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/* $OpenBSD: fmemopen.c,v 1.2 2013/03/27 15:06:25 mpi Exp $ */
/*
* Copyright (c) 2011 Martin Pieuchot <mpi@openbsd.org>
* Copyright (c) 2009 Ted Unangst
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
FILE *__sfp(void);
struct state {
char *string; /* actual stream */
size_t pos; /* current position */
size_t size; /* allocated size */
size_t len; /* length of the data */
int update; /* open for update */
};
static int
fmemopen_read(void *v, char *b, int l)
{
struct state *st = v;
int i;
for (i = 0; i < l && i + st->pos < st->len; i++)
b[i] = st->string[st->pos + i];
st->pos += i;
return (i);
}
static int
fmemopen_write(void *v, const char *b, int l)
{
struct state *st = v;
int i;
for (i = 0; i < l && i + st->pos < st->size; i++)
st->string[st->pos + i] = b[i];
st->pos += i;
if (st->pos >= st->len) {
st->len = st->pos;
if (st->len < st->size)
st->string[st->len] = '\0';
else if (!st->update)
st->string[st->size - 1] = '\0';
}
return (i);
}
static fpos_t
fmemopen_seek(void *v, fpos_t off, int whence)
{
struct state *st = v;
ssize_t base = 0;
switch (whence) {
case SEEK_SET:
break;
case SEEK_CUR:
base = st->pos;
break;
case SEEK_END:
base = st->len;
break;
}
if (off > st->size - base || off < -base) {
errno = EOVERFLOW;
return (-1);
}
st->pos = base + off;
return (st->pos);
}
static int
fmemopen_close(void *v)
{
free(v);
return (0);
}
static int
fmemopen_close_free(void *v)
{
struct state *st = v;
free(st->string);
free(st);
return (0);
}
FILE *
fmemopen(void *buf, size_t size, const char *mode)
{
struct state *st;
FILE *fp;
int flags, oflags;
if (size == 0) {
errno = EINVAL;
return (NULL);
}
if ((flags = __sflags(mode, &oflags)) == 0) {
errno = EINVAL;
return (NULL);
}
if (buf == NULL && ((oflags & O_RDWR) == 0)) {
errno = EINVAL;
return (NULL);
}
if ((st = malloc(sizeof(*st))) == NULL)
return (NULL);
if ((fp = __sfp()) == NULL) {
free(st);
return (NULL);
}
st->pos = 0;
st->len = (oflags & O_WRONLY) ? 0 : size;
st->size = size;
st->update = oflags & O_RDWR;
if (buf == NULL) {
if ((st->string = malloc(size)) == NULL) {
free(st);
fp->_flags = 0;
return (NULL);
}
*st->string = '\0';
} else {
st->string = (char *)buf;
if (oflags & O_TRUNC)
*st->string = '\0';
if (oflags & O_APPEND) {
char *p;
if ((p = memchr(st->string, '\0', size)) != NULL)
st->pos = st->len = (p - st->string);
else
st->pos = st->len = size;
}
}
fp->_flags = (short)flags;
fp->_file = -1;
fp->_cookie = (void *)st;
fp->_read = (flags & __SWR) ? NULL : fmemopen_read;
fp->_write = (flags & __SRD) ? NULL : fmemopen_write;
fp->_seek = fmemopen_seek;
fp->_close = (buf == NULL) ? fmemopen_close_free : fmemopen_close;
return (fp);
}
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