1 /* $NetBSD: open_memstream.c,v 1.1 2014/10/13 00:40:36 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2013 Advanced Computing Technologies LLC
5 * Written by: John H. Baldwin <jhb@FreeBSD.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 #if 0
32 __FBSDID("$FreeBSD: head/lib/libc/stdio/open_memstream.c 247411 2013-02-27 19:50:46Z jhb $");
33 #endif
34 __RCSID("$NetBSD: open_memstream.c,v 1.1 2014/10/13 00:40:36 christos Exp $");
35
36 #include "namespace.h"
37 #include <assert.h>
38 #include <errno.h>
39 #include <limits.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <wchar.h>
44
45 #define OFF_MAX LLONG_MAX
46
47 struct memstream {
48 char **bufp;
49 size_t *sizep;
50 size_t len;
51 size_t offset;
52 };
53
54 static int
memstream_grow(struct memstream * ms,off_t newoff)55 memstream_grow(struct memstream *ms, off_t newoff)
56 {
57 char *buf;
58 size_t newsize;
59
60 if (newoff < 0 || newoff >= SSIZE_MAX)
61 newsize = SSIZE_MAX - 1;
62 else
63 newsize = newoff;
64 if (newsize > ms->len) {
65 buf = realloc(*ms->bufp, newsize + 1);
66 if (buf != NULL) {
67 #ifdef DEBUG
68 fprintf(stderr, "MS: %p growing from %zd to %zd\n",
69 ms, ms->len, newsize);
70 #endif
71 memset(buf + ms->len + 1, 0, newsize - ms->len);
72 *ms->bufp = buf;
73 ms->len = newsize;
74 return (1);
75 }
76 return (0);
77 }
78 return (1);
79 }
80
81 static void
memstream_update(struct memstream * ms)82 memstream_update(struct memstream *ms)
83 {
84
85 *ms->sizep = ms->len < ms->offset ? ms->len : ms->offset;
86 }
87
88 static ssize_t
memstream_write(void * cookie,const void * buf,size_t len)89 memstream_write(void *cookie, const void *buf, size_t len)
90 {
91 struct memstream *ms;
92 size_t tocopy;
93 off_t more;
94
95 ms = cookie;
96 more = ms->offset;
97 more += len;
98 if (!memstream_grow(ms, more))
99 return (-1);
100 tocopy = ms->len - ms->offset;
101 if (len < tocopy)
102 tocopy = len;
103 memcpy(*ms->bufp + ms->offset, buf, tocopy);
104 ms->offset += tocopy;
105 memstream_update(ms);
106 #ifdef DEBUG
107 fprintf(stderr, "MS: write(%p, %zu) = %zu\n", ms, len, tocopy);
108 #endif
109 return (ssize_t)tocopy;
110 }
111
112 static off_t
memstream_seek(void * cookie,off_t pos,int whence)113 memstream_seek(void *cookie, off_t pos, int whence)
114 {
115 struct memstream *ms;
116 #ifdef DEBUG
117 size_t old;
118 #endif
119
120 ms = cookie;
121 #ifdef DEBUG
122 old = ms->offset;
123 #endif
124 switch (whence) {
125 case SEEK_SET:
126 /* _fseeko() checks for negative offsets. */
127 assert(pos >= 0);
128 ms->offset = pos;
129 break;
130 case SEEK_CUR:
131 /* This is only called by _ftello(). */
132 assert(pos == 0);
133 break;
134 case SEEK_END:
135 if (pos < 0) {
136 if (pos + (ssize_t)ms->len < 0) {
137 #ifdef DEBUG
138 fprintf(stderr,
139 "MS: bad SEEK_END: pos %jd, len %zu\n",
140 (intmax_t)pos, ms->len);
141 #endif
142 errno = EINVAL;
143 return (-1);
144 }
145 } else {
146 if (OFF_MAX - (ssize_t)ms->len < pos) {
147 #ifdef DEBUG
148 fprintf(stderr,
149 "MS: bad SEEK_END: pos %jd, len %zu\n",
150 (intmax_t)pos, ms->len);
151 #endif
152 errno = EOVERFLOW;
153 return (-1);
154 }
155 }
156 ms->offset = ms->len + pos;
157 break;
158 }
159 memstream_update(ms);
160 #ifdef DEBUG
161 fprintf(stderr, "MS: seek(%p, %jd, %d) %zu -> %zu\n", ms,
162 (intmax_t)pos, whence, old, ms->offset);
163 #endif
164 return (ms->offset);
165 }
166
167 static int
memstream_close(void * cookie)168 memstream_close(void *cookie)
169 {
170
171 free(cookie);
172 return (0);
173 }
174
175 FILE *
open_memstream(char ** bufp,size_t * sizep)176 open_memstream(char **bufp, size_t *sizep)
177 {
178 struct memstream *ms;
179 int save_errno;
180 FILE *fp;
181
182 if (bufp == NULL || sizep == NULL) {
183 errno = EINVAL;
184 return (NULL);
185 }
186 *bufp = calloc(1, 1);
187 if (*bufp == NULL)
188 return (NULL);
189 ms = malloc(sizeof(*ms));
190 if (ms == NULL) {
191 save_errno = errno;
192 free(*bufp);
193 *bufp = NULL;
194 errno = save_errno;
195 return (NULL);
196 }
197 ms->bufp = bufp;
198 ms->sizep = sizep;
199 ms->len = 0;
200 ms->offset = 0;
201 memstream_update(ms);
202 fp = funopen2(ms, NULL, memstream_write, memstream_seek,
203 NULL, memstream_close);
204 if (fp == NULL) {
205 save_errno = errno;
206 free(ms);
207 free(*bufp);
208 *bufp = NULL;
209 errno = save_errno;
210 return (NULL);
211 }
212 fwide(fp, -1);
213 return (fp);
214 }
215