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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;
};
struct ms_FILE {
FILE f;
struct cookie c;
unsigned char buf[BUFSIZ];
};
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)
{
struct ms_FILE *f;
char *buf;
if (!(f=malloc(sizeof *f))) return 0;
if (!(buf=malloc(sizeof *buf))) {
free(f);
return 0;
}
memset(&f->f, 0, sizeof f->f);
memset(&f->c, 0, sizeof f->c);
f->f.cookie = &f->c;
f->c.bufp = bufp;
f->c.sizep = sizep;
f->c.pos = f->c.len = f->c.space = *sizep = 0;
f->c.buf = *bufp = buf;
*buf = 0;
f->f.flags = F_NORD;
f->f.fd = -1;
f->f.buf = f->buf;
f->f.buf_size = sizeof f->buf;
f->f.lbf = EOF;
f->f.write = ms_write;
f->f.seek = ms_seek;
f->f.close = ms_close;
if (!libc.threaded) f->f.lock = -1;
return __ofl_add(&f->f);
}
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