1 | /* |
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2 | * Copyright (c) 1990 The Regents of the University of California. |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms are permitted |
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6 | * provided that the above copyright notice and this paragraph are |
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7 | * duplicated in all such forms and that any documentation, |
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8 | * advertising materials, and other materials related to such |
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9 | * distribution and use acknowledge that the software was developed |
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10 | * by the University of California, Berkeley. The name of the |
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11 | * University may not be used to endorse or promote products derived |
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12 | * from this software without specific prior written permission. |
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13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
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14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
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15 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
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16 | */ |
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17 | |
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18 | /* |
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19 | FUNCTION |
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20 | <<gets>>---get character string (obsolete, use <<fgets>> instead) |
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21 | |
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22 | INDEX |
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23 | gets |
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24 | INDEX |
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25 | _gets_r |
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26 | |
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27 | SYNOPSIS |
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28 | #include <stdio.h> |
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29 | |
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30 | char *gets(char *<[buf]>); |
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31 | |
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32 | char *_gets_r(struct _reent *<[reent]>, char *<[buf]>); |
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33 | |
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34 | DESCRIPTION |
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35 | Reads characters from standard input until a newline is found. |
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36 | The characters up to the newline are stored in <[buf]>. The |
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37 | newline is discarded, and the buffer is terminated with a 0. |
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38 | |
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39 | This is a @emph{dangerous} function, as it has no way of checking |
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40 | the amount of space available in <[buf]>. One of the attacks |
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41 | used by the Internet Worm of 1988 used this to overrun a |
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42 | buffer allocated on the stack of the finger daemon and |
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43 | overwrite the return address, causing the daemon to execute |
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44 | code downloaded into it over the connection. |
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45 | |
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46 | The alternate function <<_gets_r>> is a reentrant version. The extra |
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47 | argument <[reent]> is a pointer to a reentrancy structure. |
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48 | |
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49 | |
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50 | RETURNS |
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51 | <<gets>> returns the buffer passed to it, with the data filled |
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52 | in. If end of file occurs with some data already accumulated, |
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53 | the data is returned with no other indication. If end of file |
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54 | occurs with no data in the buffer, NULL is returned. |
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55 | |
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56 | Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, |
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57 | <<lseek>>, <<read>>, <<sbrk>>, <<write>>. |
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58 | */ |
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59 | |
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60 | #include <_ansi.h> |
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61 | #include <reent.h> |
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62 | #include <stdio.h> |
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63 | #include "local.h" |
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64 | |
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65 | char * |
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66 | _gets_r (struct _reent *ptr, |
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67 | char *buf) |
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68 | { |
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69 | register int c; |
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70 | register char *s = buf; |
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71 | FILE *fp; |
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72 | |
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73 | _REENT_SMALL_CHECK_INIT (ptr); |
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74 | fp = _stdin_r (ptr); |
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75 | CHECK_INIT (ptr, fp); |
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76 | _newlib_flockfile_start (fp); |
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77 | while ((c = __sgetc_r (ptr, fp)) != '\n') |
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78 | if (c == EOF) |
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79 | if (s == buf) |
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80 | { |
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81 | _newlib_flockfile_exit (fp); |
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82 | return NULL; |
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83 | } |
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84 | else |
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85 | break; |
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86 | else |
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87 | *s++ = c; |
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88 | *s = 0; |
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89 | _newlib_flockfile_end (fp); |
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90 | return buf; |
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91 | } |
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92 | |
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93 | #ifndef _REENT_ONLY |
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94 | |
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95 | char * |
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96 | gets (char *buf) |
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97 | { |
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98 | return _gets_r (_REENT, buf); |
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99 | } |
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100 | |
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101 | #endif |
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