2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (C) 2013 Pietro Cerutti <gahr@FreeBSD.org>
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
15 * THIS SOFTWARE IS PROVIDED BY 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 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
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
39 struct fmemopen_cookie
41 char *buf; /* pointer to the memory region */
42 bool own; /* did we allocate the buffer ourselves? */
43 char bin; /* is this a binary buffer? */
44 size_t size; /* buffer length in bytes */
45 size_t len; /* data length in bytes */
46 size_t off; /* current offset into the buffer */
49 static int fmemopen_read(void *cookie, char *buf, int nbytes);
50 static int fmemopen_write(void *cookie, const char *buf, int nbytes);
51 static fpos_t fmemopen_seek(void *cookie, fpos_t offset, int whence);
52 static int fmemopen_close(void *cookie);
55 fmemopen(void * __restrict buf, size_t size, const char * __restrict mode)
57 struct fmemopen_cookie *ck;
62 * POSIX says we shall return EINVAL if size is 0.
70 * Retrieve the flags as used by open(2) from the mode argument, and
73 rc = __sflags(mode, &flags);
80 * There's no point in requiring an automatically allocated buffer
83 if (!(flags & O_RDWR) && buf == NULL) {
88 ck = malloc(sizeof(struct fmemopen_cookie));
96 /* Check whether we have to allocate the buffer ourselves. */
97 ck->own = ((ck->buf = buf) == NULL);
99 ck->buf = malloc(size);
100 if (ck->buf == NULL) {
107 * POSIX distinguishes between w+ and r+, in that w+ is supposed to
108 * truncate the buffer.
110 if (ck->own || mode[0] == 'w') {
114 /* Check for binary mode. */
115 ck->bin = strchr(mode, 'b') != NULL;
118 * The size of the current buffer contents is set depending on the
121 * for append (text-mode), the position of the first NULL byte, or the
122 * size of the buffer if none is found
124 * for append (binary-mode), the size of the buffer
126 * for read, the size of the buffer
132 ck->off = ck->len = strnlen(ck->buf, ck->size);
143 flags & O_WRONLY ? NULL : fmemopen_read,
144 flags & O_RDONLY ? NULL : fmemopen_write,
145 fmemopen_seek, fmemopen_close);
158 * Turn off buffering, so a write past the end of the buffer
159 * correctly returns a short object count.
161 setvbuf(f, NULL, _IONBF, 0);
167 fmemopen_read(void *cookie, char *buf, int nbytes)
169 struct fmemopen_cookie *ck = cookie;
171 if (nbytes > ck->len - ck->off)
172 nbytes = ck->len - ck->off;
177 memcpy(buf, ck->buf + ck->off, nbytes);
185 fmemopen_write(void *cookie, const char *buf, int nbytes)
187 struct fmemopen_cookie *ck = cookie;
189 if (nbytes > ck->size - ck->off)
190 nbytes = ck->size - ck->off;
195 memcpy(ck->buf + ck->off, buf, nbytes);
199 if (ck->off > ck->len)
203 * We append a NULL byte if all these conditions are met:
204 * - the buffer is not binary
205 * - the buffer is not full
206 * - the data just written doesn't already end with a NULL byte
208 if (!ck->bin && ck->off < ck->size && ck->buf[ck->off - 1] != '\0')
209 ck->buf[ck->off] = '\0';
215 fmemopen_seek(void *cookie, fpos_t offset, int whence)
217 struct fmemopen_cookie *ck = cookie;
222 if (offset > ck->size) {
230 if (ck->off + offset > ck->size) {
238 if (offset > 0 || -offset > ck->len) {
242 ck->off = ck->len + offset;
254 fmemopen_close(void *cookie)
256 struct fmemopen_cookie *ck = cookie;