| The Android Open Source Project | a27d2ba | 2008-10-21 07:00:00 -0700 | [diff] [blame^] | 1 | /* $OpenBSD: fgets.c,v 1.10 2005/08/08 08:05:36 espie Exp $ */ |
| 2 | /*- |
| 3 | * Copyright (c) 1990, 1993 |
| 4 | * The Regents of the University of California. All rights reserved. |
| 5 | * |
| 6 | * This code is derived from software contributed to Berkeley by |
| 7 | * Chris Torek. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer. |
| 14 | * 2. Redistributions in binary form must reproduce the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer in the |
| 16 | * documentation and/or other materials provided with the distribution. |
| 17 | * 3. Neither the name of the University nor the names of its contributors |
| 18 | * may be used to endorse or promote products derived from this software |
| 19 | * without specific prior written permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 31 | * SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | #include <stdio.h> |
| 35 | #include <string.h> |
| 36 | #include "local.h" |
| 37 | |
| 38 | /* |
| 39 | * Read at most n-1 characters from the given file. |
| 40 | * Stop when a newline has been read, or the count runs out. |
| 41 | * Return first argument, or NULL if no characters were read. |
| 42 | * Do not return NULL if n == 1. |
| 43 | */ |
| 44 | char * |
| 45 | fgets(char *buf, int n, FILE *fp) |
| 46 | { |
| 47 | size_t len; |
| 48 | char *s; |
| 49 | unsigned char *p, *t; |
| 50 | |
| 51 | if (n <= 0) /* sanity check */ |
| 52 | return (NULL); |
| 53 | |
| 54 | _SET_ORIENTATION(fp, -1); |
| 55 | s = buf; |
| 56 | n--; /* leave space for NUL */ |
| 57 | while (n != 0) { |
| 58 | /* |
| 59 | * If the buffer is empty, refill it. |
| 60 | */ |
| 61 | if (fp->_r <= 0) { |
| 62 | if (__srefill(fp)) { |
| 63 | /* EOF/error: stop with partial or no line */ |
| 64 | if (s == buf) |
| 65 | return (NULL); |
| 66 | break; |
| 67 | } |
| 68 | } |
| 69 | len = fp->_r; |
| 70 | p = fp->_p; |
| 71 | |
| 72 | /* |
| 73 | * Scan through at most n bytes of the current buffer, |
| 74 | * looking for '\n'. If found, copy up to and including |
| 75 | * newline, and stop. Otherwise, copy entire chunk |
| 76 | * and loop. |
| 77 | */ |
| 78 | if ((int)len > n) |
| 79 | len = n; |
| 80 | t = memchr((void *)p, '\n', len); |
| 81 | if (t != NULL) { |
| 82 | len = ++t - p; |
| 83 | fp->_r -= len; |
| 84 | fp->_p = t; |
| 85 | (void)memcpy((void *)s, (void *)p, len); |
| 86 | s[len] = '\0'; |
| 87 | return (buf); |
| 88 | } |
| 89 | fp->_r -= len; |
| 90 | fp->_p += len; |
| 91 | (void)memcpy((void *)s, (void *)p, len); |
| 92 | s += len; |
| 93 | n -= len; |
| 94 | } |
| 95 | *s = '\0'; |
| 96 | return (buf); |
| 97 | } |