Initial Contribution

libc/stdio/fgetln.c

@@ -0,0 +1,150 @@
+/*	$OpenBSD: fgetln.c,v 1.7 2005/08/08 08:05:36 espie Exp $ */
+/*-
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "local.h"
+
+/*
+ * Expand the line buffer.  Return -1 on error.
+#ifdef notdef
+ * The `new size' does not account for a terminating '\0',
+ * so we add 1 here.
+#endif
+ */
+int
+__slbexpand(FILE *fp, size_t newsize)
+{
+	void *p;
+
+#ifdef notdef
+	++newsize;
+#endif
+	if ((size_t)fp->_lb._size >= newsize)
+		return (0);
+	if ((p = realloc(fp->_lb._base, newsize)) == NULL)
+		return (-1);
+	fp->_lb._base = p;
+	fp->_lb._size = newsize;
+	return (0);
+}
+
+/*
+ * Get an input line.  The returned pointer often (but not always)
+ * points into a stdio buffer.  Fgetline does not alter the text of
+ * the returned line (which is thus not a C string because it will
+ * not necessarily end with '\0'), but does allow callers to modify
+ * it if they wish.  Thus, we set __SMOD in case the caller does.
+ */
+char *
+fgetln(FILE *fp, size_t *lenp)
+{
+	unsigned char *p;
+	size_t len;
+	size_t off;
+
+	/* make sure there is input */
+	if (fp->_r <= 0 && __srefill(fp)) {
+		*lenp = 0;
+		return (NULL);
+	}
+
+	/* look for a newline in the input */
+	if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) {
+		char *ret;
+
+		/*
+		 * Found one.  Flag buffer as modified to keep fseek from
+		 * `optimising' a backward seek, in case the user stomps on
+		 * the text.
+		 */
+		p++;		/* advance over it */
+		ret = (char *)fp->_p;
+		*lenp = len = p - fp->_p;
+		fp->_flags |= __SMOD;
+		fp->_r -= len;
+		fp->_p = p;
+		return (ret);
+	}
+
+	/*
+	 * We have to copy the current buffered data to the line buffer.
+	 * As a bonus, though, we can leave off the __SMOD.
+	 *
+	 * OPTIMISTIC is length that we (optimistically) expect will
+	 * accommodate the `rest' of the string, on each trip through the
+	 * loop below.
+	 */
+#define OPTIMISTIC 80
+
+	for (len = fp->_r, off = 0;; len += fp->_r) {
+		size_t diff;
+
+		/*
+		 * Make sure there is room for more bytes.  Copy data from
+		 * file buffer to line buffer, refill file and look for
+		 * newline.  The loop stops only when we find a newline.
+		 */
+		if (__slbexpand(fp, len + OPTIMISTIC))
+			goto error;
+		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
+		    len - off);
+		off = len;
+		if (__srefill(fp))
+			break;	/* EOF or error: return partial line */
+		if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL)
+			continue;
+
+		/* got it: finish up the line (like code above) */
+		p++;
+		diff = p - fp->_p;
+		len += diff;
+		if (__slbexpand(fp, len))
+			goto error;
+		(void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
+		    diff);
+		fp->_r -= diff;
+		fp->_p = p;
+		break;
+	}
+	*lenp = len;
+#ifdef notdef
+	fp->_lb._base[len] = '\0';
+#endif
+	return ((char *)fp->_lb._base);
+
+error:
+	*lenp = 0;		/* ??? */
+	return (NULL);		/* ??? */
+}