1#include "stdio_impl.h"
2#include <errno.h>
3#include <limits.h>
4#include <string.h>
5
6struct cookie {
7	char **bufp;
8	size_t *sizep;
9	size_t pos;
10	char *buf;
11	size_t len;
12	size_t space;
13};
14
15static off_t ms_seek(FILE *f, off_t off, int whence)
16{
17	ssize_t base;
18	struct cookie *c = f->cookie;
19	if (whence>2U) {
20fail:
21		errno = EINVAL;
22		return -1;
23	}
24	base = (size_t [3]){0, c->pos, c->len}[whence];
25	if (off < -base || off > SSIZE_MAX-base) goto fail;
26	return c->pos = base+off;
27}
28
29static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
30{
31	struct cookie *c = f->cookie;
32	size_t len2 = f->wpos - f->wbase;
33	char *newbuf;
34	if (len2) {
35		f->wpos = f->wbase;
36		if (ms_write(f, f->wbase, len2) < len2) return 0;
37	}
38	if (len + c->pos >= c->space) {
39		len2 = 2*c->space+1 | c->pos+len+1;
40		newbuf = realloc(c->buf, len2);
41		if (!newbuf) return 0;
42		*c->bufp = c->buf = newbuf;
43		memset(c->buf + c->space, 0, len2 - c->space);
44		c->space = len2;
45	}
46	memcpy(c->buf+c->pos, buf, len);
47	c->pos += len;
48	if (c->pos >= c->len) c->len = c->pos;
49	*c->sizep = c->pos;
50	return len;
51}
52
53static int ms_close(FILE *f)
54{
55	return 0;
56}
57
58FILE *open_memstream(char **bufp, size_t *sizep)
59{
60	FILE *f;
61	struct cookie *c;
62	char *buf;
63
64	if (!(f=malloc(sizeof *f + sizeof *c + BUFSIZ))) return 0;
65	if (!(buf=malloc(sizeof *buf))) {
66		free(f);
67		return 0;
68	}
69	memset(f, 0, sizeof *f + sizeof *c);
70	f->cookie = c = (void *)(f+1);
71
72	c->bufp = bufp;
73	c->sizep = sizep;
74	c->pos = c->len = c->space = *sizep = 0;
75	c->buf = *bufp = buf;
76	*buf = 0;
77
78	f->flags = F_NORD;
79	f->fd = -1;
80	f->buf = (void *)(c+1);
81	f->buf_size = BUFSIZ;
82	f->lbf = EOF;
83	f->write = ms_write;
84	f->seek = ms_seek;
85	f->close = ms_close;
86
87	if (!libc.threaded) f->lock = -1;
88
89	return __ofl_add(f);
90}
91