buf_ref.c

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// SPDX-FileCopyrightText: 2009-2020 ret2libc <sirmy15@gmail.com>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_util.h>
 
struct buf_ref_user {
    RzBuffer *parent;
    ut64 offset;
    ut64 size;
};
 
struct buf_ref_priv {
    RzBuffer *parent;
    ut64 cur;
    ut64 base;
    ut64 size;
};
 
static inline struct buf_ref_priv *get_priv_ref(RzBuffer *b) {
    struct buf_ref_priv *priv = (struct buf_ref_priv *)b->priv;
    rz_warn_if_fail(priv);
    return priv;
}
 
static bool buf_ref_init(RzBuffer *b, const void *user) {
    const struct buf_ref_user *u = (const struct buf_ref_user *)user;
    struct buf_ref_priv *priv = RZ_NEW0(struct buf_ref_priv);
    if (!priv) {
        return false;
    }
 
    // NOTE: we only support readonly ref-buffers for now. Supporting
    // read-write would mean to choose how we want to handle writing to the
    // referencer. Copy-on-write? Write to the buffer underneath?
    ut64 parent_sz = rz_buf_size(u->parent);
    b->readonly = true;
    priv->parent = rz_buf_ref(u->parent);
    priv->base = RZ_MIN(u->offset, parent_sz);
    priv->size = RZ_MIN(parent_sz - priv->base, u->size);
    b->priv = priv;
    return true;
}
 
static bool buf_ref_fini(RzBuffer *b) {
    struct buf_ref_priv *priv = get_priv_ref(b);
    rz_buf_free(priv->parent);
    RZ_FREE(b->priv);
    return true;
}
 
static bool buf_ref_resize(RzBuffer *b, ut64 newsize) {
    struct buf_ref_priv *priv = get_priv_ref(b);
    ut64 parent_sz = rz_buf_size(priv->parent);
    priv->size = RZ_MIN(parent_sz - priv->base, newsize);
    return true;
}
 
static st64 buf_ref_read(RzBuffer *b, ut8 *buf, ut64 len) {
    struct buf_ref_priv *priv = get_priv_ref(b);
    if (priv->size < priv->cur) {
        return -1;
    }
    len = RZ_MIN(len, priv->size - priv->cur);
    st64 r = rz_buf_read_at(priv->parent, priv->base + priv->cur, buf, len);
    if (r < 0) {
        return r;
    }
    priv->cur += r;
    return r;
}
 
static ut64 buf_ref_get_size(RzBuffer *b) {
    struct buf_ref_priv *priv = get_priv_ref(b);
    return priv->size;
}
 
static st64 buf_ref_seek(RzBuffer *b, st64 addr, int whence) {
    struct buf_ref_priv *priv = get_priv_ref(b);
    switch (whence) {
    case RZ_BUF_CUR:
        priv->cur += addr;
        break;
    case RZ_BUF_SET:
        priv->cur = addr;
        break;
    case RZ_BUF_END:
        priv->cur = priv->size + addr;
        break;
    default:
        rz_warn_if_reached();
        return -1;
    }
    return priv->cur;
}
 
static const RzBufferMethods buffer_ref_methods = {
    .init = buf_ref_init,
    .fini = buf_ref_fini,
    .read = buf_ref_read,
    .get_size = buf_ref_get_size,
    .resize = buf_ref_resize,
    .seek = buf_ref_seek,
};