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04277e02 1/* Copyright (C) 1993-2019 Free Software Foundation, Inc.
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2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
59ba27a6 15 License along with the GNU C Library; if not, see
5a82c748 16 <https://www.gnu.org/licenses/>.
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17
18 As a special exception, if you link the code in this file with
19 files compiled with a GNU compiler to produce an executable,
20 that does not cause the resulting executable to be covered by
21 the GNU Lesser General Public License. This exception does not
22 however invalidate any other reasons why the executable file
23 might be covered by the GNU Lesser General Public License.
24 This exception applies to code released by its copyright holders
25 in files containing the exception. */
26
27#include "libioP.h"
28#include <stdio.h>
29#include <sys/param.h>
30
31char *
9964a145 32__fgets_chk (char *buf, size_t size, int n, FILE *fp)
553cc5f9 33{
9964a145 34 size_t count;
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35 char *result;
36 CHECK_FILE (fp, NULL);
37 if (n <= 0)
38 return NULL;
39 _IO_acquire_lock (fp);
40 /* This is very tricky since a file descriptor may be in the
41 non-blocking mode. The error flag doesn't mean much in this
42 case. We return an error only when there is a new error. */
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43 int old_error = fp->_flags & _IO_ERR_SEEN;
44 fp->_flags &= ~_IO_ERR_SEEN;
d18ea0c5 45 count = _IO_getline (fp, buf, MIN ((size_t) n - 1, size), '\n', 1);
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46 /* If we read in some bytes and errno is EAGAIN, that error will
47 be reported for next read. */
df6c012b 48 if (count == 0 || ((fp->_flags & _IO_ERR_SEEN) && errno != EAGAIN))
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49 result = NULL;
50 else if (count >= size)
51 __chk_fail ();
52 else
53 {
54 buf[count] = '\0';
55 result = buf;
56 }
df6c012b 57 fp->_flags |= old_error;
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58 _IO_release_lock (fp);
59 return result;
60}