1#include "stdio_impl.h"
2#include <errno.h>
3#include <string.h>
4#include <inttypes.h>
5
6struct cookie {
7	size_t pos, len, size;
8	unsigned char *buf;
9	int mode;
10};
11
12static off_t mseek(FILE *f, off_t off, int whence)
13{
14	ssize_t base;
15	struct cookie *c = f->cookie;
16	if (whence>2U) {
17fail:
18		errno = EINVAL;
19		return -1;
20	}
21	base = (size_t [3]){0, c->pos, c->len}[whence];
22	if (off < -base || off > (ssize_t)c->size-base) goto fail;
23	return c->pos = base+off;
24}
25
26static size_t mread(FILE *f, unsigned char *buf, size_t len)
27{
28	struct cookie *c = f->cookie;
29	size_t rem = c->len - c->pos;
30	if (c->pos > c->len) rem = 0;
31	if (len > rem) {
32		len = rem;
33		f->flags |= F_EOF;
34	}
35	memcpy(buf, c->buf+c->pos, len);
36	c->pos += len;
37	rem -= len;
38	if (rem > f->buf_size) rem = f->buf_size;
39	f->rpos = f->buf;
40	f->rend = f->buf + rem;
41	memcpy(f->rpos, c->buf+c->pos, rem);
42	c->pos += rem;
43	return len;
44}
45
46static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
47{
48	struct cookie *c = f->cookie;
49	size_t rem;
50	size_t len2 = f->wpos - f->wbase;
51	if (len2) {
52		f->wpos = f->wbase;
53		if (mwrite(f, f->wpos, len2) < len2) return 0;
54	}
55	if (c->mode == 'a') c->pos = c->len;
56	rem = c->size - c->pos;
57	if (len > rem) len = rem;
58	memcpy(c->buf+c->pos, buf, len);
59	c->pos += len;
60	if (c->pos > c->len) {
61		c->len = c->pos;
62		if (c->len < c->size) c->buf[c->len] = 0;
63		else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0;
64	}
65	return len;
66}
67
68static int mclose(FILE *m)
69{
70	return 0;
71}
72
73FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
74{
75	FILE *f;
76	struct cookie *c;
77	int plus = !!strchr(mode, '+');
78
79	if (!size || !strchr("rwa", *mode)) {
80		errno = EINVAL;
81		return 0;
82	}
83
84	if (!buf && size > SIZE_MAX-sizeof(FILE)-BUFSIZ-UNGET) {
85		errno = ENOMEM;
86		return 0;
87	}
88
89	f = calloc(sizeof *f + sizeof *c + UNGET + BUFSIZ + (buf?0:size), 1);
90	if (!f) return 0;
91	f->cookie = c = (void *)(f+1);
92	f->fd = -1;
93	f->lbf = EOF;
94	f->buf = (unsigned char *)(c+1) + UNGET;
95	f->buf_size = BUFSIZ;
96	if (!buf) buf = f->buf + BUFSIZ;
97
98	c->buf = buf;
99	c->size = size;
100	c->mode = *mode;
101
102	if (!plus) f->flags = (*mode == 'r') ? F_NOWR : F_NORD;
103	if (*mode == 'r') c->len = size;
104	else if (*mode == 'a') c->len = c->pos = strnlen(buf, size);
105
106	f->read = mread;
107	f->write = mwrite;
108	f->seek = mseek;
109	f->close = mclose;
110
111	if (!libc.threaded) f->lock = -1;
112
113	return __ofl_add(f);
114}
115