diff options
Diffstat (limited to 'libc/stdio/fgetln.c')
| -rw-r--r-- | libc/stdio/fgetln.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/libc/stdio/fgetln.c b/libc/stdio/fgetln.c new file mode 100644 index 0000000..946e1b7 --- /dev/null +++ b/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); /* ??? */ +} |