1/*	$OpenBSD: fmemopen.c,v 1.2 2013/03/27 15:06:25 mpi Exp $	*/
2
3/*
4 * Copyright (c) 2011 Martin Pieuchot <mpi@openbsd.org>
5 * Copyright (c) 2009 Ted Unangst
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#include <errno.h>
21#include <fcntl.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25#include "local.h"
26
27struct state {
28	char		*string;	/* actual stream */
29	size_t		 pos;		/* current position */
30	size_t		 size;		/* allocated size */
31	size_t		 len;		/* length of the data */
32	int		 update;	/* open for update */
33};
34
35static int
36fmemopen_read(void *v, char *b, int l)
37{
38	struct state	*st = v;
39	int		 i;
40
41	for (i = 0; i < l && i + st->pos < st->len; i++)
42		b[i] = st->string[st->pos + i];
43	st->pos += i;
44
45	return (i);
46}
47
48static int
49fmemopen_write(void *v, const char *b, int l)
50{
51	struct state	*st = v;
52	int		i;
53
54	for (i = 0; i < l && i + st->pos < st->size; i++)
55		st->string[st->pos + i] = b[i];
56	st->pos += i;
57
58	if (st->pos >= st->len) {
59		st->len = st->pos;
60
61		if (st->len < st->size)
62			st->string[st->len] = '\0';
63		else if (!st->update)
64			st->string[st->size - 1] = '\0';
65	}
66
67	return (i);
68}
69
70static fpos_t
71fmemopen_seek(void *v, fpos_t off, int whence)
72{
73	struct state	*st = v;
74	ssize_t		 base = 0;
75
76	switch (whence) {
77	case SEEK_SET:
78		break;
79	case SEEK_CUR:
80		base = st->pos;
81		break;
82	case SEEK_END:
83		base = st->len;
84		break;
85	}
86
87	if (off > st->size - base || off < -base) {
88		errno = EOVERFLOW;
89		return (-1);
90	}
91
92	st->pos = base + off;
93
94	return (st->pos);
95}
96
97static int
98fmemopen_close(void *v)
99{
100	free(v);
101
102	return (0);
103}
104
105static int
106fmemopen_close_free(void *v)
107{
108	struct state	*st = v;
109
110	free(st->string);
111	free(st);
112
113	return (0);
114}
115
116FILE *
117fmemopen(void *buf, size_t size, const char *mode)
118{
119	struct state	*st;
120	FILE		*fp;
121	int		 flags, oflags;
122
123	if (size == 0) {
124		errno = EINVAL;
125		return (NULL);
126	}
127
128	if ((flags = __sflags(mode, &oflags)) == 0) {
129		errno = EINVAL;
130		return (NULL);
131	}
132
133	if (buf == NULL && ((oflags & O_RDWR) == 0)) {
134		errno = EINVAL;
135		return (NULL);
136	}
137
138	if ((st = malloc(sizeof(*st))) == NULL)
139		return (NULL);
140
141	if ((fp = __sfp()) == NULL) {
142		free(st);
143		return (NULL);
144	}
145
146	st->pos = 0;
147	st->len = (oflags & O_WRONLY) ? 0 : size;
148	st->size = size;
149	st->update = oflags & O_RDWR;
150
151	if (buf == NULL) {
152		if ((st->string = malloc(size)) == NULL) {
153			free(st);
154			fp->_flags = 0;
155			return (NULL);
156		}
157		*st->string = '\0';
158	} else {
159		st->string = (char *)buf;
160
161		if (oflags & O_TRUNC)
162			*st->string = '\0';
163
164		if (oflags & O_APPEND) {
165			char	*p;
166
167			if ((p = memchr(st->string, '\0', size)) != NULL)
168				st->pos = st->len = (p - st->string);
169			else
170				st->pos = st->len = size;
171		}
172	}
173
174	fp->_flags = (short)flags;
175	fp->_file = -1;
176	fp->_cookie = (void *)st;
177	fp->_read = (flags & __SWR) ? NULL : fmemopen_read;
178	fp->_write = (flags & __SRD) ? NULL : fmemopen_write;
179	fp->_seek = fmemopen_seek;
180	fp->_close = (buf == NULL) ? fmemopen_close_free : fmemopen_close;
181
182	return (fp);
183}
184