1#include "stdio_impl.h"
 2#include <errno.h>
 3#include <limits.h>
 4#include <string.h>
 5#include <stdlib.h>
 6#include "libc.h"
 7
 8struct cookie {
 9	char **bufp;
10	size_t *sizep;
11	size_t pos;
12	char *buf;
13	size_t len;
14	size_t space;
15};
16
17struct ms_FILE {
18	FILE f;
19	struct cookie c;
20	unsigned char buf[BUFSIZ];
21};
22
23static off_t ms_seek(FILE *f, off_t off, int whence)
24{
25	ssize_t base;
26	struct cookie *c = f->cookie;
27	if (whence>2U) {
28fail:
29		errno = EINVAL;
30		return -1;
31	}
32	base = (size_t [3]){0, c->pos, c->len}[whence];
33	if (off < -base || off > SSIZE_MAX-base) goto fail;
34	return c->pos = base+off;
35}
36
37static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
38{
39	struct cookie *c = f->cookie;
40	size_t len2 = f->wpos - f->wbase;
41	char *newbuf;
42	if (len2) {
43		f->wpos = f->wbase;
44		if (ms_write(f, f->wbase, len2) < len2) return 0;
45	}
46	if (len + c->pos >= c->space) {
47		len2 = 2*c->space+1 | c->pos+len+1;
48		newbuf = realloc(c->buf, len2);
49		if (!newbuf) return 0;
50		*c->bufp = c->buf = newbuf;
51		memset(c->buf + c->space, 0, len2 - c->space);
52		c->space = len2;
53	}
54	memcpy(c->buf+c->pos, buf, len);
55	c->pos += len;
56	if (c->pos >= c->len) c->len = c->pos;
57	*c->sizep = c->pos;
58	return len;
59}
60
61static int ms_close(FILE *f)
62{
63	return 0;
64}
65
66FILE *open_memstream(char **bufp, size_t *sizep)
67{
68	struct ms_FILE *f;
69	char *buf;
70
71	if (!(f=malloc(sizeof *f))) return 0;
72	if (!(buf=malloc(sizeof *buf))) {
73		free(f);
74		return 0;
75	}
76	memset(&f->f, 0, sizeof f->f);
77	memset(&f->c, 0, sizeof f->c);
78	f->f.cookie = &f->c;
79
80	f->c.bufp = bufp;
81	f->c.sizep = sizep;
82	f->c.pos = f->c.len = f->c.space = *sizep = 0;
83	f->c.buf = *bufp = buf;
84	*buf = 0;
85
86	f->f.flags = F_NORD;
87	f->f.fd = -1;
88	f->f.buf = f->buf;
89	f->f.buf_size = sizeof f->buf;
90	f->f.lbf = EOF;
91	f->f.write = ms_write;
92	f->f.seek = ms_seek;
93	f->f.close = ms_close;
94	f->f.mode = -1;
95
96	if (!libc.threaded) f->f.lock = -1;
97
98	return __ofl_add(&f->f);
99}