1 /* $OpenBSD: fvwrite.c,v 1.20 2017/03/17 16:06:33 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 <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <errno.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 errno = EBADF;
63 return (EOF);
64 }
65
66 #define MIN(a, b) ((a) < (b) ? (a) : (b))
67 #define COPY(n) (void)memcpy(fp->_p, p, n)
68
69 iov = uio->uio_iov;
70 p = iov->iov_base;
71 len = iov->iov_len;
72 iov++;
73 #define GETIOV(extra_work) \
74 while (len == 0) { \
75 extra_work; \
76 p = iov->iov_base; \
77 len = iov->iov_len; \
78 iov++; \
79 }
80 if (fp->_flags & __SNBF) {
81 /*
82 * Unbuffered: write up to BUFSIZ bytes at a time.
83 */
84 do {
85 GETIOV(;);
86 w = (*fp->_write)(fp->_cookie, p, MIN(len, BUFSIZ));
87 if (w <= 0)
88 goto err;
89 p += w;
90 len -= w;
91 } while ((uio->uio_resid -= w) != 0);
92 } else if ((fp->_flags & __SLBF) == 0) {
93 /*
94 * Fully buffered: fill partially full buffer, if any,
95 * and then flush. If there is no partial buffer, write
96 * one _bf._size byte chunk directly (without copying).
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 /* write directly */
141 w = (*fp->_write)(fp->_cookie, p, w);
142 if (w <= 0)
143 goto err;
144 } else {
145 /* fill and done */
146 w = len;
147 COPY(w);
148 fp->_w -= w;
149 fp->_p += w;
150 }
151 p += w;
152 len -= w;
153 } while ((uio->uio_resid -= w) != 0);
154 } else {
155 /*
156 * Line buffered: like fully buffered, but we
157 * must check for newlines. Compute the distance
158 * to the first newline (including the newline),
159 * or `infinity' if there is none, then pretend
160 * that the amount to write is MIN(len,nldist).
161 */
162 nlknown = 0;
163 nldist = 0; /* XXX just to keep gcc happy */
164 do {
165 GETIOV(nlknown = 0);
166 if (!nlknown) {
167 nl = memchr(p, '\n', len);
168 nldist = nl ? nl + 1 - p : len + 1;
169 nlknown = 1;
170 }
171 s = MIN(len, nldist);
172 w = fp->_w + fp->_bf._size;
173 if (fp->_p > fp->_bf._base && s > w) {
174 COPY(w);
175 /* fp->_w -= w; */
176 fp->_p += w;
177 if (__sflush(fp))
178 goto err;
179 } else if (s >= (w = fp->_bf._size)) {
180 w = (*fp->_write)(fp->_cookie, p, w);
181 if (w <= 0)
182 goto err;
183 } else {
184 w = s;
185 COPY(w);
186 fp->_w -= w;
187 fp->_p += w;
188 }
189 if ((nldist -= w) == 0) {
190 /* copied the newline: flush and forget */
191 if (__sflush(fp))
192 goto err;
193 nlknown = 0;
194 }
195 p += w;
196 len -= w;
197 } while ((uio->uio_resid -= w) != 0);
198 }
199 return (0);
200
201 err:
202 fp->_flags |= __SERR;
203 return (EOF);
204 }
205