157 lines
3.7 KiB
C
157 lines
3.7 KiB
C
/*
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/*
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FUNCTION
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<<fgets>>---get character string from a file or stream
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INDEX
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fgets
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ANSI_SYNOPSIS
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#include <stdio.h>
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char *fgets(char *<[buf]>, int <[n]>, FILE *<[fp]>);
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TRAD_SYNOPSIS
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#include <stdio.h>
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char *fgets(<[buf]>,<[n]>,<[fp]>)
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char *<[buf]>;
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int <[n]>;
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FILE *<[fp]>;
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DESCRIPTION
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Reads at most <[n-1]> characters from <[fp]> until a newline
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is found. The characters including to the newline are stored
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in <[buf]>. The buffer is terminated with a 0.
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RETURNS
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<<fgets>> returns the buffer passed to it, with the data
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filled in. If end of file occurs with some data already
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accumulated, the data is returned with no other indication. If
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no data are read, NULL is returned instead.
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PORTABILITY
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<<fgets>> should replace all uses of <<gets>>. Note however
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that <<fgets>> returns all of the data, while <<gets>> removes
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the trailing newline (with no indication that it has done so.)
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
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*/
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#include <_ansi.h>
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#include <stdio.h>
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#include <string.h>
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#include "local.h"
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/*
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* Read at most n-1 characters from the given file.
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* Stop when a newline has been read, or the count runs out.
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* Return first argument, or NULL if no characters were read.
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*/
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char *
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_DEFUN(fgets, (buf, n, fp),
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char *buf _AND
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int n _AND
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FILE * fp)
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{
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size_t len;
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char *s;
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unsigned char *p, *t;
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if (n < 2) /* sanity check */
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return 0;
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s = buf;
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_flockfile (fp);
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#ifdef __SCLE
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if (fp->_flags & __SCLE)
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{
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int c;
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/* Sorry, have to do it the slow way */
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while (--n > 0 && (c = __sgetc (fp)) != EOF)
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{
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*s++ = c;
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if (c == '\n')
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break;
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}
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if (c == EOF && s == buf)
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{
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_funlockfile (fp);
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return NULL;
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}
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*s = 0;
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_funlockfile (fp);
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return buf;
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}
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#endif
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n--; /* leave space for NUL */
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do
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{
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/*
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* If the buffer is empty, refill it.
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*/
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if ((len = fp->_r) <= 0)
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{
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if (__srefill (fp))
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{
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/* EOF: stop with partial or no line */
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if (s == buf)
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{
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_funlockfile (fp);
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return 0;
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}
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break;
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}
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len = fp->_r;
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}
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p = fp->_p;
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/*
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* Scan through at most n bytes of the current buffer,
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* looking for '\n'. If found, copy up to and including
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* newline, and stop. Otherwise, copy entire chunk
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* and loop.
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*/
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if (len > n)
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len = n;
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t = (unsigned char *) memchr ((_PTR) p, '\n', len);
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if (t != 0)
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{
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len = ++t - p;
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fp->_r -= len;
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fp->_p = t;
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_CAST_VOID memcpy ((_PTR) s, (_PTR) p, len);
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s[len] = 0;
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_funlockfile (fp);
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return (buf);
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}
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fp->_r -= len;
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fp->_p += len;
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_CAST_VOID memcpy ((_PTR) s, (_PTR) p, len);
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s += len;
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}
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while ((n -= len) != 0);
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*s = 0;
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_funlockfile (fp);
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return buf;
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}
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