third_party/ulib/musl/src/stdio/open_wmemstream.c

#include "stdio_impl.h"
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <wchar.h>

struct cookie {
    wchar_t** bufp;
    size_t* sizep;
    size_t pos;
    wchar_t* buf;
    size_t len;
    size_t space;
    mbstate_t mbs;
};

static off_t wms_seek(FILE* f, off_t off, int whence) {
    ssize_t base;
    struct cookie* c = f->cookie;
    if (whence > 2U) {
    fail:
        errno = EINVAL;
        return -1;
    }
    base = (size_t[3]){0, c->pos, c->len}[whence];
    if (off < -base || off > SSIZE_MAX / 4 - base)
        goto fail;
    memset(&c->mbs, 0, sizeof c->mbs);
    return c->pos = base + off;
}

static size_t wms_write(FILE* f, const unsigned char* buf, size_t len) {
    struct cookie* c = f->cookie;
    size_t len2;
    wchar_t* newbuf;
    if (len + c->pos >= c->space) {
        len2 = (2 * c->space + 1) | (c->pos + len + 1);
        if (len2 > SSIZE_MAX / 4)
            return 0;
        newbuf = realloc(c->buf, len2 * 4);
        if (!newbuf)
            return 0;
        *c->bufp = c->buf = newbuf;
        memset(c->buf + c->space, 0, 4 * (len2 - c->space));
        c->space = len2;
    }

    len2 = mbsnrtowcs(c->buf + c->pos, (void*)&buf, len, c->space - c->pos, &c->mbs);
    if (len2 == -1)
        return 0;
    c->pos += len2;
    if (c->pos >= c->len)
        c->len = c->pos;
    *c->sizep = c->pos;
    return len;
}

static int wms_close(FILE* f) {
    return 0;
}

FILE* open_wmemstream(wchar_t** bufp, size_t* sizep) {
    FILE* f;
    struct cookie* c;
    wchar_t* buf;

    if (!(f = malloc(sizeof *f + sizeof *c)))
        return 0;
    if (!(buf = malloc(sizeof *buf))) {
        free(f);
        return 0;
    }
    memset(f, 0, sizeof *f + sizeof *c);
    f->cookie = c = (void*)(f + 1);

    c->bufp = bufp;
    c->sizep = sizep;
    c->pos = c->len = c->space = *sizep = 0;
    c->buf = *bufp = buf;
    *buf = 0;

    f->flags = F_NORD;
    f->fd = -1;
    f->buf = (void*)(c + 1);
    f->buf_size = 0;
    f->lbf = EOF;
    f->write = wms_write;
    f->seek = wms_seek;
    f->close = wms_close;

    return __ofl_add(f);
}