2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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18 * This product includes software developed by the University of
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36 * @(#)fgetln.c 8.2 (Berkeley) 1/2/94
37 * $FreeBSD: src/lib/libc/stdio/fgetln.c,v 1.6 1999/08/28 00:00:59 peter Exp $
38 * $DragonFly: src/lib/libc/stdio/fgetln.c,v 1.4 2004/06/07 20:35:41 hmp Exp $
47 * Expand the line buffer. Return -1 on error.
49 * The `new size' does not account for a terminating '\0',
54 __slbexpand(FILE *fp, size_t newsize)
61 if (fp->_lb._size >= newsize)
63 if ((p = realloc(fp->_lb._base, newsize)) == NULL)
66 fp->_lb._size = newsize;
71 * Get an input line. The returned pointer often (but not always)
72 * points into a stdio buffer. Fgetln does not alter the text of
73 * the returned line (which is thus not a C string because it will
74 * not necessarily end with '\0'), but does allow callers to modify
75 * it if they wish. Thus, we set __SMOD in case the caller does.
78 fgetln(FILE *fp, size_t *lenp)
84 /* make sure there is input */
85 if (fp->_r <= 0 && __srefill(fp)) {
90 /* look for a newline in the input */
91 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
95 * Found one. Flag buffer as modified to keep fseek from
96 * `optimising' a backward seek, in case the user stomps on
99 p++; /* advance over it */
100 ret = (char *)fp->_p;
101 *lenp = len = p - fp->_p;
102 fp->_flags |= __SMOD;
109 * We have to copy the current buffered data to the line buffer.
110 * As a bonus, though, we can leave off the __SMOD.
112 * OPTIMISTIC is length that we (optimistically) expect will
113 * accomodate the `rest' of the string, on each trip through the
116 #define OPTIMISTIC 80
118 for (len = fp->_r, off = 0;; len += fp->_r) {
122 * Make sure there is room for more bytes. Copy data from
123 * file buffer to line buffer, refill file and look for
124 * newline. The loop stops only when we find a newline.
126 if (__slbexpand(fp, len + OPTIMISTIC))
128 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
132 break; /* EOF or error: return partial line */
133 if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
136 /* got it: finish up the line (like code above) */
140 if (__slbexpand(fp, len))
142 (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
150 fp->_lb._base[len] = 0;
152 return ((char *)fp->_lb._base);
156 return (NULL); /* ??? */