| The Android Open Source Project | a27d2ba | 2008-10-21 07:00:00 -0700 | [diff] [blame^] | 1 | /* $OpenBSD: setvbuf.c,v 1.8 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 <stdlib.h> |
| 36 | #include "local.h" |
| 37 | |
| 38 | /* |
| 39 | * Set one of the three kinds of buffering, optionally including |
| 40 | * a buffer. |
| 41 | */ |
| 42 | int |
| 43 | setvbuf(FILE *fp, char *buf, int mode, size_t size) |
| 44 | { |
| 45 | int ret, flags; |
| 46 | size_t iosize; |
| 47 | int ttyflag; |
| 48 | |
| 49 | /* |
| 50 | * Verify arguments. The `int' limit on `size' is due to this |
| 51 | * particular implementation. Note, buf and size are ignored |
| 52 | * when setting _IONBF. |
| 53 | */ |
| 54 | if (mode != _IONBF) |
| 55 | if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) |
| 56 | return (EOF); |
| 57 | |
| 58 | /* |
| 59 | * Write current buffer, if any. Discard unread input (including |
| 60 | * ungetc data), cancel line buffering, and free old buffer if |
| 61 | * malloc()ed. We also clear any eof condition, as if this were |
| 62 | * a seek. |
| 63 | */ |
| 64 | ret = 0; |
| 65 | (void)__sflush(fp); |
| 66 | if (HASUB(fp)) |
| 67 | FREEUB(fp); |
| 68 | WCIO_FREE(fp); |
| 69 | fp->_r = fp->_lbfsize = 0; |
| 70 | flags = fp->_flags; |
| 71 | if (flags & __SMBF) |
| 72 | free((void *)fp->_bf._base); |
| 73 | flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); |
| 74 | |
| 75 | /* If setting unbuffered mode, skip all the hard work. */ |
| 76 | if (mode == _IONBF) |
| 77 | goto nbf; |
| 78 | |
| 79 | /* |
| 80 | * Find optimal I/O size for seek optimization. This also returns |
| 81 | * a `tty flag' to suggest that we check isatty(fd), but we do not |
| 82 | * care since our caller told us how to buffer. |
| 83 | */ |
| 84 | flags |= __swhatbuf(fp, &iosize, &ttyflag); |
| 85 | if (size == 0) { |
| 86 | buf = NULL; /* force local allocation */ |
| 87 | size = iosize; |
| 88 | } |
| 89 | |
| 90 | /* Allocate buffer if needed. */ |
| 91 | if (buf == NULL) { |
| 92 | if ((buf = malloc(size)) == NULL) { |
| 93 | /* |
| 94 | * Unable to honor user's request. We will return |
| 95 | * failure, but try again with file system size. |
| 96 | */ |
| 97 | ret = EOF; |
| 98 | if (size != iosize) { |
| 99 | size = iosize; |
| 100 | buf = malloc(size); |
| 101 | } |
| 102 | } |
| 103 | if (buf == NULL) { |
| 104 | /* No luck; switch to unbuffered I/O. */ |
| 105 | nbf: |
| 106 | fp->_flags = flags | __SNBF; |
| 107 | fp->_w = 0; |
| 108 | fp->_bf._base = fp->_p = fp->_nbuf; |
| 109 | fp->_bf._size = 1; |
| 110 | return (ret); |
| 111 | } |
| 112 | flags |= __SMBF; |
| 113 | } |
| 114 | |
| 115 | /* |
| 116 | * Kill any seek optimization if the buffer is not the |
| 117 | * right size. |
| 118 | * |
| 119 | * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? |
| 120 | */ |
| 121 | if (size != iosize) |
| 122 | flags |= __SNPT; |
| 123 | |
| 124 | /* |
| 125 | * Fix up the FILE fields, and set __cleanup for output flush on |
| 126 | * exit (since we are buffered in some way). |
| 127 | */ |
| 128 | if (mode == _IOLBF) |
| 129 | flags |= __SLBF; |
| 130 | fp->_flags = flags; |
| 131 | fp->_bf._base = fp->_p = (unsigned char *)buf; |
| 132 | fp->_bf._size = size; |
| 133 | /* fp->_lbfsize is still 0 */ |
| 134 | if (flags & __SWR) { |
| 135 | /* |
| 136 | * Begin or continue writing: see __swsetup(). Note |
| 137 | * that __SNBF is impossible (it was handled earlier). |
| 138 | */ |
| 139 | if (flags & __SLBF) { |
| 140 | fp->_w = 0; |
| 141 | fp->_lbfsize = -fp->_bf._size; |
| 142 | } else |
| 143 | fp->_w = size; |
| 144 | } else { |
| 145 | /* begin/continue reading, or stay in intermediate state */ |
| 146 | fp->_w = 0; |
| 147 | } |
| 148 | __atexit_register_cleanup(_cleanup); |
| 149 | |
| 150 | return (ret); |
| 151 | } |