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#ifdef __wasilibc_unmodified_upstream // WASI's SEEK_* constants have different values.
33 base = (size_t [3]){0, c->pos, c->len}[whence];
34#else
35 base = (size_t [3]) {
36 [SEEK_SET] = 0,
37 [SEEK_CUR] = c->pos,
38 [SEEK_END] = c->len
39 }[whence];
40#endif
41 if (off < -base || off > SSIZE_MAX-base) goto fail;
42 return c->pos = base+off;
43}
44
45static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
46{
47 struct cookie *c = f->cookie;
48 size_t len2 = f->wpos - f->wbase;
49 char *newbuf;
50 if (len2) {
51 f->wpos = f->wbase;
52 if (ms_write(f, f->wbase, len2) < len2) return 0;
53 }
54 if (len + c->pos >= c->space) {
55 len2 = 2*c->space+1 | c->pos+len+1;
56 newbuf = realloc(c->buf, len2);
57 if (!newbuf) return 0;
58 *c->bufp = c->buf = newbuf;
59 memset(c->buf + c->space, 0, len2 - c->space);
60 c->space = len2;
61 }
62 memcpy(c->buf+c->pos, buf, len);
63 c->pos += len;
64 if (c->pos >= c->len) c->len = c->pos;
65 *c->sizep = c->pos;
66 return len;
67}
68
69static int ms_close(FILE *f)
70{
71 return 0;
72}
73
74FILE *open_memstream(char **bufp, size_t *sizep)
75{
76 struct ms_FILE *f;
77 char *buf;
78
79 if (!(f=malloc(sizeof *f))) return 0;
80 if (!(buf=malloc(sizeof *buf))) {
81 free(f);
82 return 0;
83 }
84 memset(&f->f, 0, sizeof f->f);
85 memset(&f->c, 0, sizeof f->c);
86 f->f.cookie = &f->c;
87
88 f->c.bufp = bufp;
89 f->c.sizep = sizep;
90 f->c.pos = f->c.len = f->c.space = *sizep = 0;
91 f->c.buf = *bufp = buf;
92 *buf = 0;
93
94 f->f.flags = F_NORD;
95 f->f.fd = -1;
96 f->f.buf = f->buf;
97 f->f.buf_size = sizeof f->buf;
98 f->f.lbf = EOF;
99 f->f.write = ms_write;
100 f->f.seek = ms_seek;
101 f->f.close = ms_close;
102 f->f.mode = -1;
103
104#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
105 if (!libc.threaded) f->f.lock = -1;
106#endif
107
108 return __ofl_add(&f->f);
109}