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  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. <<gets>>---get character string (obsolete, use <<fgets>> instead)
  21.  
  22. INDEX
  23.         gets
  24. INDEX
  25.         _gets_r
  26.  
  27. ANSI_SYNOPSIS
  28.         #include <stdio.h>
  29.  
  30.         char *gets(char *<[buf]>);
  31.  
  32.         char *_gets_r(struct _reent *<[reent]>, char *<[buf]>);
  33.  
  34. TRAD_SYNOPSIS
  35.         #include <stdio.h>
  36.  
  37.         char *gets(<[buf]>)
  38.         char *<[buf]>;
  39.  
  40.         char *_gets_r(<[reent]>, <[buf]>)
  41.         struct _reent *<[reent]>;
  42.         char *<[buf]>;
  43.  
  44. DESCRIPTION
  45.         Reads characters from standard input until a newline is found.
  46.         The characters up to the newline are stored in <[buf]>. The
  47.         newline is discarded, and the buffer is terminated with a 0.
  48.  
  49.         This is a @emph{dangerous} function, as it has no way of checking
  50.         the amount of space available in <[buf]>. One of the attacks
  51.         used by the Internet Worm of 1988 used this to overrun a
  52.         buffer allocated on the stack of the finger daemon and
  53.         overwrite the return address, causing the daemon to execute
  54.         code downloaded into it over the connection.
  55.  
  56.         The alternate function <<_gets_r>> is a reentrant version.  The extra
  57.         argument <[reent]> is a pointer to a reentrancy structure.
  58.  
  59.  
  60. RETURNS
  61.         <<gets>> returns the buffer passed to it, with the data filled
  62.         in. If end of file occurs with some data already accumulated,
  63.         the data is returned with no other indication. If end of file
  64.         occurs with no data in the buffer, NULL is returned.
  65.  
  66. Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  67. <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
  68. */
  69.  
  70. #include <_ansi.h>
  71. #include <reent.h>
  72. #include <stdio.h>
  73. #include "local.h"
  74.  
  75. char *
  76. _DEFUN(_gets_r, (ptr, buf),
  77.        struct _reent *ptr _AND
  78.        char *buf)
  79. {
  80.   register int c;
  81.   register char *s = buf;
  82.   FILE *fp;
  83.  
  84.   _REENT_SMALL_CHECK_INIT (ptr);
  85.   fp = _stdin_r (ptr);
  86.   CHECK_INIT (ptr, fp);
  87.   _newlib_flockfile_start (fp);
  88.   while ((c = __sgetc_r (ptr, fp)) != '\n')
  89.     if (c == EOF)
  90.       if (s == buf)
  91.         {
  92.           _newlib_flockfile_exit (fp);
  93.           return NULL;
  94.         }
  95.       else
  96.         break;
  97.     else
  98.       *s++ = c;
  99.   *s = 0;
  100.   _newlib_flockfile_end (fp);
  101.   return buf;
  102. }
  103.  
  104. #ifndef _REENT_ONLY
  105.  
  106. char *
  107. _DEFUN(gets, (buf),
  108.        char *buf)
  109. {
  110.   return _gets_r (_REENT, buf);
  111. }
  112.  
  113. #endif
  114.