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