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122 lines
2.9 KiB
C
122 lines
2.9 KiB
C
/* Copyright (C) 1991, 1992, 1995 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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/* Reads characters from STREAM into S, until either a newline character
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is read, N - 1 characters have been read, or EOF is seen. Returns
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the newline, unlike gets. Finishes by appending a null character and
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returning S. If EOF is seen before any characters have been written
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to S, the function returns NULL without appending the null character.
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If there is a file error, always return NULL. */
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char *
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DEFUN(fgets, (s, n, stream), char *s AND int n AND register FILE *stream)
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{
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register char *p = s;
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if (!__validfp(stream) || s == NULL || n <= 0)
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{
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errno = EINVAL;
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return NULL;
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}
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if (ferror (stream))
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return NULL;
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if (stream->__buffer == NULL && stream->__userbuf)
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{
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/* Unbuffered stream. Not much optimization to do. */
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register int c = 0;
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while (--n > 0 && (c = getc (stream)) != EOF)
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if ((*p++ = c) == '\n')
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break;
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if (c == EOF && (p == s || ferror (stream)))
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return NULL;
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*p = '\0';
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return s;
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}
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/* Leave space for the null. */
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--n;
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if (n > 0 &&
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(!stream->__seen || stream->__buffer == NULL || stream->__pushed_back))
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{
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/* Do one with getc to allocate a buffer. */
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int c = getc (stream);
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if (c == EOF)
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return NULL;
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*p++ = c;
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if (c == '\n')
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{
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*p = '\0';
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return s;
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}
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else
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--n;
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}
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while (n > 0)
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{
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size_t i;
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char *found;
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i = stream->__get_limit - stream->__bufp;
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if (i == 0)
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{
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/* Refill the buffer. */
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int c = __fillbf (stream);
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if (c == EOF)
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break;
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*p++ = c;
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--n;
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if (c == '\n')
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{
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*p = '\0';
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return s;
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}
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i = stream->__get_limit - stream->__bufp;
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}
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if (i > n)
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i = n;
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found = (char *) __memccpy ((PTR) p, stream->__bufp, '\n', i);
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if (found != NULL)
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{
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stream->__bufp += found - p;
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p = found;
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break;
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}
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stream->__bufp += i;
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n -= i;
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p += i;
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}
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if (p == s)
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return NULL;
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*p = '\0';
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return ferror (stream) ? NULL : s;
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}
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