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