1 /* $NetBSD: fvwrite.c,v 1.31 2024/03/29 22:39:41 christos Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36 #if defined(LIBC_SCCS) && !defined(lint)
37 #if 0
38 static char sccsid[] = "@(#)fvwrite.c 8.1 (Berkeley) 6/4/93";
39 #else
40 __RCSID("$NetBSD: fvwrite.c,v 1.31 2024/03/29 22:39:41 christos Exp $");
41 #endif
42 #endif /* LIBC_SCCS and not lint */
43
44 #include <assert.h>
45 #include <stddef.h>
46 #include <errno.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include "reentrant.h"
51 #include "local.h"
52 #include "fvwrite.h"
53
54 /*
55 * Write some memory regions. Return zero on success, EOF on error.
56 *
57 * This routine is large and unsightly, but most of the ugliness due
58 * to the three different kinds of output buffering is handled here.
59 */
60 int
__sfvwrite(FILE * fp,struct __suio * uio)61 __sfvwrite(FILE *fp, struct __suio *uio)
62 {
63 size_t len;
64 char *p;
65 struct __siov *iov;
66 int s;
67 ssize_t w;
68 char *nl;
69 size_t nlknown, nldist;
70
71 _DIAGASSERT(fp != NULL);
72 _DIAGASSERT(uio != NULL);
73
74 if ((ssize_t)uio->uio_resid < 0) {
75 errno = EINVAL;
76 return EOF;
77 }
78 if (uio->uio_resid == 0)
79 return 0;
80 /* make sure we can write */
81 if (cantwrite(fp)) {
82 errno = EBADF;
83 return EOF;
84 }
85
86 #define MIN(a, b) ((a) < (b) ? (a) : (b))
87 #define COPY(n) (void)memcpy(fp->_p, p, (size_t)(n))
88
89 iov = uio->uio_iov;
90 p = iov->iov_base;
91 len = iov->iov_len;
92 iov++;
93 #define GETIOV(extra_work) \
94 while (len == 0) { \
95 extra_work; \
96 p = iov->iov_base; \
97 len = iov->iov_len; \
98 iov++; \
99 }
100 if (fp->_flags & __SNBF) {
101 /*
102 * Unbuffered: write up to INT_MAX bytes at a time, to not
103 * truncate the value of len if it is greater than 2^31 bytes.
104 */
105 do {
106 GETIOV(;);
107 w = (*fp->_write)(fp->_cookie, p, MIN(len, INT_MAX));
108 if (w <= 0)
109 goto err;
110 p += w;
111 len -= w;
112 } while ((uio->uio_resid -= w) != 0);
113 } else if ((fp->_flags & __SLBF) == 0) {
114 /*
115 * Fully buffered: fill partially full buffer, if any,
116 * and then flush. If there is no partial buffer, write
117 * entire payload directly (without copying) up to a multiple
118 * of the buffer size.
119 *
120 * String output is a special case: write as many bytes
121 * as fit, but pretend we wrote everything. This makes
122 * snprintf() return the number of bytes needed, rather
123 * than the number used, and avoids its write function
124 * (so that the write function can be invalid).
125 */
126 do {
127 GETIOV(;);
128 if ((fp->_flags & (__SALC | __SSTR)) ==
129 (__SALC | __SSTR) && (size_t)fp->_w < len) {
130 ptrdiff_t blen = fp->_p - fp->_bf._base;
131 unsigned char *_base;
132 int _size;
133
134 /* Allocate space exponentially. */
135 _size = fp->_bf._size;
136 do {
137 _size = (_size << 1) + 1;
138 } while ((size_t)_size < blen + len);
139 _base = realloc(fp->_bf._base,
140 (size_t)(_size + 1));
141 if (_base == NULL)
142 goto err;
143 fp->_w += _size - fp->_bf._size;
144 fp->_bf._base = _base;
145 fp->_bf._size = _size;
146 fp->_p = _base + blen;
147 }
148 w = fp->_w;
149 if (fp->_flags & __SSTR) {
150 if (len < (size_t)w)
151 w = len;
152 COPY(w); /* copy MIN(fp->_w,len), */
153 fp->_w -= (int)w;
154 fp->_p += w;
155 w = len; /* but pretend copied all */
156 } else if (fp->_p > fp->_bf._base && len > (size_t)w) {
157 /* fill and flush */
158 COPY(w);
159 /* fp->_w -= w; */ /* unneeded */
160 fp->_p += w;
161 if (fflush(fp))
162 goto err;
163 } else if (len >= (size_t)(w = fp->_bf._size)) {
164 /*
165 * write directly up to INT_MAX or greatest
166 * multiple of buffer size (whatever is
167 * smaller), keeping in the memory buffer the
168 * remaining part of payload that is smaller
169 * than buffer size.
170 */
171 if (w != 0)
172 w = MIN(w * (len / w), INT_MAX);
173 w = (*fp->_write)(fp->_cookie, p, (size_t)w);
174 if (w <= 0)
175 goto err;
176 } else {
177 /* fill and done */
178 w = len;
179 COPY(w);
180 fp->_w -= (int)w;
181 fp->_p += w;
182 }
183 p += w;
184 len -= w;
185 } while ((uio->uio_resid -= w) != 0);
186 } else {
187 /*
188 * Line buffered: like fully buffered, but we
189 * must check for newlines. Compute the distance
190 * to the first newline (including the newline),
191 * or `infinity' if there is none, then pretend
192 * that the amount to write is MIN(len,nldist).
193 */
194 nlknown = 0;
195 nldist = 0; /* XXX just to keep gcc happy */
196 do {
197 GETIOV(nlknown = 0);
198 if (!nlknown) {
199 nl = memchr(p, '\n', len);
200 nldist = nl ? (size_t)(nl + 1 - p) : len + 1;
201 nlknown = 1;
202 }
203 s = (int)MIN(len, nldist);
204 w = fp->_w + fp->_bf._size;
205 if (fp->_p > fp->_bf._base && s > w) {
206 COPY(w);
207 /* fp->_w -= w; */
208 fp->_p += w;
209 if (fflush(fp))
210 goto err;
211 } else if (s >= (w = fp->_bf._size)) {
212 w = (*fp->_write)(fp->_cookie, p, (size_t)w);
213 if (w <= 0)
214 goto err;
215 } else {
216 w = s;
217 COPY(w);
218 fp->_w -= (int)w;
219 fp->_p += w;
220 }
221 if ((nldist -= w) == 0) {
222 /* copied the newline: flush and forget */
223 if (fflush(fp))
224 goto err;
225 nlknown = 0;
226 }
227 p += w;
228 len -= w;
229 } while ((uio->uio_resid -= w) != 0);
230 }
231 return 0;
232
233 err:
234 fp->_flags |= __SERR;
235 return EOF;
236 }
237