        size_t count,
 115        FILE * __restrict fp)
 116 {
 117   size_t n;
 118 #ifdef _FVWRITE_IN_STREAMIO
 119   struct __suio uio;
 120   struct __siov iov;
 121
 122   iov.iov_base = buf;
 123   uio.uio_resid = iov.iov_len = n = count * size;
 124   uio.uio_iov = &iov;
 125   uio.uio_iovcnt = 1;
 126
 127   /*
 128    * The usual case is success (__sfvwrite_r returns 0);
 129    * skip the divide if this happens, since divides are
 130    * generally slow and since this occurs whenever size==0.
 131    */
 132
 133   CHECK_INIT(ptr, fp);
 134
 135   _newlib_flockfile_start (fp);
 136   if (ORIENT (fp, -1) != -1)
 137     {
 138       _newlib_flockfile_exit (fp);
 139       return 0;
 140     }
 141   if (__sfvwrite_r (ptr, fp, &uio) == 0)
 142     {
 143       _newlib_flockfile_exit (fp);
 144       return count;
 145     }
 146   _newlib_flockfile_end (fp);
 147   return (n - uio.uio_resid) / size;
 148 #else
 149   size_t i = 0;
 150   const char *p = buf;
 151   n = count * size;
 152   CHECK_INIT (ptr, fp);
 153
 154   _newlib_flockfile_start (fp);
 155   /* Make sure we can write.  */
 156   if (cantwrite (ptr, fp))
 157     goto ret;
 158
 159   while (i < n)
 160     {
 161       if (__sputc_r (ptr, p[i], fp) == EOF)
 162         break;
 163
 164       i++;
 165     }
 166
 167 ret:
 168   _newlib_flockfile_end (fp);
 169   return i / size;
 170 #endif
 171 }
 172
 173 #ifndef _REENT_ONLY
 174 size_t
 175 fwrite (const void *__restrict buf,
 176        size_t size,
 177        size_t count,
 178        FILE * fp)
 179 {
 180   return _fwrite_r (_REENT, buf, size, count, fp);
 181 }
 182 #endif