1/*
2 * POSIX 2008 fmemopen(3) implemented in terms of BSD funopen(3)
3 */
4
5/*
6 * Copyright (c) 2013 Taylor R. Campbell
7 * All rights reserved.
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 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#define	_BSD_SOURCE
32#define	_NETBSD_SOURCE
33
34#include <errno.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include <string.h>
38
39#include "fmemopen.h"
40
41struct fmem_cookie {
42  void *fmc_buffer;
43  size_t fmc_index;
44  size_t fmc_limit;
45};
46
47static int
48fmem_read(void *cookie, char *buffer, int n)
49{
50  struct fmem_cookie *const fmc = cookie;
51
52  if (n < 0) {                  /* paranoia */
53    errno = EINVAL;
54    return -1;
55  }
56
57  if (n > (fmc->fmc_limit - fmc->fmc_index))
58    n = (fmc->fmc_limit - fmc->fmc_index);
59
60  (void)memcpy(buffer, (char *)fmc->fmc_buffer + fmc->fmc_index, n);
61  fmc->fmc_index += n;
62  return n;
63}
64
65static int
66fmem_write(void *cookie, const char *buffer, int n)
67{
68  struct fmem_cookie *const fmc = cookie;
69
70  if (n < 0) {                  /* paranoia */
71    errno = EINVAL;
72    return -1;
73  }
74
75  if (n > (fmc->fmc_limit - fmc->fmc_index))
76    n = (fmc->fmc_limit - fmc->fmc_index);
77
78  (void)memcpy((char *)fmc->fmc_buffer + fmc->fmc_index, buffer, n);
79  fmc->fmc_index += n;
80  return n;
81}
82
83static fpos_t
84fmem_seek(void *cookie, fpos_t offset, int cmd)
85{
86  struct fmem_cookie *const fmc = cookie;
87
88  switch (cmd) {
89  case SEEK_SET:
90    if ((offset < 0) || (fmc->fmc_limit < offset))
91      goto einval;
92    fmc->fmc_index = offset;
93    return 0;
94
95  case SEEK_CUR:
96    if (offset < 0) {
97      /* Assume two's-complement arithmetic.  */
98      if ((offset == ~(fpos_t)0) || (-offset > fmc->fmc_index))
99        goto einval;
100    } else {
101      if (offset > (fmc->fmc_limit - fmc->fmc_index))
102        goto einval;
103    }
104    fmc->fmc_index += offset;
105    return 0;
106
107  case SEEK_END:
108      /* Assume two's-complement arithmetic.  */
109    if ((offset >= 0) || (offset == ~(fpos_t)0) || (fmc->fmc_limit < -offset))
110      goto einval;
111    fmc->fmc_index = (fmc->fmc_limit + offset);
112    return 0;
113
114  default:
115    goto einval;
116  }
117
118einval:
119  errno = EINVAL;
120  return -1;
121}
122
123static int
124fmem_close(void *cookie)
125{
126  struct fmem_cookie *const fmc = cookie;
127
128  free(fmc);
129
130  return 0;
131}
132
133FILE *
134fmemopen(void *buffer, size_t len, const char *mode)
135{
136  struct fmem_cookie *fmc;
137  FILE *file;
138
139  fmc = malloc(sizeof(*fmc));
140  if (fmc == NULL)
141    goto fail0;
142
143  (void)memset(fmc, 0, sizeof(*fmc));
144  fmc->fmc_buffer = buffer;
145  fmc->fmc_index = 0;
146  fmc->fmc_limit = len;
147
148  file = funopen(fmc, &fmem_read, &fmem_write, &fmem_seek, &fmem_close);
149  if (file == NULL)
150    goto fail1;
151
152  return file;
153
154fail1:
155  free(fmc);
156fail0:
157  return NULL;
158}
159