1 /* $OpenBSD: fvwrite.c,v 1.22 2024/04/28 14:28:02 millert 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 <limits.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <unistd.h>
39 #include "local.h"
40 #include "fvwrite.h"
41
42 /*
43 * Write some memory regions. Return zero on success, EOF on error.
44 *
45 * This routine is large and unsightly, but most of the ugliness due
46 * to the three different kinds of output buffering is handled here.
47 */
48 int
__sfvwrite(FILE * fp,struct __suio * uio)49 __sfvwrite(FILE *fp, struct __suio *uio)
50 {
51 size_t len;
52 char *p;
53 struct __siov *iov;
54 int w, s;
55 char *nl;
56 int nlknown, nldist;
57
58 if ((len = uio->uio_resid) == 0)
59 return (0);
60 /* make sure we can write */
61 if (cantwrite(fp))
62 return (EOF);
63
64 #define MIN(a, b) ((a) < (b) ? (a) : (b))
65 #define COPY(n) (void)memcpy(fp->_p, p, n)
66
67 iov = uio->uio_iov;
68 p = iov->iov_base;
69 len = iov->iov_len;
70 iov++;
71 #define GETIOV(extra_work) \
72 while (len == 0) { \
73 extra_work; \
74 p = iov->iov_base; \
75 len = iov->iov_len; \
76 iov++; \
77 }
78 if (fp->_flags & __SNBF) {
79 /*
80 * Unbuffered: write up to INT_MAX bytes at a time, to not
81 * truncate the value of len if it is greater than 2^31 bytes.
82 */
83 do {
84 GETIOV(;);
85 w = (*fp->_write)(fp->_cookie, p, MIN(len, INT_MAX));
86 if (w <= 0)
87 goto err;
88 p += w;
89 len -= w;
90 } while ((uio->uio_resid -= w) != 0);
91 } else if ((fp->_flags & __SLBF) == 0) {
92 /*
93 * Fully buffered: fill partially full buffer, if any,
94 * and then flush. If there is no partial buffer, write
95 * entire payload directly (without copying) up to a
96 * multiple of the buffer size.
97 *
98 * String output is a special case: write as many bytes
99 * as fit, but pretend we wrote everything. This makes
100 * snprintf() return the number of bytes needed, rather
101 * than the number used, and avoids its write function
102 * (so that the write function can be invalid).
103 */
104 do {
105 GETIOV(;);
106 if ((fp->_flags & (__SALC | __SSTR)) ==
107 (__SALC | __SSTR) && fp->_w < len) {
108 size_t blen = fp->_p - fp->_bf._base;
109 int pgmsk = getpagesize() - 1;
110 unsigned char *_base;
111 int _size;
112
113 /* Round up to nearest page. */
114 _size = ((blen + len + 1 + pgmsk) & ~pgmsk) - 1;
115 _base = recallocarray(fp->_bf._base,
116 fp->_bf._size + 1, _size + 1, 1);
117 if (_base == NULL)
118 goto err;
119 fp->_w += _size - fp->_bf._size;
120 fp->_bf._base = _base;
121 fp->_bf._size = _size;
122 fp->_p = _base + blen;
123 }
124 w = fp->_w;
125 if (fp->_flags & __SSTR) {
126 if (len < w)
127 w = len;
128 COPY(w); /* copy MIN(fp->_w,len), */
129 fp->_w -= w;
130 fp->_p += w;
131 w = len; /* but pretend copied all */
132 } else if (fp->_p > fp->_bf._base && len > w) {
133 /* fill and flush */
134 COPY(w);
135 /* fp->_w -= w; */ /* unneeded */
136 fp->_p += w;
137 if (__sflush(fp))
138 goto err;
139 } else if (len >= (w = fp->_bf._size)) {
140 /*
141 * Write directly up to INT_MAX or greatest
142 * multiple of buffer size (whichever is
143 * smaller), keeping in the memory buffer the
144 * remaining part of payload that is smaller
145 * than buffer size.
146 */
147 if (w != 0)
148 w = MIN(w * (len / w), INT_MAX);
149 w = (*fp->_write)(fp->_cookie, p, w);
150 if (w <= 0)
151 goto err;
152 } else {
153 /* fill and done */
154 w = len;
155 COPY(w);
156 fp->_w -= w;
157 fp->_p += w;
158 }
159 p += w;
160 len -= w;
161 } while ((uio->uio_resid -= w) != 0);
162 } else {
163 /*
164 * Line buffered: like fully buffered, but we
165 * must check for newlines. Compute the distance
166 * to the first newline (including the newline),
167 * or `infinity' if there is none, then pretend
168 * that the amount to write is MIN(len,nldist).
169 */
170 nlknown = 0;
171 nldist = 0; /* XXX just to keep gcc happy */
172 do {
173 GETIOV(nlknown = 0);
174 if (!nlknown) {
175 nl = memchr(p, '\n', len);
176 nldist = nl ? nl + 1 - p : len + 1;
177 nlknown = 1;
178 }
179 s = MIN(len, nldist);
180 w = fp->_w + fp->_bf._size;
181 if (fp->_p > fp->_bf._base && s > w) {
182 COPY(w);
183 /* fp->_w -= w; */
184 fp->_p += w;
185 if (__sflush(fp))
186 goto err;
187 } else if (s >= (w = fp->_bf._size)) {
188 w = (*fp->_write)(fp->_cookie, p, w);
189 if (w <= 0)
190 goto err;
191 } else {
192 w = s;
193 COPY(w);
194 fp->_w -= w;
195 fp->_p += w;
196 }
197 if ((nldist -= w) == 0) {
198 /* copied the newline: flush and forget */
199 if (__sflush(fp))
200 goto err;
201 nlknown = 0;
202 }
203 p += w;
204 len -= w;
205 } while ((uio->uio_resid -= w) != 0);
206 }
207 return (0);
208
209 err:
210 fp->_flags |= __SERR;
211 return (EOF);
212 }
213