toolchain/gcc/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  * advertising materials, and 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>>---write array elements
  21
  22 INDEX
  23         fwrite
  24
  25 ANSI_SYNOPSIS
  26         #include <stdio.h>
  27         size_t fwrite(const void *<[buf]>, size_t <[size]>,
  28                       size_t <[count]>, FILE *<[fp]>);
  29
  30 TRAD_SYNOPSIS
  31         #include <stdio.h>
  32         size_t fwrite(<[buf]>, <[size]>, <[count]>, <[fp]>)
  33         char *<[buf]>;
  34         size_t <[size]>;
  35         size_t <[count]>;
  36         FILE *<[fp]>;
  37
  38 DESCRIPTION
  39 <<fwrite>> attempts to copy, starting from the memory location
  40 <[buf]>, <[count]> elements (each of size <[size]>) into the file or
  41 stream identified by <[fp]>.  <<fwrite>> may copy fewer elements than
  42 <[count]> if an error intervenes.
  43
  44 <<fwrite>> also advances the file position indicator (if any) for
  45 <[fp]> by the number of @emph{characters} actually written.
  46
  47 RETURNS
  48 If <<fwrite>> succeeds in writing all the elements you specify, the
  49 result is the same as the argument <[count]>.  In any event, the
  50 result is the number of complete elements that <<fwrite>> copied to
  51 the file.
  52
  53 PORTABILITY
  54 ANSI C requires <<fwrite>>.
  55
  56 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  57 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  58 */
  59
  60 #if defined(LIBC_SCCS) && !defined(lint)
  61 static char sccsid[] = "%W% (Berkeley) %G%";
  62 #endif /* LIBC_SCCS and not lint */
  63
  64 #include <stdio.h>
  65 #include <string.h>
  66 #if 0
  67 #include <sys/stdc.h>
  68 #endif
  69 #include "local.h"
  70 #if 1
  71 #include "fvwrite.h"
  72 #endif
  73
  74 /*
  75  * Write `count' objects (each size `size') from memory to the given file.
  76  * Return the number of whole objects written.
  77  */
  78
  79 size_t
  80 _DEFUN (fwrite, (buf, size, count, fp),
  81         _CONST _PTR buf _AND
  82         size_t size _AND
  83         size_t count _AND
  84         FILE * fp)
  85 {
  86   size_t n;
  87   struct __suio uio;
  88   struct __siov iov;
  89
  90   iov.iov_base = buf;
  91   uio.uio_resid = iov.iov_len = n = count * size;
  92   uio.uio_iov = &iov;
  93   uio.uio_iovcnt = 1;
  94
  95   /*
  96    * The usual case is success (__sfvwrite returns 0);
  97    * skip the divide if this happens, since divides are
  98    * generally slow and since this occurs whenever size==0.
  99    */
 100
 101   _flockfile(fp);
 102   if (__sfvwrite (fp, &uio) == 0)
 103     {
 104       _funlockfile(fp);
 105       return count;
 106     }
 107   _funlockfile(fp);
 108   return (n - uio.uio_resid) / size;
 109 }