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}