newlib/libc/stdio/makebuf.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 /* No user fns here.  Pesch 15apr92. */
  18
  19 #include <_ansi.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <sys/stat.h>
  23 #include <sys/types.h>
  24 #include <sys/unistd.h>
  25 #include "local.h"
  26
  27 #define _DEFAULT_ASPRINTF_BUFSIZE 64
  28
  29 /*
  30  * Allocate a file buffer, or switch to unbuffered I/O.
  31  * Per the ANSI C standard, ALL tty devices default to line buffered.
  32  *
  33  * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
  34  * optimization) right after the _fstat() that finds the buffer size.
  35  */
  36
  37 void
  38 __smakebuf_r (struct _reent *ptr,
  39        register FILE *fp)
  40 {
  41   register void *p;
  42   int flags;
  43   size_t size;
  44   int couldbetty;
  45
  46   if (fp->_flags & __SNBF)
  47     {
  48       fp->_bf._base = fp->_p = fp->_nbuf;
  49       fp->_bf._size = 1;
  50       return;
  51     }
  52   flags = __swhatbuf_r (ptr, fp, &size, &couldbetty);
  53   if ((p = _malloc_r (ptr, size)) == NULL)
  54     {
  55       if (!(fp->_flags & __SSTR))
  56         {
  57           fp->_flags = (fp->_flags & ~__SLBF) | __SNBF;
  58           fp->_bf._base = fp->_p = fp->_nbuf;
  59           fp->_bf._size = 1;
  60         }
  61     }
  62   else
  63     {
  64       fp->_flags |= __SMBF;
  65       fp->_bf._base = fp->_p = (unsigned char *) p;
  66       fp->_bf._size = size;
  67       if (couldbetty && _isatty_r (ptr, fp->_file))
  68         fp->_flags = (fp->_flags & ~__SNBF) | __SLBF;
  69       fp->_flags |= flags;
  70     }
  71 }
  72
  73 /*
  74  * Internal routine to determine `proper' buffering for a file.
  75  */
  76 int
  77 __swhatbuf_r (struct _reent *ptr,
  78         FILE *fp,
  79         size_t *bufsize,
  80         int *couldbetty)
  81 {
  82 #ifdef _FSEEK_OPTIMIZATION
  83   const int snpt = __SNPT;
  84 #else
  85   const int snpt = 0;
  86 #endif
  87
  88 #ifdef __USE_INTERNAL_STAT64
  89   struct stat64 st;
  90
  91   if (fp->_file < 0 || _fstat64_r (ptr, fp->_file, &st) < 0)
  92 #else
  93   struct stat st;
  94
  95   if (fp->_file < 0 || _fstat_r (ptr, fp->_file, &st) < 0)
  96 #endif
  97     {
  98       *couldbetty = 0;
  99       /* Check if we are be called by asprintf family for initial buffer.  */
 100       if (fp->_flags & __SMBF)
 101         *bufsize = _DEFAULT_ASPRINTF_BUFSIZE;
 102       else
 103         *bufsize = BUFSIZ;
 104       return (0);
 105     }
 106
 107   /* could be a tty iff it is a character device */
 108   *couldbetty = S_ISCHR(st.st_mode);
 109 #ifdef HAVE_BLKSIZE
 110   if (st.st_blksize > 0)
 111     {
 112       /*
 113        * Optimise fseek() only if it is a regular file.  (The test for
 114        * __sseek is mainly paranoia.)  It is safe to set _blksize
 115        * unconditionally; it will only be used if __SOPT is also set.
 116        */
 117       *bufsize = st.st_blksize;
 118       fp->_blksize = st.st_blksize;
 119       return ((st.st_mode & S_IFMT) == S_IFREG ?  __SOPT : snpt);
 120     }
 121 #endif
 122   *bufsize = BUFSIZ;
 123   return (snpt);
 124 }