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#include "stdio_impl.h"
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <inttypes.h>
#include "libc.h"
struct cookie {
size_t pos, len, size;
unsigned char *buf;
int mode;
};
struct mem_FILE {
FILE f;
struct cookie c;
unsigned char buf[UNGET+BUFSIZ], buf2[];
};
static off_t mseek(FILE *f, off_t off, int whence)
{
ssize_t base;
struct cookie *c = f->cookie;
if (whence>2U) {
fail:
errno = EINVAL;
return -1;
}
#ifdef __wasilibc_unmodified_upstream // WASI's SEEK_* constants have different values.
base = (size_t [3]){0, c->pos, c->len}[whence];
#else
base = (size_t [3]) {
[SEEK_SET] = 0,
[SEEK_CUR] = c->pos,
[SEEK_END] = c->len
}[whence];
#endif
if (off < -base || off > (ssize_t)c->size-base) goto fail;
return c->pos = base+off;
}
static size_t mread(FILE *f, unsigned char *buf, size_t len)
{
struct cookie *c = f->cookie;
size_t rem = c->len - c->pos;
if (c->pos > c->len) rem = 0;
if (len > rem) {
len = rem;
f->flags |= F_EOF;
}
memcpy(buf, c->buf+c->pos, len);
c->pos += len;
rem -= len;
if (rem > f->buf_size) rem = f->buf_size;
f->rpos = f->buf;
f->rend = f->buf + rem;
memcpy(f->rpos, c->buf+c->pos, rem);
c->pos += rem;
return len;
}
static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
{
struct cookie *c = f->cookie;
size_t rem;
size_t len2 = f->wpos - f->wbase;
if (len2) {
f->wpos = f->wbase;
if (mwrite(f, f->wpos, len2) < len2) return 0;
}
if (c->mode == 'a') c->pos = c->len;
rem = c->size - c->pos;
if (len > rem) len = rem;
memcpy(c->buf+c->pos, buf, len);
c->pos += len;
if (c->pos > c->len) {
c->len = c->pos;
if (c->len < c->size) c->buf[c->len] = 0;
else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0;
}
return len;
}
static int mclose(FILE *m)
{
return 0;
}
FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
{
struct mem_FILE *f;
int plus = !!strchr(mode, '+');
if (!strchr("rwa", *mode)) {
errno = EINVAL;
return 0;
}
if (!buf && size > PTRDIFF_MAX) {
errno = ENOMEM;
return 0;
}
f = malloc(sizeof *f + (buf?0:size));
if (!f) return 0;
memset(f, 0, offsetof(struct mem_FILE, buf));
f->f.cookie = &f->c;
f->f.fd = -1;
f->f.lbf = EOF;
f->f.buf = f->buf + UNGET;
f->f.buf_size = sizeof f->buf - UNGET;
if (!buf) {
buf = f->buf2;
memset(buf, 0, size);
}
f->c.buf = buf;
f->c.size = size;
f->c.mode = *mode;
if (!plus) f->f.flags = (*mode == 'r') ? F_NOWR : F_NORD;
if (*mode == 'r') f->c.len = size;
else if (*mode == 'a') f->c.len = f->c.pos = strnlen(buf, size);
else if (plus) *f->c.buf = 0;
f->f.read = mread;
f->f.write = mwrite;
f->f.seek = mseek;
f->f.close = mclose;
#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
if (!libc.threaded) f->f.lock = -1;
#endif
return __ofl_add(&f->f);
}
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