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#include "stdio_impl.h"
#include <errno.h>
#include <limits.h>
#include <string.h>
struct cookie {
char **bufp;
size_t *sizep;
size_t pos;
char *buf;
size_t len;
size_t space;
};
static off_t ms_seek(FILE *f, off_t off, int whence)
{
ssize_t base;
struct cookie *c = f->cookie;
if (whence>2U) {
fail:
errno = EINVAL;
return -1;
}
base = (size_t [3]){0, c->pos, c->len}[whence];
if (off < -base || off > SSIZE_MAX-base) goto fail;
return c->pos = base+off;
}
static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
{
struct cookie *c = f->cookie;
size_t len2 = f->wpos - f->wbase;
char *newbuf;
if (len2) {
f->wpos = f->wbase;
if (ms_write(f, f->wbase, len2) < len2) return 0;
}
if (len + c->pos >= c->space) {
len2 = 2*c->space+1 | c->pos+len+1;
newbuf = realloc(c->buf, len2);
if (!newbuf) return 0;
*c->bufp = c->buf = newbuf;
memset(c->buf + c->space, 0, len2 - c->space);
c->space = len2;
}
memcpy(c->buf+c->pos, buf, len);
c->pos += len;
if (c->pos >= c->len) c->len = c->pos;
*c->sizep = c->pos;
return len;
}
static int ms_close(FILE *f)
{
return 0;
}
FILE *open_memstream(char **bufp, size_t *sizep)
{
FILE *f;
struct cookie *c;
if (!(f=malloc(sizeof *f + sizeof *c + BUFSIZ))) return 0;
memset(f, 0, sizeof *f + sizeof *c);
f->cookie = c = (void *)(f+1);
c->bufp = bufp;
c->sizep = sizep;
c->pos = c->len = c->space = 0;
c->buf = 0;
f->flags = F_NORD;
f->fd = -1;
f->buf = (void *)(c+1);
f->buf_size = BUFSIZ;
f->lbf = EOF;
f->write = ms_write;
f->seek = ms_seek;
f->close = ms_close;
if (!libc.threaded) f->lock = -1;
OFLLOCK();
f->next = libc.ofl_head;
if (libc.ofl_head) libc.ofl_head->prev = f;
libc.ofl_head = f;
OFLUNLOCK();
return f;
}
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